Proteomic analysis of embryonic axis of Pisum sativum seeds during germination and identification of proteins associated with loss of desiccation tolerance.

Seed germination is an important stage in life cycle of higher plants. The germination processes and its associated loss of desiccation tolerance, however, are still poorly understood. In present study, pea seeds were used to study changes in embryonic axis proteome during germination by 2-DE and mass spectrometry. We identified a total of 139 protein spots showing a significant (>2-fold) change during germination. The results show that seed germination is not only the activation of a series of metabolic processes, but also involves reorganization of cellular structure and activation of protective systems. To uncouple the physiological processes of germination and its associated loss of desiccation tolerance, we used the fact that pea seeds have different desiccation tolerance when imbibed in water, CaCl(2) and methylviologen at the same germination stage. We compared the proteome amongst these seeds to identify the candidate proteins associated with the loss of desiccation tolerance and found a total of seven proteins - tubulin alpha-1 chain, seed biotin-containing protein SBP65, P54 protein, vicilin, vicilin-like antimicrobial peptides 2-3, convicilin and TCP-1/cpn60 chaperonin family protein. The metabolic function of these proteins indicates that seed desiccation tolerance is related to pathogen defense, protein conformation conservation and cell structure stabilization.