Preliminary Study On Candidate Genes For Low Potassium Tolerance In Rice

The deficiency of potassium has an important influence on production of rice in South China.One of reasons for the high cost of rice industry is that the resource of potassium is rare and expensive.The low coefficient of potassium utilization in rice result in the loss of potassium which leads to pollution of water.So breeding rice which is tolerant of low potassium and raising the coefficient of potassium utilization is a requirement of current rice industry.In this study,we choice 500 kinds of hybrids what is the F16recombinant inbred lines(RILs)from Nipponbare/9311 as materials,screening and identification of rice in seedling tolerance to low potassium resource and low potassium tolerance candidate gene.The main results are as follows:(1)Nipponbare and the 9311 grow on low potassium hydroponic solution(0.01 mM K~+)and normal hydroponic solution(1 mM K~+)respectively.It is found that the growth of Nipponbare seedling,content of potassium in the roots and aboveground parts have little difference in low potassium hydroponic solution(0.01 mM K~+)and normal hydroponic solution(1 mM K~+).But the growth of 9311 seedling in hydroponic solution of 0.01 mM K~+was significantly lower than that in hydroponic solution of 1 mM K~+and have low potassium phenotype who is short and has iron rust on leaves appeared.The potassium ion in root and the aerial portion in 0.01 mM K~+solution was significantly less than that in 1 mM K~+solution.The results showed that Nipponbare low potassium tolerance rice and 9311 were low potassium sensitivity rice.(2)The 498 plants seeding of the F16 recombinant inbred lines(RILs)from Nipponbare/9311 were respectively breed in low potassium hydroponic solution(0.01 mM K~+)and normal hydroponic solution(1mM K~+).It is found that 127 strains of rice seeding growth were basically same in hydroponic solution of 0.01 mM K~+and 1 mM K~+.The properties are similar with parents(Nipponbare).It belongs to the kind of low potassium tolerance rice.Among them,two strains of MD355 and MD318 were the most resistant to low potassium situations.And 138strains of rice seeding showed obvious phenotypic differences when grow on solutions containing K~+-sufficient solution(1 mM K~+)and low-K~+conditions(0.01 mM)respectively.They stunted stature and iron mottling leaves,It is more sensitive to ow potassium than parent(Nipponbare)and belongs to the kind of low potassium sensitivity rice.The MD262 and MD282 two lines showed the most obvious potassium deficiency phenotype.(3)We carried out whole-genome sequencing of the F16 RILs(20low-K~+tolerant lines and 20 low-K~+sensitive lines),two parent lines(Nipponbare and 9311).They were mixed into two sample pools for resequencing by using the method of mixed pool analysis(BSA)and sequencing for parents.Through the functional annotation of 36polymorphic site,two possible gene-OsHAK3 and OsNAC25 to low potassium tolerance were found.Bioinformatics revealed that OsHAK3and OsNAC25 encode potassium transporter.(4)Yeast functional complementation experiments showed that OsHAK3 and OsNAC25 could be as functional complementation of yeast potassium absorbing mutant CY162 when the external potassium concentration was 0.01mM.In this study,we screened out 127 strains of Low Potassium Tolerant Rice,which were similar to those of their parent-Nipponbare,and screened out 138 strains of the low potassium sensitive rice for similar to their parent-9311,which were rich in the resources of Low Potassium Tolerant Rice.It was found that OsHAK3 and OsNAC25 might be took part in absorbing or transporting of potassium in rice under low potassium in the first time.The purpose of this study is to provide a basis for the analysis of the mechanism of the low potassium tolerance of rice,and to provide the basis for the development of Low Potassium Tolerant Rice Varieties.