Identification of Candidate Genes for Hypoxia Tolerance in Rice by Genome-Wide Association Analysis and Transcriptome Sequencing

Direct-seeded rice has gained increasing popularity due to its advantage of lower labor costs. Flooding/hypoxia is an important abiotic stress with severe negative impacts on the germination and emergence of direct-seeded rice. Hence, improving the hypoxic germination tolerance of rice is an important way to promote the further development of direct-seeded rice. In this study, 276 rice germplasms were used as materials to analyze the correlation traits of hypoxia tolerance in rice by genome-wide association analysis (GWAS). In addition, transcriptome sequencing was performed on the strong and weak hypoxic tolerance varieties under flooding and normal conditions. By comparing the results of GWAS and transcriptome sequencing, the candidate genes were further screened and analyzed.As a result, a total of 86 genes related to hypoxic germination tolerance were detected by GWAS, and 51 genes were mapped by GWAS and transcriptome sequencing. Combined with gene functional annotation and haplotype analysis, five important candidate genes related to hypoxia tolerance were screened, including LOC_Os01g07420, LOC_Os02g01890, LOC_Os03g45720, LOC_Os04g56920, and LOC_Os11g41680. The findings may provide an important foundation for mining and cloning of genes for hypoxic germination tolerance in rice with biotechnological improvement.