The Molecular And Physiological Mechanisms Of The Drought Tolerance Variance Between Yangdao 2 And Yangdao 6

There is a great urgency in addressing the problem of water shortage in China, which will affect economic and social sustainable development in the future. Drought stress has been found to be one of the major factors causing rice yield loss, since rice demands tremendous amounts of water during growth. Therefore, it is important to explore the physiological and biochemical mechanisms of drought tolerance, which will help to provide gene resources to breed rice cultivars with more drought tolerance.In this study, we screened two rice cultivars with different drought tolerance but genetically close-related. Rice gene microarrays were used to profile genome-wide gene expression in rice seedlings under drought treatment. Several physiological and biochemical indexes were assayed based on the analysis of the microarray data. The results were summed as follows:Y6 showed enhanced drought tolerance as compared with Y2, and the main phynotype was that Y6 seedlings exhibited slight leaf rolling after drought treatment and high survival rate after rewatering. Furthermore, the detached leaves from Y6 seedlings lose water more slowly than the leaves from Y2.The expression of abundant genes changed after drought treatment; Two rice cultivars showed similarities but also differences with gene expression profiles; The differential expressed genes were involved in several physiological and chemical processes including ROS metabolism. DNA fragment deletion is one of the causes of differential expressed genes between two rice cultivars.The activities of SOD and CAT in leaves increased both in two rice cultivars after drought treatment. However, Y6 showed relatively higher activities of SOD and CAT compared with Y2. After drought for a long time, Y6 accumulated less H2O2 and other reactive oxygen species compared to Y2.