Comparative proteomics of tuber induction, development and maturation reveal the complexity of tuberization process in potato (Solanum tuberosum L.)

Tuberization in potato (Solanum tuberosum L.) is a developmental process that serves a double function, as a storage organ and as a vegetative propagation system. It is a multistep, complex process and the underlying mechanisms governing these overlapping steps are not fully understood. To understand the molecular basis of tuberization in potato, a comparative proteomic approach has been applied to monitor differentially expressed proteins at different development stages using two-dimensional gel electrophoresis (2-DE). The differentially displayed proteomes revealed 219 protein spots that change their intensities more than 2.5-fold. The LC-ES-MS/MS analyses led to the identification of 97 differentially regulated proteins that include predicted and novel tuber-specific proteins. Nonhierarchical clustering revealed coexpression patterns of functionally similar proteins. The expression of reactive oxygen species catabolizing enzymes, viz., superoxide dismutase, ascorbate peroxidase and catalase, were induced by more than 2-fold indicating their possible role during the developmental transition from stolons into tubers. We demonstrate that nearly 100 proteins, some presumably associated with tuber cell differentiation, regulate diverse functions like protein biogenesis and storage, bioenergy and metabolism, and cell defense and rescue impinge on the complexity of tuber development in potato.