Comparative expression of Rboh gene in Citrullus lanatus and Citrullus colocynthis under drought stress

Citrullus colocynthis is a very drought tolerant cucurbit species which widely distributed in the deserts of Mediterranean region and Middle East. One of the possible mechanisms involved in the tolerance response of this plant could be overexpression of Rboh gene which its protein product are involved in the production of ROS signal molecules. In this research, Rboh gene expression during drought stress, were studied in C. colocynthis and watermelon. Seeds after sterilization and germination in germinator transfer to pots containing sand and 5 leave plants treated by PEG 8000 15%. At times zero, 3, 9, 18 hours after treatment relative water content of leaves and Quantitative gene expression of Rboh by Real Time PCR method was studied. The results showed a significant decrease in relative water content in both species but in C. colocynthis this decrease was less remarkably. After PEG treatment the expression of Rboh increased in two species but expression level in C. colocynthis was more than watermelon. Expression of Rboh which play an important role in response to stress stimulus, was rapidly and strongly induced by PEG treatment in C. colocynthis rather than C. lanatus. The result can be a confirmation that Rboh Play a critical role in C. colocynthis tolerant against the drought stress.