Expression profiling of starchy endosperm metabolic proteins at 21 stages of wheat grain development.

Proteomic analysis of albumins and globulins (alg) present in starchy endosperm of wheat (Triticum aestivum cv Récital), at 21 stages of grain development, led to the identification of 487 proteins. Four main developmental phases of these metabolic proteins, with three subphases in phase three and two in phase four, were shown. Hierarchical cluster analysis revealed nine major expression profiles throughout grain development. Classification of identified proteins in 17 different biochemical functions provided a uniform picture of temporal coordination among cellular processes. Proteins involved in cell division, transcription/translation, ATP interconversion, protein synthesis, protein transport, along with amino acid, lipid, carbohydrate and nucleotide metabolisms were highly expressed in early and early mid stages of development. Protein folding, cytoskeleton, and storage proteins peaked during the middle of grain development, while in later stages stress/defense, folic acid metabolism, and protein turn over were the abundant functional categories. Detailed analysis of stress/defense enzymes revealed three different evolutionary profiles. A global map with their predicted subcellular localizations and placement in grain developmental scale was constructed. The present study of complete grain development enriched our knowledge on proteome expression of alg, successively from endosperm cell division and differentiation to programmed cell death.