Identification Of Leaf Rust Resistance Genes In 70 Wheat Cultivars(Lines)and QTL Analysis Of Resistance To Leaf Rust And Stripe Rust In Xu’ai RIL

Leaf rust and stripe rust have seriously affected wheat yield and quality in many countries and regions.At present,the effective measures to control leaf rust and stripe rust are to find new resistance genes by genetic means and to breed new resistance varieties of wheat.This method is safer and more environmentally friendly than using fungicides and has been the basis of wheat sustainable production so far.This study is divided into two parts.One part is to screen out slow rust varieties and make use of them by analyzing leaf rust resistance through gene derivation and molecular marker Identification of 70 wheat varieties.In the other part,the QTL for resistance to leaf rust and stripe rust in adult stage was mapped by RIL population constructed by wheat cultivar Xu’ai/Zhengzhou 5389,aiming to find QTL sites for resistance to both,and lay a foundation for fine mapping and map-based cloning.1.The wheat seedlings growing to one leaf and 35 vector varieties containing known resistance genes to leaf rust were inoculated with 18 physiological races of different virulence of leaf rust.Based on the phenotypes of 35 vector cultivars against different physiological species of leaf rust,nine resistance genes including Lr1,Lr10,Lr13,Lrl7,Lr18,Lr21,Lr26,Lr34 and Lr37 were found in the tested cultivars by gene derivation and molecular markers.33 slow rust cultivars were screened out by field inoculation of 3 highly virulent mixed leaf rust species,which laid a foundation for the cultivation of new cultivars containing leaf rust resistance genes.2.Xu’ai showed good resistance to stripe rust and leaf rust during the epidemic period.It is of great significance to find and excavate QTL sites for resistance to leaf rust and stripe rust in adults.A total of 158 families with Xu’ai/Zhengzhou 5389 RIL were used to analyze the genotype of each family using SSR markers.The mixed physiological races of leaf rust and stripe rust were artificially inoculated in the experimental fields of Baoding,Mianyang and Zhoukou of Henan,respectively,to investigate their ultimate severity.The software such as Mapchart,Map Manager QTXB17 and QTL ICI Mapping were used to analyze the genotype and final field severity,construct the genetic Map and conduct QTL Mapping of rust resistance genes.A total of 9 QTL sites were detected by QTL analysis for leaf rust resistance and stripe rust resistance in dwarf cultivars at adult stage,including 3 QTL sites for leaf rust resistance,3 QTL sites for stripe rust resistance,and 3 QTL sites for both resistance to leaf rust and stripe rust.The phenotypic contribution rates of one QTL for resistance to leaf rust and one for resistance to stripe rust on chromosome 1A were 12.8-14.3%and 1.4-3.3%,respectively,which might be new QTL sites detected.The QTL site for resistance to both leaf rust and stripe rust on chromosome 1B was detected as Lr46/Yr29.The QTL for resistance to stripe rust was only detected in one environment with a 6.7%contribution of explanative phenotype,which may be related to Yr29.The phenotypic contribution rates of the two loci on chromosome 4B were 1.5-7.2%and 4.0-8.0%,respectively,which may be new QTL loci with minor effect.One resistance locus was detected in only one environment,and the phenotypic contribution rate was 10.4%.Whether it is a new QTL locus needs to be further verified.One QTL for stripe rust resistance explained 6.5-13.3%of the phenotypic contribution,suggesting that it might be a new QTL.A QTL locus for resistance to leaf rust was detected on chromosome 6A in three environments,explaining the phenotypic contribution of 15.3-20.1%,which may be a new QTL locus.The QTL sites of resistance to leaf rust and stripe rust detected in this study could provide a theoretical basis for the subsequent cultivation of new high-quality resistant cultivars.