| Wheat leaf rust, caused by Puccinia tirticina(Pt), can cause severe yield loss and great quality reduction. Resistant cultivars are the most economical, safety,environmentally-friendly and efficient way for reducing the losses caused by the disease.Wheat leaf rust resistance can be divided into seedling resistance and adult plant resistance.Seedling resistance is effective at whole growth stages, and usually confer high resistance,but it may lose resistance when virulent races emerge or increase. Adult plant resistance is non-race specific resistance controlled by polygene, and it is considered as durable resistance. Common wheat(Triticum asetivum L.) is grown in wide area in China with different environments, and the popular Pt races in different wheat grown area are different.There are rich wheat genotypes in China, but the leaf rust resistance genes in the genotypes are not available. This study mainly includes two parts :1. This study intends to use the molecular marker to identify the leaf rust resistance genes in 460 Chinese wheat cultivars, which came from Anhui, Beijing, Gansu, Guizhou,Hebei, Henan, Heilongjiang, Hubei, Jiangsu, Ningxia, Qinghai, Shandong, Shanxi, Shaanxi,Sichuan and Xinjiang provinces in China. Lr1, Lr9, Lr19, Lr24, Lr26, Lr34 and Lr46 were detected using their specific markers. The 460 cultivars was also planted and inoculated with the mixture of the P. triticina THTT, THTS, THTQ and PHPS in the field in Baoding to score leaf rust severity. The results showed that three genes Lr9, Lr19 and Lr24 were not present in the 460 cultivars. A total of 220 cultivars may contain Lr1, accounted for 47.8%of the 460 cultivars, and the mean FDS of lines with Lr1 was 35.1% and the mean AUDPC was 373.6; A total of 154 cultivars contained Lr26, accounted for 33.5%, and the mean FDS and mean AUDPC were 34.9% and 388.9, respectively; In all 59 cultivars carried Lr34, accounted for 12.8%, the mean FDS was 31.5% and mean AUDPC was333.0; Other 89 cultivars had Lr46, accounted for 19.3%, the mean FDS and AUDPC was48.4% and 509.5, respectively. In addition, among the 460 cultivars 61 cultivars showed high resistance, accounted for 13.3% of all the tested cultivars, and their average FDS was under 5%, they might contain major resistance genes. One hundred and eleven cultivarsshowed slow rusting resistance, accounted for 24.1%, and their average FDS was 5%~20%,AUDPC was 187.8, they might contain adult plant resistance genes. One hundred and seventeen cultivars were intermediate resistant, accounted for 25.4%, and their average FDS was 20%~40%, AUDPC was 368.3. In all 39 cultivars showed high susceptible,accounted for 8.5%, and their average FDS was more than 80%, AUDPC was 813.5, they didn’t contain any resistance gene. The results showed that the composition and distribution of the resistance genes in the cultivars were complex in our country and many useful leaf rust resistance genes were present in Chinese wheat cultivars. In general the leaf rust resistance in the cultivars needs to be further improved.2. The second part of this paper is QTL mapping for adult-plant resistance gene to leaf rust in Italian wheat cultivar Libellula. Common wheat cultivar Libellula is an Italian high-quality cultivar with high resistance to the leaf rust and powdery mildew, which was introduced in the 1970 s, and had been planted for more than 30 years in Gansu province of China. To identified the APR genes in Libellula, 250 F2:3 lines from the cross Libellula/Huixianhong were planted in the field of Baoding and Zhoukou during2012-2013 and 2013-2014 crop seasons. The mixture of the P. triticina THTT, THTS,THTQ and PHPS were inoculated to the F2:3 lines in the field to identify the leaf rust resistance in the population. Five resistant and susceptible lines were selected to build the small resistant and susceptible groups, respectively. A total of 1123 SSR markers were screened between parents and small resistant and susceptible groups, and 16 polymorphic markers were used to detect the 250 F2:3 lines from the cross of Libellula/Huixianhong to construct genetic linkage maps. Phenotypic and genotypic data were combined to map adult plant resistance QTLs in Libellula using software Mapmanager QTXb20 and QTL Ici Mapping 3.2. One APR QTL was identified in the F2:3 lines, located on 7DS. The QTL was flanked by Xbarc126-X cslv34, and it was considered as Lr34, the QTL explained39.5% 、 19.2% 、 43.9% and 21.1% of the phenotypic variation in the four different environment respectively. The other APR QTLs in Libellula need to be further test by more molecular markers in near future. |
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