# Virulence Characterization of Puccinia striiformis f. sp. tritici in China in 2020 Using Wheat Yr Single-Gene Lines

## TL;DR

This study analyzed the virulence of a wheat rust fungus in China in 2020 to help breed more resistant wheat varieties.

## Contribution

The study identified 33 Pst races and their virulence patterns using Yr single-gene lines in China in 2020.

## Key findings

- PstCN-062 and PstCN-001 were the most prevalent races in 2020.
- High virulence was observed for Yr8, Yr44, and YrExp2 genes.
- No isolates were virulent to Yr5, Yr10, Yr15, and Yr32.

## Abstract

Wheat stripe (yellow) rust, caused by the fungus Puccinia striiformis f. sp. tritici (Pst), is one of the most threatening wheat diseases worldwide. Monitoring the virulence of Pst population is essential for managing wheat stripe rust. In this study, 18 wheat Yr single-gene lines were used to identify the virulence patterns of 67 isolates collected from 13 provinces in China in 2020, from which 33 Pst races were identified. The frequency of virulence to different Yr genes varied from 1.49% to 97.01%, with 4.48% to Yr1, 26.87% to Yr6, 11.94% to Yr7, 95.52% to Yr8, 19.40% to Yr9, 11.94% to Yr17, 2.99% to Yr24, 35.82% to Yr27, 38.81% to Yr43, 97.01% to Yr44, 8.96% to YrSP, 1.49% to Yr85, 95.52% to YrExp2, and 7.46% to Yr76. None of the isolates were virulent to Yr5, Yr10, Yr15, and Yr32. Among the 33 races, PstCN-062 (with virulence to Yr8, Yr44, and YrExp2) and PstCN-001 (with virulence to Yr8, Yr43, Yr44, and YrExp2) were the prevalent races, with frequencies of 28.36% and 11.94%, respectively. These results provide valuable information for breeding resistant wheat cultivars for controlling stripe rust.