Wheat Genotypes Tolerance Identification To Low Potassium Stress At Seeding Stage And Genome-Wide Association Analysis Of Low Potassium Tolerance Related Traits

Potassium is a mineral nutrient that limits the growth of wheat.The lack of potassium in wheat can lead to the decline of stress resistance,quality and yield.Screening wheat varieties resistant low potassium,and researching the genetic mechanism of resistant low potassium is an important way to alleviate the shortage of potash resources and guarantee the national food security.In this research,198 wheat varieties(lines)from the southern of Yellow & Huai river valley facultative wheat region were used as the material.All the population were grown in low potassium conditions and normal potassium conditions.To research the effect of 20 wheat seedling traits by low potassium stress through solution culture,We used principal component analysis(PCA)and membership function analysis to evaluate the low potassium tolerance of wheat varieties(lines).Associated analysis was used to low potassium tolerance coefficient of 20 wheat seedling traits by using 35 K high density SNP chip in Wheat.candidate genes were searched and analyzed by the SNP extension sequence of a significant association site.The results are as follows:(1)In this study,the difference of 20 wheat seedling traits between genotype and two potassium levels were highly significant.Compared with the normal level of potassium,16 seedling traits(SPAD,SH,RL,SFW,RFW,TFW,SDW,RDW,TDW,SKCE,RKCE,TKCE,SKC,RKC,RSKC,TKC)of wheat under low-potassium stress were declined significantly,4 seedling traits(RSDW,SKUI,RKUI,TKUI)of wheat were increased significantly.RSKC has higher genotype variation in low-potassium level,normal potassium level and low potassium tolerance coefficient,which correlate with most of the traits significantly.So the low potassium tolerance coefficient of RSKC can be used as an important screening index of low potassium tolerance in wheat seedling stage through solution culture.(2)The low potassium comprehensive evaluation value(D-value)of wheat was calculated by the principal component analysis and membership function analysis,and 198 wheat varieties(lines)were divided into four groups by cluster analysis: strong type of low-potassium tolerant wheat(3 wheat),week type of low potassium tolerant wheat(18 wheat),sensitive type wheat(142 wheat)and sensitive type of low potassium tolerant wheat(35 wheat).Among them,strong type of low-potassium tolerant wheat were Xiaoyan 81,Yanke 028 and Shumai 3.(3)Associated analysis showed that 199 SNP markers were correlate significantly(P<0.001)with low potassium tolerance coefficient at seeding stage.These markers were located on 20 chromosome except 4D chromosome.Single marker loci phenotypic variation ranged from 5.69%-11.59%.Forty markers were associated significantly with more than two traits.Six markers were associated significantly with five or more traits.These six markers were AX-94966068(1B),AX-94412451(5B),AX-95190993(6B),AX-94684890(6B,AX-94642776(2D)and AX-94836731(2D)。(4)66 candidate genes were found associated with stress response by the search and analysis of candidate genes.RHM1 encoded by Traes CS5D02G032700,which found involved in root hair formation in Arabidopsis;TBL10 encoded by Traes CS1A02G046400,which found involved in O-acetylation with celelular component,and participate in abiotic stress response;Rop GEF14 encoded by Traes CS6D02G244200 or Traes CS6A02G270900,which found involved in signal transduction process of ROP;CAT3 encoded by Traes CSU02G105300,which found involved in plant stress response(Salt-alkali,drought,oxidation,low temperature and low potassium,etc).KUP1 encoded by Traes CS2B02G306000,which found involved in transport of potassium from root to shoot under potassium deficiency stress.