Abstract: 【Objective】The objectives of this study are to understand the resistance to Puccinia striiformis of wheat cultivars and the distribution and application of Yr genes in the main wheat growing regions, to give some suggestions for the farmers and governors when they choose cultivars, and to prolong the planting years of cultivars based on the harbored Yr genes. 【Method】 There were four races, designating CYR32, CYR33, G22-9 and G22-14 used to identify stripe rust resistance of 79 wheat cultivars or lines from main wheat producing areas in China at seedling stage in greenhouse. The seedlings were put into barrels for keeping humidity in dark for 12-18 h at (10±1)℃ after inoculation, then they were put into greenhouse at 16 to 18℃ in the day time and 14 to 16℃ in the nighttime with 16 hours’ light and 8 hour’s darkness. The investigation was carried out 15 days after inoculation as 0-9 scales. And CYR32 and CYR33 were used for further resistance evaluation at the adult stage at Langfang Station of Hebei Province. In order to keep soil humidity, enough water should be irrigated before the inoculation of adult plants was carried out at jointing stage. The urediniospore suspensions were adjusted to 1 g urediniospores﹕300 mL mineral oil and sprayed the susceptible control cv. Mingxian 169. After the mineral oil evaporated thoroughly, the plants were sprayed water by hand-hold sprayer and covered with plastic film for 12-16 h for keeping moisture. The incidence, severity and infection type were recorded at least twice to keep the severer records as the final data. Then the authors screened these wheat cultivars with the closely linked molecular markers of wheat stripe rust resistance genes Yr5 (Wmc175F/R), Yr10 (SC₂₀₀F/R), Yr18 (csLv34 F/R), Yr26 (We173) and 1B/1R (AF1/AF4) translocation lines. With all data were integrated, such as pedigree of cultivars (lines), resistance to the 4 races, and molecular detection, the yellow rust resistance genes were postulated. 【Result】Among all tested cultivars or lines at seedling stage, 16 (20.3%) were resistant to CYR32 and CYR33, 4 (5.1%) were resistant to G22-9 and G22-14, only 4 (5.1%) cultivars showed resistance to 4 races of Puccinia striiformis f. sp. tritici (Pst). However, there were 24 (30.4%) showed resistance to CYR32 and CYR33 at adult stage. As for wheat cultivars at all growth stages, 12 (15.2%) were resistant to CYR32, 16 (20.3%) were resistant to CYR33 and only 11 (14.0%) were resistant to both CYR32 and CYR33. Only 4 (5.1%) cultivars showed resistance to CYR32, CYR33, G22-9 and G22-14 at seedling stage and CYR32 and CYR33 at adult stage, respectively. After all the information integrated, such as pedigree of cultivars (lines), resistance to the 4 races, and molecular detection, it showed that 4 (5.1%) tested cultivars contained Yr5, 8 (10.1%) contained Yr10, 3 (3.8%) contained Yr18, 1 (1.3%) contained Yr26, 35 (44.3%) contained 1B/1R, and 4 cultivars contained 2 Yr genes, and Yuanfeng 139 contained Yr5, Yr10 and Yr26.【Conclusion】The 79 cultivars (lines) have low resistance to the prevalent 4 races and the usage of 1B/1R translocation line was still high. In the future breeding, the utilization of effective resistance genes such as Yr5 and Yr18 should be increased. Pyramiding multi-gene varieties with effective durable resistance should be strengthened and the use of 1B/1R translocation line should be decreased.

Key words: wheat, wheat stripe rust, resistance evaluation, resistance gene, molecular detection