Character Analysis And Molecular Mapping Of Water-soaked Spot Leaf Mutant Wss1 In Rice

Rice?Oryza sativa L.?is one of the most important food crops in the world.It provides food to more than half of the world's population and occupies a pivotal position in food production.A water-soaked spot mutant?termed as wss1?was selected from the population derived EMS-treated seeds of the indica rice variety JG30.Some leaves of the wss1 showed water-soaked spots at the tillering stage and these water-soaked spot leaves dead at booting stage.In this study,we carried out systematic study on wss1,the results are as follows:1.Compared with the wild type JG30,the mutant's plant height decreased about 30%,the seed setting rate reduced 22%,the number of grains per panicle reduced 50%and the leaf senescence,while the grain shape and the weight of 1000 grains did not change significantly.2.Microscopic observation of the water-soaked spot leaf epidermal cell of wss1 and leaf epidermal cell of the wild type JG30 showed that the epidermal cells shape of wss1 changed,the epidermal cells arrangement became irregular,the epidermal cells membrane was damaged and vacuole collapse.3.For disease symptom evaluation,the wild type JG30 and the mutant wss1 were inoculated by using leaf-tip clipping method with Xoo strain PXO99^A.The lesion length of mutant plants is longer than the wild type after 14 days'inoculation.4.A F₂ segregating population was constructed by a cross between the japonica rice line 02428and wss1.Genetic analysis showed that the water-soaked spot phenotype was controlled by a recessive gene.5.According to the re-sequencing results of JG30 and 02428,240 pairs of InDel markers were developed among 12 chromosomes.6.The mutant gene was mapped in the centromere region of chromosome 11,between markers Ch11-33 and Ch11-123 with a physical distance of 1200kb,and in this region 11 co-segregating markers were identified.7.In the mapping region 36 functional genes were predicted on the rice genome website.Primers were designed to amplify the DNA sequences of the coding regions and 1.5kb promoter regions of the 36 predicted functional genes.The amplicons were sequenced and no sequence difference between wss1 and JG30 was found.8.qRT-PCR was used to analysis the expression of the 36 predicted functional genes and results showed that five genes differentially expressed between wss1 and JG30.The five differentially expressed genes are candidate genes of wss1.