Virulence characterization of Puccinia striiformis f. sp. tritici in China using the Chinese and Yr single-gene differentials

Authors: ZHOU, AIHONG - Northwest A&f University; WANG, JIE - Northwest A&f University; Chen, Xianming; XIA, MINGHAO - Northwest A&f University; FENG, YAOXUAN - Northwest A&f University; JI, FAN - 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: 9/14/2023
Publication Date: 3/1/2024
Citation: Zhou, A., Wang, J., Chen, X., Xia, M., Feng, Y., Ji, F., Huang, L., Kang, Z., Zhan, G. 2024. Virulence characterization of Puccinia striiformis f. sp. tritici in China using the Chinese and Yr single-gene differentials. Plant Disease. 108:671-683. https://doi.org/10.1094/PDIS-08-23-1524-RE.
DOI: https://doi.org/10.1094/PDIS-08-23-1524-RE

Interpretive Summary: Stripe rust (also known as yellow rust, Yr) is one of the most important diseases of wheat, which seriously threatens the safety of wheat production. Resistant breeding is the most effective means to control stripe rust. Therefore, identifying races of the stripe rust pathogen is essential for developing resistant varieties. In this study, a total of 119 and 149 races were identified from 608 isolates collected from 16 provinces in China using both Chinese set and the Yr single-gene set of differentials. On the Chinese differentials, the three most predominant races were CYR34, G22-14, and CYR32, and all isolates were avirulent to Zhong 4 and Triticum spelta Album (Yr5). The virulence frequencies to all other Chinese differentials were over 60.00%, indicating that there were insufficient virulence discriminations of Chinese differentials. Based on the Yr single-gene differentials, the three most predominant races were VP1, VP2, and VP3. The virulence frequencies to several resistance genes including Yr1, Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44, and YrExp2 were high (> 60%); Yr10, Yr24, Yr76, and YrSP are moderate (38-53%); and those to Yr32 and YrTr1 were low (< 20%). Both Yr5 and Yr15 were resistant to all isolates. The 16 provincial populations were clustered into 6 and 8 groups based on the Chinese differentials and Yr single-gene differentials, respectively. In addition, we also found that same races identified using the Chinese differentials can be further differentiated on the Yr differentials. The results are useful for understanding the pathogen population and for breeding resistant wheat varieties.

Technical Abstract: Stripe rust (Also know yellow rust, Yr) caused by Puccinia striiformis f. sp. tritici (Pst) is one of the most important diseases of wheat, which seriously threatens the safety of wheat production. Resistant breeding is the most effective means to control stripe rust. Therefore, identifying Pst races is essential for developing resistant cultivars. In this study, a total of 119 and 149 races were identified from 608 isolates collected from 16 provinces in 4 major stripe rust epidemic regions in China using both Chinese set and the Yr single-gene set of differentials. On the Chinese differentials, the three most predominant races were CYR34 (23.52%), G22-14 (9.87%), and CYR32 (8.88%), and all isolates were avirulent to Zhong 4 and Triticum spelta Album (Yr5). The virulence frequencies to all other Chinese differentials were over 60.00%, which indicates that there are insufficient virulence discriminations of Chinese differentials. Based on the Yr single-gene differentials, the three most predominant races were VP1 (7.89%), VP2 (4.77%), and VP3 (4.60%). The virulence frequencies to several resistance genes including Yr1 (68.26%), Yr6 (89.90%), Yr7 (93.91%), Yr8 (73.19%), Yr9 (75.82%), Yr17 (92.60%), Yr27 (67.43%), Yr43 (74.84%), Yr44 (91.28%), and YrExp2 (89.47%) were high (> 60%); Yr10 (37.83%), Yr24 (39.14%), Yr76 (45.56%), and YrSP (52.96%) are moderate; and those to Yr32 (14.64%) and YrTr1 (6.41%) were low (< 20%). Both Yr5 and Yr15 were resistant to all isolates. Using the Nei's genetic distance, the 16 provincial Pst populations were clustered into 6 and 8 groups based on the Chinese differentials and Yr single-gene differentials, respectively. In addition, we also found that same races identified using the Chinese differentials can be further differentiated on the single-gene differentials.