QTL Mapping Of Adult-plant Resistance To Stripe Rust In A Wheat Landrace Baimangmai

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici?Pst?and spreaded through air,has been one of the the most destructive plant foliar diseases in the world,and is particularly more widespread and severer in China.Based on abundant researches and practices,it has been showing that application of resistant cultivars is one of the most economic,safe and effective measures to control wheat stripe rust.However,due to high level of homogenization of the stripe rust resistance resources in wheat cultivars and high virulence variability in wheat stripe rust pathogen population,the loss of resistance of commercial cultivars to stripe rust occurred frequently,resulting in the prevalence of the disease.Therefore,constant exploration of new resistance sources for stripe rust can set a better foundation for resistance breeding and reasonable cultivars distribution.It is generally believed adult-plant resistance to stripe rust possesses a wider resistance spectrum and higher stability and durability of disease resistance,and has been paid more attention and deeply studied in utilization areas.Wheat landraces are most precious genetic germplasm resources in China and possess a wealth of allelic variation and excellent disease resistance and stress tolerance.Landrace Baimangmai is with good agronomic characters and highly resistant to stripe rust in adult-plant stage.It is of important theoretical and practical significance to research and utilize of its stripe rust resistance.In this study resistance identification were conducted to analyze the expression period of resistance,and its relationship with environmental temperature for recombinant inbred lines?RIL?of Taichung29 and Baimangmai;Quantitative trait locus?QTL?for stripe rust resistance genes were mapped by the wheat 90K SNP iSelect Assay and SSR technology.The major results were listed as follows:?1?Landrace Baimangmai was susceptible to the presently major predominant races CYR32,CYR33 and new pathotype G22-9 in seedling stage,and nearly immune to highly resistant at adult-plant stage,indicating that is adult-plant resistance.This material showed good resistance to stripe rust in multi-location resistance investigation,and can be used in disease resistance breeding.?2?The resistance expression of Baimangmai began in tillering stage and reached medium resistance level in jointing stage.Infection types gradually decreased with plant growth and finally reached the highest resistance level in heading stage.The resistance expression of Baimangmai to the tested races was not sensitive to temperature treatments and showed immunity or higher resistance in the temperatures 18? and 30? environment.?3?The adult-plant resistance was evaluated by 160 RIL of the cross Baimangmai with Taichuang29 at Langfang?Hebei?,Jiangyou?Sichuan?and Tianshui?Gansu?in 2015 and 2016.The RIL and two parental cultivars were genotyped with SSR molecular markers and Wheat 90K SNP iSelect assay.The linkage maps were constructed with 110 SSR markers and 6846 SNP markers,and successfully linked to 19 wheat chromosomes except 4D and 5D,covering wheat genome 3192.36 cM with average genetic distance 0.46 cM.QTL for resistance to stripe rust was analyzed by phenotype of three places in the past two years?three replicates?.A total of 3 adult plant resistance QTL to stripe rust were located on chromosome 2BS,4BL and 3BS,which were named QYr.caas-2BS2,QYr.caas-4BL and QYr.caas-3BS respectively,and were all from landrace Baimangmai.QYr.caas-2BS2 located on chromosome 2BS,between SNP markers BS00089734-51 and Kukri-c36783-91,was detected in Langfang?2015/2016?,Jiangyou?2015/2016?,Qingshui?2015/2016?two years in 6 environmental conditions.The resistance expression of QYr.caas-2BS2 can be stable and explain 8.25-16.24%of the phenotypic variation.QYr.caas-4BL located on chromosome 4BL,between SNP markers Ra_c10455₃226 and wsnp_Ex_c5479₉671318,was detected in Langfang?2015/2016?,Jiangyou?2015/2016?,Qingshui?2015/2016?6 environmental conditions,accounting for 9.28-20.00%of phenotypic variation.QYr.caas-3BS located on chromosome 3BS,between SNP markers Excalibur_c19743₁757 and Tdurum_contig34149₂19,was obtained only in 2014-2015 annual environmental conditions in Jiangyou,accounting for 8.83%of phenotypic variation.Accumulation analysis showed that resistance level of 3 QTL was close to that of Baimangmai and resistance level of two major QTLs reached to high-level resistance.