Preliminary Mapping Of Stripe Rust Resistance Genes In Wheat-rye Chromosome Translocation Line

Wheat stripe rust is one of the most serious diseases caused by typical air-borne fungi races(Puccinia stiiformis f.sp.tritici).The disease is featured by its prevalence,strong outbreak,wide distribution and harmful impacts etc.Stripe rust is widely distributed in China,which threatens the production of winter wheat in the northwest,southwest,and Huang-Huai Plain as well as of spring wheat in the northwest area.It has been shown that breeding and growing resistant cultivars is the most economical,effective,safe and environment-friendly strategy to improve wheat stripe rust resistance.At present,although many resistant genes for stripe rust have been discovered,few of them are employed in wheat breeding practice.Thus,identification of novel stripe rust resistant genes is of great importance for modern breeding practice pursuing disease resistant wheat cultivars.Phenotypic characterization showed that the wheat-rye 1BL/1RS translocation line K13-868 is highly resistant to prevalent virulent PST(or strains)in China,but the underlying resistant genes mechanisms are remained unknown.The present thesis aimed at dissecting genetic architecture of strip rust resistance of K13-868 taking advantage of F2 and F2: 3 genetic analysis populations genotyped by SSR and 660 K SNP chip and explored new excellent stripe rust resistance genes.It is excepted providing genetic resources for the durable resistant to stripe rust for the breeding of wheat varieties and providing efficient means of molecular marker-assisted selective breeding(MAS),so as to change the current situation of narrow genetic basis and single resistance source of main varieties.The main findings are as follows:1.The resistance of wheat-rye 1BL/1RS translocation line K13-868 was investigated by inoculation of Chinese prevalent isolates of Puccinia striiformis(CYR32,CYR33,CYR34?Gui22-14)at seeding stage in greenhouse as well as at adult-plant stage in field trail in Wenjiang.The results showed while K13-868 was moderately susceptible to stripe rust at seeding stage,it is highly resistant at adult-plant stage.2.The infection type(IT)and max disease severity(MDS)were recorded for 274 F2 plants and F2: 3 lines at adult plant stage in Wenjiang in 2017 and 2018,respectively.IT,MDS and r AUDPC showed continuous distribution with broad variation.IT and MDS showed high broad-sense heritability,0.9404 and 0.9997,respectively,suggesting that the strip rust resistance in K13-868 is a quantitative trait and highly heritable.3.Genetic effects of 1RS translocation fragment on resistance of stripe rust were detected and 122 of the 274 individual plants were 1BL/1RS translocation lines.Combined with the results of disease resistance traits in the field,the correlation coefficient between the resistance and 1RS translocation of 274 individual plants was 0.056,indicating that the main gene of resistance to stripe rust might not exist in 1RS translocation fragment of K13-868.4.Genotyping using 660 K SNP chip showed that 538 of 630517 SNP exhibited the same difference between parent and R bulks,S bulks,of which 213(39.59%),61(11.34%)and 51(9.4%)were distributed on 2A,3A and 1B,respectively,indicating that there might be stripe rust resistance associated QTLs on chromosome 2A,3A and 1B.5.Three strip rust resistance-associated QTLs were detected on short-arm of chromosome 2A and 3A by employing Inclusive Composite Interval Mapping(ICIM).The QTL on 2A(Yr.sicau-2A.1)was flanked by SSR Xwmc522(3.8c M)and Mag3807(12.4 c M)explaining 10.29% of the phenotypic variation;QYr.sicau-2A.2 was flanked by SSR Mag380 and XSicau2(9c M)and explained 17.4% of the phenotypic variation.In addition,the QTL on 3A(QYr.sicau-3A)explaining 6.38% of the phenotypic variation was flanked by SSR X3A-ISBP396(20c M)and Xwmc264(11cM).