Relevant bibliographies by topics / Plants Effect of photooxidative stress on

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Academic literature on the topic 'Plants Effect of photooxidative stress on'

Author: Grafiati
Published: 11 December 2022
Last updated: 25 January 2023

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Journal articles on the topic "Plants Effect of photooxidative stress on"

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Shibaeva, T. G., E. G. Sherudilo, A. A. Rubaeva, and A. F. Titov. "Effect of end-of production continuous lighting on yield and nutritional value of Brassicaceae microgreens." BIO Web of Conferences 48 (2022): 02005. http://dx.doi.org/10.1051/bioconf/20224802005.

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The effect of continuous lighting applied in the end-of-production period on growth and nutritional quality of radish (Raphanus sativus var. radicula), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa. var. nipposinica) and arugula (Eruca sativa) was investigated in growth chambers under LED lighting. Microgreens were grown under 16 h photoperiod and 3 days before harvest half of plants were placed under continuous lighting conditions. Pre-harvest continuous lighting treatment increased yield, robustness index, and shorten time to harvest in radish, broccoli, mizuna and arugula microgreens. The end-of-production treatment has also led to higher content of compounds with antioxidative properties (flavonoids, proline) and increased the activity of antioxidant enzymes (CAT, APX, GPX) by inducing mild photooxidative stress. Increased antioxidative status added nutritional value to microgreens that can be used as functional foods providing health benefits. Pre-harvest treatment by continuous lighting is suggested as the practice than can allow producers to increase yield, aesthetic appeal, nutritional quality, and market value of Brassicacea microgreens.
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Lascano, H. Ramiro, Mariana N. Melchiorre, Celina M. Luna, and Victorio S. Trippi. "Effect of photooxidative stress induced by paraquat in two wheat cultivars with differential tolerance to water stress." Plant Science 164, no. 5 (May 2003): 841–48. http://dx.doi.org/10.1016/s0168-9452(03)00073-6.

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Quina, Frank H., Paulo F. Moreira, Carolina Vautier-Giongo, Daniel Rettori, Rita F. Rodrigues, Adilson A. Freitas, Palmira F. Silva, and António L. Maçanita. "Photochemistry of anthocyanins and their biological role in plant tissues." Pure and Applied Chemistry 81, no. 9 (August 19, 2009): 1687–94. http://dx.doi.org/10.1351/pac-con-08-09-28.

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Anthocyanins, the major red, purple, and blue pigments of plants, absorb visible as well as UV radiation and are effective antioxidants and scavengers of active oxygen species. In plant leaves, one of the functional roles proposed for anthocyanins is protection of the photosynthetic apparatus from the effects of excess incident visible or UV-B radiation and photooxidative stress. In essence, a photoprotective role requires that the excited singlet states of both complexed and uncomplexed anthocyanins deactivate back to the ground state so quickly that intersystem crossing, photoreaction, and diffusion-controlled quenching processes cannot compete. Studies of the photochemical properties of synthetic analogs of anthocyanins and of several naturally occurring anthocyanins show that this is indeed the case, uncomplexed anthocyanins decaying back to the ground state via fast (subnanosecond) excited-state proton transfer (ESPT) and anthocyanin-copigment complexes by fast (subpicosecond) charge-transfer-mediated internal conversion.
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Romanowska, Elzbieta, Marta Powikrowska, Maksymilian Zienkiewicz, Anna Drozak, and Berenika Pokorska. "High light induced accumulation of two isoforms of the CF1 alpha-subunit in mesophyll and bundle sheath chloroplasts of C4 plants." Acta Biochimica Polonica 55, no. 1 (March 7, 2008): 175–82. http://dx.doi.org/10.18388/abp.2008_3110.

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The effect of light irradiance on the amount of ATP synthase alpha-subunit in mesophyll (M) and bundle sheath (BS) chloroplasts of C(4) species such as maize (Zea mays L., type NADP-ME), millet (Panicum miliaceum, type NAD-ME) and guinea grass (Panicum maximum, type PEP-CK) was investigated in plants grown under high, moderate and low light intensities equal to 800, 350 and 50 micromol photons m(-2) s(-1), respectively. The results demonstrate that alpha-subunit of ATP synthase in both M and BS chloroplasts is altered by light intensity, but differently in the investigated species. Moreover, we identified two isoforms of the CF(1) alpha-subunit, called alpha and alpha. The CF(1) alpha-subunit was the major isoform and was present in all light conditions, whereas alpha was the minor isoform in low light. A strong increase in the level of the alpha-subunit in maize mesophyll and bundle sheath thylakoids was observed after 50 h of high light treatment. The alpha and alpha-subunits from investigated C(4) species displayed apparent molecular masses of 64 and 67 kDa, respectively, on SDS/PAGE. The presence of the alpha-subunit of ATPase was confirmed in isolated CF(1) complex, where it was recognized by antisera to the alpha-subunit. The N-terminal sequence of alpha-subunit is nearly identical to that of alpha. Our results indicate that both isoforms coexist in M and BS chloroplasts during plant growth at all irradiances. We suggest the existence in M and BS chloroplasts of C(4) plants of a mechanism(s) regulating the ATPase composition in response to light irradiance. Accumulation of the alpha isoform may have a protective role under high light stress against over protonation of the thylakoid lumen and photooxidative damage of PSII.
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Foyer, Christine H., Maud Lelandais, and Karl J. Kunert. "Photooxidative stress in plants." Physiologia Plantarum 92, no. 4 (December 1994): 696–717. http://dx.doi.org/10.1111/j.1399-3054.1994.tb03042.x.

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Foyer, Christine H., Maud Lelandais, and Karl J. Kunert. "Photooxidative stress in plants." Physiologia Plantarum 92, no. 4 (December 1994): 696–717. http://dx.doi.org/10.1034/j.1399-3054.1994.920422.x.

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Staudt, Michael, Juliane Daussy, Joseph Ingabire, and Nafissa Dehimeche. "Growth and actual leaf temperature modulate CO2 responsiveness of monoterpene emissions from holm oak in opposite ways." Biogeosciences 19, no. 20 (October 26, 2022): 4945–63. http://dx.doi.org/10.5194/bg-19-4945-2022.

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Abstract. Climate change can profoundly alter volatile organic compound (VOC) emissions from vegetation and thus influence climate evolution. Yet, the short- and long-term effects of elevated CO2 concentrations on emissions in interaction with temperature are not well enough understood, especially for VOCs other than isoprene. To gain additional insight, we conducted a study on holm oak, which is known for its strong foliar monoterpene emissions that are directly linked to their synthesis. We measured CO2-response curves of emissions, CO2–H2O gas exchanges and chlorophyll fluorescence at two assay temperatures (30 and 35 ∘C) on saplings of four populations grown under normal and double CO2 concentrations combined with two temperature growth regimes differing by 5 ∘C (day/night: 25/15 and 30/20 ∘C). A stepwise reduction in CO2 resulted in a decrease in emissions, occasionally preceded by an increase, with the overall decrease in emissions being greater at 35 ∘C than at 30 ∘C assay temperature. During ramping to high CO2, emissions remained mostly unchanged at 35 ∘C, whereas at 30 ∘C they often dropped, especially at the highest CO2 levels (≥ 1200 ppm). In addition to the actual leaf temperature, the high CO2 responsiveness of emissions was modulated by the plant's growth temperature with warm-grown plants being more sensitive than cool-grown plants. In contrast, growth CO2 had no significant effect on the CO2 sensitivity of emissions, although it promoted plant growth and the leaf emission factor. Correlation analyses suggest that the emission response to CO2 depended primarily on the availability of energetic cofactors produced by photosynthetic electron transport. This availability was likely limited by different processes that occurred during CO2 ramping including photooxidative stress and induction of protective and repair mechanisms as well as competition with CO2 fixation and photorespiration. In addition, feedback inhibition of photosynthesis may have played a role, especially in leaves whose emissions were inhibited only at very high CO2 levels. Overall, our results confirm an isoprene-analogous behavior of monoterpene emissions from holm oak. Emissions exhibit a non-linear response curve to CO2 similar to that currently used for isoprene emission in the MEGAN model, with no difference between major individual monoterpene species and plant chemotype. Simulations estimating the annual VOC releases from holm oak leaves at double atmospheric CO2 indicate that the observed high-CO2 inhibition is unlikely to offset the increase in emissions due to the predicted warming.
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Camejo, Daymi, Ana Jiménez, Juan José Alarcón, Walfredo Torres, Juana María Gómez, and Francisca Sevilla. "Changes in photosynthetic parameters and antioxidant activities following heat-shock treatment in tomato plants." Functional Plant Biology 33, no. 2 (2006): 177. http://dx.doi.org/10.1071/fp05067.

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Seedlings of two tomato genotypes, Lycopersicon esculentum Mill. var. Amalia and the wild thermotolerant type Nagcarlang, were grown under a photoperiod of 16 h light at 25°C and 8 h dark at 20°C. At the fourth true leaf stage, a group of plants were exposed to a heat-shock temperature of 45°C for 3 h, and measurements of chlorophyll fluorescence, gas-exchange characteristics, dark respiration and oxidative and antioxidative parameters were made after releasing the stress. The heat shock induced severe alterations in the photosynthesis of Amalia that seem to mitigate the damaging impact of high temperatures by lowering the leaf temperature and maintaining stomatal conductance and more efficient maintenance of antioxidant capacity, including ascorbate and glutathione levels. These effects were not evident in Nagcarlang. In Amalia plants, a larger increase in dark respiration also occurred in response to heat shock and the rates of the oxidative processes were higher than in Nagcarlang. This suggests that heat injury in Amalia may involve chlorophyll photooxidation mediated by activated oxygen species (AOS) and more severe alterations in the photosynthetic apparatus. All these changes could be related to the more dramatic effect of heat shock seen in Amalia than in Nagcarlang plants.
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Junker-Frohn, Laura Verena, Anita Kleiber, Kirstin Jansen, Arthur Gessler, Jürgen Kreuzwieser, and Ingo Ensminger. "Differences in isoprenoid-mediated energy dissipation pathways between coastal and interior Douglas-fir seedlings in response to drought." Tree Physiology 39, no. 10 (October 1, 2019): 1750–66. http://dx.doi.org/10.1093/treephys/tpz075.

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ABSTRACT Plants have evolved energy dissipation pathways to reduce photooxidative damage under drought when photosynthesis is hampered. Non-volatile and volatile isoprenoids are involved in non-photochemical quenching of excess light energy and scavenging of reactive oxygen species. A better understanding of trees’ ability to cope with and withstand drought stress will contribute to mitigate the negative effects of prolonged drought periods expected under future climate conditions. Therefore we investigated if Douglas-fir (Pseudotsuga menziesii(Mirb.)) provenances from habitats with contrasting water availability reveal intraspecific variation in isoprenoid-mediated energy dissipation pathways. In a controlled drought experiment with 1-year-old seedlings of an interior and a coastal Douglas-fir provenance, we assessed the photosynthetic capacity, pool sizes of non-volatile isoprenoids associated with the photosynthetic apparatus, as well as pool sizes and emission of volatile isoprenoids. We observed variation in the amount and composition of non-volatile and volatile isoprenoids among provenances, which could be linked to variation in photosynthetic capacity under drought. The coastal provenance exhibited an enhanced biosynthesis and emission of volatile isoprenoids, which is likely sustained by generally higher assimilation rates under drought. In contrast, the interior provenance showed an enhanced photoprotection of the photosynthetic apparatus by generally higher amounts of non-volatile isoprenoids and increased amounts of xanthophyll cycle pigments under drought. Our results demonstrate that there is intraspecific variation in isoprenoid-mediated energy dissipation pathways among Douglas-fir provenances, which may be important traits when selecting provenances suitable to grow under future climate conditions.
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Ramel, Fanny, Alexis S. Mialoundama, and Michel Havaux. "Nonenzymic carotenoid oxidation and photooxidative stress signalling in plants." Journal of Experimental Botany 64, no. 3 (August 21, 2012): 799–805. http://dx.doi.org/10.1093/jxb/ers223.

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Dissertations / Theses on the topic "Plants Effect of photooxidative stress on"

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Shumbe, Leonard Tansie. "Singlet Oxygen Signaling and Acclimation of Plants to Environmental Constraints." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4109.

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En conditions de stress biotiques et abiotiques la production de plusieurs espèces réactives de l’oxygène (ERO) dans différents compartiments spécialisés de la cellule végétale est inévitable. L’oxygène singulet (1O2) a été identifié comme la principale ERO produite dans le chloroplaste au cours d’un stress lumineux. Cette ERO est très réactive et a une durée de vie courte d’environ 3 s dans les tissus biologiques, ce qui amène à penser que l’oxygène singulet agit principalement par cytotoxicité. Cependant, il a été récemment établi que l’oxygène singulet fonctionne aussi comme une molécule signal impliquée dans la signalisation rétrograde chloroplaste-noyau conduisant soit à la mort cellulaire programmée, soit à l’acclimatation. En raison des propriétés particulières de l’oxygène singulet, il est peu probable que cette ERO voyage en dehors du chloroplaste pour induire des changements d’expression de gènes nucléaires. Une possibilité est que l’oxygène singulet agisse via des médiateurs. Nous avons identifié un produit d’oxydation du β-carotène, le dihydroactinidiolide (dhA), comme intermédiaire dans la voie de signalisation de l’oxygène singulet, qui agit d’une manière similaire à un autre produit d’oxydation du β-carotène, le β-cyclocitral, précédemment identifié comme intermédiaire dans la voie de signalisation de l’oxygène singulet. Nous avons aussi mis en évidence le rôle dans la voie de signalisation régulée par le β-cyclocitral de la protéine MBS1 (METHYLENE BLUE SENSITIVITY 1), et montré que la mort cellulaire programmée induite par l’oxygène singulet chez l’Arabidopsis est controllée par une serine-threonine kinase, OXI1 (OXIDATIVE SIGNAL INDUCIBLE 1)
During biotic and abiotic stress conditions, the production of several reactive oxygen species (ROS) at different specialized compartments of the cell is inevitable. Singlet oxygen (1O2) was identified to be the predominant ROS produced in the chloroplast during high light stress. This molecule is highly reactive, with a short life time of about 3 µs in biological tissues. Such properties make believe that the predominant effect of 1O2 in plants is cytotoxicity. However, 1O2 has been identified to function as a chloroplast-to-nucleus retrograde signaling molecule, leading to acclimation or programmed cell death (PCD). Cognizant of the properties of 1O2, it is most unlikely to travel directly from the chloroplast to the nucleus to signal changes in nuclear gene expression. One possibility is that 1O2 carries out this signaling function with the help of mediators. We identify a β-carotene oxidation product, dihydroactinidiolide (dhA) as a 1O2 signaling intermediate, which function similarly to the β-carotene oxidation product β-cyclocitral, previously identified to be a mediator of 1O2 plastid-nuclear retrograde signaling in Arabidopsis. We reveal a dependence of the β-cyclocitral-mediated signaling pathway on the MBS1 (METHYLENE BLUE SENSITIVITY 1) protein, and show that Programmed cell death induced by 1O2 is mediated by the serine-threonine kinase, OXI1(OXIDATIVE SIGNAL INDUCIBLE 1)
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Mateo, Alfonso. "Roles of LESIONS SIMULATING DISEASE1 and Salicylic Acid in Acclimation of Plants to Environmental Cues : Redox Homeostasis and physiological processes underlying plants responses to biotic and abiotic challenges." Doctoral thesis, Stockholm University, Department of Botany, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-698.

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In the natural environment plants are confronted to a multitude of biotic and abiotic stress factors that must be perceived, transduced, integrated and signaled in order to achieve a successful acclimation that will secure survival and reproduction. Plants have to deal with excess excitation energy (EEE) when the amount of absorbed light energy is exceeding that needed for photosynthetic CO2 assimilation. EEE results in ROS formation and can be enhanced in low light intensities by changes in other environmental factors.

The lesions simulating disease resistance (lsd1) mutant of Arabidopsis spontaneously initiates spreading lesions paralleled by ROS production in long day photoperiod and after application of salicylic acid (SA) and SA-analogues that trigger systemic acquired resistance (SAR). Moreover, the mutant fails to limit the boundaries of hypersensitive cell death (HR) after avirulent pathogen infection giving rise to the runaway cell death (rcd) phenotype. This ROS-dependent phenotype pointed towards a putative involvement of the ROS produced during photosynthesis in the initiation and spreading of the lesions.

We report here that the rcd has a ROS-concentration dependent phenotype and that the light-triggered rcd is depending on the redox-state of the PQ pool in the chloroplast. Moreover, the lower stomatal conductance and catalase activity in the mutant suggested LSD1 was required for optimal gas exchange and ROS scavenging during EEE. Through this regulation, LSD1 can influence the effectiveness of photorespiration in dissipating EEE. Moreover, low and high SA levels are strictly correlated to lower and higher foliar H2O2 content, respectively. This implies an essential role of SA in regulating the redox homeostasis of the cell and suggests that SA could trigger rcd in lsd1 by inducing H2O2 production.

LSD1 has been postulated to be a negative regulator of cell death acting as a ROS rheostat. Above a certain threshold, the pro-death pathway would operate leading to PCD. Our data suggest that LSD1 may be subjected to a turnover, enhanced in an oxidizing milieu and slowed down in a reducing environment that could reflect this ROS rheostat property. Finally, the two protein disulphide isomerase boxes (CGHC) present in the protein and the down regulation of the NADPH thioredoxin reductase (NTR) in the mutant connect the rcd to a putative impairment in the reduction of the cytosolic thioredoxin system. We propose that LSD1 suppresses the cell death processes through its control of the oxidation-reduction state of the TRX pool. An integrated model considers the role of LSD1 in both light acclimatory processes and in restricting pathogen-induced cell death.

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Eakes, Donald Joseph. "Moisture stress conditioning, potassium nutrition, and tolerance of Salvia splendens 'Bonfire' to moisture stress." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54350.

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The objective of this study was to determine the leaf water relations, gas exchange, and growth of the bedding plant salvia Salvia splendens 'Bonfire‘ as influenced by moisture stress conditioning (MSC - exposing plants to 4 sublethal dry-down cycles) and potassium (K) nutrition. Plants were fertilized with one of six K rates: 25, 75, 150, 300, 450, and 600 ppm as KCl in experiment one. Seven weeks after seeding plants were subjected to MSC. MSC and increasing K rate resulted in osmotic adjustment and increased cellular turgor potentials. Foliar K content increased as osmotic potentials decreased due to treatment. Although there was no interaction, MSC and high K rates both reduced transpiration (E), leaf conductance (g₁), and daily gravimetric water loss during well watered conditions. Greatest shoot dry weight occurred for plants grown with 300 ppm K and no-MSC. Gas exchange of salvia as influenced by MSC during the onset of moisture stress was determined in experiment two. On day one following final irrigation, MSC plants had lower mid-day E, g₁, hourly gravimetric water loss per unit leaf area, and net photosynthesis (Pn) compared to controls, despite no differences in leaf water potential (ψ₁). Percentage of stomatal inhibition of Pn (SI) was greater for MSC plants than controls with no differences in mesophyllic resistance to CO₂ (rm). On day two, MSC plants had greater Pn, E, g₁, and hourly gravimetric water loss per unit leaf area, while SI and rm were lower than controls. MSC plants maintained positive Pn rates and turgor to lower ψ₁ than control plants. Water use efficiency (WUE) estimates for MSC plants were greater than for controls. Salvia plants were fertilized with 75, 300, or 600 ppm K to determine the influence of K rate on gas exchange during the onset of moisture stress in a third experiment. On day one following final irrigation, plants grown with K rates of 300 and 600 ppm had lower E, g₁, hourly gravimetric water loss per unit leaf area, and Pn compared to 75 ppm K plants. On day two, 600 ppm K plants had greater Pn, E, and g₁ as the experiment was terminated compared to plants grown with 75 ppm K, although ψ₁ was similar. Potassium rate had little affect on WUE.
Ph. D.
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Choudhury, Feroza Kaneez. "Rapid Metabolic Response of Plants Exposed to Light Stress." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157543/.

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Environmental stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. So, in our study we have taken an metabolomics approach to identify the rapid response of plants to light stress. In the first part we have focused on the ultrafast (0-90 sec) metabolic response of local tissues to light stress and in the second part we analyzed the metabolic response associated with rapid systemic signaling (0-12 min). Analysis of the rapid response of Arabidopsis to light stress has revealed 111 metabolites that significantly alter in their level during the first 90 sec of light stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during light stress in Arabidopsis and that the accumulation of total glutathione during light stress is dependent on an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could be used to augment the rapid response of plants to abiotic stress. In addition, it highlights the important role of glutathione in initial stage of light stress response. Light-induced rapid systemic signaling and systemic acquired acclimation (SAA) are thought to play an important role in the response of plants to different abiotic stresses. Although molecular and metabolic responses to light stress have been extensively studied in local leaves, and to a lesser degree in systemic leaves, very little is known about the metabolic responses that occur in the different tissues that connect the local to the systemic leaves. These could be important in defining the specificity of the systemic response as well as in supporting the propagation of different systemic signals, such as the reactive oxygen species (ROS) wave. Here we report that local application of light stress to one rosette leaf resulted in a metabolic response that encompassed local, systemic and transport tissues (tissues that connect the local and systemic tissues), demonstrating a high degree of physical and metabolic continuity between different tissues throughout the plant. We further show that the response of many of the systemically altered metabolites could be associated with the function of the ROS wave, and that the level of eight different metabolites is altered in a similar way in all tissues tested (local, systemic, and transport tissues). These compounds could define a core metabolic signature for light stress that propagates from the local to the systemic leaves. Taken together, our findings suggest that metabolic changes occurring in cells that connect the local and systemic tissues could play an important role in mediating rapid systemic signaling and systemic acquired acclimation to light stress.
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Kalifa, Ali. "Salt stress, and phosphorus absorption by potato plants cv. 'Russet Burbank'." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29727.pdf.

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Attumi, Al-Arbe. "Effect of salt stress on phosphorus and sodium absorptions by soybean plants." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20242.

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The radiotracer methodology was combined with the Hoagland solution culture of growing soybean in a greenhouse to investigate the absorptions of phosphorus (P), calcium (Ca), and sodium (Na) as a function of salinity. Salt stress was varied by using zero to 120 mM NaCl. The research was initiated because of a need to increase soybean production in the saline soils of the semi-arid regions of the world. Although P absorption increased with time at each concentration of NaCl, increasing its concentrations ([NaCl]) to 120 mM reduced P uptake considerably. The addition of inorganic P (Pi) to the salt medium improved P absorption significantly (P < 0.0001) in stem, petiole, and roots. Polynomial regressions showed the relationship between 22Na activity and [NaCl] for leaves and petiole to be cubic (R2 = 1) while in the stem a quadratic relationship prevailed. A maximum of P and Na absorption was observed at 40 mM NaCl. The relationship between 32P activity and increasing [NaCl] was linear for the roots (a positive slope) and the stem (a negative slope). 45Ca and 32P dual labelling part of the experiments failed to produce results because an unexpectedly high degree of tissue quenching which prevented from obtaining the minimum counting requirements for separation. Shoot fresh and dry weights decreased linearly with increasing [NaCl] as did the root fresh and dry weights. Leaf chlorophyll content during the last week of the final harvest showed a linear relationship with time. Chlorophyll increased with time linearly when the growth medium contained zero and 40 mM NaCl; whereas a negative slope was obtained for 80 and 120 mM NaCl. It seems that P fertilization of the soil could ameliorate the salt effect. 22 Na uptake results indicated that there is a mechanism for exclusion of Na from soybean plant parts.
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Larsson, Marie-France. "The Effect of Plants on Individuals' Stress Level in an Indoor Work Environment." Thesis, Mid Sweden University, Department of Social Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-11141.

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Many instances of sick leave can be linked to diseases caused by stress. An efficient way to counter the negative effects of stress is coping. However, trying to fit coping activities into an already busy schedule can be stressful in itself. Therefore it is interesting to study passive stress-reducing methods, for instance interaction with nature. This paper studied the effect of the presence of plants in a work-like environment on the stress level of 30 participants divided equally in a control group and a test group by measuring their heart rate. A factorial analysis of variance and a multivariate analysis of variance were used to analyze the data. Despite the heart rate of the control group being on an average 5 beats per minute higher than the test group, the difference was found not to be statistically significant. An explanation for this could be the poor reliability of heart rate as a measure of stress.

Keywords: coping, heart rate, indoors, nature, plants, stress, work

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Wongareonwanakij, Sathaporn. "Effects of water stress and partial soil-drying on senescence of sunflower plants." Title page, contents and summary only, 1995. http://web4.library.adelaide.edu.au/theses/09A/09aw872.pdf.

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Bibliography: leaves 98-123. This thesis investigates the symptoms of leaf senescence in response to plant shoot water stress and demonstrates the effect of a non-hydraulic root signal in the senescence response of mature leaves of sunflower. The alleviation of the leaf soluble protein loss rate by excision of the root system in drying soil indicates that this signal originates in roots in dry soil and acts to promote protein loss.
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Zhou, Maoqian 1961. "Nitrogen fixation by alfalfa as affected by salt stress and nitrogen levels." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277231.

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The growth and Nitrogen fixation by one low salt tolerant alfalfa (Medicago sativa L.) and two germination salt tolerant selections inoculated with were investigated at two salt levels (0, -0.6 Mpa) and two N rates (1, 5ppm) using a system which automatically recirculates a nutrient solution. The high level of salinity (-0.6 Mpa osmotic potential of culture solution) resulted in substantial reduction in the N fixation percentage and total fixed N. The effect of salinity was more pronounced for later cuttings than for the earlier cutting. The N fixation percentages were substantially decreased by increasing N level and the reduction was enhanced by time. The N treatment levels did not exhibit a significant effect on total fixed N. Cultivars did not differ in either growth or N fixation. However, the interaction of N and salinity significantly decreased the percentage and amount of N fixation.
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Le, Fevre Ruth Elizabeth. "Phytate and plant stress responses." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708218.

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Books on the topic "Plants Effect of photooxidative stress on"

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M, Orcutt David, and Hale Maynard G, eds. The physiology of plants under stress. New York: Wiley, 1996.

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Kadukova, Jana. Phytoremediation and stress: Evaluation of heavy metal-induced stress in plants. Hauppauge, N.Y: Nova Science Publishers, 2010.

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S, Basra Amarjit, ed. Stress-induced gene expression in plants. Chur, Switzerland: Harwood Academic Publishers, 1994.

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A, Khan Nafees, and Singh Sarvajeet, eds. Abiotic stress and plant responses. New Delhi: I.K. International Pub. House, 2008.

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Josipovic, Stanislas. Heat stress: Causes, treatment and prevention. Hauppauge, N.Y: Nova Science Publishers, 2012.

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Lutz, Nover, Neumann Dieter, and Scharf Klaus-Dieter, eds. Heat shock and other stress response systems of plants. Berlin: Springer-Verlag, 1989.

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Handbook of plant and crop stress. 3rd ed. Boca Raton: CRC Press, 2011.

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Leonard, R. E. The response of plant species to low-level trampling stress on Hurricane Island, Maine. [Broomall, Pa.]: U.S. Dept. of Agriculture, Forest Service, Northeastern Forest Experiment Station, 1985.

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Leonard, R. E. The response of plant species to low-level trampling stress on Hurricane Island, Maine. [Broomall, Pa.]: U.S. Dept. of Agriculture, Forest Service, Northeastern Forest Experiment Station, 1985.

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S, Basra Amarjit, and Basra Ranjit K, eds. Mechanisms of environmental stress resistance in plants. Amsterdam, The Netherlands: Harwood Academic, 1997.

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Book chapters on the topic "Plants Effect of photooxidative stress on"

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Carmody, Melanie, and Barry Pogson. "Systemic Photooxidative Stress Signalling." In Long-Distance Systemic Signaling and Communication in Plants, 251–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-36470-9_13.

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Karpinski, Stanislaw, Gunnar Wingsle, Barbara Karpinska, and Jan-Erik Hällgren. "Redox Sensing of Photooxidative Stress and Acclimatory Mechanisms in Plants." In Regulation of Photosynthesis, 469–86. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/0-306-48148-0_27.

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Kaur, Harpreet, Renu Bhardwaj, Vinod Kumar, Anket Sharma, Ravinder Singh, and Ashwani Kumar Thukral. "Effect of pesticides on leguminous plants." In Legumes under Environmental Stress, 91–101. Chichester, UK: John Wiley & Sons, Ltd, 2015. http://dx.doi.org/10.1002/9781118917091.ch6.

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Ivanov, Anatoly A. "Response of Wheat Seedlings to Combined Effect of Drought and Salinity." In Stress Responses in Plants, 159–98. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13368-3_7.

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Pérez-Pastor, Alejandro, M. Carmen Ruiz-Sánchez, and María R. Conesa. "Drought stress effect on woody tree yield." In Water Stress and Crop Plants, 356–74. Chichester, UK: John Wiley & Sons, Ltd, 2016. http://dx.doi.org/10.1002/9781119054450.ch22.

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Khalid, Muhammad Fasih, Iqra Zakir, Rashid Iqbal Khan, Sobia Irum, Samreen Sabir, Nishat Zafar, Shakeel Ahmad, Mazhar Abbas, Talaat Ahmed, and Sajjad Hussain. "Effect of Water Stress (Drought and Waterlogging) on Medicinal Plants." In Medicinal Plants, 169–82. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-5611-9_6.

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Srivastava, Kavita, Sachidanand Singh, Anupam Singh, Tanvi Jain, Rahul Datta, and Abhidha Kohli. "Effect of Temperature (Cold and Hot) Stress on Medicinal Plants." In Medicinal Plants, 153–68. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-5611-9_5.

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Hajiboland, R. "Effect of Micronutrient Deficiencies on Plants Stress Responses." In Abiotic Stress Responses in Plants, 283–329. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0634-1_16.

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Koshita, Yoshiko. "Effect of Temperature on Fruit Color Development." In Abiotic Stress Biology in Horticultural Plants, 47–58. Tokyo: Springer Japan, 2014. http://dx.doi.org/10.1007/978-4-431-55251-2_4.

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Tripathi, Durgesh Kumar, Swati Singh, Shweta Singh, Devendra Kumar Chauhan, Nawal Kishore Dubey, and Rajendra Prasad. "Silicon as a beneficial element to combat the adverse effect of drought in agricultural crops." In Water Stress and Crop Plants, 682–94. Chichester, UK: John Wiley & Sons, Ltd, 2016. http://dx.doi.org/10.1002/9781119054450.ch39.

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Conference papers on the topic "Plants Effect of photooxidative stress on"

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"Effect of melatonin deficiency and disruption of its receptor signaling pathway on photosynthetic parameters and expression of chloroplast genes in plants of Arabidopsis thaliana under photooxidative stress." In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Novosibirsk ICG SB RAS 2021, 2021. http://dx.doi.org/10.18699/plantgen2021-030.

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Baranova, E. N. "The effect of edaphic stress factors on plant cell compartments." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-57.

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Popescu, Monica. "ASCOPHYLLUM NODOSUM SEAWEED EXTRACT EFFECT ON DROUGHT STRESS IN BEAN PLANTS." In 17th International Multidisciplinary Scientific GeoConference SGEM2017. Stef92 Technology, 2017. http://dx.doi.org/10.5593/sgem2017h/63/s25.017.

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Arkhipova, T. N., and E. V. Martynenko. "The effect of hormone producing bacteria on plant growth and stress tolerance." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-48.

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Zeng, Lizhang, and Da Xing. "Alteration in delayed fluorescence characterize the effect of heat stress on plants." In Photonics Asia 2004, edited by Yun-Jiang Rao, Osuk Y. Kwon, and Gang-Ding Peng. SPIE, 2005. http://dx.doi.org/10.1117/12.572779.

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Kreslavsky, V. D., A. Yu Khudyakova, and V. Yu Lyubimov. "The effect of the phytochrome system on the stress resistance of the photosynthetic apparatus." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-237.

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Ponomareva, M. L., and S. N. Ponomarev. "Features of adaptation to winter stress and the effect of proline accumulation in winter cereals." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-362.

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Evseeva, N. V., A. Yu Denisova, G. L. Burygin, N. N. Pozdnyakova, and O. V. Tkachenko. "Coinoculation effect of potato microclones by rhizosphere bacteria under osmotic stress in vitro." In 2nd International Scientific Conference "Plants and Microbes: the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.067.

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Al-qahtani, Noora Saad, and Talaat Ahmed. "Effect of Seagrass Liquid Extracts on Bell Pepper (Capsicum annuum) Under Salt stress Conditions." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0104.

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Salinity is considered as major environmental challenge that affects crop growth and productivity. This study investigated the application of Haodule univervis seagrass liquid extract on bell pepper (Capsicum annuum L.) under salt stress conditions. The salinity treatments were applied by irrigating bell pepper plants with 0, 50, 100, 150, and 200 mM/l of NaCl with four replications. The bell pepper plants were divided into two groups: one group was sprayed with seagrass extract, and the other group was sprayed with distilled water. The salt treatment was applied at every 10 days interval for only three treatments, and the bell pepper leaves were sprayed about seven days after the salt treatment. The results showed an increase in relative water content (RWC) of salt stressed bell pepper plants sprayed with seagrass extract from 0- 100 mM of NaCl treatment, while RWC decreased at 150 and 200 mM NaCl treatments compared to the control. This indicates stressed bell pepper plants sprayed with seagrass extract had higher RWC than plants sprayed with water at 0-100 mM NaCl treatments. Chlorophyll concentration was decreased dramatically in plants sprayed with water at 50mM of NaCl level. However, chlorophyll concentration increased slightly in plants sprayed with water at 100 mM NaCl level then start declined gradually at 150 mM and 200mM NaCl level. The plants sprayed with seagrass extract showed an increase in chlorophyll concentration at 100 and 150 mM NaCl treatment compared to the control. Fresh weights of plants sprayed with seagrass extract were declined at 50-150 mM NaCl compared to the control. However, the highest dry weights of plants sprayed with seagrass at 100 mM NaCl treatment. In addition, plants sprayed with water did not show variations in fresh and dry weights.
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Ozolina, N. V., V. V. Gurina, and I. S. Nesterkina. "The effect of different types of abiotic stress on the dynamics of the content of common sterols of beet tonoplast (Beta vulgaris L.)." In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-324.

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Reports on the topic "Plants Effect of photooxidative stress on"

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Kirova, Elisaveta. Effect of Nitrogen Nutrition Source on Antioxidant Defense System of Soybean Plants Subjected to Salt Stress. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, February 2020. http://dx.doi.org/10.7546/crabs.2020.02.09.

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Alchanatis, Victor, Stephen W. Searcy, Moshe Meron, W. Lee, G. Y. Li, and A. Ben Porath. Prediction of Nitrogen Stress Using Reflectance Techniques. United States Department of Agriculture, November 2001. http://dx.doi.org/10.32747/2001.7580664.bard.

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Commercial agriculture has come under increasing pressure to reduce nitrogen fertilizer inputs in order to minimize potential nonpoint source pollution of ground and surface waters. This has resulted in increased interest in site specific fertilizer management. One way to solve pollution problems would be to determine crop nutrient needs in real time, using remote detection, and regulating fertilizer dispensed by an applicator. By detecting actual plant needs, only the additional nitrogen necessary to optimize production would be supplied. This research aimed to develop techniques for real time assessment of nitrogen status of corn using a mobile sensor with the potential to regulate nitrogen application based on data from that sensor. Specifically, the research first attempted to determine the system parameters necessary to optimize reflectance spectra of corn plants as a function of growth stage, chlorophyll and nitrogen status. In addition to that, an adaptable, multispectral sensor and the signal processing algorithm to provide real time, in-field assessment of corn nitrogen status was developed. Spectral characteristics of corn leaves reflectance were investigated in order to estimate the nitrogen status of the plants, using a commercial laboratory spectrometer. Statistical models relating leaf N and reflectance spectra were developed for both greenhouse and field plots. A basis was established for assessing nitrogen status using spectral reflectance from plant canopies. The combined effect of variety and N treatment was studied by measuring the reflectance of three varieties of different leaf characteristic color and five different N treatments. The variety effect on the reflectance at 552 nm was not significant (a = 0.01), while canonical discriminant analysis showed promising results for distinguishing different variety and N treatment, using spectral reflectance. Ambient illumination was found inappropriate for reliable, one-beam spectral reflectance measurement of the plants canopy due to the strong spectral lines of sunlight. Therefore, artificial light was consequently used. For in-field N status measurement, a dark chamber was constructed, to include the sensor, along with artificial illumination. Two different approaches were tested (i) use of spatially scattered artificial light, and (ii) use of collimated artificial light beam. It was found that the collimated beam along with a proper design of the sensor-beam geometry yielded the best results in terms of reducing the noise due to variable background, and maintaining the same distance from the sensor to the sample point of the canopy. A multispectral sensor assembly, based on a linear variable filter was designed, constructed and tested. The sensor assembly combined two sensors to cover the range of 400 to 1100 nm, a mounting frame, and a field data acquisition system. Using the mobile dark chamber and the developed sensor, as well as an off-the-shelf sensor, in- field nitrogen status of the plants canopy was measured. Statistical analysis of the acquired in-field data showed that the nitrogen status of the com leaves can be predicted with a SEP (Standard Error of Prediction) of 0.27%. The stage of maturity of the crop affected the relationship between the reflectance spectrum and the nitrogen status of the leaves. Specifically, the best prediction results were obtained when a separate model was used for each maturity stage. In-field assessment of the nitrogen status of corn leaves was successfully carried out by non contact measurement of the reflectance spectrum. This technology is now mature to be incorporated in field implements for on-line control of fertilizer application.
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Mosquna, Assaf, and Sean Cutler. Systematic analyses of the roles of Solanum Lycopersicum ABA receptors in environmental stress and development. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604266.bard.

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Drought and other abiotic stresses have major negative effects on agricultural productivity. The plant hormone abscisic acid (ABA) regulates many responses to environmental stresses and can be used to improve crop performance under stress. ABA levels rise in response to diverse abiotic stresses to coordinate physiological and metabolic responses that help plants survive stressful environments. In all land plants, ABA receptors are responsible for initiating a signaling cascade that leads to stomata closure, growth arrest and large-scale changes in transcript levels required for stress tolerance. We wanted to test the meaning of root derived ABA signaling in drying soil on water balance. To this end we generated transgenic tomato lines in which ABA signaling is initiated by a synthetic agonist- mandipropamid. Initial study using a Series of grafting experiments indicate that that root ABA signaling has no effect on the immediate regulation of stomata aperture. Once concluded, these experiments will enable us to systematically dissect the physiological role of root-shoot interaction in maintaining the water balance in plants and provide new tools for targeted improvement of abiotic stress tolerance in crop plants.
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Fromm, Hillel, and Joe Poovaiah. Calcium- and Calmodulin-Mediated Regulation of Plant Responses to Stress. United States Department of Agriculture, September 1993. http://dx.doi.org/10.32747/1993.7568096.bard.

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We have taken a molecular approach to clone cellular targets of calcium/calmodulin (Ca2+/CaM). A 35S-labeled recombinant CaM was used as a probe to screen various cDNA expression libraries. One of the isolated clones from petunia codes for the enzyme glutamate decarboxylase (GAD) which catalyzes the conversion of glutamate to g-aminobutyric acid (GABA). The activity of plant GAD has been shown to be dramatically enhanced in response to cold and heat shock, anoxia, drought, mechanical manipulations and by exogenous application of the stress phytohormone ABA in wheat roots. We have purified the recombinant GAD by CaM-affinity chromatography and studied its regulation by Ca2+/CaM. At a physiological pH range (7.0-7.5), the purified enzyme was inactive in the absence of Ca2+ and CaM but could be stimulated to high levels of activity by the addition of exogenous CaM (K0.5 = 15 nM) in the presence of Ca2+ (K 0.5 = 0.8 mM). Neither Ca2+ nor CaM alone had any effect on GAD activity. Transgenic tobacco plants expressing a mutant petunia GAD lacking the CaM-binding domain, or transgenic plants expressing the intact GAD were prepared and studied in detail. We have shown that the CaM-binding domain is necessary for the regulation of glutamate and GABA metabolism and for normal plant development. Moreover, we found that CaM is tightly associated with a 500 kDa GAD complex. The tight association of CaM with its target may be important for the rapid modulation of GAD activity by Ca2+ signaling in response to stresses.
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Handa, Avtar K., Yuval Eshdat, Avichai Perl, Bruce A. Watkins, Doron Holland, and David Levy. Enhancing Quality Attributes of Potato and Tomato by Modifying and Controlling their Oxidative Stress Outcome. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586532.bard.

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General The final goal and overall objective of the current research has been to modify lipid hydroperoxidation in order to create desirable phenotypes in two important crops, potato and tomato, which normally are exposed to abiotic stress associated with such oxidation. The specific original objectives were: (i) the roles of lipoxygenase (LOX) and phospholipids hydroperoxide glutathione peroxidase (PHGPx) in regulating endogenous levels of lipid peroxidation in plant tissues; (ii) the effect of modified lipid peroxidation on fruit ripening, tuber quality, crop productivity and abiotic stress tolerance; (iii) the effect of simultaneous reduction of LOX and increase of PHGPx activities on fruit ripening and tuber quality; and (iv) the role of lipid peroxidation on expression of specific genes. We proposed to accomplish the research goal by genetic engineering of the metabolic activities of LOX and PHGPx using regulatable and tissue specific promoters, and study of the relationships between these two consecutive enzymes in the metabolism and catabolism of phospholipids hydroperoxides. USA Significant progress was made in accomplishing all objectives of proposed research. Due to inability to regenerate tomato plants after transforming with 35S-PHGPx chimeric gene construct, the role of low catalase induced oxidative stress instead of PHGPx was evaluated on agronomical performance of tomato plant and fruit quality attributes. Effects of polyamine, that protects DNA from oxidative stress, were also evaluated. The transgenic plants under expressing lipoxygenase (LOX-sup) were crossed with catalase antisense (CAT-anti) plants or polyamine over producing plants (SAM-over) and the lines homozygous for the two transgenes were selected. Agronomical performance of these line showed that low catalase induced oxidative stress negatively affected growth and development of tomato plants and resulted in a massive change in fruit gene expression. These effects of low catalase activity induced oxidative stress, including the massive shift in gene expression, were greatly overcome by the low lipoxygenase activity. Collectively results show that oxidative stress plays significant role in plant growth including the fruit growth. These results also for the first time indicated that a crosstalk between oxidative stress and lipoxygenase regulated processes determine the outcome during plant growth and development. Israel Regarding PHGPx, most of the study has concentrated on the first and the last specific objectives, since it became evident that plant transformation with this gene is not obvious. Following inability to achieve efficient transformation of potato and tomato using a variety of promoters, model plant systems (tobacco and potato cell cultures, tobacco calli and plantlets, and Arabidopsis) were used to establish the factors and to study the obstacles which prohibited the regeneration of plants carrying the genetic machinery for overproduction of PHGPx. Our results clearly demonstrate that while genetic transformation and over-expression of PHGPx occurs in pre-developmental tissue stage (cell culture, calli clusters) or in completed plant (Arabidopsis), it is likely that over-expression of this enzyme before tissue differentiation is leading to a halt of the regeneration process. To support this assumption, experiments, in which genetic engineering of a point-mutated PHGPx gene enable transformation and over-expression in plants of PhSPY modified in its catalytic site and thus inactive enzymatically, were successfully carried out. These combined results strongly suggest, that if in fact, like in animals and as we established in vitro, the plant PHGPx exhibits PH peroxidase activity, these peroxides are vital for the organisms developmental process.
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Cohen, Roni, Kevin Crosby, Menahem Edelstein, John Jifon, Beny Aloni, Nurit Katzir, Haim Nerson, and Daniel Leskovar. Grafting as a strategy for disease and stress management in muskmelon production. United States Department of Agriculture, January 2004. http://dx.doi.org/10.32747/2004.7613874.bard.

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The overall objective of this research was to elucidate the horticultural, pathological, physiological and molecular factors impacting melon varieties (scion) grafted onto M. cannonballus resistant melon and squash rootstocks. Specific objectives were- to compare the performance of resistant melon germplasm (grafted and non-grafted) when exposed to M. cannoballus in the Lower Rio Grande valley and the Wintergarden, Texas, and in the Arava valley, Israel; to address inter-species relationships between a Monosporascus resistant melon rootstock and susceptible melon scions in terms of fruit-set, fruit quality and yield; to study the factors which determine the compatibility between the rootstock and the scion in melon; to compare the responses of graft unions of differing compatibilities under disease stress, high temperatures, deficit irrigation, and salinity stress; and to investigate the effect of rootstock on stress related gene expression in the scion. Some revisions were- to include watermelon in the Texas investigations since it is much more economically important to the state, and also to evaluate additional vine decline pathogens Didymella bryoniae and Macrophomina phaseolina. Current strategies for managing vine decline rely heavily on soil fumigation with methyl bromide, but restrictions on its use have increased the need for alternative management strategies. Grafting of commercial melon varieties onto resistant rootstocks with vigorous root systems is an alternative to methyl bromide for Monosporascus root rot/vine decline (MRR/VD) management in melon production. Extensive selection and breeding has already produced potential melon rootstock lines with vigorous root systems and disease resistance. Melons can also be grafted onto Cucurbita spp., providing nonspecific but efficient protection from a wide range of soil-borne diseases and against some abiotic stresses, but compatibility between the scion and the rootstock can be problematic. During the first year experiments to evaluate resistance to the vine decline pathogens Monosporascus cannonballus, Didymella bryoniae, and Macrophomina phaseolina in melon and squash rootstocks proved the efficacy of these grafted plants in improving yield and quality. Sugars and fruit size were better in grafted versus non-grafted plants in both Texas and Israel. Two melons (1207 and 124104) and one pumpkin, Tetsukabuto, were identified as the best candidate rootstocks in Texas field trials, while in Israel, the pumpkin rootstock RS59 performed best. Additionally, three hybrid melon rootstocks demonstrated excellent resistance to both M. cannonballus and D. bryoniae in inoculated tests, suggesting that further screening for fruit quality and yield should be conducted. Experiments with ABA in Uvalde demonstrated a significant increase in drought stress tolerance and concurrent reduction in transplant shock due to reduced transpiration for ‘Caravelle’ plants. In Israel, auxin was implicated in reducing root development and contributing to increased hydrogen peroxide, which may explain incompatibility reactions with some squash rootstocks. However, trellised plants responded favorably to auxin (NAA) application at the time of fruit development. Gene expression analyses in Israel identified several cDNAs which may code for phloem related proteins, cyclins or other factors which impact the graft compatibility. Manipulation of these genes by transformation or traditional breeding may lead to improved rootstock cultivars. Commercial applications of the new melon rootstocks as well as the ABA and TIBA growth regulators have potential to improve the success of grafted melons in both Israel and Texas. The disease resistance, fruit quality and yield data generated by the field trials will help producers in both locations to decide what rootstock/scion combinations will be best.
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Wolf, Shmuel, and William J. Lucas. Involvement of the TMV-MP in the Control of Carbon Metabolism and Partitioning in Transgenic Plants. United States Department of Agriculture, October 1999. http://dx.doi.org/10.32747/1999.7570560.bard.

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The function of the 30-kilodalton movement protein (MP) of tobacco mosaic virus (TMV) is to facilitate cell-to-cell movement of viral progeny in infected plants. Our earlier findings have indicated that this protein has a direct effect on plasmodesmal function. In addition, these studies demonstrated that constitutive expression of the TMV MP gene (under the control of the CaMV 35S promoter) in transgenic tobacco plants significantly affects carbon metabolism in source leaves and alters the biomass distribution between the various plant organs. The long-term goal of the proposed research was to better understand the factors controlling carbon translocation in plants. The specific objectives were: A) To introduce into tobacco and potato plants a virally-encoded (TMV-MP) gene that affects plasmodesmal functioning and photosynthate partitioning under tissue-specific promoters. B) To introduce into tobacco and potato plants the TMV-MP gene under the control of promoters which are tightly repressed by the Tn10-encoded Tet repressor, to enable the expression of the protein by external application of tetracycline. C) To explore the mechanism by which the TMV-MP interacts with the endogenous control o~ carbon allocation. Data obtained in our previous project together with the results of this current study established that the TMV-MP has pleiotropic effects when expressed in transgenic tobacco plants. In addition to its ability to increase the plasmodesmal size exclusion limit, it alters carbohydrate metabolism in source leaves and dry matter partitioning between the various plant organs, Expression of the TMV-MP in various tissues of transgenic potato plants indicated that sugars and starch levels in source leaves are reduced below those of control plants when the TMV-MP is expressed in green tissue only. However, when the TMV-MP was expressed predominantly in PP and CC, sugar and starch levels were raised above those of control plants. Perhaps the most significant result obtained from experiments performed on transgenic potato plants was the discovery that the influence of the TMV-MP on carbohydrate allocation within source leaves was under developmental control and was exerted only during tuber development. The complexity of the mode by which the TMV-MP exerts its effect on the process of carbohydrate allocation was further demonstrated when transgenic tobacco plants were subjected to environmental stresses such as drought stress and nutrients deficiencies, Collectively, these studies indicated that the influence of the TMV-MP on carbon allocation L the result of protein-protein interaction within the source tissue. Based on these results, together with the findings that plasmodesmata potentiate the cell-to-cell trafficking of viral and endogenous proteins and nucleoproteins complexes, we developed the theme that at the whole plant level, the phloem serves as an information superhighway. Such a long-distance communication system may utilize a new class of signaling molecules (proteins and/or RNA) to co-ordinate photosynthesis and carbon/nitrogen metabolism in source leaves with the complex growth requirements of the plant under the prevailing environmental conditions. The discovery that expression of viral MP in plants can induce precise changes in carbon metabolism and photoassimilate allocation, now provide a conceptual foundation for future studies aimed at elucidating the communication network responsible for integrating photosynthetic productivity with resource allocation at the whole-plant level. Such information will surely provide an understanding of how plants coordinate the essential physiological functions performed by distantly-separated organs. Identification of the proteins involved in mediating and controlling cell-to-cell transport, especially at the companion cell-sieve element boundary, will provide an important first step towards achieving this goal.
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Seginer, Ido, Daniel H. Willits, Michael Raviv, and Mary M. Peet. Transpirational Cooling of Greenhouse Crops. United States Department of Agriculture, March 2000. http://dx.doi.org/10.32747/2000.7573072.bard.

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Background Transplanting vegetable seedlings to final spacing in the greenhouse is common practice. At the time of transplanting, the transpiring leaf area is a small fraction of the ground area and its cooling effect is rather limited. A preliminary modeling study suggested that if water supply from root to canopy is not limiting, a sparse crop could maintain about the same canopy temperature as a mature crop, at the expense of a considerably higher transpiration flux per leaf (and root) area. The objectives of this project were (1) to test the predictions of the model, (2) to select suitable cooling methods, and (3) to compare the drought resistance of differently prepared seedlings. Procedure Plants were grown in several configurations in high heat load environments, which were moderated by various environmental control methods. The difference between the three experimental locations was mainly in terms of scale, age of plants, and environmental control. Young potted plants were tested for a few days in small growth chambers at Technion and Newe Ya'ar. At NCSU, tomato plants of different ages and planting densities were compared over a whole growing season under conditions similar to commercial greenhouses. Results Effect of spacing: Densely spaced plants transpired less per plant and more per unit ground area than sparsely spaced plants. The canopy temperature of the densely spaced plants was lower. Air temperature was lower and humidity higher in the compartments with the densely spaced plants. The difference between species is mainly in the canopy-to-air Bowen ratio, which is positive for pepper and negative for tomato. Effect of cooling methods: Ventilation and evaporative pad cooling were found to be effective and synergitic. Air mixing turned out to be very ineffective, indicating that the canopy-to-air transfer coefficient is not the limiting factor in the ventilation process. Shading and misting, both affecting the leaf temperature directly, proved to be very effective canopy cooling methods. However, in view of their side effects, they should only be considered as emergency measures. On-line measures of stress: Chlorophyll fluorescence was shown to accurately predict photosynthesis. This is potentially useful as a rapid, non-contact way of assessing canopy heat stress. Normalized canopy temperature and transpiration rate were shown to correlate with water stress. Drought resistance of seedlings: Comparison between normal seedlings and partially defoliated ones, all subjected to prolonged drought, indicated that removing about half of the lowermost leaves prior to transplanting, may facilitate adjustment to the more stressful conditions in the greenhouse. Implications The results of this experimental study may lead to: (1) An improved model for a sparse canopy in a greenhouse. (2) A better ventilation design procedure utilizing improved estimates of the evaporation coefficient for different species and plant configurations. (3) A test for the stress resistance of transplants.
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Chen, Junping, Zach Adam, and Arie Admon. The Role of FtsH11 Protease in Chloroplast Biogenesis and Maintenance at Elevated Temperatures in Model and Crop Plants. United States Department of Agriculture, May 2013. http://dx.doi.org/10.32747/2013.7699845.bard.

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specific objectives of this proposal were to: 1) determine the location, topology, and oligomerization of FtsH11 protease; 2) identify the substrate/s of FtsH11 and the downstream components involved in maintaining thermostability of chloroplasts; 3) identify new elements involved in FtsH11 protease regulatory network related to HT adaptation processes in chloroplast; 4) Study the role of FtsH11 homologs from crop species in HT tolerance. Background to the topic: HT-tolerant varieties that maintain high photosynthetic efficiency at HT, and cope better with daily and seasonal temperature fluctuations are in great need to alleviate the effect of global warming on food production. Photosynthesis is a very complex process requiring accurate coordination of many complex systems and constant adjustments to the changing environments. Proteolytic activities mediated by various proteases in chloroplast are essential part of this process and critical for maintaining normal chloroplast functions under HT. However, little is known about mechanisms that contribute to adaptation of photosynthetic processes to HT. Our study has shown that a chloroplast-targeted Arabidopsis FtsH11 protease plays an essential and specific role in maintaining thermostability of thylakoids and normal photosynthesis at moderate HT. We hypothesized that FtsH11 homologs recently identified in other plant species might have roles similarly to that of AtFtsH1. Thus, dissecting the underlying mechanisms of FtsH11 in the adaptation mechanisms in chloroplasts to HT stress and other elements involved will aid our effort to produce more agricultural products in less favorable environments. Major conclusions, solutions, achievements - Identified the chloroplast inner envelope membrane localization of FtsH11. - Revealed a specific association of FtsH11 with the a and b subunits of CPN60. - Identified the involvement of ARC6, a protein coordinates chloroplast division machineries in plants, in FtsH11 mediated HT adaptation process in chloroplast. -Reveal possible association of a polyribonucleotide nucleotidyltransferase (cpPNPase), coded by At3G03710, with FtsH11 mediated HT adaptation process in chloroplast. - Mapped 4 additional loci in FtsH11 mediated HT adaptation network in chloroplast. - Demonstrated importance of the proteolytic activity of FtsH11 for thermotolerance, in addition to the ATPase activity. - Demonstrated a conserved role of plant FtsH11 proteases in chloroplast biogenesis and in maintaining structural and functional thermostability of chloroplast at elevated temperatures. Implications, both scientific and agricultural:Three different components interacting with FtsH11 were identified during the course of this study. At present, it is not known whether these proteins are directly involved in FtsH11mediated thermotolerance network in chloroplast and/or how these elements are interrelated. Studies aiming to connect the dot among biological functions of these networks are underway in both labs. Nevertheless, in bacteria where it was first studied, FtsH functions in heat shock response by regulating transcription level of σ32, a heat chock factor regulates HSPsexpression. FtsH also involves in control of biosynthesis of membrane components and quality control of membrane proteins etc. In plants, both Arc 6 and CPN60 identified in this study are essential in chloroplast division and developments as mutation of either one impairs chloroplast division in Arabidopsis. The facts that we have found the specific association of both α and β CPN60 with FtsH11 protein biochemically, the suppression/ enhancement of ftsh11 thermosensitive phenotype by arc6 /pnp allele genetically, implicate inter-connection of these networks via FtsH11 mediated network(s) in regulating the dynamic adaptation processes of chloroplast to temperature increases at transcriptional, translational and post-translational levels. The conserved role of FtsH11 proteases in maintaining thermostability of chloroplast at HT demonstrated here provides a foundation for improving crop photosynthetic performance at high temperatures.
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10

Barg, Rivka, Kendal D. Hirschi, Avner Silber, Gozal Ben-Hayyim, Yechiam Salts, and Marla Binzel. Combining Elevated Levels of Membrane Fatty Acid Desaturation and Vacuolar H+ -pyrophosphatase Activity for Improved Drought Tolerance. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7613877.bard.

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Background to the topic: In previous works we have shown that Arabidopsis and tomato over-expressing H+-pyrophosphatase show increased tolerance to drought imposed by withholding irrigation of young plants in pots (Park et al. 2005). In addition, young tobacco plants over-expressing fatty acid desaturase 3 (OEX-FAD3) also showed increasing tolerance to drought stress (Zhang et al 2005), and similarly OEX-FAD3 young tomato plants (unpublished data from ARO), hence raising the possibility that pyramiding the two could further improve drought tolerance in tomato. Based on these findings the specific objects originally set were: 1. To analyze the impact of pyramiding transgenes for enhanced fatty acid desaturation and for elevated H+-PPase activity on tomato yielding under water deficit stress conditions. 2. To elucidate the biochemical relationship between elevated desaturation of the membrane lipids and the activities of selected vacuolar transporters in the context of drought responses. 3. To explore the S. pennellii introgression lines as alternative genetic sources for drought tolerance related to enhanced fatty acid desaturation and/or H+-PPase activity. 4. Since OEX-FAD3 increases the levels of linolenic acid which is the precursor of various oxylipins including the stress hormone Jasmonate. (JA), study of the effect of this transgene on tolerance to herbivore pests was added as additional goal. The Major conclusions, solutions, and achievements are: (1) The facts that ectopic over-expression of vacuolarH+-PPases (in line OEX-AVP1) does not change the fatty acid profile compared to the parental MoneyMaker (MM) line and that elevated level of FA desaturation (by OEX-FAD3) does not change the activity of either H+-PPase, H+-ATPaseor Ca2+ /H+ antiport, indicate that the observed increased drought tolerance reported before for increase FA desaturation in tobacco plants and increased H+PPase in tomato plants involves different mechanisms. (2) After generating hybrid lines bringing to a common genetic background (i.e. F1 hybrids between line MP-1 and MM) each of the two transgenes separately and the two transgenes together the effect of various drought stress regimes including recovery from a short and longer duration of complete water withhold as well as performance under chronic stresses imposed by reducing water supply to 75-25% of the control irrigation regime could be studied. Under all the tested conditions in Israel, for well established plants grown in 3L pots or larger, none of the transgenic lines exhibited a reproducible significantly better drought tolerance compare to the parental lines. Still, examining the performance of these hybrids under the growth practices followed in the USA is called for. (3) Young seedlings of none of the identified introgression lines including the S. pennellii homologs of two of the H+-PPase genes and one of the FAD7 genes performed better than line M82 upon irrigation withhold. However, differences in the general canopy structures between the IL lines and M82 might mask such differences if existing. (4). Over-expression of FAD3 in the background of line MP-1 was found to confer significant tolerance to three important pest insects in tomato: Bordered Straw (Heliothis peltigera), Egyptian cotton leafworm (Spodoptera littoralis) and Western Flower Thrips (Frankliniella occidentalis). Implications: Although the original hypothesis that pyramiding these two trasgenes could improve drought tolerance was not supported, the unexpected positive impact on herbivore deterring, as well as the changes in dynamics of JA biosynthesis in response to wounding and the profound changes in expression of wound response genes calls for deciphering the exact linolenic acid derived signaling molecule mediating this response. This will further facilitate breeding for herbivore pest and mechanical stress tolerance based on this pathway.
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