Identification Of Leaf Rust Resistance Of Foreign Wheat Varieties (Lines) And QTL Analysis For Adult-Plant Resistance To Wheat Leaf Rust In Libellula

Wheat leaf rust is widespread in China,which seriously damages the quality and yield of wheat.Leaf rust has the characteristics of early onset,rapid expansion,long peak period,widespread occurrence and strong adaptability to climate conditions.As the physiological race of wheat leaf rust continues to mutate with the change of climatic conditions resulting in the gradual loss of wheat disease resistance genes,it is necessary to continuously identify and locate new disease resistance genes and identify new disease resistance varieties.Important role:the content of this study mainly includes identification of wheat leaf rust resistance genes and QTL mapping of adult plant leaf rust resistance.The research results are as follows:1.In this study,gene postulation,combining with molecular marker detection,pedigree analysis and identification of slow rusting resistance,were used to determine the leaf rust resistance genes carried by the varieties.17 Puccinia triticina (Pt) races with different levels of virulence were inoculated to all the 69 foreign wheat materials and 36 tester lines with known leaf rust resistance genes at seedling stage in the greenhouse.Moreover,11 molecular markers closed to known leaf rust resistance genes were used to test all the varieties for molecular marker detection.In order to clarify the resistance of wheat varieties at the adult stage,the 71 wheat materials,including Zhengzhou 5389 as the susceptible check and SAAR as the slow-rusting resistance check,were planted in the field in Baoding,Hebei province,and Huangfan District,Zhoukou,Henan province in the 2017-2018 cropping seasons.The final disease severity (FDS) was identified,and the slow rusting resistance varieties were classified as with FDS values significantly less than or not significantly different from the slow rusting resistance check,SAAR.Results showed that six wheat leaf rust resistance genes,Lr1,Lr10,Lr19,Lr26,Lr34 and Lr37 were detected in 69 wheat varieties (lines) singly or in combination.The seedling resistance genes,Lr1,Lr10,Lr19 and Lr26 were identified in 6,19,5 and 10 varieties,respectively.The adult leaf rust resistance genes,Lr34 and Lr37 were identified in 10 and 26 varieties,respectively,and 46 wheat varieties were identified as ones with slow rusting in the field.The identification results of 69 leaf rust resistance genes from foreign materials can lay the foundation for gene layout and breeding of durable disease resistant varieties.2.The wheat variety,Libellua,is produced from Italy and has been used in our country for many years based on it’s good resistance.In order to study the leaf rust resistance of wheat variety Libellula at the adult stage,248 RIL lines from Libellula ×Huixian Hong were used for QTL analysis.All the RIL lines were genotyped using wheat 55K SNP array,and the possible chromosomal positions of QTL were initially determined.After screening SSR primers,the software Map Manager QTXb20 was used to comprehensively analyze the genotypic data of the RIL population and FDS data in 7 environmental fields to obtain the marker heredity group and the linkage genetic distance(cM) between each marker.Combining with software QTL Ici mapping4.0 for QTL locus analysis.,a total of six QTLs were detected in the RIL population,five of which were with micro-effect to leaf resistance and a single gene was with a major resistance effect,the QTLs were located at 1A,1B,3A,4B,6A and 7D chromosomes,named as QLr.hbau-1A,QLr.hbau-1B,QLr.hbau-3A,QLr.hbau-4B,QLr.hbau-6A and Lr34,respectively.Among them,QLr.hbau-1A was detected in 6 environments,explaining the phenotypic variation of 4.8-9.7%;QLr.hbau-1B and QLr.hbau-3A were detected in 2 environments,explaining separately 5.15%-5.64% and 5.31%-5.87% phenotypic variation;QLr.hbau-4B and QLr.hbau-6A detected in 4 environments,explaining 8.14%-10.86% and 6.36%-10.38%,respectively.Lr34 was detected in 7 environments,explaining 3.64%-36.28% phenotypic variation.The QTLs of adult plant resistance to leaf rust in the study should provide a theoretical basis for breeding of durable disease-resistant varieties in wheat breeding programs.