| Rice is one of the world’s major food crops,which plays an important role in world food security. Promotion and application of three-line hybrid rice has made a great contribution to China and the world’s food production. Due to various reasons, China’s food security is facing increasing challenges. Increase of rice production in ensuring food security in our country has an important role.Seeding rate is an important factor in rice yield components. It is more and more evident in the three-line hybrid rice production. Under normal circumstances, a combination of three-line hybrid rice seed rate is generally only about 80%, while the rate of conventional rice varieties and hybrid rice seed varieties are more than 90%. The difference is very significant. It also indicates that the three-line hybrid rice production has huge room for improvement. If they can equally increase the seeding rate to 90%, three-line hybrid rice production level will take a big leap. Therefore, the study of rice seed rate has a very significant meaning. Development of sequencing technology provides us a new way and an important aspect to make a breakthrough.Our laboratory has a CMS line G80A. we found that the seed setting rate is only 60% in any combination with it. We think CMS line G80A is an extremely low material three-line hybrid rice seed rate. In this study, G80A, G80B respectively hybridize with Shuhui527 Fl do for the study. Under room temperature and high temperature conditions, by Booting Stage Infloresence transcriptome sequencing, differential expression analysis and bioinformatics analysis, we screen setting rate related control genes. Target gene is obtained in crosses G80A/Shuhui 527, G80B/Shuhui 527,11-32A/Shuhui 527, II-32B/ Shuhui527, the G46A/Shuhui527 and G46B/Shuhui 527 were Q-PCR validation. The results are as follows:1 Pollen fertility test results show:at room temperature processing conditions, all hybrid combinations are normal pollen staining. This can exclude the viewpoint that low pollen fertility caused by weak recovery power leads to decrease of rice seed rate.2 Under normal temperature processing, sterile line G80A/Shuhui 527 seed rate was 62%, II-32A/Shuhui527 and G46A/Shuhui 527 seed rate was 80% and 78%, respectively. Maintain sterile line G80B/Shuhui 527 seed was 93%. Ⅱ-32B/Shuhui527 and seed rate of G46B/Shuhui 527 was separately 90% and 93%. These show that three lines’ infertile exits cytoplasmis can cause three-line hybrid rice low seed rate.3 At high temperature treatment, the sterile line G80A/Shuhui 527 seed was 31%, Ⅱ-32A/ Shuhui527 and G46A/Shuhui 527 setting rate was separately 42% and 45%. Maintain sterile line G80B/Shuhui 527 seed was 56%, Ⅱ-32B/527 Shuhui setting rate and G46B/ Shuhui527 was respectively 65% and 66%. These show that temperature influences setting rate of rice, while the three-line hybrid rice seed rate is more obviously influenced by high temperatures.4 By transcriptome sequencing, differential gene screening and Q-PCR validation, we access to 7 gene which affect the rate of three-line hybrid rice seed rate.5 We screened differentially expressed genes by KEGG pathway analysisand GO enrichment analysis, And got 22 possible three-line hybrid rice seed and high temperatures reduce the excessive rate-related genes.They are LOC_Os02g52780, LOC_Os03g60080, LOC_Os05g38290, LOC_Os05g41780, LOC_Os08g43700, LOC_Os12g02980. the expression of these genes in the three-line hybrid rice young panicle were significantly lower than normal rice young panicle.In summary, this study will contribute to the genetic mechanism of three-line hybrid rice seed rate control analysis, and lay the foundation for molecular improvement of hybrid rice seed rate. |
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