| Wheat is one of the most important crops in China,which is related to national food security.Therefore,high and stable yield of wheat is very important.Powdery mildew of wheat is a destructive disease caused by Blumeria graminis f.sp.tritici（Bgt）seriously threatening yield and quality worldwide.Comprehensive dissection of new resistance-related genes is necessary to control this disease.Although many disease resistance genes have been discovered,most of them have lost their resistance to powdery mildew.Among the limited disease resistance genes,most of them have unfavorable factors,such as pleiotropy,genetic linkage burden and lagging competition.The carrier agronomic characters are poor,which greatly affects the utilization in production.Therefore,it is of practical significance to discover new broad-spectrum powdery mildew resistance genes from vector materials with excellent traits.LS5082 is a Chinese wheat breeding line with resistance to powdery mildew.Many years of field identification and seedling strain identification show that LS5082 has a broad spectrum of resistance to powdery mildew.Therefore,this study intends to identify the resistance gene in LS5082,apply the resistance gene to marker assisted selection breeding,and analyze the expression pattern of the genes related to powdery mildew resistance in LS5082 after infection.The results are as follows:（1）Genetic analysis of disease resistance: LS5082,three susceptible parents（Shannong 29,shimai 22 and huixianhong）and their hybrid offspring were identified by using different powdery mildew strains,and the resistant and susceptible individual plants were counted for genetic analysis of disease resistance.It was found that LS5082 carried a dominant powdery mildew resistance gene,which was temporarily named PmLS5082.（2）Molecular marker localization: BSR-Seq was used to sequenced and analyze the susceptible pool and the resistant pool.The SNP closely related to PmLS5082 was designed and the molecular markers were designed.7 common SSR markers（YTU19-005,YTU19-007,YTU19-009,YTU19-011,YTU19-012,YTU19-014）and 2 KASP markers（YTU19-KASP26,YTU19-KASP96）were screened.Combined with the molecular marker screening results of known powdery mildew resistance gene linkage on 2BL chromosome,PmLS5082 was mapped to a 0.7 c M genetic interval on chromosome arm 2BL,which was aligned to a 0.7 Mb physical interval of 710.3-711.0 Mb.（3）Comparative analysis with Pm: By distinguishing PmLS5082 from the known powdery mildew resistance genes on the 2BL chromosome arm,it is found that PmLS5082 is different from the reported pm6,pm33,pm51,pm52,pm63,pm64,Pm Q,Pm KN0816,MLZec1 and MLAB10 on the 2BL chromosome from the perspectives of gene source,chromosome location,gene recessiveness,interval characteristics and resistance spectrum,indicating that PmLS5082 is likely to be a new powdery mildew resistance gene.（4）Candidate gene / regulatory gene analysis: 10,646 DEGs between the susceptible pool and the resistant pool were analyzed by COG and KEGG pathway enrichment analysis.In the candidate interval of 0.7Mb（710.3～711.0Mb）,13 DEGs related to disease resistance or stress tolerance were selected for expression pattern analysis after inoculation with Bgt isolate E09.The results showed that six genes showed significant expression differences between LS5082 and shimai 22 after inoculation with Bgt isolate E09,especially the gene encoding an LRR receptor-like serine-protein（Traes CS2B02G524300.1）can be regarded as an important candidate gene / key regulatory gene of PmLS5082.（5）Marker assisted selection: In order to speed up the breeding and utilization of PmLS5082,we developed 10 closely linked markers including 2 KASP markers,were confirmed to be suitable for marker-assisted selection of PmLS5082 in different genetic backgrounds.In particular,the common SSR markers YTU19-005 and YTU19-KASP96 have the best retrieval effect,and can effectively track PmLS5082 with different detection platforms. |
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