Screening Of Stripe Rust Resistance And Molecular Detection Of Yr Genes Of Wheat Germplasms Of ICARDA

Stripe rust of wheat is an airborne leaf disease caused by Puccinia striiformis,which is a worldwide infectious disease.China is the largest wheat stripe rust area in the world.The epidemic year seriously affects wheat yield and threatens the safe production of wheat.Cultivating disease-resistant varieties is the most effective and environmentally friendly measure to control wheat stripe rust.The lack of resistance sources of wheat stripe rust in China,the single distribution of resistance genes and the continuous renewal and variation of Puccinia striiformis have brought great difficulties to the prevention and control of wheat stripe rust in China.Therefore,it is particularly important to collect disease-resistant materials extensively,excavate new disease-resistant genes,and diversify the resistance genes of wheat varieties.Breeding practice shows that introducing and rationally utilizing foreign germplasm resources is an effective way of disease resistance breeding.The objectives of this study were to characterize the stripe rust resistance of the 203 ICARDA germplasm,to select sources with durable resistance and to identify which sources of resistance were based on known genes and which were based on new genes.These potentially new sources will be able to identify novel resistance gene and apply in breeding program.203 ICARD materials were inoculated in Yangling in 2016(CYR32,CYR33)and 2017-2018(CYR32,CYR34)for identification of disease resistance in adult stage.In 2018,Wanjia Village in pingnan Town,Tianshui County Gansu Province,and Haijin Village in Wudu Town,Jiangyou County,Sichuan Province,which were the two natural disease nurseries at the key node of the epidemic development of stripe rust,were tested for disease resistance in field adult stage.In the greenhouse in 2018,CYR32 and CYR34 races with the highest prevalent frequency were used to identify the disease resistance at seedling stage.Combining with the results of disease resistance at seedling stage and adult stage,the comprehensive disease resistance characteristics of the materials were evaluated.Disease-resistant genes were widely used in wheat varieties in China,but now they lost resistance,they were not widely used but still expressed resistance were selected.The stable molecular markers developed by Yr5,Yr9,Yr10,Yr15,Yr17,Yr18 and Yr26 were used to detect the known disease-resistant genes in the materials with stable adult resistance.Combining with resistance spectrum analysis,it was speculated that the disease-resistant genes might be carried.K-means clustering method and pedigree were used to evaluate the genetic diversity among the stable adult resistant materials.Among 203 materials,107 materials showed stable adult stage resistance.including 31(29.0%)materials also performed resistance at seedling stage,2(1.9%)materials and 28(26.2%)materials respectively showed high resistance to CYR32 and CYR34 at seedling stage,only 1(0.9%)materials showed resistance to 2 races of Puccinia striiformis f.sp.tritici(Pst),76(71.0%)materials exhibited resistance only at adult-plant stage.Molecular analysis showed that Yr9(51),Yr10(2),Yr17(30)and Yr18(56)were detected in 107 materials,and these genes existed in the form of individual or several combinations of genomes;Yr5,Yr15,Yr26 were not detected.No genes were detected in 12 materials with good resistance to stripe rust,presumably carrying known genes with undeveloped molecular markers or new genes.The investigation of 107 materials of agronomic traits showed that with outstanding agronomic traits and good performance of multiple agronomic traits could be screened out,which could provide references for breeders to select resistant sources and improve the utilization rate of resistant sources.107 materials were selected with stable resistance combing seedling and adult-plant response,12 resistant materials may contained new rust resistance gene.These germplasms should be useful in further genetic analysis and breeding program,to develop new sources of resistance to stripe rust in wheat.43 materials containing gene aggregation provided a basis for rational distribution of stripe rust genes.The agronomic traits of 107 materials were mastered,and 31 materials with outstanding agronomic traits could provide basis for breeders to use resistant resources efficiently.