Analysis of the grasspea proteome and identification of stress-responsive proteins upon exposure to high salinity, low temperature, and abscisic acid treatment.

Abiotic stress causes diverse biochemical and physiological changes in plants and limits crop productivity. Plants respond and adapt to such stress by altering their cellular metabolism and activating various defense machineries. To understand the molecular basis of stress tolerance in plants, we have developed differential proteomes in a hardy legume, grasspea (Lathyrus sativus L.). Five-week-old grasspea seedlings were subjected independently to high salinity, low temperature and abscisic acid treatment for duration of 36h. The physiological changes of stressed seedlings were monitored, and correlated with the temporal changes of proteome using two-dimensional gel electrophoresis. Approximately, 400 protein spots were detected in each of the stress proteome with one-fourth showing more than 2-fold differences in expression values. Eighty such proteins were subjected to LC-tandem MS/MS analyses that led to the identification of 48 stress-responsive proteins (SRPs) presumably involved in a variety of functions, including metabolism, signal transduction, protein biogenesis and degradation, and cell defense and rescue. While 33 proteins were responsive to all three treatments, 15 proteins were expressed in stress-specific manner. Further, we explored the possible role of ROS in triggering the stress-induced degradation of large subunit (LSU) of ribulose-1,5-bisphosphate carboxylase (Rubisco). These results might help in understanding the spectrum of stress-regulated proteins and the biological processes they control as well as having implications for strategies to improve stress adaptation in plants.