Molecular Diversity Of Twenty-three Near Isogenic Lines Resistant To Wheat Leaf Rust And A SRAP Marker Of Lr19 In Wheat

Wheat leaf rust is an important disease in the production of wheat. Screening and breeding for resistance cultivars are considered to be the most economical, environmental, and effective appropriate strategy to reduce the disease damages. It is a long and important task to study, discover, and mark constantly the leaf rust resistance genes. Gene Lr19 was located on the chromosome 7DL of wheat. It is a very effective leaf rust resistance gene. The Lr19 was firstly transferred into the wheat genome from Thinopyrum sp. in the form of substitution line 'Agrus' in 1966. Lr19 has great potential to be used for wheat production so far. It is important to establish the higher density genetic map and isolate the resistance gene.SRAP, sequence-related amplified polymorphism, is a new marker system based on PCR. It is effective, credible, simple, and economical, which not only absorbs some advantages from RFLP, RAPD, SSR and AFLP, but also overcomes their some disadvantages.This research firstly applied SRAP technique in wheat leaf rust, and establish and optimize SRAP-PCR system of wheat genome. Adapting to the study of wheat genome, a steady system was developed.Total twenty-three near-isogenic lines resistant to wheat leaf rust in Thatcher background and Thatcher were employed to carry out SRAP markers. Forty-one of 128 SRAP primer combinations amplified a total of 537 reproducible fragments. Among them, 49.5ï¼…fragments were polymorphic, and 115 of them were specific bands(10.6ï¼…). Six to forty one fragments were amplified by per primer combination, with the average of 13.1 bands. The number of polymorphic fragments for each primer combination varied from one to thirteen, with the average of 2. 8 bands. A duster analysis was performed using NTSYSpc Version 2.10e software. The results revealed twenty-three wheat leaf rust resistance genes and Thatcher into two clusters of A and B with the similarity coefficient of 0.72. Ninety six percent of them were clustered into duster B, which was divided into two groups,â… andâ…¡. Ninety five percent of the near isogenic lines in cluster B were classified into groupâ…¡. Groupâ…¡included four small groups with 0.785 similarity coefficient.SRAP analysis was firstly carried out based on Thatcher, twenty-three near-isogenic lines and F₂ generation of TcLr19×Thatcher to developing molecular markers for gene Lr19 resistance to wheat leaf rust. A marker linked to Lr19 resistance traits was obtained. It was M73 with a distance of 2.6 cM to Lr19. The result may facilitate the establishment of the higher density genetic map, wheat marker-assisted selection breeding program, and eventual cloning of gene Lr19.The sequence of M73 was analyzed by BLAST. The results showed the identities of the sequence and partial sequence of Triticum turgidum HMW-glutenin locus were 86ï¼…. The identities of the sequence and partial sequence of Triticum aestivum BAC1031P08, 754K10, 1344C16 were 86ï¼…. The identities of the sequence and partial sequence of Triticum aestivum NBS-type putative resistance protein were 45ï¼…. So SRAP technique is feasible to the research on wheat leaf rust resistance gene markering and cloning.