Molecular Identification Of Resistance Genes To Stripe Rust Of Two Wheat Cultivars And Preliminary Exploration Of Breeding Utilization Value In Wheat Landraces

Wheat stripe rust is one of the serious hazards to the safe production of wheat all over the world and causes severe damage to wheat yield.Currently,effective measures for controlling stripe rust is by discovering resistance genes and breeding resistant varieties.It is necessary to increase the discovery and utilization of novel wheat stripe rust resistance genes,broaden the selection range for stripe rust resistance breeding,and improve the diversity of resistance genes in wheat varieties.The previous researches showed Benyouzimai（BYZ）and Hongmangmaizi（HM）had excellent agronomic characteristics of early maturity,multiple effective tillers and so on.Both of them have stable adult-plant resistance（APR）to the physiological subspecies and pathogenic groups of stripe rust,and are excellent materials for wheat yield and stripe rust resistance breeding.In order to identify the genes for APR to stripe rust,BYZ and HM were used as the resistance parent,and Avocet S was used as the susceptible parent to construct genetic analysis and molecular mapping populations.Xikemai 5 and Mianmai 1618 were used as recurrent parents for breeding improvement populations.Based on the selection strategy combining molecular marker-assisted selection,phenotypic identification and yield trait evaluation,some intermediate materials were created with coordinated yield and stripe rust resistance.The main findings are as follows:1.A genetic analysis and molecular mapping population was constructed between BYZ and Avocet S,and F₂、F_2:3 populations were obtained by crossing two parents.Genetic analysis showed that the APR to stripe rust in BYZ was controlled by multiple QTLs.Using Wheat55K SNP arrays and wheat exome capture sequencing,combined with bulked-segregant analysis（BSA）,two QTLs controlling the APR to stripe rust in BYZ were mapped on the short arm of chromosome 5B and chromosome 7D,namely QYr.BYZ-5BS、QYr.BYZ-7DS.QYr.BYZ-7DS can explain 27.36%-29.90%of the phenotypic variation.Based on stripe rust resistance identification,genetic mapping,and physical mapping,QYr.BYZ-7DS showed collinearity with Yr18 which is a gene known to control the APR to stripe rust,and the genetic effect of QYr.BYZ-7DS is derived from Yr18;QYr.BYZ-5BS can explain 9.06%-11.07%of the phenotypic variation.By molecular mapping,QYr.BYZ-5BS was located between markers KP5B＿78.49 and KP5B＿83.68,with a genetic span of 3.78 c M.The validation of the specific marker showed that the flanking marker KP5B＿83.68 could be used for molecular marker-assisted breeding of QYr.BYZ-5BS.2.A genetic analysis and molecular mapping population was constructed between HM and Avocet S,and F₂、F_2:3 populations were obtained by crossing two parents.Genetic analysis showed the APR to stripe rust in HM was controlled by multiple QTLs.Using Wheat55K SNP arrays and wheat exome capture sequencing,combined with bulked-segregant analysis（BSA）,two QTLs were mapped on chromosomes 7A and 7D that controlled the APR to stripe rust in HM,namely QYr.HM-7AL and QYr.HM-7DS.The analysis of stripe rust resistance identification,genetic mapping,and physical mapping showed the genetic effect of QYr.HM-7DS was derived from Yr18 and QYr.HM-7DS could explain 24.33%-40.58%of the phenotypic variation;QYr.HM-7AL can explaining 11.64%-15.25%of the phenotypic variation and is located between markers KP7A＿527.12 and KP7A＿533.57,with a genetic span of 1.42 c M.The validation of the specific marker showed that the flanking marker KP7A＿533.57 could be used for molecular marker-assisted breeding of QYr.HM-7AL.3.The genetic effect analysis population（BC₁F₂）was constructed by crossing and backcrossing with BYZ as donor parent and XK5 as recurrent parent.Based on the tracking of specific markers of stripe rust resistance genes,the analysis of resistance phenotype and yield-related traits,it was found that the infection type of stripe rust was negatively correlated with thousand-grain weight.Meanwhile,it was found that QYr.BYZ-5BS+Yr18controlling the APR to stripe rust in BYZ had a positive effect on the tillering number of wheat.Through the comprehensive evaluation of stripe rust resistance and yield-related traits,six individual plants with the genetic background of XK5,carrying the target gene of stripe rust resistance from BYZ and displaying excellent yield-related traits were preliminarily selected.4.The genetic effect analysis population（BC₁F₂）was constructed by crossing and backcrossing with HM as donor parent and MM1618 as recurrent parent.According to the analysis,the infection type of stripe rust was negatively correlated with plant height,thousand-grain weight,grain length and grain width.At the same time,it was found that QYr.HM-7AL controlling the APR to stripe rust in HM had a positive effect on the improvement of yield-related traits（spike length and tiller number）of wheat.Through the comprehensive evaluation of stripe rust resistance and yield-related traits,six individual plants with the genetic background of MM1618,carrying the target gene of stripe rust resistance from HM and displaying excellent yield-related traits were preliminarily selected.