Molecular Mapping Of Leaf Rust Resistance Gene In Chinese Wheat Line L224-3

Among the three wheat rusts, wheat leaf rust occurred in more wide area than striperust and stem rust. Leaf rust can cause significant yield loss in wheat-growing regionswhen the disease is severely prevalent, and it can also have influence on the wheat quality.With global warming, climatic conditions will become more favorable for the occurrenceand spread of leaf rust. The leaf rust resistance can be divided into race specific resistanceand non-race specific resistance. Race specific resistance is controlled by single gene andexpresses mostly at seedling stage, and may lose effectiveness when virulent races emergeor increase. Non-race specific resistance is controlled by polygene, often expressesresistance at adult plant stage, displays as quantitative trait, and the resistance is consideredas durable resistance. In order to understand the resistance present in lines both of seedlingand adult plant resistance should be studied. Wheat line L224-3was developed byHuangfanqu Farm of Henan Province and showed high resistance to most of Pucciniatriticina pathotypes in the field. Identifying and mapping the leaf rust resistance gene(s) inL224-3is very useful for breeding wheat cultivars with durable resistance to leaf rust.In the study F2:3population from the cross L224-3/Zhengzhou5389were inoculatedwith pathotype FHDQ for genetic analysis for leaf rust resistance, and molecular markerswere used to map the seedling resistance gene in L224-3. F2:3population from the crossL224-3/Zhengzhou5389were also planted in the field. The phenotype data in the fieldfrom two years and genotype data of SSR markers were combined to analyze the leaf rustresistant QTL loci present in L224-3. The results were showed as follows:1. Wheat line L224-3and37check lines with known leaf rust resistance genes wereinoculated with15pathotypes at seedling stage to postulate gene in L224-3. The resultshowed that L224-3had high resistant to all Lr26non-virulent pathotypes, so L224-3contained Lr26. Due to resistance to some Lr26virulent pathotypes, L224-3may carryother resistance gene.2. A total of144F2:3lines from the cross L224-3/Zhengzhou5389were inoculated withpathotype FHDQ for genetic analysis of leaf rust resistance in L224-3. The results showedthat the resistance of L224-3was controlled by a single dominant gene, tentatively designated LrL224.3. Bulked Segregate Analysis and molecular makers were used to map LrL224. Linkageanalysis were conducted using the software MapManager QTXb20. Results indicated thatfour SSR markers (barc8, gwm582, wmc419, and wmc694) and one STS marker(ω-secali/Glu-B3) on1B were closely linked to LrL224. The two flanking SSR loci werebarc8and gwm582, with the genetic distances of4.3and4.6cM, respectively.4. LrL224was located on1BL, and it showed different seedling reaction with other geneson1B. Therefore LrL224is likely to be a new leaf rust resistance gene.5. F2:3population from the cross L224-3/Zhengzhou5389were inoculated with mixed P.triticina pathotypes for scoring leaf rust severities in the field during two years. When thefinal disease severity (FDS) of susceptible parent Zhengzhou5389reached100%, the FDSof resistant parent L224-3was less than10%in the two years, indicating that the diseasedeveloped well in both seasons.6. A total of188F2:3lines from the cross L224-3/Zhengzhou5389were detected by SSRmarkers for mapping adult plant resistance QTLs to leaf rust. In the first year, four QTLs(QLr.hbau-2AS.1、QLr.hbau-2AS.2、QLr.hbau-2DS.1and QLr.hbau-2DL) for adult plantresistance to leaf rust were detected on chromosomes2A and2D, and the closely linkedmolecular markers were barc124、wmc474、barc297and cfd36, respectively. Each of theQTLs explained23.39%、7.48%、16.81%and37.67%of phenotypic variance, respectively.In the second year, three QTLs (QLr.hbau-2AS.1、QLr.hbau-2AS.2and QLr.hbau-2DL) foradult plant resistance to leaf rust were detected on chromosomes2A and2D, and theclosely linked molecular markers were barc124、wmc453、barc297and cfd36, respectively.Each of the QTLs explained23.60%、11.94%and62.00%of phenotypic variance,respectively.