Abstract
To understand molecular mechanisms of drought/strong light stress-tolerance in wild watermelon, changes in the protein composition in the leaves under stress were analyzed by proteomic approach. Two-dimensional gel electrophoresis showed approximately 900 protein spots, 9% of which were up-regulated and 3% were down-regulated by the drought treatment. These stress-responsive proteins were subsequently analyzed by mass spectrometry and database analysis. Interestingly, about 40% of the up-regulated proteins were heat shock proteins, which were categorized into 5 families. This observation suggests that wild watermelon has robust mechanisms for preventing proteins from denaturing caused by oxidative and/or thermal damages. Other up-regulated proteins included factors related to antioxidative defense, protein degradation/synthesis and signaling. Moreover, small G proteins such as Rab and Arf were also up-regulated and would be involved in membrane traffic during stress. These results suggest that wild watermelon has advanced adaptive and defensive mechanisms for surviving drought/strong light stresses.
