Hanlin Lai

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a highly destructive airborne disease capable of long-distance spore transmission, cross-regional colonization, and widespread epidemics. This pathogen poses a severe threat to global wheat production, including China, where it causes substantial yield losses. To investigate the population structure, source, and dispersal pathways of Pst in the Ili region of Xinjiang, we genotyped 310 (2021) and 268 (2022) Pst isolates from 144 wheat fields using 18 kompetitive allele-specific PCR (KASP)-SNP markers. Genetic diversity analysis identified 162 and 115 multilocus genotypes in 2021 and 2022, respectively, with higher diversity in Gongliu, Qapqal, and Zhaosu compared with other regions. Population structure analysis revealed substantial gene flow between the winter Pst population in Qapqal and the spring Pst population in Xinyuan, as well as between the spring Pst populations in Zhaosu and Tekes. In contrast, the Tekes population showed minimal gene flow with other groups. Bayesian information criterion (BIC) and discriminant analysis of principal components (DAPC) delineated distinct clusters within the spring wheat Pst populations from Zhaosu and Tekes, alongside significant genetic exchange between the 2021 and 2022 populations. Furthermore, the Ili Pst population showed significant differentiation from global counterparts (Ecuador, Ethiopia, Italy, Mexico, and the United States). Integrating genetic structure analysis with high-altitude airflow trajectories, we identified two major Pst migration routes in the Ili region, mainly from Qapqal to Xinyuan, and secondarily from the spring wheat-growing areas of Zhaosu to Xinyuan.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a globally significant fungal disease that seriously threatens wheat yield, particularly in China. This study investigates the genetic structure and reproductive patterns of Pst populations in Ili, Xinjiang, using 12 pairs of Simple Sequence Repeat (SSR) molecular markers. Analyses of 79 Pst isolates from either spring or winter wheat areas in Ili revealed three primary genetic clusters, indicating notable differences between populations associated with spring and winter wheat. The STRUCTURE results, complemented by UPGMA and PCoA analyses, highlight significant genetic diversity within these populations, with evidence of genetic recombination and sexual reproduction in certain areas. Pst populations in Ili exhibit a mixed mode of reproduction, predominantly sexual in Qapqal and Xinyuan D and primarily asexual within the spring wheat populations. The gene flow analysis underscores extensive inter-population communication, which facilitates the spread and adaptation of the pathogen across diverse wheat-growing environments. This study marks the first documentation of sexual reproduction in Pst within Xinjiang, providing new insights into its spread and genetic variation. These findings suggest that sexual reproduction may play a role in the regional adaptation and evolution of Pst, impacting future management strategies for wheat stripe rust in Xinjiang and potentially in broader Central Asian contexts.

A walnut–wheat intercropping pattern is practiced widely in southern Xinjiang to alleviate the contradiction between the lack of cultivated land resources and to increase economic value. Previous studies have confirmed that an alley cropping pattern could change the microclimate by supplying additional ecological functions such as windbreak, light interception, water conservation, etc. Cereal aphids (including Sitobion avenae, Rhopalosiphum padi, Metopolophium dirhodum, etc.) are commonly spread pests that harm wheat plants. But, the difference in population numbers between local patterns is still unknown. Pesticide reduction is the national strategy in China to alleviate the contraction between the demand of grain yield and environment protection. Plant protection-unmanned aerial vehicles (UAV) spraying pesticides are the most efficient method to control pests. However, compared to traditional artificial spraying method, how the UAV spraying method affect the control effect of reduced concentration pesticide is unclear. In order to address this problem, we conducted field investigations at Zepu county in southern Xinjiang to test the difference between walnut–wheat intercropping and wheat monocropping patterns for three consecutive years. And, we employed the field experiments to ensure the effectiveness of the reduced concentration common pesticides through the UAV spraying method. In conclusion, we conducted a comparison of the control effects of two spraying methods under conditions of reduced pesticide usage. Our findings revealed that the population of cereal aphids was larger in the intercropping pattern compared to the monocropping pattern. Although the control effect of the reduced treatment was lower than the regular dosage, some treatments still demonstrated sufficient capability to eliminate aphids, particularly when considering the effect within major varieties. Additionally, the use of the UAV spraying method exhibited a satisfactory effect when compared to the traditional artificial spraying method.