Journal articles: '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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Chen, Defu, Haiwei Chen, Luhua Zhang, Xiaoli Shi, and Xiwen Chen. "Tocopherol-deficient rice plants display increased sensitivity to photooxidative stress." Planta 239, no. 6 (April 2, 2014): 1351–62. http://dx.doi.org/10.1007/s00425-014-2064-8.

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Gori, Antonella, Cecilia Brunetti, Luana Beatriz dos Santos Nascimento, Giovanni Marino, Lucia Guidi, Francesco Ferrini, Mauro Centritto, Alessio Fini, and Massimiliano Tattini. "Photoprotective Role of Photosynthetic and Non-Photosynthetic Pigments in Phillyrea latifolia: Is Their “Antioxidant” Function Prominent in Leaves Exposed to Severe Summer Drought?" International Journal of Molecular Sciences 22, no. 15 (August 2, 2021): 8303. http://dx.doi.org/10.3390/ijms22158303.

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Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate.

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Gould, Kevin S. "Nature's Swiss Army Knife: The Diverse Protective Roles of Anthocyanins in Leaves." Journal of Biomedicine and Biotechnology 2004, no. 5 (2004): 314–20. http://dx.doi.org/10.1155/s1110724304406147.

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Anthocyanins, the pigments responsible for spectacular displays of vermilion in the leaves of deciduous trees, have long been considered an extravagant waste of a plant's resources. Contemporary research, in contrast, has begun to show that the pigments can significantly influence the way a leaf responds to environmental stress. Anthocyanins have been implicated in tolerance to stressors as diverse as drought, UV-B, and heavy metals, as well as resistance to herbivores and pathogens. By absorbing high-energy quanta, anthocyanic cell vacuoles both protect chloroplasts from the photoinhibitory and photooxidative effects of strong light, and prevent the catabolism of photolabile defence compounds. Anthocyanins also mitigate photooxidative injury in leaves by efficiently scavenging free radicals and reactive oxygen species. Far from being a useless by-product of the flavonoid pathway, these red pigments may in some instances be critical for plant survival.

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MARTIN, R. E., D. J. THOMAS, D. E. TUCKER, and S. K. HERBERT. "The effects of photooxidative stress on photosystem I measured in vivo in Chlamydomonas." Plant, Cell and Environment 20, no. 12 (December 1997): 1451–61. http://dx.doi.org/10.1046/j.1365-3040.1997.d01-47.x.

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Williamson, John D., Dianne B. Jennings, Wei-Wen Guo, D. Mason Pharr, and Marilyn Ehrenshaft. "Sugar Alcohols, Salt Stress, and Fungal Resistance: Polyols—Multifunctional Plant Protection?" Journal of the American Society for Horticultural Science 127, no. 4 (July 2002): 467–73. http://dx.doi.org/10.21273/jashs.127.4.467.

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The traditional use of polyols as osmotica in plant culture media is based on the assumption that polyols are not taken up or metabolized by cells. In reality, polyols are significant photosynthetic products and efficiently utilized metabolites in a large number of plants. In addition to these metabolic roles, initial interest in polyols focused primarily on their function as osmoprotectants. This was hypothesized to be due to their ability to act as compatible solutes. More recent research, however, indicates much broader roles for polyols in stress responses based on their significant antioxidant capacity. These include protection against salt and photooxidative stress as well as a potential role in plant pathogen interactions.

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Sirikhachornkit, Anchalee, Jai W. Shin, Irene Baroli, and Krishna K. Niyogi. "Replacement of α-Tocopherol by β-Tocopherol Enhances Resistance to Photooxidative Stress in a Xanthophyll-Deficient Strain of Chlamydomonas reinhardtii." Eukaryotic Cell 8, no. 11 (November 2009): 1648–57. http://dx.doi.org/10.1128/ec.00124-09.

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ABSTRACT Tocopherols (vitamin E) comprise a class of lipid-soluble antioxidants synthesized only in plants, algae, and some cyanobacteria. The majority of tocopherols in photosynthetic cells is in the α form, which has the highest vitamin E activity in humans, whereas the β, γ, and δ forms normally account for a small percentage of total tocopherols. The antioxidant activities of these forms of tocopherol differ depending on the experimental system, and their relative activities in vivo are unclear. In a screen for suppressors of the xanthophyll-deficient npq1 lor1 double mutant of Chlamydomonas reinhardtii, we isolated a vte3 mutant lacking α-tocopherol but instead accumulating β-tocopherol. The vte3 mutant contains a mutation in the homolog of a 2-methyl-6-phytyl-1,4-benzoquinone methyltransferase gene found in plants. The vte3 npq1 lor1 triple mutant with β-tocopherol survived better under photooxidative stress than did the npq1 lor1 mutant, but the vte3 mutant on its own did not have an obvious phenotype. Following transfer from low light to high light, the triple mutant showed a higher efficiency of photosystem II, a higher level of cell viability, and a lower level of lipid peroxide, a marker for oxidative stress, than did the npq1 lor1 mutant. After high-light transfer, the level of the photosystem II reaction center protein, D1, was also higher in the vte3 npq1 lor1 mutant, but the rate of D1 photodamage was not significantly different from that of the npq1 lor1 mutant. Taken together, these results suggest that the replacement of α-tocopherol by β-tocopherol in a xanthophyll-deficient strain of Chlamydomonas reinhardtii contributes to better survival under conditions of photooxidative stress.

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Yeh, Hui-Ling, Tsen-Hung Lin, Chi-Chih Chen, Tian-Xing Cheng, Hsin-Yang Chang, and Tse-Min Lee. "Monodehydroascorbate Reductase Plays a Role in the Tolerance of Chlamydomonas reinhardtii to Photooxidative Stress." Plant and Cell Physiology 60, no. 10 (June 14, 2019): 2167–79. http://dx.doi.org/10.1093/pcp/pcz110.

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Abstract Monodehydroascorbate reductase (MDAR; EC 1.6.5.4) is one of the key enzymes in the conversion of oxidized ascorbate (AsA) back to reduced AsA in plants. This study investigated the role of MDAR in the tolerance of Chlamydomonas reinhardtii P.A. Dangeard to photooxidative stress by overexpression and downregulation of the CrMDAR1 gene. For overexpression of CrMDAR1 driven by a HSP70A:RBCS2 fusion promoter, the cells survived under very high-intensity light stress (VHL, 1,800 μmolï¿½m−2ï¿½s−1), while the survival of CC-400 and vector only control (vector without insert) cells decreased for 1.5 h under VHL stress. VHL increased lipid peroxidation of CC-400 but did not alter lipid peroxidation in CrMDAR1 overexpression lines. Additionally, overexpression of CrMDAR1 showed an increase in viability, CrMDAR1 transcript abundance, enzyme activity and the AsA: dehydroascorbate (DHA) ratio. Next, MDAR was downregulated to examine the essential role of MDAR under high light condition (HL, 1,400 μmolï¿½m−2ï¿½s−1). The CrMDAR1 knockdown amiRNA line exhibited a low MDAR transcript abundance and enzyme activity and the survival decreased under HL conditions. Additionally, HL illumination decreased CrMDAR1 transcript abundance, enzyme activity and AsA:DHA ratio of CrMDAR1-downregulation amiRNA lines. Methyl viologen (an O2ï¿½− generator), H2O2 and NaCl treatment could induce an increase in CrMDAR1 transcript level. It represents reactive oxygen species are one of the factor inducing CrMDAR1 gene expression. In conclusion, MDAR plays a role in the tolerance of Chlamydomonas cells to photooxidative stress.

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Kirchhoff, Helmut. "Structural changes of the thylakoid membrane network induced by high light stress in plant chloroplasts." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1640 (April 19, 2014): 20130225. http://dx.doi.org/10.1098/rstb.2013.0225.

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Land plants live in a challenging environment dominated by unpredictable changes. A particular problem is fluctuation in sunlight intensity that can cause irreversible damage of components of the photosynthetic apparatus in thylakoid membranes under high light conditions. Although a battery of photoprotective mechanisms minimize damage, photoinhibition of the photosystem II (PSII) complex occurs. Plants have evolved a multi-step PSII repair cycle that allows efficient recovery from photooxidative PSII damage. An important feature of the repair cycle is its subcompartmentalization to stacked grana thylakoids and unstacked thylakoid regions. Thus, understanding the crosstalk between stacked and unstacked thylakoid membranes is essential to understand the PSII repair cycle. This review summarizes recent progress in our understanding of high-light-induced structural changes of the thylakoid membrane system and correlates these changes to the efficiency of the PSII repair cycle. The role of reversible protein phosphorylation for structural alterations is discussed. It turns out that dynamic changes in thylakoid membrane architecture triggered by high light exposure are central for efficient repair of PSII.

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Kouril, R., D. Lazar, H. Lee, J. Jo, and J. Naus. "Moderately Elevated Temperature Eliminates Resistance of Rice Plants with Enhanced Expression of Glutathione Reductase to Intensive Photooxidative Stress." Photosynthetica 41, no. 4 (December 1, 2003): 571–78. http://dx.doi.org/10.1023/b:phot.0000027522.35486.f6.

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Stefanov, Martin A., Georgi D. Rashkov, and Emilia L. Apostolova. "Assessment of the Photosynthetic Apparatus Functions by Chlorophyll Fluorescence and P700 Absorbance in C3 and C4 Plants under Physiological Conditions and under Salt Stress." International Journal of Molecular Sciences 23, no. 7 (March 29, 2022): 3768. http://dx.doi.org/10.3390/ijms23073768.

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Functions of the photosynthetic apparatus of C3 (Pisum sativum L.) and C4 (Zea mays L.) plants under physiological conditions and after treatment with different NaCl concentrations (0–200 mM) were investigated using chlorophyll a fluorescence (pulse-amplitude-modulated (PAM) and JIP test) and P700 photooxidation measurement. Data revealed lower density of the photosynthetic structures (RC/CSo), larger relative size of the plastoquinone (PQ) pool (N) and higher electron transport capacity and photosynthetic rate (parameter RFd) in C4 than in C3 plants. Furthermore, the differences were observed between the two studied species in the parameters characterizing the possibility of reduction in the photosystem (PSI) end acceptors (REo/RC, REo/CSo and δRo). Data revealed that NaCl treatment caused a decrease in the density of the photosynthetic structures and relative size of the PQ pool as well as decrease in the electron transport to the PSI end electron acceptors and the probability of their reduction as well as an increase in the thermal dissipation. The effects were stronger in pea than in maize. The enhanced energy losses after high salt treatment in maize were mainly from the increase in the regulated energy losses (ΦNPQ), while in pea from the increase in non-regulated energy losses (ΦNO). The reduction in the electron transport from QA to the PSI end electron acceptors influenced PSI activity. Analysis of the P700 photooxidation and its decay kinetics revealed an influence of two PSI populations in pea after treatment with 150 mM and 200 mM NaCl, while in maize the negligible changes were registered only at 200 mM NaCl. The experimental results clearly show less salt tolerance of pea than maize.

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Rezaie, Parizad, Maryam Pourhajibagher, Nasim Chiniforush, Nava Hosseini, and Abbas Bahador. "The Effect of Quorum-Sensing and Efflux Pumps Interactions in Pseudomonas aeruginosa Against Photooxidative Stress." Journal of Lasers in Medical Sciences 9, no. 3 (July 28, 2018): 161–67. http://dx.doi.org/10.15171/jlms.2018.30.

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Agati, Giovanni, Cecilia Brunetti, Alessio Fini, Antonella Gori, Lucia Guidi, Marco Landi, Federico Sebastiani, and Massimiliano Tattini. "Are Flavonoids Effective Antioxidants in Plants? Twenty Years of Our Investigation." Antioxidants 9, no. 11 (November 9, 2020): 1098. http://dx.doi.org/10.3390/antiox9111098.

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Whether flavonoids play significant antioxidant roles in plants challenged by photooxidative stress of different origin has been largely debated over the last few decades. A critical review of the pertinent literature and our experimentation as well, based on a free-of-scale approach, support an important antioxidant function served by flavonoids in plants exposed to a wide range of environmental stressors, the significance of which increases with the severity of stress. On the other side, some questions need conclusive answers when the putative antioxidant functions of plant flavonoids are examined at the level of both the whole-cell and cellular organelles. This partly depends upon a conclusive, robust, and unbiased definition of “a plant antioxidant”, which is still missing, and the need of considering the subcellular re-organization that occurs in plant cells in response to severe stress conditions. This likely makes our deterministic-based approach unsuitable to unveil the relevance of flavonoids as antioxidants in extremely complex biological systems, such as a plant cell exposed to an ever-changing stressful environment. This still poses open questions about how to measure the occurred antioxidant action of flavonoids. Our reasoning also evidences the need of contemporarily evaluating the changes in key primary and secondary components of the antioxidant defense network imposed by stress events of increasing severity to properly estimate the relevance of the antioxidant functions of flavonoids in an in planta situation. In turn, this calls for an in-depth analysis of the sub-cellular distribution of primary and secondary antioxidants to solve this still intricate matter.

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Arora, Rajeev, Dharmalingam S. Pitchay, and Bradford C. Bearce. "EFFECT OF WATER STRESS ON HEAT STRESS TOLERANCE IN GERANIUM." HortScience 31, no. 6 (October 1996): 915A—915. http://dx.doi.org/10.21273/hortsci.31.6.915a.

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This study evaluated the effect of reversible water stress on heat stress tolerance (HST) in greenhouse-grown geraniums. Water stress was imposed by withholding irrigation until pots reached ≈30% (by weight) of well-watered (control) plant pots, and maintaining this weight for 7 days. Control plants were watered to just below field capacity, every other day. Leaf xylem water potential (LXWP, MPa), leaf-relative water content (LRWC,%), media water content (MWC, % fresh weight), and heat stress tolerance (HST, LT50) were determined for control and stressed plants. HST (LT50), defined as temperature causing half-maximal percent injury, was based on electrolyte leakage from leaf disks subjected to 25 to 60C. Control-watering was restored in stressed plants and above measurements made after 7 days of recovery. Data indicate: 1) LXWP, LRWC, and MWC in control and stressed plants were –0.378 and –0.804 MPa, 92.31% and 78.69% and 82.86% and 15.5%, respectively; 2) HST increased significantly in stressed as compared to control plants (LT50 of 55C vs. 51C); 3) control plants were near maximally injured by 53C treatment and sustained more than 3-fold greater injury than stressed plants at 53C. In recovered plants, LXWP and RWC reversed back to control levels, paralleled by loss of higher HST.

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Silva, E. C., P. L. Abhayawardhana, A. V. Lygin, C. L. Robertson, M. Liu, Z. Liu, and R. W. Schneider. "Coumestrol Confers Partial Resistance in Soybean Plants Against Cercospora Leaf Blight." Phytopathology® 108, no. 8 (August 2018): 935–47. http://dx.doi.org/10.1094/phyto-05-17-0189-r.

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Although previous research showed that the purple symptom of Cercospora leaf blight (CLB) is associated with lower biomass of Cercospora cf. flagellaris and lower concentrations of cercosporin, a reactive oxygen species producer, as compared with blighted leaves, the hypothesis that the purple symptom is a plant reaction to the pathogen has never been tested. In this study, we demonstrated that high levels of coumestrol (COU) were associated with purple symptoms of CLB and that COU has strong antioxidant activity. Additionally, we found that COU is restricted to the pigmented areas of purple leaves, and the pigmentation is restricted to the adaxial surfaces, suggesting that COU may be acting as a sunscreen. Even though COU is associated with the purple leaf symptom, this coumestan is not the direct cause of discoloration in that COU is colorless. Quantification of chlorophyll a and b and total carotenoids suggested that blighted but not purple or asymptomatic leaves were undergoing photooxidative stress. Because the purple symptom is associated with high COU concentrations, lower biomass of C. cf. flagellaris, and lower cercosporin concentrations, we conclude that the purple symptom is a disease resistance reaction, mediated in part by COU, which provides a high level of antioxidant activity and, hence, partial resistance.

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MOON, Yu Ran, Min Hee LEE, Altanzaya TOVUU, Choon-Hwan LEE, Byung Yeoup CHUNG, Youn-Il PARK, and Jin-Hong KIM. "Acute Exposure to UV-B Sensitizes Cucumber, Tomato, and Arabidopsis Plants to Photooxidative Stress by Inhibiting Thermal Energy Dissipation and Antioxidant Defense." Journal of Radiation Research 52, no. 2 (2011): 238–48. http://dx.doi.org/10.1269/jrr.10133.

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Miyagawa, Y., M. Tamoi, and S. Shigeoka. "Evaluation of the Defense System in Chloroplasts to Photooxidative Stress Caused by Paraquat Using Transgenic Tobacco Plants Expressing Catalase from Escherichia coli." Plant and Cell Physiology 41, no. 3 (March 1, 2000): 311–20. http://dx.doi.org/10.1093/pcp/41.3.311.

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Ali-Ahmad, M., and S. M. Basha. "Effect of Water Stress on Composition of Peanut Leaves." Peanut Science 25, no. 1 (January 1, 1998): 31–34. http://dx.doi.org/10.3146/i0095-3679-25-1-8.

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Abstract Water stress was induced in peanut (Arachis hypogaea L. cv. Marc 1) plants by withholding water for 5 to 20 d. Leaves from the water-stressed plants were analyzed to determine the effect of water stress on amino acids, sugars, protein content, and polypeptide composition of peanut plants. The results showed that the total protein content of the leaves significantly increased when peanut plants were subjected to water stress for 5 to 20 d as compared to irrigated controls. Analysis of the leaf protein by SDS polyacrylamide gel electrophoresis showed higher levels of polypeptides in stressed leaves compared to the control leaves. Peanut leaves from water-stressed plants also showed higher amounts of free amino acids and soluble sugars as compared to the irrigated plants. Thus, water stress enhanced accumulation of proteins, free amino acids, and soluble sugars in the peanut plants.

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Viljevac, Marija, Krunoslav Dugalić, Ines Mihaljević, Domagoj Šimić, Rezica Sudar, Zorica Jurković, and Hrvoje Lepeduš. "Chlorophyll content, photosynthetic efficiency and genetic markers in two sour cherry (Prunus cerasus L.) genotypes under drought stress." Acta Botanica Croatica 72, no. 2 (October 1, 2013): 221–35. http://dx.doi.org/10.2478/botcro-2013-0003.

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Abstract - Drought is a limiting factor in fruit production today. Identification of sour cherry genotypes tolerant to drought will enable the sustainability of fruit production. The aim of our study was to select sour cherry genotypes according to their genetic background as well as drought tolerance and investigate possible mechanisms of drought tolerance through the changes in photosynthetic apparatus (i.e. photosynthetic pigment content) and photosynthesis process assessed through the chlorophyll fluorescence transient. All of them together with molecular markers (SSRs and AFLPs), relative water content (RWC) as indicator of plant water status distinguish two genotypes (Kelleris 16 and OS), which are the opposite in regards to drought tolerance. Down-regulation of photosynthesis in drought-treated Kelleris 16 plants was seen as changes in antenna complexes of PSII (decreased total chlorophylls content (a+b) and chlorophylls ratio (a/b)). Despite unchanged maximum quantum yield of PSII in drought-treated leaves of genotype OS, overall photosynthetic performance expressed as PIABS was down-regulated in both investigated genotypes. However, decrement of PIABS was much pronounced in genotype Kelleris 16, mainly because of changes in a certain fraction of RCs, which become dissipative centres, seen as increase in ABS/RC and DI0/RC, in order to avoid photooxidative damage of photosynthetic apparatus. Also, electron transport, seen as decrease in ET0/(TR0-ET0) and ET0/RC, was impaired which lead to impaired CO2 fixation and photosynthesis. The described changes in the functioning of photosynthetic apparatus in drought-treated plants of Kelleris 16 constitute the main distinction between the two investigated genotypes regarding drought adaptation mechanisms.

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Mudge, Kenneth W., Kent S. Diebolt, and Thomas H. Whitlow. "Ectomycorrhizal Effect on Host Plant Response to Drought Stress." Journal of Environmental Horticulture 5, no. 4 (December 1, 1987): 183–87. http://dx.doi.org/10.24266/0738-2898-5.4.183.

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Ectomycorrhizal symbiosis affects the water relations and drought resistance of woody landscape trees and shrubs in the families Pinaceae, Fagaceae, Betulaceae, and others. It has frequently been observed that host plants mycorrhizal with drought-adapted fungi exhibit improved growth and survival during drought and more rapid recovery after rewatering than non-mycorrhizal plants or plants mycorrhizal with fungi not adapted to dry sites. Relatively few studies have addressed the effect of mycorrhizae on the physiological response of host plants to drought stress. It is suggested that some fungi confer drought tolerance to their host, while others confer drought avoidance. Possible mechanisms by which mycorrhizae influence host water relations are discussed.

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DAI, Hao. "Ecological effect of photorespiration of plants under environmental stress." CHINESE JOURNAL OF ECO-AGRICULTURE 16, no. 5 (March 2, 2009): 1326–30. http://dx.doi.org/10.3724/sp.j.1011.2008.01326.

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Fathi, Amin, and Davood Barari Tari. "Effect of Drought Stress and its Mechanism in Plants." International Journal of Life Sciences 10, no. 1 (February 10, 2016): 1–6. http://dx.doi.org/10.3126/ijls.v10i1.14509.

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Drought is the most important abiotic factor limiting growth, adversely affect growth and crop production. Stresses, resulting in the non-normal physiological processes that influence one or a combination of biological and environmental factors. Stress can damage which has occurred as a result of an abnormal metabolism and may reduce growth, plant death or the death of the plant develops. Production is limited by environmental stresses, according to different scholars estimates, only 10 percent of the world's arable land is free from Stress, in general, a major factor in the difference between yield and potential performance, environmental stresses. Drought and stress is the most common environmental stresses that almost 25 percent of agricultural lands for agricultural farm products in the world is limited. Drought risk to successful production of crops worldwide and occurs when a combination of physical and environmental factors causing stress in plants and thus reduce production.International Journal of Life Sciences 10 (1) : 2016; 1-6

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Kleiber, Tomasz, Włodzimierz Krzesiński, Katarzyna Przygocka-Cyna, and Tomasz Spiżewski. "Alleviation Effect of Selenium on Manganese Stress of Plants." Ecological Chemistry and Engineering S 25, no. 1 (March 1, 2018): 143–52. http://dx.doi.org/10.1515/eces-2018-0010.

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Abstract Mn, as Fe, Zn, Cu and Ni is a heavy metal and also a necessary element all the living organisms. Excessive Mn nutrition causes a strong oxidative stress. The aim of the studies was to determination the effect of Se treatment (as sodium selenite Na2O4Se3) to alleviate the Mn stress of plants. Because of its sensitivity to oxidative stress induced by excessive concentrations of Mn a model plant was lettuce (Lactuca sativa L. ‘Sunny’). The studies were conducted in a controlled environment growth room in stable climate conditions: 16 h photoperiod; temperature light/dark 18.0 ±0.5°C/16.0 ±0.5°C; relative humidity 70-80%; quantum flux density 195-205 μmol m−2 s−1. Plants were grown hydroponically in nutrient solution characterized by excessive Mn content (19.2 mg dm−3) and different contents of Se (control; 0.77, 1.05, 1.33 mg dm−3). In all the combination were also tested different foliar sprays (distilled water and a 0.005% Se solution). Plants grown under conditions described above take up and transported Se from nutrient solutions into their leaves with a significant reduction of Mn concentration and changes in the plant nutrient status. With the increase in the concentrations of Se clearly narrowed quantitative relations in the leaves between this element and micro-metallic. Increasing Se levels in nutrient solution has a positive influence on the growth of plants, but Se foliar treatment generally decreases plant yield. The study shown that Se application may lead to alleviation of Mn stress of plants, with simultaneous reduce in Mn concentration in leaves - which may be of practical importance also in the cultivation of more economically important species.

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Robert, Germán, Mariana Melchiorre, Roberto Racca, Victorio Trippi, and H. Ramiro Lascano. "Apoplastic superoxide level in wheat protoplast under photooxidative stress is regulated by chloroplast redox signals: Effects on the antioxidant system." Plant Science 177, no. 3 (September 2009): 168–74. http://dx.doi.org/10.1016/j.plantsci.2009.05.001.

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Asadova, B. "Salinity Factor Effect on Barley Seedlings Incubation." Bulletin of Science and Practice 8, no. 1 (January 15, 2022): 81–85. http://dx.doi.org/10.33619/2414-2948/74/11.

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Stress factors limit the development of living organisms, especially plants, and reduce their productivity. In this regard, the study of the effects of stress factors on plants and the discovery of adaptation mechanisms play an important role in the regulation of stress in the cell. From a biological point of view, stress is considered to be any change in the external environment that impairs the normal development of the plant or changes it in a negative direction. Stresses cause changes in the physiological activity of plants, weaken the process of biosynthesis in the cell, disrupt normal life and ultimately can cause plant death.

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Thakur, Jaya, and Bharat Shinde. "Effect of water stress and AM fungi on the growth performance of pea." International Journal of Applied Biology 4, no. 1 (June 29, 2020): 36–43. http://dx.doi.org/10.20956/ijab.v4i1.9446.

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The study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi inoculation on growth of pea grown under water stressed pot culture conditions. Water stress was given to the pea plants after 30 days at the interval of 4, 8 and 12 days. The data was collected at an interval of 15 days. Three replicates of each set were maintained. . The mixture of AM fungi used for current experiment included the species of Acaulospora denticulata, A. gerdemannii, Glomus macrocarpum, G. maculosum, G. fasciculatum and Scutellospora minuta. The mycorrhizal plants have shown more shoot and root length as compared to the control plants. The height of shoot and root was significantly decreased with the increase in drought stress. Mycorrhizal plants with low water stress showed enhanced shoot and root length than high water stress. The mycorrhizal plants have shown more number of leaves than control plants during drought stress. The number of leaves significantly reduced with the increase in drought stress. The leaves produced by the control plants were comparatively smaller than those of mycorrhizal plants. The dry weight of root and shoot of both control and mycorrhizal plants decreased with the increase in water stress. Mycorrhizal plants showed more dry weight of shoot and root as compared to control plants. Plants inoculated with AM fungi produce more dry weight than the control plants. The fresh weight of both control and mycorrhizal plants has been decreased with the increase in water stress interval and also the fresh weight of root and shoot was observed higher in mycorrhizal plants as compared to those of control plants.

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Broin, Mélanie, and Pascal Rey. "Potato Plants Lacking the CDSP32 Plastidic Thioredoxin Exhibit Overoxidation of the BAS1 2-Cysteine Peroxiredoxin and Increased Lipid Peroxidation in Thylakoids under Photooxidative Stress." Plant Physiology 132, no. 3 (July 2003): 1335–43. http://dx.doi.org/10.1104/pp.103.021626.

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DARCAN, Cihan, and Önder İDİL. "THE EFFECT OF ANTİOXİDANTS AND PH ON PHOTOOXİDATİVE STRESS WİTH METHYLENE BLUE OF ESCHERICHIA COLI, S. AUREUS VE C. ALBICANS." Eskişehir Teknik Üniversitesi Bilim ve Teknoloji Dergisi - C Yaşam Bilimleri Ve Biyoteknoloji 10, no. 1 (January 25, 2021): 69–78. http://dx.doi.org/10.18036/estubtdc.632471.

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Hassan, A., Chen Qibing, Liu Yinggao, Jiang Tao, Guo Li, Mingyan Jiang, Li Nian, Lv Bing-Yang, and Liu Shiliang. "Do plants affect brainwaves? Effect of indoor plants in work environment on mental stress." European Journal of Horticultural Science 85, no. 4 (August 26, 2020): 279–83. http://dx.doi.org/10.17660/ejhs.2020/85.4.9.

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Motyleva, Svetlana, Nayalya Kozak, and Ludmila Kabashnikova. "Effect of drought stress on metabolite synthesis in Actinidia Arguta Leaves." BIO Web of Conferences 43 (2022): 01021. http://dx.doi.org/10.1051/bioconf/20224301021.

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In the context of global climatic changes, water stress, which causes drought, is one of the limiting factors affecting the environment and negatively affects the growth and development of cultivated plants. The stressful impact of dry conditions causes changes in the biochemical processes of plants. Herein, we studied the change in antioxidant activity, the amount of phenolic compounds and the peculiarities of the synthesis of some metabolites in Actinidia. argutа leaves, Taezhny Dar variety, under drought stress. All parameters were measured in leaves of control plants and after drought stress. Biennial plants were grown in separate pots and kept in an open area under a canopy to keep out the rain. Antioxidant activity and the amount of phenolic compounds were determined spectrophotometrically. Under conditions of moisture deficiency, the antioxidant activity and the amount of phenolic compounds in the leaves are higher than in the control. The composition of metabolites in the leaf extract was determined by gas chromatography-mass spectrometry. Under drought stress, changes in the synthesis of primary and secondary metabolites occur. In the leaves of control plants, 14 substances were identified, of which 6 are organic acids and 8 are carbohydrate substances. In the leaves of plants under drought stress, 37 compounds were recorded, that is, more than 2 times more than in the leaves of control plants, 23 substances of a carbohydrate nature were identified, including Myo-Inositol, which has antioxidant properties. The main carbohydrates in the leaves of the control plants of actinidia were turanose and mannobiose; under drought conditions, sucrose; its content increased 15 times in comparison with the control plants. The phenolic compounds Quininic acid and Caffeic acid are synthesized in the leaves of Actinidia arguta plants subjected to drought.

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Orhan, Cemal, Mehmet Tuzcu, Hasan Gencoglu, Emre Sahin, Nurhan Sahin, Ibrahim Hanifi Ozercan, Tejas Namjoshi, et al. "Different Doses of β-Cryptoxanthin May Secure the Retina from Photooxidative Injury Resulted from Common LED Sources." Oxidative Medicine and Cellular Longevity 2021 (February 10, 2021): 1–15. http://dx.doi.org/10.1155/2021/6672525.

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Retinal damage associated with loss of photoreceptors is a hallmark of eye diseases such as age-related macular degeneration (AMD) and diabetic retinopathy. Potent nutritional antioxidants were previously shown to abate the degenerative process in AMD. β-Cryptoxanthin (BCX) is an essential dietary carotenoid with antioxidant, anti-inflammatory, and provitamin A activity. It is a potential candidate for developing intervention strategies to delay the development/progression of AMD. In the current study, the effect of a novel, highly purified BCX oral formulation on the rat retinal damage model was evaluated. Rats were fed with BCX for four weeks at the doses of 2 and 4 mg/kg body weight in the form of highly bioavailable oil suspension, followed by retinal damage by exposing to the bright light-emitting diode (LED) light (750 lux) for 48 hrs. Animals were sacrificed after 48 hours, and eyes and blood samples were collected and analyzed. BCX supplementations (2 and 4 mg/kg) showed improvements in the visual condition as demonstrated by histopathology of the retina and measured parameters such as total retinal thickness and outer nuclear layer thickness. BCX supplementation helped reduce the burden of oxidative stress as seen by decreased serum and retinal tissue levels of malondialdehyde (MDA) and restored the antioxidant enzyme activities in BCX groups. Further, BCX supplementation modulated inflammatory markers (IL-1β, IL-6, and NF-κB), apoptotic proteins (Bax, Bcl-2, caspase 3), growth proteins and factors (GAP43, VEGF), glial and neuronal proteins (GFAP, NCAM), and heme oxygenase-1 (HO-1), along with the mitochondrial stress markers (ATF4, ATF6, Grp78, Grp94) in the rat retinal tissue. This study indicates that oral supplementation of BCX exerts a protective effect on light-induced retinal damage in the rats via reducing oxidative stress and inflammation, also protected against mitochondrial DNA damage and cellular death.

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Laman, N. A., K. R. Kem, V. I. Anikeev, V. N. Zhabinskii, and N. B. Khripach. "Features of the brassinosteroid effect on plants under salt stress." Doklady of the National Academy of Sciences of Belarus 66, no. 2 (May 6, 2022): 199–205. http://dx.doi.org/10.29235/1561-8323-2022-66-2-199-205.

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The dependence of the protective effect of brassinosteroids (BS) in a wide range of concentrations on the growth of the root system of fiber flax (Linum usitatissimum L.) and spring barley (Hordeum vulgare L.) seedlings under salt stress was studied. A narrow range of BS concentrations was revealed, in which they cause a weakening of the inhibitory effect of salinity on the root system of seedlings. An almost complete coincidence of the BS concentration ranges was noted, in which the maximum stress-protective effect of phytohormones was observed for the both crops (6,9 ⋅ 10–7–5,9 ⋅ 10–8 М for fiber flax and 2,8 ⋅ 10–7–2,4 ⋅ 10–8 М for spring barley). In the experiment with winter wheat (Triticum aestivum L.), which lasted 19 days, already on the 6th day before the seedlings were placed under stress conditions, the elongation of the seedlings treated with exogenous brassinosteroids was noted. By the end of the experiment (in the second leaf unfolding phase), all brassinosteroids showed a pronounced protective-stimulating effect under the salinity conditions that depended on the chemical structure of the hormone and changed in the brassinolide > homobrassinolide > homocastasterone > epibrassinolide series.

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Mohammed, Samar Jasim, Zainab Jassim Mohammed, and Israa Ibrahim Lazim. "An Update on The effect of water stress on plants." Plant Biotechnology Persa 4, no. 2 (December 1, 2022): 0. http://dx.doi.org/10.52547/pbp.4.2.9.

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Cordero, Irene, María Dolores Jiménez, Juan Antonio Delgado, Luis Balaguer, José J. Pueyo, and Ana Rincón. "Local adaptation optimizes photoprotection strategies in a Neotropical legume tree under drought stress." Tree Physiology 41, no. 9 (February 22, 2021): 1641–57. http://dx.doi.org/10.1093/treephys/tpab034.

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Abstract Photoprotection is a plant functional mechanism to prevent photooxidative damage by excess light. This is most important when carbon assimilation is limited by drought, and as such, it entails a trade-off between carbon assimilation vs stress avoidance. The ecological adaptation of plants to local water availability can lead to different photoprotective strategies. To test this, we used different provenances of Caesalpinia spinosa (Mol.) Kuntze (commonly known as ‘tara’) along a precipitation gradient. Tara is a Neotropical legume tree with high ecological and commercial value, found in dry tropical forests, which are increasingly threatened by climate change. Morphological and physiological responses of tara provenances were analysed under three different treatments of drought and leaflet immobilization, i.e., light stress, in a common garden greenhouse experiment. Tara quickly responded to drought by reducing stomatal conductance, evapotranspiration, photochemical efficiency, carbon assimilation and growth, while increasing structural and chemical photoprotection (leaflet angle and pigments for thermal dissipation). Leaflet closure was an efficient photoprotection strategy with overall physiological benefits for seedlings as it diminished the evaporative demand and avoided photodamage, but also entailed costs by reducing net carbon assimilation opportunities. These responses depended on seed origin, with seedlings from the most xeric locations showing the highest dehydration tolerance, suggesting local adaptation and highlighting the value of different strategies under distinct environments. This plasticity in its response to environmental stress allows tara to thrive in locations with contrasting water availability. Our findings increase the understanding of the factors controlling the functional ecology of tara in response to drought, which can be leveraged to improve forecasts of changes in its distribution range, and for planning restoration projects with this keystone tree species.

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Rai, Ashutosh Kumar, Ashutosh Prakash Dubey, Santosh Kumar, Debashis Dutta, Mukti Nath Mishra, Bhupendra Narain Singh, and Anil Kumar Tripathi. "Carotenoid Biosynthetic Pathways Are Regulated by a Network of Multiple Cascades of Alternative Sigma Factors in Azospirillum brasilense Sp7." Journal of Bacteriology 198, no. 21 (August 22, 2016): 2955–64. http://dx.doi.org/10.1128/jb.00460-16.

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ABSTRACTCarotenoids constitute an important component of the defense system against photooxidative stress in bacteria. InAzospirillum brasilenseSp7, a nonphotosynthetic rhizobacterium, carotenoid synthesis is controlled by a pair of extracytoplasmic function sigma factors (RpoEs) and their cognate zinc-binding anti-sigma factors (ChrRs). Its genome harbors two copies of the gene encoding geranylgeranyl pyrophosphate synthase (CrtE), the first critical step in the carotenoid biosynthetic pathway in bacteria. Inactivation of each of twocrtEparalogs found inA. brasilensecaused reduction in carotenoid content, suggesting their involvement in carotenoid synthesis. However, the effect ofcrtE1deletion was more pronounced than that ofcrtE2deletion. Out of the five paralogs ofrpoHinA. brasilense, overexpression ofrpoH1andrpoH2enhanced carotenoid synthesis. Promoters ofcrtE2andrpoH2were found to be dependent on RpoH2 and RpoE1, respectively. Using a two-plasmid system inEscherichia coli, we have shown that thecrtE2gene ofA. brasilenseSp7 is regulated by two cascades of sigma factors: one consisting of RpoE1and RpoH2 and the other consisting of RpoE2 and RpoH1. In addition, expression ofcrtE1was upregulated indirectly by RpoE1 and RpoE2. This study shows, for the first time in any carotenoid-producing bacterium, that the regulation of carotenoid biosynthetic pathway involves a network of multiple cascades of alternative sigma factors.IMPORTANCECarotenoids play a very important role in coping with photooxidative stress in prokaryotes and eukaryotes. Although extracytoplasmic function (ECF) sigma factors are known to directly regulate the expression of carotenoid biosynthetic genes in bacteria, regulation of carotenoid biosynthesis by one or multiple cascades of sigma factors had not been reported. This study provides the first evidence of the involvement of multiple cascades of sigma factors in the regulation of carotenoid synthesis in any bacterium by showing the regulation of a gene encoding geranylgeranyl pyrophosphate synthase (crtE2) by RpoE1→RpoH2→CrtE2 and RpoE2→RpoH1→CrtE2 cascades inA. brasilense. It also provides an insight into existence of an additional cascade or cascades regulating expression of another paralog ofcrtE.

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Jabeen, Dr Munifa, and Atiqa Jabeen. "Role of Compatible Solutes in Alleviating Effect of Abiotic Stress in Plants." International Research Journal of Education and Innovation 3, no. 1 (March 31, 2022): 141–53. http://dx.doi.org/10.53575/irjei.v3.01.14(22)141-153.

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Plants face assorted of abiotic stresses such as, salinity, drought and heavy metals which produce ROS, and finally inhibit normal growth plant production. To stop cellular destruction due to oxidative stress, these abiotic stresses increase complex reactions in plants to avoid damage and boost their sustainability under severe stress situations. Plants produce several organic solutes known as osmoprotectant such as, polyamines, sugars, proline and glycinebetaine (GB), to adjust the cellular mechanism and stable the membrane structure and proteins towards environmental stress. As well, they also defend the plant cells from oxidative stress by stopping the accumulation of damaging effect of ROS. In this review, we have deliberated the mechanisms of organic solutes as well as several functions in plants under abiotic stress situations. The organic solutes that are also known as osmolytes/osmoprotectants comprise soluble sugars, proline and glycinebetaine.

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Nigwekar, Ashok S., and Prakash D. Chavan. "The effect of water stress on nitrogen metabolism of horsegram Dolichos biflorus L." Acta Societatis Botanicorum Poloniae 59, no. 1-4 (2014): 73–80. http://dx.doi.org/10.5586/asbp.1990.007.

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Horsegram plants were raised in terule soil in earthen pots and subjected to various durations of water stress (7, 14 and 21 days). Total nitrogen contents were reduced in water-stressed plants but differently in different plant parts. Nitrate content and nitrate reductase activity decreased with stress. This species possesses a good capacity for accumulation of free proline under water stress. Analysis of amino acid composition also revealed marked changes in the levels of various amino acids in water-stressed plants. Accumulation of γ-aminobutyric acid in water-stressed plants was observed.

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Swearingin, Patricia. "The Effect of Salinity on Strawberry Stress and Growth on Two Soil Types." HortScience 30, no. 4 (July 1995): 912B—912. http://dx.doi.org/10.21273/hortsci.30.4.912b.

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Plants of strawberry (Fragaria × ananassa cv. Tristar) of the same size were grown in 4-inch plastic plots either containing sand or organic soil mix. Plants were watered with solutions of 10, 25, and 50 mM of NaCl, and some with distilled water used as control. Under sunny conditions, the chlorophyll fluorescence measurements indicated that plants growing in sandy soil with 50 and 25 mM of NaCI with Fv/Fm values less than 0.40 tend to show salinity stress after 10 days with 50 mM NaCI, and after 15 days with 25 mM NaCI. Plants grown in organic soil mix do not show stress symptoms at any of the given NaCI concentrations. Plants growing under cloudy days do not show stress symptoms, whether or not the plants were grown in sandy soil or organic soil mix. No significant differences were detected on the total average shoot and root dry weights of plants grown in sandy soils and organic soil mix. However, highly significant differences was detected on the total average shoot dry weight growing under organic soil mix. These data indicate that organic matter reduces the effect of Na+ and Cl– on strawberry plant growth by decreasing the physiological stress during bright, sunny days. Plant tissue analysis shows that plants grown in organic soil mix absorb far less Na+ and Cl– than in sandy soil. Also, it does seem that strawberry plants can tolerate low concentrations of NaCI ions in the soil solution.

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Dyki, Barbara, Jan Borowski, and Waldemar Kowalczyk. "Effect of copper deficiency and of water stress on the microstructure of tomato leaf surface." Acta Agrobotanica 51, no. 1-2 (2013): 119–25. http://dx.doi.org/10.5586/aa.1998.011.

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The reaction of tomato plants cv. Tukan F<sub>1</sub> to copper deficiency and to water stress was compared. Plants grown in copper deficiency and in conditions of water stress were significantly smaller than controls. They had also lower turgor. The epidermis cells of the upper side leaf in the plants growing in copper deficiency or water stress conditions were smaller than in control plants. However the stomata and trichomes number of leaves plants with copper or water deficiency grown were bigger in comparision with control. The pores of stomata were always larger in leaves of control plants than in other objects.

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Hao, Qianyi, Guangwang Zhang, Xilong Zuo, Ying He, and Hanlai Zeng. "Cia Zeaxanthin Biosynthesis, OsZEP and OsVDE Regulate Striped Leaves Occurring in Response to Deep Transplanting of Rice." International Journal of Molecular Sciences 23, no. 15 (July 28, 2022): 8340. http://dx.doi.org/10.3390/ijms23158340.

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The rice leaf color mutant B03S was previously generated from the photoperiod- and thermo-sensitive genic male sterile (PTGMS) rice line Efeng 1S, of which male sterility manifests by photoperiod and temperature but exhibits mainly temperature-sensitive characteristics. After these plants were deeply transplanted, the new leaves manifested typical zebra stripe patterns. Here, B03S was subjected to deep and shallow transplanting, shading with soil and aluminum foil, and control conditions in situ to determine the cause of the striped-leaf trait. The direct cause of striped leaves is the base of the leaf sheath being under darkness during deep transplanting, of which the critical shading range reached or exceeds 4 cm above the base. Moreover, typical striped leaves were analyzed based on the targeted metabolome method by ultra-performance liquid chromatography/tandem mass spectrometry (UPLC–MS/MS) combined with transcriptome and real-time quantitative PCR (qPCR)-based verification to clarify the metabolic pathways and transcriptional regulation involved. Carotenoids enter the xanthophyll cycle, and the metabolites that differentially accumulate in the striped leaves include zeaxanthin and its derivatives for photooxidative stress protection, driven by the upregulated expression of OsZEP. These findings improve the understanding of the physiological and metabolic mechanisms underlying the leaf color mutation in rice plants, enrich the theoretical foundation of the nonuniform leaf color phenomenon widely found in nature and highlight key advancements concerning rice production involving the transplanting of seedlings or direct broadcasting of seeds.

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Gupta, Sonal, and Ashwini A. Waoo. "Effect of salinity stress on phytochemical characteristics of Centella asiatica." Journal of Applied and Natural Science 14, no. 2 (June 18, 2022): 684–91. http://dx.doi.org/10.31018/jans.v14i2.3387.

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Salinity is one of the predominant abiotic stresses which affects plant growth by inducing excessive production of reactive oxygen species (ROS) that leads to oxidative damage of plant cells. Plants alleviate salinity stress by regulating intracellular concentrations of various phytochemicals like phenol, tannin, antioxidants, etc. The present work aimed to study the impact of salt stress on the production of various phytochemicals like phenol, tannin, flavonoids, antioxidants, total protein content, etc. The Salt stress response of the test plant Centella asiatica was studied by irrigating variant concentrations (50mM, 100mm, 150mm, 200mM, 250mm) of salt (NaCl). The phytochemical activity of the plants grown under salinity stress was estimated by using an appropriate biochemical assay. Comparative analysis of the photochemical activity of the test plants in comparison with the control revealed that various phytochemicals were increased in response to salt stress. Salt stress increased the levels of antioxidants from 10.79 to 14.31 μg/ml), phenol from 30.8 to 43.3 in μg/ml, flavonoids (from 490 to 683.33 in μg/ml), tannin from 55.5 to 64.5 in μg/ml, and proteins from 5720 to 6080 in μg/ml in the C. asiatica plants. To sum up, salt stress elicited phytochemical accumulation in the C. asiatica plant, thereby improving the plant's growth by enhancing its resistance to salt stress. This finding may play an important role in the sustainable cultivation of commercially important crops like C. asiatica.

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