Changes in Protein Expression in Peanut Leaves in the Response to Progressive Water Stress

This investigation was carried out at the Department of Plant Science and Agricultural Resources, Khon Kaen University in the rainy season of 2011. The objective of this study was to identify proteins in leaves of drought-susceptible peanut plants when regulated by progressive water stresses. The drought-susceptible peanut plants of Khon Kaen 4 cultivar were grown in pots under controlled environment. At day 30 after seed emergence, the plants were subjected to stress conditions for 5 and 6 days. The results showed that withheld water supply for 5 and 6 days gave moderately and severely water stresses, respectively. Under moderate water stress conditions, two up-regulated and eight down-regulated proteins were attained. The up-regulated proteins were striated fibre assembling and flap endonuclease 1. The down-regulated proteins were peptidyl-prolyl cis-trans isomerase FKBP4, tRNA(Ile)-lysidine synthase, chloroplastic, chloroplastic thioredoxin F-type, cytidinedeaminase 7, ALF domain class transcription factor, nudix hydrolase 8, pentatricopeptide repeat super-family protein, putative and ribulose-1,5-bisphosphate carboxylase/oxygenase, a large sub-unit. Under severe water stress conditions, two proteins, i.e., tRNA(Ile) lysidine synthase, chloroplastic and ALF domain class transcription factor did not change their relative abundance significantly where it indicated drought acclimation. The remaining proteins displayed significant changes and the changes were the same as those found in the peanut leaves when deprived water for 5 days. Up-regulated proteins are responsible for alleviating oxidative damages to plant genome and mediating plants responsive to the environmental factors in providing mechanical support, barriers and a rapid transport route. Down-regulated proteins were associated with drought susceptibility of the Khon Kaen 4 peanut plants.