Molecular Mapping Of Leaf Rust Resistance Gene In Wheat Lines Zhou 8425B And Guizhou 98-18

Wheat leaf rust, caused by Puccinia triticina, is one of the most important diseases affected the wheat production word widely. It is adapted to a wide range of climates, occurs wherever wheat is grown, and can cause significant yield losses, inferior grain quality and economic losses. Resistant cultivars are the most efficient, economic and environmentally-friendly way for reducing the losses caused by the disease. It is very important to find and map new leaf rust resistance genes for breeding resistant cultivars.The method of researching leaf rust resistance gene can be choiced based on different research objectives and test conditions. EST (expressed sequence tags, EST) marker is a technique which can detect the DNA mutation from the genome scale by utilizing a particular section of the cDNA clone sequence corresponding to a kind of mRNA derived from different tissues and amplifying the genome DNA specifically through primers designed by their nucleotide sequences. SSR (simple sequence repeat) can detect the DNA mutation by using the DNA sequence of both sides of a section containing different tandem repeat core sequence as primers and amplifying the genome DNA containing repeat sequence. Wheat lines Zhou 8425B and Guizhou 98-18 give low infection types to most of Chinese current leaf rust pathotypes. In this study, the leaf rust resistance gene in Guizhou 98-18 was researched by gene postulation, the genetic analysis, and SSR technique and EST markers and BSA were used to mapping leaf rust resistance gene LrZH84 in Zhou8425B. The main results are as follows:1) The resistance genes in Guizhou 98-18 were identified by comparing the reaction of Guizhou 98-18 with 35 near-isogenic lines with known resistance genes to 14 Puccinia triticina races. The result showed that Guizhou 98-18 might contain a new leaf rust resistant gene.2) GuiZhou 98-18/ZhengZhou 5389 and their F1 and F2 populations were inoculated for wheat leaf rust resistance with Chinese pathotypes THTT in the greenhouse. Results indicated that GuiZhou 98-18 carries a single dominant resistance gene, temporarily designated LrG98.3) SSR and STS primers were used to test the parents and their resistant and susceptible bulks. The polymorphic markers between the resistant and susceptible bulks were used for analyzing the F2 populations. Linkage analysis was conducted with the software MapManager QTXb20. Results indicated that the dominant resistance gene LrG98 in Guizhou 98-18 was closely linked to the four known loci (Xgwm582,Xbarc240,Lr26,Xwmc694) on the 1B chromosome, and the genetic distance ranged from 3.8cM to 10.9cM. The nearest markers close to LrG98 are SSR marker Xbarc582-1B and STS marker of Lr26 with genetic distances of 3.8cM, respectively.4) Using the 101 pairs of EST primers selected from the 1B chromosome in wheat conducted PCR amplification to test the Zhou 8425B,Chinese spring and their resistant and susceptible bulks established by BSA. The results showed that 5 pairs of primers could amplify polymorphic fragments. The stable and clear polymorphic markers of EST could be amplified between the resistant and susceptible parents and individual plants only by primer BF482555_cp after repeat with the annealing temperature 55℃and time of extension 45s. The marker was designated as BF482555. The polymorphic EST marker was used for analyzing the F2 and F3 populations. Linkage analysis was conducted with the software MapManager QTXb20. Results indicated that the dominant resistance gene LrZH84 in Zhou 8425B was closely linked to the EST marker BF482555 located on chromosome 1BL, and the genetic distance detected in the F2 and F3 populations were 3.8 cM and 4.5 cM, respectively. The marker was dominant polymorphic fragments in the resistant and susceptible cultivars.