Possible chromosomal location of genes determining the osmoregulation of wheat (original) (raw)
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Different Accumulation of Free Amino Acids during Short- and Long-Term Osmotic Stress in Wheat
The Scientific World Journal, 2012
The effect of wheat chromosome 5A on free amino acid accumulation induced by osmotic stress was compared in chromosome 5A substitution lines with different freezing tolerance. Treatment with 15% polyethylene glycol (PEG) resulted in greater total free amino acid content even after 3 days compared to the controls. The ratio of amino acids belonging to various amino acid families differed after 3-week treatment in the control and PEG-treated plants only in the case of the freezing-sensitive substitution line. There was a transient increase with a maximum after 3 days in the amounts of several amino acids, after which their concentrations exhibited a more gradual increase. During the first days of osmotic stress the Glu, Gln, Asp, Asn, Thr, Ser, Leu, and His concentrations were greater in the tolerant substitution line than in the sensitive one, while the opposite relationship was observed at the end of the PEG treatment. The coordinated changes in the levels of individual amino acids indicated that they are involved in both the short-and long-term responses to osmotic stress. The alterations differed in the two chromosome 5A substitution lines, depending on the stress tolerance of the chromosome donor genotype.
Environmental and Experimental Botany, 2007
Several genes affecting abiotic stress tolerance are located on chromosome 5A of wheat. The objective of this study was to determine the regions of the 5A chromosome, which control the salt tolerance and accumulation of free amino acids and polyamines. For this purpose, three deletion lines, 5AL-20, 5AL-8, 5AL-10, lacking increasingly large sections of chromosome 5A from the moderately salt-tolerant Triticum aestivum cv. Chinese Spring (CS) were compared. Treatment with NaCl resulted in a significantly greater decrease in fresh weight in the deletion lines than in CS. The amino acid composition was affected by both salt treatment and chromosome deletions. Among the most abundant amino acids, the relative amount of Gaba was greater in CS, while that of glutamate was greater in the deletion lines under control conditions. This difference was also observed after salt stress in the case of glutamate. Consequently, the absolute amount of glutamate was also higher in the deletion lines than in CS under both control and stress conditions. Chromosome deletions also affected the arginine, proline, valine and lysine levels. Following 100 mM NaCl treatment the putrescine and spermidine contents were lower in the deletion lines compared to the CS, while 200 mM NaCl resulted in higher putrescine content. Chromosome regions affecting amino acid and polyamine levels could be determined in the present genetic system. The distal part of the chromosome 5A may be involved in the control of salt tolerance through the regulation of Glu levels.
Molecular mapping of genomic regions associated with wheat seedling growth under osmotic stress
Biologia Plantarum, 2008
A quantitative trait loci (QTL) approach was applied to dissect the genetic control of the common wheat seedling response to osmotic stress. A set of 114 recombinant inbred lines was subjected to osmotic stress from the onset of germination to the 8th day of seedling development, induced by the presence of 12 % polyethylene glycol. Root, coleoptile and shoot length, and root/shoot length ratio were compared under stress and control conditions. In all, 35 QTL mapping to ten chromosomes, were identified. Sixteen QTL were detected in controls, 17 under stressed conditions, and two tolerance index QTL were determined. The majority of the QTL were not stress-specific. In regions on five chromosome arms (1AS, 1BL, 2DS, 5BL and 6BL) the QTL identified under stress co-mapped with QTL affecting the same trait in controls, and these were classified as seedling vigour QTL, in addition to those expressed in controls. Tolerance-related QTL were detected on four chromosome arms. A broad region on chromosome 1AL, including five QTL, with a major impact of the gene Glu-A1 (LOD 3.93) and marker locus Xksuh9d (LOD 2.91), positively affected root length under stress and tolerance index for root length, respectively. A major QTL (LOD 3.60), associated with marker locus Xcdo456a (distal part of chromosome arm 2BS) determined a tolerance index for shoot length. Three minor QTL (LOD < 3.0) for root length and root/shoot length ratio under osmotic stress were identified in the distal parts of chromosome arms 6DL (marker locus Xksud27a) and 7DL (marker locus Xksue3b). Selecting for the favourable alleles at marker loci associated with the detected QTL for growth traits may represent an efficient approach to enhance the plants’ ability to maintain the growth of roots, coleoptile and shoots in drought-prone soils at the critical early developmental stages.
PLOS ONE, 2015
High temperature (HT, heat) stress is detrimental to wheat (Triticum aestivum L.) production. Wild relatives of bread wheat may offer sources of HT stress tolerance genes because they grow in stressed habitats. Wheat chromosome translocation lines, produced by introgressing small segments of chromosome from wild relatives to bread wheat, were evaluated for tolerance to HT stress during the grain filling stage. Sixteen translocation lines and four wheat cultivars were grown at optimum temperature (OT) of 22/14°C (day/night). Ten days after anthesis, half of the plants were exposed to HT stress of 34/26°C for 16 d, and other half remained at OT. Results showed that HT stress decreased grain yield by 43% compared with OT. Decrease in individual grain weight (by 44%) was the main reason for yield decline at HT. High temperature stress had adverse effects on leaf chlorophyll content and Fv/Fm; and a significant decrease in Fv/Fm was associated with a decline in individual grain weight. Based on the heat response (heat susceptibility indices, HSIs) of physiological and yield traits to each other and to yield HSI, TA5594, TA5617, and TA5088 were highly tolerant and TA5637 and TA5640 were highly susceptible to HT stress. Our results suggest that change in Fv/Fm is a highly useful trait in screening genotypes for HT stress tolerance. This study showed that there is genetic variability among wheat chromosome translocation lines for HT stress tolerance at the grain filling stage and we suggest further screening of a larger set of translocation lines.
Genotype Dependent Adaptation of Wheat Varieties to Water Stress in vitro
Journal of Plant Physiology, 1989
Callus cultures of four varieties of hexaploid wheat (Triticum aestivum L.) were maintained on media containing various concentrations of mannitol. The induced osmotic stress inhibited growth and increased the percent dry matter and the level of free amino acids of the calli. Bigger changes were observed in drought sensitive «<Cappelle Desprez») and moderate resistant «<Chinese Spring») varieties than in drought resistant ones «<Saberbeg» and «Plainsman»). The putrescine content was highly increased in the drought sensitive variety. The cadaverine level was enhanced during osmotic stress in the drought sensitive and in one of the drought resistant varieties. The extractable protein content was decreased in drought sensitive and in moderate resistant varieties. During osmotic stress the aminopeptidase and carboxipeptidase activity increased significantly in the drought sensitive variety. Endopeptidase activity was low in all samples and no correlation was found between its activity and osmotic stress.
The aim of the present work is to provide information for the establishment of gene bank and to obtain comparative data for the new transgenic lines to be established in a later stage of this project. For revealing traits for drought tolerance, wheat species of different ploidy levels and hexaploid cultivars of different stress tolerance were chosen. For gene isolation the osmotic stress resistant Triticum aestivum L. cv. Kobomugi, and the sensitive cv. Öthalom were chosen. Osmotic treatment was administrated using PEG 6000 at a final concentration of 400 mOsm (19.0%). Significant differences were found between the two cultivars in carbohydrate accumulation, in changes in water relation and chlorophyll fluorescence parameters measured in vivo. It is suggested that cv. Kobomugi may be a useful source for isolation of drought tolerance-related genes.
Comparison of physiological effects of osmotic stress on two wheat genotypes
Botanica, 2021
Revealing stress tolerance mechanisms in plants would contribute to the selection of crop varieties with a higher capacity for surviving in unfavourable environments. In this regard, it is essential to identify possible physiological features that might be beneficial for increasing plant resistance to stress. Two contrasting common wheat (Triticum aestivum L.) cultivars with different drought tolerance were subjected to 48 h treatment with 20% polyethylene glycol 8000, which provoked an extra degree of osmotic and oxidative stress as well as distinct physiological responses. Better water retention capacity in leaves and lesser extent of membrane injury found in cultivar ‘Guinness’ compared to cultivar ‘Niki’ correlated with increased osmotic adjustment by accumulating higher amounts of proline and higher antioxidant scavenging capacity in the former. Compared to soluble sugars and total free amino acids, proline contributed to a greater extent to preserving leaf water. It was specul...
Acta Physiologiae Plantarum, 2011
A series of substitution lines of variety 'Timstein' (Tim) into genetic background of Chinese Spring (CS) were used in this study. Analysis of variance indicated that significant differences exist among the substitution lines for all the traits under study except stomatal width (SW) in the water-stressed condition and stomatal length, and photosynthesis rate (PR) in the well-watered experiment. Correlation analysis indicated that PR and stomatal conductance (SC) were most important in affecting yield under the both experiments. Chromosomal analysis indicated that grain weight was affected by many chromosomes as it was expected due to its complexity under both well-watered and water-stressed conditions. In well-watered experiment, no substitution line was significantly different from recipient variety for PR. Despite results in well-watered experiment, chromosomes 3A, 3B, 4B, and 3D from variety Timestin increased PR when substituted into variety CS under the water-stressed experiment. In well-watered experiment, chromosome 7D of variety Timetin had the main effect on increasing SC, and chromosome 1A had a diverse effect on this character when substituted into recipient variety. However chromosomes 3A, 3B, 4B, and 1D of Timestin increased SC under water-stressed conditions. It was also revealed that in general the chromosomes expressed their independent effects on the characters regardless of environment. Nonetheless, some chromosomes indicated similar effects under the two conditions. Among them, chromosome 1A of Timestin reduced yield, chromosomes 2B, 7B, and 5D increased the amount of grain yield, and chromosome 1D increased SC under both conditions.
Identification of Stress Responsive Genes by Using Molecular Markers to Develop Tolerance in Wheat
Springer Nature Singapore, 2019
Global climate change, which is rising steeply in the world today, has caused further increases in the influence of abiotic stress factors. Abiotic stresses such as drought, high salinity, and high temperatures are common detrimental environmental circumstances that extremely influence growth, cultivation, and productivity worldwide. Traditionally, the varietal selection is based on morphological feature; hence, polygenic characters were very difficult to analyze, and thus such constraints can be overcome by using molecular marker-assisted selection (MAS). As markers are currently available for relatively few traits, MAS must be integrated with the ongoing conventional breeding to maximize its impact. Molecular markers are useful tools to determine the variation in the DNA sequence and eventually the regions of DNA or the genes controlling the qualitative and/or quantitative traits of agronomic significance. The aim of the presented research was to detect the genes and gene loci responsible for the tolerance to salt stress, drought, and high temperatures in wheat using various molecular markers. Wheat genotypes with contrasting stress tolerance, architectonics, productivity, and other physiological traits kept in the gene fund of the Research Institute of Crop Husbandry were used as research objects. Plants were cultivated in the Absheron experimental base under natural conditions (Baku, Azerbaijan). Salt tolerance potential of wheat genotypes was examined genetically based on PCR analysis using various molecular markers associated with salt tolerance. According to the results of the molecular analysis performed with RAPD (OPZ 09) markers linked with salt tolerance, expected 590 bp DNA fragments were amplified in 39% of bread wheat and 27% of durum wheat genotypes. At the same time, salt tolerance gene Nax1 was examined with gwm312 primer in durum wheat genotypes. An expected 200 bp amplicon indicating the existence of this gene in the Barakatli 95, Garabag, Shiraslan 23, Sharg, and Gyrmyzy bugda genotypes was successfully amplified. This amplicon was also synthesized in Barakatli 95, Garabag, Shiraslan 23, and Gyrmyzy bugda genotypes using wmc170 primer linked to salt tolerance locus in durum wheat genotypes. The study of physiological senescence of the flag leaf playing the pivotal role in the uptake of solar energy and stipulating plant productivity in wheat is very important for providing high productivity under stress. Therefore, using RAPD OPH13 marker, the existence of a gene locus linked to the physiological life-span of flag leaf was examined in wheat genotypes under drought stress. Based on the analysis of electrophoretic profiles of PCR results, expected 450 bp fragments were synthesized in 30 wheat genotypes. This result confirms the existence of a gene locus providing the physiological youth of flag leaf, which is considered as the drought tolerance indicator in these genotypes. The existence of the studied locus was not confirmed in 19% of the genotypes. Tolerance to heat stress is a complex phenomenon and controlled by multiple genes imparting a number of physiological and biochemical changes. To differentiate the heat-tolerant and heat-susceptible genotypes of wheat, a heat shock protein (HSP16.9) was taken as a target gene, and domestic genotypes were examined using allele-specific PCR primers. The obtained results can be used in wheat breeding programs for developing wheat varieties tolerant to stresses.
Studies on Resistance to Biotic and Abiotic Stresses in Wheat
2016
remain in my heart. I am deeply grateful to my co-supervisor Dr. Urmil Bansal for her incredible guidance and edifying training and suggestions during the course of the research. I am truly indebted to her detailed training and assistance in conducting the molecular research and for her constant advises and counselling during the course of my studentship. My deepest gratitude goes to associate-supervisor Assoc. Prof. Margaret Barbour for professional assistance and implausible training, guidance and support in conducting the physiology experiments. My thoughtful thanks also go to Dr. Peng Zhang for her professional help and guidance in molecular cytology. I also extend my gratefulness to National Agricultural Research Organisation of Uganda for awarding me the scholarship and Grains Research and Development Corporation (GRDC) for funding part of my research. I am forever grateful to Dr. William Wagoire for believing in me and for strongly supporting my bid for further studies. I cherish your professional and parental guidance during the time we worked together and during the course of my PhD study. My special thanks to Emeritus Prof. Robert McIntosh for giving valuable time to discuss my results and suggesting valuable information during the study. My sincere appreciation goes to Profs. Robert Park and Peter Sharp for their advice when I was applying for my PhD program at University of Sydney. I express my cordial thanks to my fellow students and friends