Guangchen Zhang;Zimeng Liu;Youhong Liu;Noriyuki Kuya;Yimin Hua;Hongru Shi;Weilin Zhao;Yang Han;Tetsuro Yamamoto;Wenfu Chen;Jian Su

Rice Research Institute, Shenyang Agricultural University, Shenyang 110161, China;Institute of Crop Cultivation and Tillage, Heilongjiang Academy of Agricultural Sciences/Heilongjiang Provincial Key Laboratory of Crop Molecular Design and Germplasm Innovation, Haerbin 150086, China;Rice Research Institute, Shenyang Agricultural University, Shenyang 110161, Chin;Institute of Plant Science and Resources, Okayama University, Okayama 710-0046, Japan;Center of Seed Industry Development of Liaoning Province, Shenyang 110034, China;Institute of Crop Science, National Agriculture and Food Research Organization, Ibaraki 305-8518, Japan

iTRAQ-based proteomics;direct-seeding;anaerobic germination;weedy rice;differentially abundant protei

Direct-seeding of rice has become popular in recent years due to its low cost and convenience, however, hypoxic condition limits seedling establishment. In this study, weedy rice WR04-6 with high germination ability under anaerobic conditions was used as a gene donor, and we successfully improved the seedling establishment rate of rice cultivar Qishanzhan (QSZ) based on selection of a new rice line R42 from the recombinant inbred line population. R42 inherited high anaerobic germination (AG) ability, and was used for isobaric tags for relative and absolute quantitation (iTRAQ)-based comparative proteomic studies with QSZ to further explore the molecular mechanism of AG. A total of 719 differentially abundant proteins (DAPs) were shared by R42 and QSZ responded to AG, and thus defined as common response DAPs. A total of 300 DAPs that responded to AG were only identified from R42, which were defined as tolerance-specific DAPs. The common response and tolerance-specific DAPs had similar biochemical reaction processes and metabolic pathways in response to anoxic stress, however, they involved different proteins. The tolerance-specific DAPs were involved in amino acid metabolism, starch and sucrose metabolism, tricarboxylic acid cycle pathway, ethylene synthesis pathway, cell wall-associated proteins and activity of active oxygen scavenging enzyme. The in silico protein-protein interactions for the top 60 DAPs indicated that tolerance-specific DAPs had relatively independent protein interaction networks in response to an anoxic environment compared with common response DAPs. The results of physiological indicators showed alpha-amylase and superoxide dismutase activities of R42 were significantly increased under anoxic conditions compared with aerobic conditions. Multiple lines of evidence from western blot, physiological analysis and quantitative real-time PCR jointly supported the reliability of proteomics data. In summary, our findings deepened the understanding of the molecular mechanism for the rice response to AG.