The objective of this study is to evaluate the application value of the high temperature adult plant (HTAP) resistance gene Yr52 in wheat production for improving stripe rust resistance. And wheat lines with good agronomic characters and high disease resistance were developed and selected. It laid a foundation for making full use of the existing HTAP resistance resources and improving the yield related traits.

The stripe rust resistance gene Yr52 was introgressed to Lunxuan 987 (LX987), Bainong Aikang 58 (AK58) and Han 6172 (H6172) by backcrossing and self-crossing combined with marker-assisted selection breeding. Adult-plant resistance of donor parent, receptor cultivars and their progeny lines were evaluated in the disease nursery fields at Mianyang, Sichuan and Yangling, Shaanxi by mixed endemic physiological races CYR32, CYR33 and CYR34. In comparison to the Chinese Spring reference genome, the flanking SSR markers Xcfa2040 (6.8 cm-Yr52) and Xbarc182 (1.2 cm-Yr52) of Yr52 were combined to search for markers of 35K SNP chip in the physical interval of target genes, and developed into derived cleaved amplified polymorphic sequences (dCAPS) and kompetitive allele specific PCR (KASP) markers. The resistance gene Yr52 was detected in BC₂F_5:6 progeny lines.

The evaluation of adult plant resistance and agronomic traits indicated that nineteen BC₂F_5:6 lines with LX987 background was obtained: Among of them, 11 were high resistance (IT=0-3, DS=1%-20%), 8 were moderate resistance (IT=4-6, DS=15%-30%), the average thousand kernel weight (TKW), kernels per spike (KPS), productive tiller number per line (PTN), plant height (PH) and spike length (SL) was 45.33 g, 46, 7, 113.26 cm and 10.05 cm, respectively. Four BC₂F_5:6 families with AK58 background: all showed high resistance (IT=0-3, DS=5%-25%); the average TKW, KPS, PTN, PH and SL were 44.67 g, 48, 7, 96.54 cm and 10.17 cm, respectively. Five BC₂F_5:6 lineages with H6172 background showed high resistance to stripe rust (IT=0-3, DS=5%-20%). The average TKW, KPS, PTN, PH and SL were 43.74 g, 49, 8, 109.72 cm and 10.06 cm, respectively. The detection rate of three simple sequence repeat (SSR) molecular markers Xbarc182, Xcfa2040 and Xwmc557 linked to Yr52, in offspring population were 78.57%, 66.67% and 66.67%, respectively. One dCAPS marker Xdcaps-Yr52-1 and one KASP marker Xkasp-Yr52-1 were successfully developed, and the detection rates were 73.68% and 41.67%, respectively. The agronomic traits of lines with high (IT=0-3) and medium (IT=4-6) resistance levels were compared. The results showed that the average TKW (P>0.05), PTN (P>0.05) and KPS (P<0.05) of lines with IT=0-3 were higher than those of families with moderate resistance level lines (IT=4-6). Five lines with disease resistance and stable agronomic traits were selected by evaluated of PH=80-105 cm, PTN≥6, KPS≥45, TKW≥42 g, SL≥8 cm.

Yr52 was found to be resistant to all of the present predominant races in the adult plant stage. After introgression Yr52 into the main susceptible Chinese wheat varieties, the progeny lines with good disease resistance and agronomic characters could be used for breeding resistance varieties with multi-gene polymerization, it is enriching for the diversity of disease resistance genes and achieving durable utilization. The development of molecular markers will facilitate detect the utilization of Yr52 gene in resistance identification of germplasm in the future.

To clarify the virulence structure and genetic diversity of Pst populations in the major winter-increasing areas of China, and to provide reference for the prevention and control of Pst and the rational layout of wheat resistance genes in the winter-increasing areas and the wheat production in Huang-huai-hai.

A total of 148 Pst isolates were collected and isolated from the major winter-increasing areas such as Sichuan Basin, Hubei and southern Henan, and the virulence phenotype was identified by using Chinese differentials and single-gene lines, and 17 pairs of KASP-SNP primers were used to mark the isolates and complete the genotype analysis.

Based on the Chinese differentials, 14 known races and 63 unknown pathotypes were identified, among which CYR34 (16.2%), G22-14 (12.2%), CYR32 (6.8%), CYR33 (5.4%) were the dominant races (pathotypes); based on the single-gene lines, 113 races (pathotypes) were identified, among which race1 (7.4%), race2 (3.4%), race3 (3.4%) were the dominant races (pathotypes). The Guinong 22 group was the largest epidemic group of Pst population in China’s winter-increasing area, and all tested Pst isolates did not infect single-gene lines varieties carrying Yr5 and Yr15. The virulence phenotype and genotype of CYR34 and G22-14 showed diversification by single-gene lines virulence identification and molecular marker, indicating that there was high differentiation within these two dominant races. The clustering based on the virulence data of two sets of differentials showed that the Pst populations in Sichuan Basin and southern Hubei were similar, while the Pst populations in northwestern Hubei and southern Henan were similar; the genetic clustering based on KASP-SNP molecular data showed that there was genotype differentiation between the Pst populations in Sichuan Basin, southern Hubei and northwestern Hubei, southern Henan; Structure analysis showed that Sichuan Basin, southern Hubei population mainly had two genetic backgrounds, northwestern Hubei, southern Henan population mainly had one genetic background; population genetic differentiation analysis showed that Sichuan Basin Pst population and southern Henan Pst population had the largest Fst value, which was 0.118, with the largest genetic difference and obvious genetic differentiation; northwestern Hubei population and southern Henan population had the smallest degree of genetic differentiation, Fst value was 0.010; gene flow analysis obtained Nm value between northwestern Hubei population and southern Henan population was 25.236, Nm>4, there was a high-level gene flow between them, northwestern Hubei and southern Henan population and Sichuan Basin population had Nm values of 2.923 and 1.864 respectively, both had a low-level gene flow; genetic diversity analysis results showed that Sichuan Basin, southern Hubei region Pst population had a high-level of genetic diversity, northwestern Hubei, southern Henan Pst population had a low-level of genetic diversity. The above conclusions all support that Sichuan Basin, southern Hubei population has genetic differentiation with northwestern Hubei, southern Henan population.

Single-gene lines can accurately identify Chinese Pst races; Pst populations in China’s major winter-increasing areas have different sources.