Project description:Background: MicroRNAs regulate various biological processes in plants. Considerable data are available on miRNAs involved in the development of rice, maize and barley. In contrast, little is known about miRNAs and their functions in the development of wheat. In this study, five small RNA (sRNA) libraries from wheat seedlings, flag leaves, and developing seeds were developed and sequenced to identify miRNAs and understand their functions in wheat development. Results: Twenty-four known miRNAs belonging to 15 miRNA families were identified from 18 MIRNA loci in wheat in the present study, including 15 (9 MIRNA loci) first identified in wheat, 13 miRNA families (16 MIRNA loci) being highly conserved and 2 (2 MIRNAs loci) moderately conserved. In addition, fifty-five novel miRNAs were also identified. The potential target genes for 15 known miRNAs and 37 novel miRNAs were predicted using strict criteria, and these target genes are involved in a wide range of biological functions. Four of the 15 known miRNA families and 22 of the 55 novel miRNAs were preferentially expressed in the developing seeds with logarithm of the fold change of 1.0~7.6, and half of them were seed-specific, suggesting that they participate in regulating wheat seed development and metabolism. From 5 days post-anthesis to 20 days post-anthesis, miR164 and miR160 increased in abundance in developing seeds, whereas miR169 decreased, suggesting their coordinating functions in the different developmental stages of wheat seed. Moreover, eight known miRNA families and 28 novel miRNAs exhibited tissue-biased expression in wheat flag leaves, with the logarithm of the fold changes of 0.5~5.2. The putative targets of these tissue-preferential miRNAs were involved in various metabolism and biological processes, suggesting complexity of the regulatory networks in different tissues. Our data also suggested that wheat flag leaves have more complicated regulatory networks of miRNAs than developing seeds. Conclusions: Our work identified and characterised wheat miRNAs, their targets and expression patterns. This study is the first to elucidate the regulatory networks of miRNAs involved in wheat flag leaves and developing seeds, and provided a foundation for future studies on specific functions of these miRNAs.
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: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:Transcript changes in response to low temperature Total RNA for RNA-seq analysis were extracted from wheat leaf tissues with three biological replicates for each growth condition.
Project description:The Reduced Height (Rht) genes formed the basis for the green revolution in wheat by decreasing plant height and increasing productive tillers. There are two current widely used Rht mutant alleles, Rht-B1b and Rht-D1b. Both reduce plant height by 20% and increase seed yield by 5-10%. They are also associated with decreased seed size and protein content. Here we tested the degree to which Rht-B1b impacts flag leaf photosynthetic rates and carbon and nitrogen partitioning to the flag leaf and grain during grain fill under field conditions using near isogenic lines (NILs) that were either standard height (Rht-B1a) or semi-dwarf (Rht-B1b). The results demonstrate that at anthesis, Rht-B1b reduces flag leaf photosynthetic rate per unit area by 18% and chlorophyll A content by 23%. Rht-B1b significantly reduced grain protein beginning at 14 days post anthesis with the greatest difference seen at 21 days post anthesis (DPA) (12%). Rht-B1b also significantly decreased individual seed weight beginning at 21 DPA and by 15.2% at 28 DPA. Global expression analysis using RNA extracted from developing leaves and stems demonstrated that genes associated with carbon and nitrogen metabolism are not substantially altered by Rht-B1b. From this study, we conclude that Rht-B1b reduces flag leaf photosynthetic rate at flowering while changes in grain composition begin shortly after anthesis.
Project description:Differential gene expression analysis of RNASeq data from flag leaves from Triticum aestivm L. cv Thatcher at different time points and infection statuses upon infection with the leaf rust pathogen Pucinia triticina TBDG (11-180-1).