| Energy from photosynthesis is the direct source of the plants organs development, and the yield formation is the result of the accumulation of photosynthate production. The nonstructural carbohydrate(NSC) is an important component of photosynthetic products, glucose, fructose, sucrose, starch and other non-structural carbohydrates are important substances involving in plant physiological metabolism. It is very important for increasing the yeild that the rice accumulates NSC in stems and sheaths before heading stage and transport them to the kernels efficiently. In order to further understand the connection between nonstructural carbohydrate content differences and yield formation of rice, this study investigated the relevant sugar content and yield characters in 529 core germplasm, and tried to find some relevant candidate genes by GWAS analysis. Results are as follows:1. The correlations among the sugar content traits in 529 core germplasm were analyzed. More than half of the phenotypic were correlative, and achieved the significant level(P < 0.05) or extremely significant level(P < 0.01). The correlation coefficient is 0.713 between the YH-Sta and JH-Sta, 0.635 between the YH-Fru and QH-Fru, 0.703 between the YH-Fru and QH-Fru, 0.814 between YM-Glu and YM-SS,0.567 between the QM-Glu and QM-SS, 0.593 between the JM-Suc and JM-SS.The correlation coefficients among the JM-Glu, YH-Suc and YH-Fru and JM-Glu, JM-Fru and JM-Suc are above 0.5.In addition, there are some negative relationship between phenotypic data, which mainly exists in the starch and other sugars.2. The significant differences among the sugar content and yield traits in 529 core germplasm were analyzed. The differences in single sugar content in one subpopulation at heading stage vary greatly, and it shows the same feature:FL<FLS<FLI. Besides, the contents of different sugars in the same tissue at the same stage is varied. As a kind of storage carbohydrates, the contents of starch in stems and sheaths are higher than functional leaf. Among the different subpopulations, the JM-SS in the Indica is higher than Japonica, specifically, the content between the glucose and fructose is semblable, and the difference exists in the sucrose content.3. The significant sites of the sugar content and yield traits in 529 core germplasm by GWAS were analyzed. A large amount of significant sites are discovered. One of them, the significant site of YH-Sta is located in chromosome 3, the position is 27745185 bp, the phenotypic variation is 25.48%, and the MAF is 0.395. The site is very close to the SUS1 gene which is 27926794 bp. And the sucrose synthase translated by the SUS1 gene is very important to the physiological processes of photosynthate transport and storage in rice.4. The diversity of the SUS1 gene were analyzed. The SUS1 has 6 haplotypes, the SNP loci in Hap1, Hap3 and Hap6, in Hap2 and Hap5 are almost the same respectively. When analyzing the effect of haplotype, group construction of the core collection materials were considered, and t-test were performed to determine the content of sucrose in each subpopulation. Our results shows that the difference of the level of flag leaf and sheath at the heading stage is significant, the difference of the level of flag leaf at the ripening period and stem at the heading stage is highly significant. By analyzing the expression profile database, we found that SUS1 have a relatively high expression in the rice seedling materials that were treated with 3 kinds of plant hormone, indicating that SUS1 may involve in regulation of plant hormones. Besides, SUS1 also showed peculiarly high expression level in the developing endosperm. It is worth exploring the role of SUS1 that plays in the rice yield formation process. |
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