Abstract
Rice is one of the most important crops in the world. Rice production consumes lots of water and significantly suffers from drought stress. The water-saving and drought-resistance rice (WDR) confers good drought resistance and performs well in water-saving cultivation. A hybrid WDR variety Hanyou73 (HY73) exhibited superior drought resistance compared with its parents Hanhui3 (HH3) and Huhan7A (HH7A). Studies on drought resistance related traits revealed that HY73 performed like HH3 and HH7A on drought tolerance (DT) and drought avoidance (DA), respectively. Transcriptomes were analyzed for samples with various phytohormone treatment and abiotic stresses, in which HY73 was closer to HH3 in leaf while HH7A in root samples. HY73 and its parents differed largely in DEGs. GO analysis for DEGs suggested the different pathways of drought response in HH3 and HH7A. Parent-like expression analysis revealed that higher-parent-like expression pattern is prevailing in HY73, and the expression patterns significantly altered between abiotic-stressed/phytohormone-treated and control samples, which might help HY73 to adapt to different environments. WGCNA analysis for parent-like expression genes revealed some functional genes related with drought resistance that should contribute to the superior drought resistance of HY73. Genetic variation on promotor sequence was confirmed as the reason for flexible parent-like gene expression in HY73. Our study uncovered the important roles of complementation of beneficial traits from parents and flexible gene expression in drought resistance of HY73, which could facilitate the cultivation of new WDR varieties.