Molecular Cytogenetic Identification Of The Wheat-psathyrostachys Huashanica Derivative Lines And Mapping Of Powdery Mildew Resistance Genes

Wheat powdery mildew（Pm）,caused by Blumeria graminis f.sp.tritici,is a common and important disease in China and even in the world,which seriously restricts the increase of wheat yield and quality.To control wheat powdery mildew,digging and locating new powdery mildew resistance genes continuously,cultivating and planting wheat varieties with powdery mildew resistance is the most effective and fundamental measure.Our team have created some wheat-P.huashanica derived progenies by chromosome engineering and distant hybridization,and five resistant plants were screened under preliminary identification of powdery mildew,among which wheat-P.huashanica derived progenies with No.H5-5-4-2-2-2 and H3-5-9-3-1-4 showed excellent resistance to powdery mildew.In this study,H5-5-4-2-2-2 and H3-5-9-3-1-4 were determined by cytology analysis and molecular marker analysis,to clarify the introduction of exogenous chromosome fragments,and to determine attribution and location analysis of exogenous chromosomes or genes.In addition,the F₂segregation population and F_2:3population from H3-5-9-3-1-4×Mingxian169 were constructed.The susceptible and resistant pools were established according to BSA method,and were screened by SSR molecular marker and 660K SNP chip.Combined with the scanning results,the powdery mildew resistance gene from H3-5-9-3-1-4was mapped preliminary with the linkage SSR markers.The main results of this experiment are as follows:1.The powdery mildew reaction of five wheat-P.huashanica derived progenies,P.huashanica and wheat parent 7182,susceptible control Mingxian 169 was tested at seedling stage and adult stage by with E09 isolates.The results showed that H5-5-4-2-2-2 and H3-5-9-3-1-4 exhibited similar resistance to powdery mildew with their wild parents P.huashanica in the two stages,and both of them were immune or highly resistant to powdery mildew;while H18-1-3-1-6-2 and H30-4-4-1-6-2 were moderately susceptible at seedling stage but highly resistant at adult stage,H30-2-3-1-1 was highly susceptible at seedling stage and moderately susceptible at adult stage.2.The chromosome number and structure of H5-5-4-2-2-2 and H3-5-9-3-1-4 were identified by cytology and genomic in situ hybridization（GISH）,the results showed that H5-5-4-2-2-2 contained a pair of alien chromosomes from P.huashanica and 42 wheat chromosomes,and the additional alien chromosomes had partial homology with the first homologous group of wheat chromosomes through EST-STS molecular marker analysis,so we identified H5-5-4-2-2-2 was a wheat-P.huashanica 1Ns disomic addition line.The root tip cells of H3-5-9-3-1-4 contained 42 chromosomes,and no obvious fluorescence hybridization signal was observed by GISH identification.The reason may be that the imported foreign fragment was too small.Combined with the results of SSR marker analysis and disease resistance identification,we inferred that H3-5-9-3-1-4 is an introgressive line of wheat-P.huashanica.3.The identification of of powdery mildew resistance at adult stage was performed for the F₁and F₂populations from the cross between H3-5-9-3-1-4×Mingxian 169 and their F_2:3lines.All F₁plants were immune to powdery mildew,F₂population and F_2:3lines presented character segregation,and the segregation ratio of resistance and sensitivity was3:1 and 1:2:1,respectively.Therefore the resistance gene named Pm H3-5-9-3-1-4temporarily in introgression line H3-5-9-3-1-4 was controlled by dominant gene.4.SSR marker screening and 660K SNP chip scanning were carried out in resistance and susceptible bulks constructed according bulked segregant analysis（BSA）method.SSR marker Xbarc321 located on the 3A chromosome was found can amplified polymorphic bands between resistance,susceptible parents and bulks;according to the results of 660k SNP,1616 polymorphic SNP markers were detected among the bulks,of which more polymorphic sites were located on 3A chromosome,up to 284,and most of them were concentrated in 5-20 c M region of 3AS.5.According to the target region,SSR primers were selected and synthesized for linkage analysis,the markers Xbarc310 and Xbarc321 were closely linked to Pm H3-5-9-3-1-4.The sequence of linkage was Xbarc310-Pm H3-5-9-3-1-4-Xbarc321,and the linkage distances were 7.5 c M and 3.2 c M,respectively.And we inferred that Pm H3-5-9-3-1-4 may be a new powdery mildew resistance gene on 3AS chromosome.