QTL Mapping For Adult-plant Resistance Gene To Leaf Rust In Chinese Wheat Cultivar Weimai 8

Leaf rust caused by Puccinia triticina, is an airborne foliar fungal disease of wheat that occurs in wheat growing areas all over the world. In China, the southwest and the northwest are the two most vulnerable regions where it causes serious yield losses.The adult-plant resistance(APR) or slow rusting is controlled by several genes, shows durable resistance. There are a lot of slow leaf rust of wheat cultivars in our country, but slow leaf rust genes in the most of cultivars is not clear, so exploring slow rusting resistance genes in a wheat cultivar and close linked molecular markers contribute to disease resistance breeding and crop improvement.Chinese wheat cultivar Weimai 8 was developed by Weifang Agriculture Academy of Science by crossing 88-3149(female parent) and Aus621108(male parent). It resists to powdery mildew and leaf rust. Weimai 8 is susceptible to leaf rust in the seedling stage, but in adult plant stage shows slow rusting resistance. This study reported QTL analysis and molecular mapping of leaf rust APR genes in Weimai 8 and provided theoretical basis and molecular markers for leaf rust resistance in wheat.In order to understand the genetic background of the resistance genes, 179 F2:3 families derived from the cross Weimai 8 and Zhengzhou 5389(susceptible to leaf rust) were used to construct linkage map. Weimai 8, Zhengzhou 5389 and 179 F2:3 families were made leaf rust APR tests in the field in three years(2011-2013), and infected with equal amounts of P. triticina pathotypes THTT, THTS and THTQ, and get the phenotypic data. Meanwhile, using 1240 pairs of SSR markers and two pairs of SCAR markers distributed across 21 wheat chromosomes, we screened polymorphism among the two parents and ten families. The polymorphic molecular markers were further validated by the 179 F2:3 families, and get the genotype data. The linkage map of detected QTL was constructed by using phenotypic data and genotype data with the Map Manager QTXb20. The software QTL Icimapping 3.2 was deployed to detect the QTL loci.Results showed that there was a major QTL on chromosome 2AS in three years tests, temporarily named QLr.hbau-2AS in charge of the resistance. QLr.hbau-2AS provided by the resistant parent Weimai 8, was between SSR markers cfd36 and barc1138, with interval length of 2.58 c M. In the three years(2011-2013), it explained 25.79%, 71.55% and 60.72% of the phenotypic variation, respectively, which proved that the leaf rust resistance of QTL QLr.hbau-2AS was less affected by the environment and is relatively stable. Overall, 13 molecular markers were found linking with QLr.hbau-2AS. Lr37 is a designated gene located on chromosome 2AS, and is a major resistance gene. And according the comparison of seedling leaf rust resistance, QLr.hbau-2AS may not be Lr37, but a new QTL.