Proteomic analysis of cotyledonary explants during shoot organogenesis in Vigna radiata

Vigna radiata or mungbean belongs to the legume family of plants. Mature mungbean seeds are rich source of dietary proteins for human nutrition. The present study was aimed to analyze the comparative protein profiles of two cotyledon types, Cot and Cot E, prior to and during early time points of shoot morphogenic induction to understand the unique differential regeneration response in these two explant types which was reported earlier. These explants were grown separately in vitro on the shoot induction medium (SIM) containing Gamborg's B5 basal nutrient composition supplemented with 15 mu M N-6-benzyladenine. Isolation and characterization of the proteomes from Cot and Cot E explants at different time points, during early events of shoot differentiation, were performed using two dimensional gel electrophoresis following matrix assisted laser desorption-ionization tandem mass spectrometry. A total of 112 differentially identified proteins were classified according to their putative biological function. The differential control of protein synthesis between these explants under control condition, i.e. before in vitro culture, was also noted. In Cot E explants SIM induced prompt acquisition of competence for direct shoot morphogenesis probably through fast phytohormone signaling. Over accumulated proteins in Cot E indicated stimulation of several metabolic and associated pathways earlier than Cot explants. Abundance of stress and defense related proteins in Cot E explants was presumably to cope up with stressful cultural condition. Enhanced accumulation of folding-assisted proteins involved in organogenesis mediated cellular reprogramming in Cot E explants contributed further in rapid and efficient regeneration responsiveness.