Spatial distribution of proteins and metabolites in developing wheat grain and their differential regulatory response during the grain filling process

Grain filling and proper grain development are essential biological processes in the plant’s life cycle, which majorly contributes to the final seed yield and quality in all cereal crop. However, very scarcely this knowledge is available in the literature regarding how the different wheat grain components contribute to the overall development of the seed. We performed a proteomics and metabolomics analysis in four different developing components of the wheat grain (seed coat, embryo, endosperm and cavity fluid) to characterize molecular processes during early and late grain development. In-gel shotgun proteomics analysis in 12, 15, 20 and 25 days after anthesis (DAA) lead us to identify and quantify 15,484 proteins out of which 410 differentially expressed proteins (DEPs) were identified in the seed coat, 815 in embryo, 372 in endosperm and 492 in cavity fluid. The abundance of selected protein candidates revealed spatially and temporally resolved protein functions associated with development and grain filling. Multiple proteins such as pyruvate phosphate dikinase (PPDK) and 14 -3- 3 undergo a major change in abundance during wheat grain development. Proteins binned into the functional category of cell growth /division were highly expressed during early stages (12 and 15 DAA) whereas those of starch biosynthesis in the middle or late stages. At the metabolome level all tissues and especially the cavity fluid showed highly distinct metabolite profiles. The tissue specific data are integrated with biochemical networks to explore a comprehensive map of molecular processes during grain filling and developmental processes.