Phenotypic Analysis And Gene Mapping Of Two Sparse Panicle Mutants A514 And C769 In Rice

Nearly half of the world’s population feed on rice.Rice yield is directly linked to grain stability in China and the world.The panicle architecture is one of the key factors determining rice yield.Exploring the molecular mechanism of rice panicle development can guide rice panicle architecture improvement and increase rice yield.In our laboratory,the mutant library of rice variety Kongyu131（KY131）was established by Ethyl methane sulfonate（EMS）mutagenesis,and a number of mutants with obvious sparse panicle phenotypes were obtained,including A514 and C769.The A514 mutant showed a phenotype with reduced secondary branches and spikelets,and the C769 mutant showed a phenotype with reduced branches and spikelets at all levels.In this study,target genes of the two rice sparse panicle mutants were cloned by the modified MutMap method which provided new genetic resource and genetic germplasm for improvement of rice panicle morphology,breeding of new rice varieties and consummation of the panicle morphology’s molecular regulatory network.The main results obtained are as follows:1.The F₂ generation sequencing populations of the two materials were constructed separately,and it had confirmed that the mutant phenotypes were controlled by single recessive gene through Chi-square test.The modified MutMap method was used to clone the gene,and the results showed that:the target gene of A514 material was located at 35 Mb on chromosome 1,and the candidate segment was reduced to 213.8 Kb.The target gene of C769 material was located at 25 Mb on chromosome 6,and the candidate segment was reduced to 253.6 Kb.By SNP site analysis and expression level detection,it was revealed that A514＿candi＿11 and A514＿candi＿14 might be the target gene of A514 material,C769＿candi＿3 might be the target gene of C769 material.2.Detecting the expression profiles of A514＿candi＿11,A514＿candi＿14 and C769＿candi＿3.The results showed regular changes with the development of panicle,indicated that the three candidate genes might be the target genes that cause the sparse panicle phenotype.Using CRISPR/Cas9 technology to create A514 and C769 candidate gene loss-of-function materials:A514＿candi＿11 and A514＿candi＿14 did not show a sparse panicle phenotype,and further analysis showed that LAX1 gene might be the target gene of A514 material;The panicle length in C769＿candi＿3 mutant shorter than the wild-type and the number of branches and spikelets decreased,behaved as sparse panicle.The results indicated that C769＿candi＿3 might be the target gene of C769material.In this study,the target genes of the two materials were cloned by modified MutMap method,the CRISPR/Cas9 technology was used to knockout the function of candidate genes which laid a foundation for gene function research.Searching for new panicle morphology gene ultimately serves the research of gene function and answers the question of how gene regulate panicle development.Through phenotypic investigation,expression profile analysis of known panicle morphogenetic genes and structural analysis of the candidate genes,we predicted that the target genes of the two materials were likely to play their roles by influencing the function of the known panicle morphogenetic genes,which provided a good idea and research point for the subsequent gene function research.