Dissertations / Theses on the topic 'Caryopse'

La fissuration correspond à une déchirure du péricarpe et de l'albumen des caryopses de mai͏̈s qui se produit au cours du développement et semble dépendre de facteurs environnementaux et génétiques. Le travail réalisé au cours de cette thèse représente la première étude visant à définir les causes de ce phénomène agronomique d'importance économique majeure. Pour caractériser le phénotype des caryopses fissurés ou sensibles à la fissuration, leurs propriétés biochimiques et biophysiques ont été évaluées par spectroscopie proche de l'infra-rouge et comparées à celles des caryopses sains et non sensibles. Le taux de protéines plus élevé dans les caryopses fissurateurs pourrait être utilisé comme un critère de prédiction de la sensibilité à la fissuration. Par ailleurs, l'acide abscissique a été dosé au cours du temps. L'augmentation du taux de cette hormone en fin de maturation dans les caryopses non sensibles n'est pas retrouvée dans les caryopses fissurateurs. Pour définir les facteurs environnementaux favorisant la fissuration, des caryopses de génotypes sensibles ont été cultivés in vitro dans différentes conditins de température et d'humidité. Des fissures ont été observées mais la variabilité des résultats n'a pas permis de mettre en évidence un effet significatif de ces paramètres. Une recherche de "quantitative trait loci" a révélé une forte héritabilité de la fissuration mais aucun locus d'importance majeure n'a été identifié. Des analyses d'expression différentielle par hybridation soustractive ont permis d'isoler deux amplicons spécifiquement exprimés dans des caryopses de génotype sensible dont l'un est homologue à un gène induit par l'acide abscissique. Un troisième amplicon, exprimé spécifiquement dans des caryopses de génotype sain, est partiellement homologue à des régulateurs de la transcription. Les trois gènes correspondants sont exprimés à la foi dans les caryopses et dans les tissus végétatifs.

La caractérisation, in vivo, de la matière première au cours de son développement, jusqu'à maturation, a été effectuée sur des variétés cultivées en champs dans les conditions agronomiques actuelles. L'étude de sa transformation en malterie a été menée sur des échantillons prélevés directement au cours d'un maltage industriel. Les techniques d'observation structurale et ultrastructurale ont permis de situer les amyloplastes dans leur environnement, au sein du caryopse : répartition cellulaire des différentes populations d'amyloplastes et matériel intersticiel et/ou adhérent. Ces techniques ont, par ailleurs, permis le suivi des modifications morphologiques intervenant au cours de la "germination" induite par le maltage. Ensuite, l'évolution du taux d'amidon, de l'amylose et de l'amylopectine a été suivie tout au long du développement du grain d'orge, de la maturation, puis au cours des étapes de maltage. Cette étude a été effectuée par dosage colorimétrique et adaptation de la chromatographie de perméation de gel. Enfin, on a déterminé la localisation des enzymes amylolytiques (alpha et beta-amylases) à des stades donnés du développement du grain d'orge et au cours des différentes étapes de sa transformation en malt

L'absorption et le devenir du triticonazole dans la plante de ble ont ete etudies de l'imbibition au stade gonflement, a partir de semences traitees avec du triticonazole-14c. Durant la phase d'imbibition de la semence, des quantites importantes de triticonazole penetrent dans le caryopse. Le produit se repartir dans les teguments et l'embryon et semble par la sutie etre peu transporte dans les parties aeriennes. De la levee au stade gonflement, le triticonazole est essentiellement absorbe par les racines et transporte dans les parties aeriennes par les vaisseaux du xyleme. Le produit se repartit dans les feuilles selon un gradient de concentration decroissant des etages foliaires inferieurs vers les etages foliaires superieurs. La concentration en triticonazole dans les parties aeriennes de la plante diminue fortement du stade 2-3 feuilles au stade gonflement. Cette dilution est due a la croissance vegetale et a la metabolisation de la matiere active dans les feuilles. De plus, le chargement de matiere active dans les parties aeriennes pourrait etre limite par la position du systeme racinaire par rapport a la zone de repartition du triticonazole dans le sol. La diminution de la concentration en matiere active dans les feuilles est probablement la cause de la baisse d'efficacite du triticonazole contre differentes maladies foliaires. Les possibilites de prolonger l'efficacite du triticonazole contre les maladies foliaires par une augmentation de la dose de traitement, par l'utilisation de l'enantiomere actif seul ou par un travail sur la formulation ont ete etudiees

Considerable research has been concentrated on the foliage application of Cycoce, whereas little attention has focused on its use in seed application. Imbibition of caryopses of wheat (Triticum aestivum L.) in (2-chloroethyl) trimethylammonium chloride (Cycocel/CCC) resulted in a reduction in germination rate and a stunting of seedling growth. This was consistent with the appearance of a thicker stem, with shorter leaves than the control. Chlorophyll content per unit weight of leaf and numbers of tillers initiated both increased in comparison to controls. However, Cycocel treatment was accompanied by an enhanced survival capacity of seedlings when they were subjected to water limitation under growth room conditions. Seedlings grown from caryopses imbibed in 0.4 % Cycocel and exposed to a 7-day cycle of watering remained green and turgid beyond the time when the controls had wilted and died. Seedlings, at the fourth leaf stage, showed no wilting 23 days after watering had been withheld totally. Enhanced survival was also noted in seedlings when caryopses had been imbibed in Cycocel for 24 hours followed by a period of dry storage for up to 2 weeks prior to sowing. Enhanced survival was also detected as a carryover into the tillers, and the subsequent GEN2 seedlings, derived from GEN1plants. Cycocel pre-treatment did not alter Stomatal Index to an extent which could lead to enhanced water use efficiency, nor to the accumulation of proline to bring compatible solutes into equilibrium. However, the pre-treatment with Cycocel was found to enhance growth as a counter to water stress, and maintained fresh and dry weight of shoots when examined under the polyethylene glycol (PEG) induced stress. At the anatomical level the microscopic investigation of the GEN2 leaf tissues, derived from GENl plant, revealed a fully turgid cell structure, cells did not collapse and tissues were not distorted after the extraction of chlorophyll when compared with the control of the continuous watering as well as the moderate watering regime. Additionally, the cortex of GENl plants derived from pre-treated caryopses, showed a bright fluorescing unidentified deposition under Nutrient Solution (NS). This was more much greater when sampled from the NS + PEG treatments. From the results achieved Cycocel pre-treatment of caryopses appeared to have potential in manipulating wheat plants against water limitation. However, the mechanism (s) by which this can be achieved was not fully resolved in this study. Further investigations are required at the biochemistry and molecular level, particularly in relation to potential carryover effects between generations.

Digitaria californica is a warm-season grass native to western hemisphere deserts. This study was conducted to measure: (1) seed dormancy, and the effects of (2) wetting and drying on germination, and (3) glumes on water uptake and loss. Dormancy was measured with weekly germination trials for 12 weeks. Complete and naked caryopses were exposed to a 24-h dry period after 12, 24, 36, and 48-h imbibition, and rewetting for 2 weeks. Water uptake and loss patterns were also measured. Germination percentage increased from about 40% initially to 94% after 9 weeks. Germination speed decreased from 5 days to about 2 days over the same period. Drying reduced percent germination of the 36- and 48-h imbibition treatments for complete caryopses, and that of the 24-, 36-, and 48-h imbibition treatments for naked caryopses. Complete caryopses also seemed to imbibe faster. Moisture loss for complete and naked caryopses appeared similar. Short imbibition periods do not induce germination in this species.

La valeur semouliere des bles durs (triticum durum desf. ) reste souvent definie par connaissance empirique. La comprehension des bases de la fragmentation et du fractionnement du grain, et la maitrise des effets des facteurs agronomiques et genotypiques sur ces aspects etaient les objectifs de ce travail. Les facteurs intrinseques de la valeur semouliere mis en evidence sont : le rapport albumen sur enveloppes, la resistance mecanique de l'albumen amylace et l'aptitude a dissocier les parties peripheriques du grain de l'albumen amylace. La valeur semouliere est influencee par le genotype, par les traitements agronomiques (stress azote ou hydrique), et plus faiblement, par le lieu de culture et l'annee de recolte. Elle peut donc representer un objectif de selection. Le rapport albumen sur enveloppes, dont rendent compte la section et la surface du grain, s'est revele sensible au genotype et aux traitements agronomiques. A taille de grain egale, des differences significatives de comportement en mouture entre les varietes ont ete enregistrees. Plus qu'une notion de taille de grain, il semble judicieux de parler de conformation (sphericite, profondeur du sillon. . ). La mise au point d'un micromoulin permettant l'enregistrement de l'energie de broyage, a permis de suivre le comportement a la fragmentation des grains. Les indices de broyabilite prenant en compte l'energie de broyage et la reduction granulometrique sont les meilleurs predicteurs de la valeur semouliere. Cette etude a debouche sur la mise au point d'un microtest. La fractionnabilite, etudiee au niveau tissulaire et cellulaire semble etre en relation avec la teneur en composes phenoliques, et plus particulierement, en acides ferulique et diferulique. Des methodes de dosage par clhp et microspectroflurimetrie ont ete developpees. L'heterogeneite de repartition en ces composes au niveau des parois de la cellule de la couche a aleurone a ete demontree et semble liee a la plus ou moins grande aptitude au fractionnement.

碩士
國立成功大學
生命科學系碩博士班
96
Economically grasses are the most important plant family, in addition, they are the widely distributed group of vascular plants and have an extraordinary range of adaptation. In the grass family (Poaceae), the genus Digitaria are numerous and widely distributed in Taiwan. Fifteen taxa including fourteen species and two varieties are recognized, and are a difficult taxonomic group. The caryopsis morphology and seedling leaf anatomy of these taxa were studied by microscopy, and these data were entered as a DELTA database and then the cluster analysis was conducted by UPGMA and PCO. In general, the caryopsis are oblong-ovate, and the embryo are longer then 1/3 length of the caryopsis. Meanwhile, the punctuate hilium are 1/10~2/10 length of the caryopsis. There are some differences in the length of caryopsis and the ratios of length to width of the caryopsis. Their first leaves are horizontal or ascendant, and the shapes are various (oblong, oblong-lanceolate, lanceolate). The ratios of length to width of the first leaf are usually smaller than 7. The characters of leaf cross section are basically the same. However, there are some differences in the leaf lower epidermis especially the length of long cells, stomata, and macrohairs, etc. when measured.The results show the caryopsis morphology and seedling leaf anatomy characters are useful for species identification in the genus Digitaria in Taiwan. A key to species of the genus Digitaria in Taiwan is made based on the characteristics of caryopsis morphology and seedling leaf anatomy.

碩士
國立臺灣大學
農藝學研究所
100
Temperature stress impacts grain quality and yield in grain-filling stage of rice. Ethylene manipulation during heading stage of rice correlates positively with chalkiness. In this study, rice cultivar TK9 was used as experimental material. After flowering, the flowering rice plants were moved to growth chamber for temperature treatments (20, 25 and 35 oC) for 15 days. In order to understand the regulatory mechanism between ethylene and temperature treatments, GC was utilized to analysis the ethylene evolution rate in the temperature treatment phase. Mature grain quality and storage content and physiologic responses of the developing grain were investigated. Real-time quantitative PCR was further utilized as a tool to realize the responses of the gene expression involved in related physiological processes. In appearance of the grain quality analysis, high temperature defected grain quality. Poor grain quality, grain weight reducing and lower storage contents were occurred by high temperature. Superior spikelets had higher grain weight and better quality than inferior spikelets. The percentage of sterility spikelets was the highest at low temperature treatment. In physiologic analysis, including chlorophyll, H2O2, and ATP assays, high temperature increased H2O2 accumulation and chlorophyll degeneration and also decreased ATP concentration, but low temperature had opposite results. Both high and low temperatures caused acidification and cell death. In ethylene evolution rate analysis, both high and low temperatures accelerated ethylene evolution peak, and inferior spikelets had higher amount of ethylene evolution than superior spikelets. In gene expression analysis, high temperature restrained the gene expressions of starch synthesis enzymes, protein synthesis enzymes, anti-oxidation enzymes and PDHA3, and it as well increased the gene expressions of ADH and PAO. Compared with high temperature, low temperature delayed the time of the gene expressions of starch synthesis enzymes and protein synthesis enzymes. Genes involved in ethylene synthesis and ethylene transcription factors all induced at the early stage of developing caryopsis under high temperature. Treatment of high temperature (35 oC) with 1-aminocyclopropane-1-carboxylate (AOA) increased the content of starch and protein, grain weight and the percentage of perfect grains. Treatment of normal temperature (25 oC) with 1-aminocyclopropane-1-carboxylate (ACC) decreased yield and the appearance quality. These results revealed that temperature stress influence physiological pathways by ethylene, and the inhibition of ethylene synthesis can improve the appearance quality and grain yield at the early grain-filling stage.

碩士
國立臺灣大學
農藝學研究所
103
Rice chalky grain formation under high temperature is known to be related to the metabolic alteration under stress. Internal oxygen concentration is crucial for maintaining energy balance for starch, protein, and lipid assimilations during rice grain development. Documents revealed that hypoxia metabolism may occur in developing endosperm under high temperature. Therefore, it has hypothesized that internal oxygen level might be correlated with the chalkiness formation of rice grain under high temperature. However, no method for measuring internal oxygen concentration in rice grain has been developed in the world so far. Thus, the aim of the present study was to establish possible methods for measuring oxygen level in developing rice grain, and hope to clarify the relationship between oxygen concentration and grain chalkiness formation under high temperature. A high quality cultivar Tai-keng 9 (TK 9) was used as material which were exposed to high temperature (35 oC) or control temperature (25 oC) treatment during the grain-filling stage . Caryopsis samples were collected at different development stages base on the cumulative temperature after flowering. In this research, a planar oxygen sensor (PreSens, Germany) was used to measure internal oxygen of caryopsis and an oxygen microsensor (PreSens, Germany) was used to verify the value of oxygen concentration. The results showed that oxygen concentration of caryopsis decreased from external to internal at every grain-filling stage, that is, it is hypoxia at central endosperm. At the same time, caryopsis oxygen concentration under high temperature seemed to be lower than the control, although it didn’t show statistically significant difference. Due to the high time consuming for the oxygen measurement of rice caryopsis, the number of experimental replicate was very much limited; which would lead a large measurement variation at the present study. In summary, the present study has established the method of measuring internal oxygen concentration in developing rice caryopsis, and showed the preliminary results about the change of oxygen concentration at different stages. In the future, the method can be modified and improved to understand the relationship among internal oxygen level, metabolism process, and grain quality formation, especially under stressful environments.

博士
國立臺灣大學
農藝學研究所
93
Chapter 1 Proteins are essential to rice caryopsis development and quality formation. High temperature is an important environmental factor which may decrease grain quality. In the present study rice caryopsis proteins were profiled by two-dimensional polyacrylamide gel electrophoresis, and differentially expressed proteins were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Expressions of more than 400 polypeptide spots during caryopsis development, in response to temperature treatments or between varieties were monitored. Among them, more than 70 differentially expressed polypeptides were analyzed by LCMSMS and 54 proteins were identified with known functions. Of these, 21 were involved with carbohydrate metabolism, 14 with protein synthesis and sorting, and 9 with stress responses. Waxy (Wx) proteins and glutelins were the most prominous spots increased significantly during development. Allergen-like proteins, pyruvate orthophosphate dikinase and NADH-dependent sorbitol dehydrogenase, were also expressed during development, implying their physiological roles in caryopsis. Expression of large isoforms of Wx proteins was correlated with the amylose content of rice caryopsis. One protein with high GC content in its DNA sequence was correlated with the chalky trait of kernels. High temperature (35/30 ℃) decreased expression of Wx proteins, allergen-like proteins and elongation factor 1 β, but increased expression of small heat shock proteins (sHSP), glyceraldehyde-3-phosphate dehydrogenase and prolamin. The level of sHSP was positively correlated with the appearance of chalky kernels. During development, glutelins were phosphorylated and glycosylated, indicating these molecules were post-translationally modified. Possible functions of the expression of candidate proteins on grain quality are discussed. In addition, the expression of related genes at the RNA level were also monitored by RT-PCR. Chapter 2 Temperature is a major environmental factor on grains quality formation. High temperature may reduce rice grains quality. The components of starch and proteins are the other factors to influence the grain quality of rice. Under temperature influences, the final grain quality of caryopsis is determined by the physiological responses of biochemical processes and dry mass accumulation during caryopsis development. The present study focused on the relationship between the effects of high temperature on gene expression profilings and grain quality formation during developmental stages in rice caryopsis. The result of thermo-images analysis showed that rice panicles or grains dissipated heat slowly as compared to other organs, implying that rice panicles may be more sensitive and vulnerable to high-temperature environment. High temperature leads to decrease in panicle weight, filled spikelets rate, thousand spikelets weight and grains yield; produced sever chalky appearance kernels on panicles. High temperature influenced endosperm cell differentiation and reduced DNA endoreduplication. In japonica type rice, high temperature also resulted in lower amylose and protein contents. In grain physical chemical properties, high temperature decreased viscosity but increased pasting temperature and gel consistency of brown rice flour. At molecular basis, high temperature reduced the expression of GBSS in Japonica rice varieties; as TNG67, however, high temperature enhanced starch synthase II gene expression in Indica rice varieties, as TN1. Either the decrease of GBSS or increase of starch synthase II would lead to a lower amylase ratio in rice grains. Prolamins contents declined in mature rice grains of all three cultivars grown at high temperature. However, the effects of high temperature on storage proteins were different with varieties. The changing in amylose and protein contents may cause the observed negative effect of physical chemical characteristics of the rice flour. In addition, high temperature could enhance the proteins expression of 16.9c HSP, 17.9 HSP, 18 HSP, glyceraldehyde-3- phosphate dehydrogenase and elongation factor 1 beta, while reduced the expression of nucleotide diphosphate kinase and allergen-like proteins. Based on the present results, high temperature caused a complex physiological and metabolic responses related to starch and protein accumulation and packing in rice grains. Thus resulted in defective quality of rice grain. A schematic model has been proposed to depict the influence of high temperature on grain quality formation in rice.

博士
國立臺灣大學
農藝學研究所
101
The chalkiness of rice grain is a primary defect under high temperature stress. The building of chalky endosperm was a result of low energy status, high oxidative stress, high endosperm acidification, and high ethylene evolution within caryopsis developing under high temperature. To gain insight into the mechanisms caused the physiological and biochemical changes, the expression profiles of miRNAs under high temperature in the developing caryopsis of TK9 were studied by microarray analyses. TK9 (Oryza sativa L. Japonica cv. Taiken 9) is a heat sensitive rice variety having a higher ratio of chalky grain under high temperature. After verified by qRT-PCR (real-time quantitative reverse transcriptase-polymerase chain reaction), thirty six miRNAs were confirmed to respond to high temperature. Compared the chromosomal locations of potential miRNA targets with that of QTLs (quantitative trait loci) related to the buildup of chalky endosperm, thirty out of 81 potential target genes were confirmed to be separately down-regulated by 17 miRNAs. Under high temperature, at 6- to 9-day caryopsis, two miRNAs, miR812 and miR818, were induced, while their predicted target genes, citrate carrier and pex14, showed expected inverse patterns. The decreased expressions of citrate export (citrate carrier) from mitochondria and pex14 may result in improved TCA cycle and reduced function of peroxisome, respectively. Moreover, the transcriptomes of a high temperature resistant mutant, SA1737, and its corresponding wild type, TNG67 (Oryza sativa L. Japonica cv. Tainung 67) was profiled by DNA microarray analyses. In total, 6,009 genes having significantly different expression levels were detected in compare with high temperature. 7 of them are the putative target genes of 5 miRNAs. These miRNAs in TK9 involving in responsiveness to high temperature indicated that miRNAs may have a regulatory role in the development of chalky grain upon high temperature. LON protease was a predicted target of siR806, suppression of LON protease in SA1737 suggested inhibition of proteolysis within mitochondria was crucial for the resistance to high temperature in developing caryopsis. LPP3 (lipid phosphate phosphatase 3), the enzyme catalyzed the dephosphorylation of PA (phosphatidic acid) was predicted to be a regulatory target of miR319. Suppression of LPP3 and accumulation of PA in TNG67 could activate ethylene signaling pathway under high temperature. In addition, two genes (pyruvate kinase and alcohol dehydrogenase) involved in energy metabolism were examined in TK9. Both genes were co-regulated under high temperature, indicating that the energy production in developing caryopsis has been switched to the anaerobic pathway. Furthermore, to test whether ethylene accumulation in the developing caryopsis is related to the endosperm acidification and chalky occurrence under high temperature, an inhibitor of ethylene production (AgNO3) was applied to the developing caryopses of TK9 plants. As expected, the level of endosperm acidification and the ratio of chalky occurrence were reduced under high temperature. In this study, we identified miRNA-mediated regulations that responded to high temperature in developing rice grain. The data shed light on transcriptional gene regulations in chalky grain development under high temperature. The information obtained here could further be used by breeders to develop potential strategies for breeding heat-tolerant rice cultivars.

Molecular genetic analyses focused on selected aspects of technological quality were carried out on 25 wheat genotypes with non-standard coloured caryopses. Occurrence of null alleles was observed for the GBSSI gene responsible for amylose synthesis, the so-called waxy gene. Null allele Wx-B1 was found in 20 % of the genotypes, other null alleles were not observed. Allelic state of Pina and Pinb genes affecting caryopsis hardness was analysed too. Allele identification of three genotypes was not successful. In the Pina case, only the wild-type allele Pina-D1a was present, in the Pinb wider variability was observed, 36 % of the genotypes carried wild-type Pinb-D1a allele, 40 % carried Pinb-D1b allele and 12 % Pinb-D1d allele. Instrumental hardness was measured and it correlated with the detected allelic state. Caryopses texture was determined based on the laser beam transmission through the caryopsis. Occurrence of mealy caryopses ranged from 0 % to 100 %. Caryopsis texture and hard-ness do not correlate neither on the instrumental nor on the genetic basis. Null allele Wx-B1 occurrence did not influence the caryopsis hardness nor their texture. Partial sequences of F3H a DFR structural genes of the anthocyanin biosynthetic pathway were obtained at five genotypes with blue, purple and white caryopses. Single nucleotide polymorphisms among individual gene copies were observed.