QTL Mapping For The Adult Plant Stripe Rust Resistance In Wheat

Wheat stripe rust?Yr?,caused by Puccinia striiformis f.sp.tritici,is a worldwide disease causing severe yield losses.Breeding resistant variety is the most economical and effective way to control stripe rust and maintain wheat production.Wheat Yr resistances can be divided into race-specific resistance and non–race specific resistance.The former,also known as vertical resistance,seedling resistance and all stage resistance,is mostly controlled by major gene and highly specialized for physiological races of pathogenic bacteria.The resistance cab be lost easily with the variation of physiological races.The latter is also known as horizontal resistance or adult plant resistance with no selective to races,which is thought to be controlled by multiple genes,and is more durability to disease resistance.Therefore,identify the gene/QTL for adult plant resistance and develop linked markers used in marker assisted selection is much more meaningful to improve wheat Yr resistance.In this study,a recombinant inbred line?RIL?population?F₆?containing 155 lines derived from the cross between Tutoumai?TTM,susceptible at seedling stage and resistant at adult plant stage?and Siyang936?SY936,susceptible at both seedling and adult plant stages?was used for mapping QTL of Yr resistance at adult plant stage..The main results were as follows:1.All the RIL and their parents were inoculated with CYR29,CYR31,CYR32,SY11,and SY14 races at seedling stage and all lines showed highly susceptible to Yr.While inoculated at adult plant stage with the same races under filed conditions at four consecutive years,the parent SY936 was still susceptible and TTM became resistant to Yr,and the RIL population showed containued variation,which further demonstrated that the resistant genes of TTM belongs to adult plant resistance.2.A genetic linkage map harboring 23 linkage groups was constructed by joinmap4.0using 498 SNP markers.The total length of chromosome covered by the map was 1904.95cM,and the average marker spacing was 3.83 cM.3.Three environment?years?stabe major QTL?QYr.sdau-1BL,QYr.sdau-5BL,and QYr.sdau-6BL?were detected using the phenotype data of infection type?IT?,maximum disease severities?MDS?and area under the disease progress curve?AUDPC?throught CIM implemented in WinQTLCart2.5.The phenotypic variation explained by these three QTL were 8.0-21.2%,10.1-22.7%,and 11.1-18.0%for QYr.sdau-1BL,QYr.sdau-5BL,and QYr.sdau-6BL,respectively.The favorable alleles of QYr.sdau-1BL and QYr.sdau-6BL were denotated by TTM,and that of QYr.sdau-6BL was contributed by parent SY936.4.Through BSR-Seq analysis,nine significant intervals were obtained with the SNP allele ratio above the threshold value of 0.7.These intervals were located on chromosomes 1B,1D,2A,2D,4A,4B,5A,5B and 7A,with the average allele ratios of significant SNP were0.71,0.80,0.77,0.81,0.75,0.72,0.77,0.83 and 0.81,respectively.KASP primers were designed using the short sequences flanking significant SNPs within the above nine intervals,and were used to validate the target interval in the RIL population.Finally,13 KASP markers in the five intervals of 1BL,1DS,2AS,2DL,and 4AL were significantly correlated with the adult plant resistance stripe rust?P<0.05?.The resistant alleles of intervals on 1BL,1DS,and2AS were from TTM,and that of intervals on 4AL was from SY936.5.By comparing the results of GBS linkage analysis and BSR-Seq analysis,one QTL QYr.sdau-1BL located at the range of 653-682 Mb of chromosome 1BL was commonly identified,which was further mapped into 654-677 Mb by integrating GBS markers and 9KASP markers developed within the interval.