QTL Mapping And Development Of CAPS Markers For Stem Strength In Wheat

Increasing yield is one of the important goals of wheat breeding.Lodging is one of the main factor that decreases wheat yield.Stem strength is an important indicator of lodging resistance,therefore,it is helpful for MAS to identify the major loci for stem strength and develop molecular markers closely linked with the major loci.In this study,we used a natural population consisted of 105 wheat varieties with significant differences of genetic background and determined the phenotypic data of stem strength in 2014,2015 and 2016.A total of 369SSR markers were used to genotype the panel and perform association analysis by GLM and MLM.Then,the Annong 0711/Henong 825 RILs population?F₆,362 lines?was used to validate the effects of the two major loci for lodging resistance on chromosomes 5A and 3B.Furthermore,the two parents?Annong 0711 and Henong 825?and two bulks from Annong0711/Henong 825 RILs population were genotyped using the 660K SNP array.According to SNP markers within the major QTL region,the two CAPS markers were developed to confirm the stability and phenotypic effects of the major locus on chromosome 5A.The results can lay the foundation for breeding wheat varieties with lodging resistance and also provide useful information for understanding the genetic mechanism of lodging resistance in wheat.The main results are as follows:?1?Stem strength phenotypes were determined in the natural population consisted of 105 wheat varieties in three environments.The correlation analysis showed that there were significantly positive correlations?P<0.01?among stem strengths,indicating stability of the stem strength trait across environments.?2?SSR genotypes and stem strength phenotypic data of the natural population were used to perform association analysis by GLM and MLM.A total of 53 markers were significantly associated with stem strength,mainly distributing on chromosomes 1D?3A?3B?4B?5A and6D.Thirteen markers significantly associated with stem strength were detected in more than two environments,and located on chromosomes 4BL?barc1096,barc199,and gwm495?,7BL?barc176?,3BS?barc268?,and 3AL.?barc314?,4AL?barc343?,3DS?cfd152?,6DL?cfd37?,6AS?gwm459?,2BS?wmc154?,1D/2A?wmc179?,and 4BS?wmc413?;Particularly,three markers significantly associated with stem strength were detected in all three environments,and distributed on chromosomes 4BL?barc1096?,3AL?barc314?,and 3BS?barc268?.?3?Using the Annong 0711×Henong 825 RILs?F₆?population containing 362 lines,39polymorphic SSR markers were screened on chromosomes 5A and 3B.The two loci Qssahau-5A and Qssahau-3B on chromosomes 5A and 3B were mapped the interval of gwm443-gwm156 and barc358-wmc615,explaining 3.02%-3.20%and 2.42%-3.38%of phenotypic variations,respectively.?4?Two CAPS markers AX-109445097?28.28 Mb?and AX-95200348?445.27 Mb?on chromosome 5A were developed based on the two SNP markers from the Wheat 660K Chip through scanning the two parents and two bulks of Annong 0711/Henong 825 population.The results showed that the CAPS marker AX-109445097 is closely linked to the Qssahau-5A locus.