Project description:Water soluble carbohydrates (WSC, composed of mainly fructans, sucrose, glucose and fructose) deposited in wheat stems are important carbon sources for grain filling. Variation in stem WSC concentrations among wheat genotypes is one of the genetic factors influencing grain weight and yield under water-limited environments. Here, we describe the molecular dissection of carbohydrate metabolism in stems, at the WSC accumulation phase, of recombinant inbred SB (Seri/Babax) lines of Triticum aestivum differing in stem WSC concentrations. Affymetrix GeneChip analysis of carbohydrate metabolic enzymes revealed that the mRNA levels of two fructan synthetic enzyme families (sucrose:sucrose 1-fructosyltransferase and sucrose:fructan 6-fructosyltransferase) in the stem were positively correlated with stem WSC and fructan concentrations, while the mRNA levels of enzyme families involved in sucrose hydrolysis (sucrose synthase and soluble acid invertase) were inversely correlated with WSC concentrations. Differential regulation of the mRNA levels of these sucrose hydrolytic enzymes in SB lines resulted in genotypic differences in these enzyme activities. Down-regulation of sucrose synthase and soluble acid invertase in high WSC lines was accompanied by significant decreases in the mRNA levels of enzyme families related to sugar catabolic pathways (fructokinase and mitochondrion pyruvate dehydrogenase complex) and enzyme families involved in diverting UDP-glucose to cell wall synthesis (UDP-glucose 6-dehydrogenase, UDP-glucuronate decarboxylase and cellulose synthase), resulting in a reduction in cell wall polysaccharide contents (mainly hemicellulose) in the stem of high WSC lines. These data suggest that differential carbon partitioning in the wheat stem is one mechanism that contributes to genotypic variation in WSC accumulation. We used Affymetrix GeneChip to dissect genotypic variation in carbohydrate metabolism related to water soluble carbohydrate accumulation in stems of wheat. Keywords: Genotypic differences in water soluble carbohydrate metabolism in stem
Project description:Fructans represent the major component of water soluble carbohydrates (WSCs) in the maturing stem of temperate cereals and are an important temporary carbon reserve for grain filling. Theoretically, genotypic variation in carbon reserve accumulation is determined by relative carbon availability and demand at the whole plant level. To evaluate the importance of source carbon availability in fructan accumulation and its associated molecular mechanisms, we performed comparative analyses of individual WSC components and the expression profiles of genes involved in major carbohydrate metabolism and photosynthesis in flag leaves of recombinant inbred lines derived from a cross between wheat cultivars Seri M82 and Babax (SB lines). High sucrose levels in the mature flag leaf (source carbon organ) were found to be positively associated with WSC and fructan concentrations in both the leaf and stem of SB lines in several field trials. Analysis of Affymetrix expression array data revealed that high leaf sucrose lines grown in abiotic-stress-prone environments had high expression levels of a number of genes in the leaf involved in the sucrose synthetic pathway and photosynthesis, such as Calvin cycle genes, antioxidant genes involved in the removal of chloroplast H2O2 and genes involved in energy dissipation. The expression of the majority of genes involved in fructan and starch synthetic pathways were positively correlated with sucrose levels in the leaves of these SB lines.
Project description:Water soluble carbohydrates (WSC, composed of mainly fructans, sucrose, glucose and fructose) deposited in wheat stems are important carbon sources for grain filling. Variation in stem WSC concentrations among wheat genotypes is one of the genetic factors influencing grain weight and yield under water-limited environments. Here, we describe the molecular dissection of carbohydrate metabolism in stems, at the WSC accumulation phase, of recombinant inbred SB (Seri/Babax) lines of Triticum aestivum differing in stem WSC concentrations. Affymetrix GeneChip analysis of carbohydrate metabolic enzymes revealed that the mRNA levels of two fructan synthetic enzyme families (sucrose:sucrose 1-fructosyltransferase and sucrose:fructan 6-fructosyltransferase) in the stem were positively correlated with stem WSC and fructan concentrations, while the mRNA levels of enzyme families involved in sucrose hydrolysis (sucrose synthase and soluble acid invertase) were inversely correlated with WSC concentrations. Differential regulation of the mRNA levels of these sucrose hydrolytic enzymes in SB lines resulted in genotypic differences in these enzyme activities. Down-regulation of sucrose synthase and soluble acid invertase in high WSC lines was accompanied by significant decreases in the mRNA levels of enzyme families related to sugar catabolic pathways (fructokinase and mitochondrion pyruvate dehydrogenase complex) and enzyme families involved in diverting UDP-glucose to cell wall synthesis (UDP-glucose 6-dehydrogenase, UDP-glucuronate decarboxylase and cellulose synthase), resulting in a reduction in cell wall polysaccharide contents (mainly hemicellulose) in the stem of high WSC lines. These data suggest that differential carbon partitioning in the wheat stem is one mechanism that contributes to genotypic variation in WSC accumulation. We used Affymetrix GeneChip to dissect genotypic variation in carbohydrate metabolism related to water soluble carbohydrate accumulation in stems of wheat. Experiment Overall Design: 8 genotypes of recombinant inbred lines Seri M82 x Babax with 2 biological replicates per genotype. Grown in the field under rain-fed conditions
Project description:Fructans represent the major component of water soluble carbohydrates (WSCs) in the maturing stem of temperate cereals and are an important temporary carbon reserve for grain filling. Theoretically, genotypic variation in carbon reserve accumulation is determined by relative carbon availability and demand at the whole plant level. To evaluate the importance of source carbon availability in fructan accumulation and its associated molecular mechanisms, we performed comparative analyses of individual WSC components and the expression profiles of genes involved in major carbohydrate metabolism and photosynthesis in flag leaves of recombinant inbred lines derived from a cross between wheat cultivars Seri M82 and Babax (SB lines). High sucrose levels in the mature flag leaf (source carbon organ) were found to be positively associated with WSC and fructan concentrations in both the leaf and stem of SB lines in several field trials. Analysis of Affymetrix expression array data revealed that high leaf sucrose lines grown in abiotic-stress-prone environments had high expression levels of a number of genes in the leaf involved in the sucrose synthetic pathway and photosynthesis, such as Calvin cycle genes, antioxidant genes involved in the removal of chloroplast H2O2 and genes involved in energy dissipation. The expression of the majority of genes involved in fructan and starch synthetic pathways were positively correlated with sucrose levels in the leaves of these SB lines. 8 genotypes of recombinant inbred lines Seri M82 x Babax with 2 biological replicates per genotype. Grown in the field under irrigated conditions.
Project description:To better understand the regulatory mechanisms of water stress response in wheat, the transcript profiles in roots of two wheat genotypes, namely, drought tolerant 'Luohan No.2' (LH) and drought susceptible 'Chinese Spring' (CS) under water-stress were comparatively analyzed by using the Affymetrix wheat GeneChip®. A total of 3831 transcripts displayed 2-fold or more expression changes, 1593 transcripts were induced compared with 2238 transcripts were repressed, in LH under water-stress; Relatively fewer transcripts were drought responsive in CS, 1404 transcripts were induced and 1493 were repressed. Comparatively, 569 transcripts were commonly induced and 424 transcripts commonly repressed in LH and CS under water-stress. 689 transcripts (757 probe sets) identified from LH and 537 transcripts (575 probe sets) from CS were annotated and classified into 10 functional categories, and 74 transcripts derived from 80 probe sets displayed the change ratios no less than 16 in LH or CS. Several kinds of candidate genes were differentially expressed between the LH and CS, which could be responsible for the difference in drought tolerance of the two genotypes.
Project description:To better understand the regulatory mechanisms of water stress response in wheat, the transcript profiles in roots of two wheat genotypes, namely, drought tolerant 'Luohan No.2' (LH) and drought susceptible 'Chinese Spring' (CS) under water-stress were comparatively analyzed by using the Affymetrix wheat GeneChip®. A total of 3831 transcripts displayed 2-fold or more expression changes, 1593 transcripts were induced compared with 2238 transcripts were repressed, in LH under water-stress; Relatively fewer transcripts were drought responsive in CS, 1404 transcripts were induced and 1493 were repressed. Comparatively, 569 transcripts were commonly induced and 424 transcripts commonly repressed in LH and CS under water-stress. 689 transcripts (757 probe sets) identified from LH and 537 transcripts (575 probe sets) from CS were annotated and classified into 10 functional categories, and 74 transcripts derived from 80 probe sets displayed the change ratios no less than 16 in LH or CS. Several kinds of candidate genes were differentially expressed between the LH and CS, which could be responsible for the difference in drought tolerance of the two genotypes. Two common wheat (Triticum aestivum L.) cultivars, Luohan No.2 (LH) and Chinese Spring (CS), were used for this study. Seedlings at the two leaf stage were stressed by cultured in PEG solutions for 6h, and some other seedlings were cultured in tap water as control. Root samples of LH and CS at 6h after the stress treatment and untreated control were prepared for microarray analysis.
Project description:Based on EST-based in silico gene expression analysis a 15k oligonucleotid microarray has been developped in order to monitor environmental stress-dependent gene expression changes in the wheat caryopsis. Using this array, the effect of water withdrawal, with and and without additional heat stress, during the first five days of grain development (0-5 DAA) has been investigated on two wheat cultivars differing in their drought sensitivity. The combined effect of heat and drought (DH) on gene expression was much significant (8-10% of the investigated genes changed >2-fold) in contrast to drought alone (1.5%). Drought and heat stress resulted in the co-ordinated change of the expression of storage proteins, some enzymes involved in sugar/starch metabolism, cell division-related and histone proteins, certain transcription factors, heat shock proteins, proteases and aquaporins. The potential link between the observed gene expression changes and the parallel histological observations indicating the accelerated development of the stressed grains is discussed.