Molecular Marker Development And Marker-assisted Selection Breeding Of Wheat Stripe Rust Resistance Gene Yr52

Wheat stripe rust caused by Puccinia striiformis f.sp.tritici（Pst）,is one of the most devastating rust diseases in wheat production over the years.The high temperature adult plant（HTAP）resistance gene Yr52 was found to be resistant to all of the present predominant races in the adult plant stage.The objective of this study is to evaluate the application value of the stripe rust resistance gene Yr52 in wheat production by molecular marker-assisted selection（MAS）.And wheat lines with good agronomic characters and high disease resistance were developed and selected.It laid a foundation for making full use of the existing HTAP resistance resources and improving the yield related traits.PI 660057,a common wheat cultivar with stripe rust disease-resistant gene Yr52,was used as research materials.The genetic linkage mapping population of JM47/PI 660057 was constructed,to development molecular marker and mapping.At the same time,the stripe rust resistance gene Yr52 was introgressed to Lunxuan 987（LX987）,Bainong Aikang 58（AK58）and Han 6172（H6172）by backcrossing and self-crossing combined with marker-assisted selection breeding.The resistance of parents and their progeny lines were evaluated in the disease nursery fields at Mianyang,Sichuan and Yangling,Shaanxi and agronomic traits was evaluated.Wheat lines with good agronomic characters and high disease resistance were developed and selected.The main results obtained in this study are as follows:1.A genetic mapping population of 1890 F₂generation from JM47/PI 660057 were obtained.Four markers were developed within the physical range of the target gene:A dCAPS marker Xdcaps-Yr52-1 was obtained;Three KASP markers,named Xkasp-Yr52-1,Xkasp-Yr52-2and Xkasp-Yr52-3,respectively.A 3.01 c M interval flanked by KASP markers Xkasp-Yr52-2and Xkasp-Yr52-3.The linkage relationship with the target gene was:Xkasp-Yr52-2-Yr52-Xbarc182-Xkasp-Yr52-3,and the relative genetic distance between moleculars was 1.0-Yr52-1.2-0.8 c M.2.Three backcrosses LX987//LX987/PI 660057,AK58//AK58/PI 660057 and H6172//H6172/PI 660057 were constructed.Total obtained 28 BC₂F₄lines after screened based on the field disease resistance and agronomic traits in 2017-2019.The evaluation of adult plant resistance and agronomic traits in 2020-2021 indicated that nineteen BC₂F_5:6lines with LX987 background was obtained:Among of them,11 were high resistance（IT=0-3,DS=1%-20%）,8 were moderate resistance（IT=4-6,DS=15%-30%）,the average thousand kernel weight（TKW）,kernels per spike（KPS）,productive tiller number per line（PTN）,plant height（PH）and spike length（SL）was 45.33 g,46,7,113.26 cm and 10.05 cm,respectively.Four BC₂F_5:6families with AK58 background:all showed high resistance（IT=0-3,DS=5%-25%）;the average TKW,KPS,PTN,PH and SL were 44.67 g,48,7,96.54cm and 10.17 cm,respectively.Five BC₂F_5:6lineages with H6172 background showed high resistance to stripe rust（IT=0-3,DS=5%-20%）.The average TKW,KPS,PTN,PH and SL were 43.74 g,49,8,109.72 cm and 10.06 cm,respectively.3.The detection rate of three simple sequence repeat（SSR）molecular markers Xbarc182,Xcfa2040,Xwmc557 linked to Yr52 and developed one dCAPS marker Xdcaps-Yr52-1 and one KASP marker Xkasp-Yr52-1 in offspring population were 78.57%,66.67%,66.67%and73.68%and 41.67%,respectively.The agronomic traits of lines with high（IT=0-3）and medium（IT=4-6）resistance levels were compared.The results showed that the average TKW（P>0.05）,PTN（P>0.05）and KPS（P<0.05）of lines with IT=0-3 were higher than those of families with moderate resistance level lines（IT=4-6）.Five lines with disease resistance and stable agronomic traits were selected by evaluated of PH=80-105 cm,PTN≥6,KPS≥45,TKW≥42 g,SL≥8 cm.In this study,dCAPS and KASP markers were successfully developed within the physical range of the target gene,providing reference range for fine localization of Yr52.Yr52 was introgressed to the main varieties that lost resistance in China,offspring lines resistance increase helps to protect the TKW,KPS and PTN;And breded and selected lines with good disease resistance and agronomic characters.It provides effective material for breeding polymerized resistant varieties in the future.