关键词: 水稻, 种子活力, 耐低氧萌发, 全基因组关联分析, 转录组分析

Abstract:

【Background】 The low seedling rate of direct seeding rice is an important factor limiting its yield. Mining rice materials with high seed viability and low oxygen germination ability is the key to improving the seedling rate and solving the problem of seedlings in direct seeding rice. 【Objective】 The key phenotypic traits affecting the rate of emergence and tolerance of seedlings were analyzed, and the relevant genetic loci and candidate genes were mined to provide a theoretical and material basis for the study of direct seeding rice cultivars and the mechanism of resistance to flooding. 【Method】 Using 200 rice germplasms from a wide range of sources. The germination test was carried out in an aerobic environment, and the seed viability phenotype was measured including germination rate, germination index and viability index; The coleoptile length and coleoptile diameter were measured under hypoxic conditions. The flood-tolerant seedling experiment was carried out, the water depth was 10cm, and the flood-tolerant seedling rate was measured after 20d. The correlation between various traits was analyzed, and the key traits affecting the rate of tolerance to flooding were explored. Genome-wide association analysis was performed on the above six phenotypes by simplified genome sequencing, and SNP sites significantly associated with traits were identified and within the correlation interval. Screening candidate genes related to the research purpose; transcriptome detection under the conditions of aerobic, anaerobic and oxygen content conversion of 02428 and YZX two materials, combined with genome-wide association analysis results, analysis of differences in expression patterns of candidate genes. 【Result】 Seed viability, coleoptile phenotype and seedling rate showed extensive genetic variation among 200 materials. Among them, the variation of coleoptile length and viability index was the most abundant, and the coefficient of variation was the largest. At the same time, the results of correlation analysis showed that there was a significant positive correlation between the coleoptile length, viability index and the seedling rate. Through genome-wide association analysis, 8 sites significantly associated with the viability index and 15 sites significantly associated with the coleoptile length were identified. Based on the correlation of seed growth and development and stress resistance, six candidate genes related to viability index and seven candidate genes related to the coleoptile length were screened in the relevant interval. Further comparison of 13 genes in aerobic and anaerobic the expression patterns and expression changes under oxygen conversion conditions showed that the three genes Os02g0657000, Os03g0592500 and Os08g0380100 showed different expression patterns when the oxygen content changed, and the expression amount changed significantly, showing sensitivity to oxygen treatment. 【Conclusion】 Seed viability and coleoptile length were closely related to the rate of flooding and seedling emergence, which could be used as an important trait for screening flood-tolerant rice materials. Combining genome-wide association analysis, transcriptome analysis and gene expression pattern can improve the screening efficiency of candidate genes for hypoxia tolerance germination of rice seeds; flooding tolerance of rice seedlings may be regulated by genes related to stress and photosynthesis..

Key words: rice, seed vitality, hypoxia-resistant germination, genome-wide association analysis, transcriptome analysis