Molecular Genetic Variation And Adaptation Mechanisms Of Long-day Suppression Genes For Heading Date In Oryza Sativa

Understanding the formation and evolutionary mechanism of the diversity of flowering time in rice will help interpret rice regional adaptability and provide a basis for expanding planting area of varieties.Previous studies showed that long-day suppression genes had important impacts on the diversity of flowering time.However,how the genetic variation and adaptation mechanism of long-day suppression genes was associated with flowering time in different varieties in cultivated rice remained unknown.In this research,we sequenced 148 accessions of cultivated rice and wild rice for long-day suppression genes(DTH8,Ghd7,Hd1,OsPRR37,Phy B,OsCOL4,Hd6 and Se5)to study the relationship between the variations and the flowering time,detect the selection signal and linkage relationship of mutation sites during the domestication of cultivated rice,and determine haplotype genetic relationship and molecular evolution patterns of each gene based on phylogeographic.We obtained the following results:1.Accept Hd6 and Se5,the other 6 long-day suppression genes had higher nucleotide polymorphism in both wild rice and cultivated rice populations.The genetic diversity of the wild rice population was significantly higher than that of the 2 subpopulations(indica and japonica)of the cultivated rice.DTH8,Ghd7,Hd1,PhyB obtained relatively higher diversity in the wild rice population,and it were or more than 2 times higher than that of indica and japonica population,respectively.2.Within DTH8,14 variations were detected,and 2 variations were detected in Hd1 and 3variations were detected in OsPRR37 respectively,which were significantly related to flowering time.In addition,3 variation loci of DTH8 and 2 variation loci of Hd1 were due to the base deletion,and one base deletion loci of DTH8 formed corresponding nonfunctional alleles.3.The haplotypes of cultivated rice for long-day suppression genes were located mainly in the top of the Network.Besides,the haplotypes of 2 subpopulations(indica and japonica)for DTH8,Ghd7,Hd1 and PhyB were respectively aggregate distribution in the Network,and prevalent haplotypes of indica and japonica population have different geographical distribution pattern.4.Linkage disequilibrium results showed that the most of the variation loci were significantly correlated within genes(DTH8,Ghd7,Hd1,OsPRR37,PhyB and OsCOL4),and more than half of loci also showed significant correlation between genes(DTH8,Ghd7 and PhyB).The results of this study indicated that the insertion and deletion or loss of function of gene might play an important impact on the diversity of flowering time in cultivated rice.Among the long-day suppression genes,DTH8,Ghd7,Hd1 and PhyB had obvious selection signal during the domestication process of cultivated rice.Meanwhile,specific alleles were evolved to adapt to different geographic regions.In addition,DTH8,Ghd7 and PhyB showed significant correlation between genes,therefore,there might have co-evolution process during the domestication,so as to affect the diversity of flowering time and the adaptability to different regions.