Comparison of drought responsive protein patterns in 'leung pratew123' rice oryza sativa L.cv. leung pratew123 and its drought resistant mutant line

The proteome-level study of the stress-susceptible (SS) Oryza sativa L. cv. Leung Pratew123 and its stress-resistant (SR) mutant line, Leung Pratew123-TC171 were conducted to identify a drought response mechanism in SR line. Based on the proteomics data, two proteins; GT-2 LIKE 1 (GTL1) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) which are involved in stomata density reduction and e- transfer in Calvin Cycle, respectively were selected for further study. It was found that the SR rice had the lower stomatal density than SS rice when grown under drought stress. This is consistent with the lower level of GTL1 protein found in SR during drought stress. In addition, SR showed higher relative water content than SS after drought treatment. Besides, measurement of the leaf gas exchange parameters was conducted in the old and the young leaves in both SS and SR. After 3 days of drought stress (12.5% PEG), old leaf of SR had significant higher net photosynthetic rate and water use efficiency than SS. Likewise, effective quantum yield of PSII photochemistry (ΦPSII) and electron transport rate were also higher in SR than SS line. Similarly, higher GAPDH level under drought stress was found in SR line. Moreover, transpiration rate in the young leaf was significantly lower in SR line. Overall, SR rice mediates drought stress through GTL1 which regulates stomatal density leading to less water loss in the newly developed leaves, while in the old leaves the adaptation in GAPDH helps protecting photosystem under drought stress.