Stripe Rust Resistance And Genes In Wheat Cultivars And Lines From Inoculum Overwintering Region In Sichuan Basin

Wheat is the staple crop in China,the planting area is about twenty-four million hectares,the output is about one hundred million tons every year.The yield is second only to corn and rice.Sripe rust,caused by P.striiformis f.sp.tritici(Pst)occurred in our country frequently,caused the loss of wheat production in China.Stripe rust has the characteristics of strong popularity,wide spread and destructive,and it is a serious threat to wheat grain production safety in our country.To grow resistant cultivars reasonably is the most economic,safe and effective method to prevente and control the disease.However,the strong variability characteristics wheat stripe rust,makes the new small in environment and rise constantly,disease resistant varieties are improved more slowly,the ability of resistant varieties will continue to be disappear.The fact that lacking of effective resistance source and irrational using of resistance genes,make the most basic measure through the resistant cultivar control stripe rust cannot play its proper role.Sichuan basin is the most important area in China's overwintering region,and it is the most important source of stripe rust output to cause stripe rust epidemic in east region in pring next year.A total of 161 wheat samples in the study,incuding 43 varieties and 118 advanced lines of wheat,were tested at seedlings stage with four Chinese predominant stripe rust races CYR32,CYR33,V26/G22-9 and V26/CM42 of Puccinia striiformis f.sp.Tritici and we established an evaluation system of the single stripe rust race in greenhouse in Yangling.In field tests,wheat entries were evaluated for stripe rust resistance in Yangling,Shaanxi,artificially inoculated with mixture of CYR32 and CYR33.In Tianshui,Gansu Province,an over-summering region,the entries were evaluated under natural infection in 2015 and 2016,based on the seedling and field reactions,the resistance of the germplasms was classified and assessed.Based on the reactions of Yr single-gene lines,Pedigree tracking technology,molecular markers for Yr5,Yr9,Yr10,Yr15,Yr17,Yr18,Yr26 were used to detect the corresponding genes.The results showed that among the tested materials 12(7.45%)lines were resistance both at seedling and adult stages,28(17.39%)were resistant at adult plant stage,121(75.16%)were susceptible.Molecular tests showed 26 germplasms may contain Yr9 gene and 4 may contain Yr10,20 materials may contain Yr17 gene and 8 may contain Yr18 gene,65 lines(varieties)may contain Yr26 gene,other materials controlled by unknown resistance genes.And Yr5 and Yr15 were absent in the test lines.The results showed that the level of resistance of wheat varieties(lines)in the region of Sichuan basin to tested races is extremely low,and Yr26 materials were used with high frequency especially.With the rise of new stripe rust races V26/G22-9 and V26/CM42,most varieties(lines)lose their resistance to disease.Based on the characteristics of Sichuan basin,It was recommended that in order to improve the resistance level of the local wheat varieties,improve the diversity of resistance genes by use current resistant genes more scientific and reasonable,more genetic breeding methods and use of resistant varieties is important.At the same time,to ensure the safety of the wheat in the eastern part of China,we should strengthen the prediction and control of stripe rust disease to avoid the popularity of stripe rust.