Probing early wheat grain development via transcriptomic and proteomic approaches.

To understand the molecular changes taking place during the early grain development in common wheat, we profiled transcriptome and proteome of two cultivars, "P271" and "Chinese Spring" (CS) with large and small grains, respectively. More than 85,000 genes and 7500 proteins were identified to express during early grain development in two wheat cultivars. We observed enrichment in the number of genes falling in the functional categories-carbohydrate metabolism, amino acid metabolism, lipid metabolism, and cofactor as well as vitamin metabolism with progression in grain development, which indicates towards the importance of these metabolic pathways during grain maturation. Many genes showed inconsistency between transcription and translation, which suggested a role of post-transcriptional events that determine the fate of nascent transcript/protein, in the early grain development. In silico localization of differentially expressed genes/proteins between CS and P271 to wheat chromosomes, exhibited a biased genomic distribution with chromosomes 1A, 4B, and 5B contributing primarily to it. These results corroborated the earlier findings, where chromosomes 1A, 4B, and 5B were reported to harbor genes/QTLs for yield contributing traits such as grain length and thickness. Collectively, this study reveals the molecular changes taking place during early grain development, through light on the regulation of these processes, and allows identification of the gene candidates contributing to the contrasting grain characteristics of CS and P721. This information has implications in the future wheat breeding for the enhanced grain yield.