| Rice is the main source of global food, it served as a staple food for half of the world’s population. The yield improvement is the main target of rice production and scientific research. The rice flowering time is the key and influential factor of the yield production, it adapts to seasonal changes to maximize the utility of sunshine in specific ecological systems. Identification and utilization of flowering-related genes are the basic premises to carry out the suitable rice breeding program. At the present, association analysis of candidate genes has been used to investigate the important agronomic traits during the domestication process. Ghd8, as an HAP3 subfamily gene of HAP family, regulates rice flowering time. In order to identify the HAP gene mechanism in rice flowering time, the rice HAP family genes diversity between rice core germplasm and wild type(wt), and the HAP family expansion mode were analyzed. Taken advantage of the relationship between the rice HAP family genes and traits associated with rice heading stage, the function of most HAP family genes were verified, through transgenic technology and mutant analysis. In view of the HAP complex exist in trimeric form hypothesis, it proved that HAP proteins had interaction relationship and interaction between Ghd7 and Ghd8. The results were as follows:In this study, 529 rice germplasm and 107 common wild rice(Oryza rufipogon) varieties were handled to carry out the analysis of its nucleic acid diversity of 35 rice HAP family genes. The data showed that when comparing the average of nucleic acid diversity, HAP gene family was higher than the whole genome diversity of wild-type. For most HAP gene family; in Indica and Japonica rice, it had great differences on FST values(higher than 0.25), indicated that the HAP gene family had a strong differentiation. Os HAP2E/2G, Os HAP2F/2H, Os HAP3D/3E, Os HAP3F/3I, Os HAP5A/5B and Os HAP5D/5E, Os HAP3 J and Os HAP3 G were obtained through block replication and tandem duplication, respectively. The correlation data between 529 rice germplasm HAP gene and riceheading date showed that only four genes were related to heading date, especially, there were no association genes from HAP2 sub-family. Through the analysis of 23 HAP family genes of transgenic or mutant plants, the results revealed that including the cloned gene Ghd8, there were four HAP genes control flowering, which linked to three genes. HAP5, HAP2 and HAP3 subfamily members formed trimers. Through yeast, two-hybrid assay indicated that Ghd8 had interactions with HAP2 and HAP5, while Os HAP5 A, Os HAP5 B were interacted with Hd1 which provides the direction to study how Os HAP5 B regulates flowering and provides the possibility to study Ghd8 regulating mechanism of rice flowering.Rice has an abundant natural variation of grain shape; it is one of the most important agronomic traits for artificial selection in rice breeding, which determines the grain appearance and weight. The recombinant inbred lines between big grain variety "Nanyangzhan” and small grain variety "Chuan 7"; near from the centromere of chromosome 3, showed main effect QTL that influence grain length and weight, which away from GL3.1. After constructed NILs, the candidate genes GL3.2 were idetified by genetic analysis and map-based cloning. When “Chuan 7” genotype RNAi-GL3.2 transferred to “Chuan 7”, the grain length recorded 6.3 mm on the RNAi gene transferred material, which was 0.3 mm longer than the wild type(6.0 mm). Through association analysis and sequencing, a key SNP that led to the termination of transcription resulted in the differences between the two genotypes. |
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