| Wheat is an important food crop,planted in more than 122 countries and regions around the world.Wheat is one of the important sources of starch,digestible protein,carbohydrate and fiber,which is consumed by at least ten million people.It is of great significance to identify salt tolerant germplasm resources in semi-arid areas of China.In this study,281 winter wheat varieties from China and foreign countries were selected for comprehensive evaluation of salt tolerance and selection of salt tolerance indexes.The 90K SNP and 50K SNP chips were used as natural populations of 205 Winter Wheat Varieties(lines)and F6 constructed by hybridization with berkut and worrakatta from CIMMYT as parents,respectively The whole genome association analysis and whole genome linkage analysis were carried out in 233 families.The main results are as follows:1.The salt tolerance of 281 Winter Wheat Varieties(lines)during seed germination was evaluated by using 350 mmol/L NaCl to simulate salt stress.Under NaCl stress,the measured value of each index was lower than that of the control,and there was a very significant or significant positive correlation between each salt tolerance index.Using the method of relative salt damage rate to analyze the salt tolerance,it was found that there were great differences among different wheat varieties(lines),and the range of relative salt damage rate was By cluster analysis,the materials can be divided into five types according to their salt tolerance:high tolerance(9/3.20%),salt tolerance(18/6.41%),medium tolerance(30/10.68%),sensitivity(151/53.74%)and high sensitivity(73/25.98%).Factor analysis showed that the load of germination rate,seedling height and coleoptile length in germination factor and elongation factor were 0.64,0.87 and 0.92 respectively.The above results showed that germination rate,seedling height and coleoptile length could be used as reliable indicators for salt tolerance identification in wheat germination period.Nine high tolerance varieties,Xindong 24,Shidong 8,Neixiang 5,Yinong 20,Xindong 7,gongnong19,Taishan 5,luofulin 10 and Barra,provided basic materials for further stress resistance breeding and salt tolerance gene mining.2.Combined with the data of salt tolerance phenotype and 15831 SNP markers of wheat genome,the whole genome association analysis was carried out.Using the optimized mixed linear model(Q+k)for QQ map,139,108 and 20 SNP loci with salt tolerance were detected under the average value of two conditions,salt tolerance coefficient and comprehensive salt tolerance coefficient(D value)at the level of P≤1×10-4,respectively,with the interpretation rates ranging from 5.4%to 20.5%,5.6%to 21.7%and 5.5%to 14.9%respectively;significant correlation loci were screened 28 candidate genes were found in the upstream and downstream 1MB regions,most of which were endonuclease,F-box family protein,transmembrane protein Serine/threonine protein kinase and receptor like protein Kinase),transcription factor.3.Using 50K SNP chip to connect the data from CIMMYT 20 major QTL loci were detected in the F6 population(233 families)constructed by berkut and worrakatta as parents.They were located on chromosome 3a,4a,4D,6a,6D and 7a,respectively.The LOD value ranged from 2.51 to 4.75,and the phenotypic variation rate ranged from 4.96%to 8.84%,among them QRN.xjau-The variation rate of 4D phenotype was the highest(8.84%).QTLs related to salt tolerance are clustered on chromosomes,mainly on chromosome 3a and 4D,which may be related to the significant or extremely significant correlation between salt tolerance related traits.QTL clusters were found on chromosome 3A and 4D.The SNP and QTL located on 3A chromosome,662.94-700.22 Mb,697.55-721.35 Mb,21.22-47.08 Mb and 697.55-724.31 Mb are the same site,which can be further studied.In addition,10 candidate genes were selected from the QTL cluster,including serine/threonine protein kinase,protein kinase,F-box family protein and glutathione family protein. |
