Identification Of Leaf Rust Resistance Genes In 58 Wheat Lines And QTL Mapping For Adult-Plant Resistance To Leaf Rust In Xinong 1163-4

Wheat leaf rust,caused by Puccinia triticina(Pt),is the most devastating disease of wheat worldwide.The disease can spread over long distances through air currents,causing huge yield and quality reductions.It has been proved that the most economical,safe and effective measure to prevent and control the disease is to select and use disease-resistant cultivars,and to discover and locate new disease-resistant genes is the basis for breeding disease resistant cultivars.The present study mainly focuses on the following two parts:In the first part,58 wheat lines and 17 P.triticina pathotypes were tested with 36 differential lines with known leaf rust resistance genes to identify and to postulate Lr genes at the seedling stage.Molecular marker detection was also used to confirm the postulated resistance genes in the lines.Results showed that Lr1 was identified in 9 lines.Lr10 was present in 9 lines.Lr11 was present in 11 lines and Lr14a was present in 3 lines.Lr15 was present in 4 lines.Lr26 was present in 5 lines.The result of molecular marker for Lr34 indicated that 10 lines carried this gene.Lr37 and Lr46 were detected in 23 and 57 lines,respectively.In the second part,QTL analysis of adult plant resistance to leaf rust for Xinong1163-4/Thatcher and 187 F2:3 lines was conducted and Xinong 1163-4 showed good resistance to leaf rust at adult plant stage,suggesting it might contain adult rust resistance genes.A total of 187 F2:3 lines and the parents were sown in Baoding,Hebei province field nursery during the 2015-2016,2016-2017,2018-2019 and 2019-2020 cropping reasons,and in Zhoukou,Henan province during the 2018-2019 cropping reasons.Inoculation was conducted with mixed P.triticina pathotypes in the field at the tilling stage.FDS(Final disease severity)was scored after inoculation.SSR and SNP markers were used to screen markers between the resistant and susceptible parents.The polymorphic markers between parents were used to detect the entire 187 F2:3 lines population.QTL analysis was performed using the phenotypic data.In the present experiment,a total of two QTLs were detected in the population.One QTL was located on chromosome 5B,temporay named QLr.hbau-5B.QLr.hbau-5B was detected in six environments explains by 9.7%to 17.9%of the phenotypic variance,and was located closely to the known Lr gene QLr.fcu-5BL,might be the same with the APR QTL which was previously located on chromosome 5B.One QTL was located on chromosome 7B,temporay named QLr.hbau-7B.This QTL was detected in two environments and explaining 11.5%to 11.8%of the phenotypic variance.There were several known leaf rust resistance QTLs near this locus,and their relationship needs further study.