Virulence, structure, and triadimefon sensitivity of the Puccinia striiformis f. sp. tritici Population in Shaanxi Province, China

Authors: ZHOU, AIHONG - Northwest A&f University; XIA, MINGHAO - Northwest A&f University; Chen, Xianming; FENG, YAOXUAN - Northwest A&f University; LIU, XINYUN - Northwest A&f University; JIN, YONGJIN - Northwest A&f University; HUANG, LILI - Northwest A&f University; KANG, ZHENSHENG - Northwest A&f University; ZHAN, GANGMING - Northwest A&f University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2024
Publication Date: 1/2/2025
Citation: Zhou, A., Xia, M., Chen, X., Feng, Y., Liu, X., Jin, Y., Huang, L., Kang, Z., Zhan, G. 2025. Virulence, structure, and triadimefon sensitivity of the Puccinia striiformis f. sp. tritici Population in Shaanxi Province, China. Plant Disease. 25(109):183-197. https://doi.org/10.1094/PDIS-07-24-1474-RE.
DOI: https://doi.org/10.1094/PDIS-07-24-1474-RE

Interpretive Summary: Stripe rust is the most damaging fungal disease on wheat in China, especially in Shaanxi Province, an important epidemiological region connecting the western over-summer regions and the central and eastern spring epidemic regions in the country. In the present study, 291 isolates of the stripe rust pathogen from Shaanxi were studied for their virulence using two sets of wheat differentials, population structure using single-nucleotide polymorphism (SNP) markers, and sensitivity to triadimefon fungicide. When the isolates were tested on the Chinese differentials of 19 wheat cultivars, 72 races were identified, which belonged to three groups, including the Guinong 22 group (48.45%), Hybrid 46 group (31.62%), and Suwon 11 group (19.93%). The three most predominant races were CYR34 (15.46%), G22-14 (11.68%), and CYR32 (10.65%). When the isolates were tested on the 18 Yr single-gene differentials, 95 races were identified, but none of the isolates were virulent to either Yr5 or Yr15. Cluster analyses of the virulence data based on the two sets of differentials and the SNP marker data consistently separated the pathogen population into two subpopulations in the central part and southern part of the province. When the isolates were tested with different concentrations of triadimefon to determine their sensitivity, a wide range of half maximal effective concentration (EC50) values was observed, from 0.03 to 5.99 µg/mL with a mean value of 0.46 µg/mL, and most isolates were sensitive (90.72%). The correlation analyses of the virulence, SNP marker, and the triadimefon sensitivity data showed no significant correlations, except a logarithmic relationship between the EC50 value and the number of avirulence factors. This was the first to determine the relationship of virulence and SNP markers with triadimefon sensitivity in a regional population of the stripe rust pathogen, and the results should be useful for breeding resistant wheat cultivars and integrated management of stripe rust.

Technical Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is the most damaging fungal disease on wheat in China, especially in Shaanxi Province, an important epidemiological region connecting the western Pst over-summer regions and the central and eastern spring epidemic regions in the country. In the present study, 291 Pst isolates from Shaanxi Province were studied for their virulence using two sets of wheat differentials, population structure using single-nucleotide polymorphism (SNP) markers, and sensitivity to triadimefon fungicide. When the isolates were tested on the Chinese differentials of 19 wheat cultivars, 72 races were identified, which belonged to three groups, including the Guinong 22 group (48.45%), Hybrid 46 group (31.62%), and Suwon 11 group (19.93%). The three most predominant races were CYR34 (15.46%), G22-14 (11.68%), and CYR32 (10.65%). When the isolates were tested on the 18 Yr single-gene differentials, 95 races were identified, but none of the isolates were virulent to either Yr5 or Yr15. Cluster analyses of the virulence data based on the two sets of differentials and the SNP marker data consistently separated the Shaanxi Pst population into two subpopulations in the central part and southern part of the province. When the isolates were tested with different concentrations of triadimefon to determine their sensitivity, a wide range of half maximal effective concentration (EC50) values was observed, from 0.03 to 5.99 µg mL-1 with a mean value of 0.46 µg mL-1, and most isolates were sensitive (90.72%). The correlation analyses of the virulence, SNP marker, and the triadimefon sensitivity data showed no significant correlations, except a logarithmic relationship between the EC50 value and the number of avirulence factors. This was the first to determine the relationship of virulence and SNP markers with triadimefon sensitivity in a regional Pst population, and the results should be useful for breeding resistant wheat cultivars and integrated management of stripe rust.