Inheritance and linkage of virulence genes in chinese predominant race CYR32 of the wheat stripe rust pathogen Puccinia striiformis f. sp. tritici

Authors: WANG, LONG - Northwest Agricultural & Forestry University; ZHENG, DAN - Northwest Agriculture And Forestry University; ZUO, SHUXIA - Northwest Agriculture And Forestry University; Chen, Xianming; ZHUANG, HUA - Northwest Agriculture And Forestry University; HUANG, LILI - Northwest Agricultural & Forestry University; KANG, ZHENSHENG - Northwest Agriculture And Forestry University; ZHAO, JIE - Northwest Agriculture And Forestry University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2018
Publication Date: 2/18/2018
Citation: Wang, L., Zheng, D., Zuo, S., Chen, X., Zhuang, H., Huang, L., Kang, Z., Zhao, J. 2018. Inheritance and linkage of virulence genes in chinese predominant race CYR32 of the wheat stripe rust pathogen Puccinia striiformis f. sp. tritici. Frontiers in Plant Science. https://doi:10.3389/fpls.2018.00120.
DOI: https://doi.org/10.3389/fpls.2018.00120

Interpretive Summary: The stripe rust pathogen seriously threatens wheat production worldwide. The obligate biotrophic fungus is highly capable of producing new virulent races that can overcome resistance. In the present study, 127 progeny isolates were obtained by selfing a representative Chinese race, CYR32, on barberry plants. The parental isolate and progeny isolates were characterized by testing on 25 wheat lines with different stripe rust resistance genes and 10 simple sequence repeat (SSR) markers. The 127 isolates were classified into 27 virulence phenotypes, and 65 multi-locus genotypes. All progeny isolates and the parental isolates were avirulent to 8 resistance genes; but virulent to 7 resistance genes. Virulences of the parental isolate to 9 resistance genes and the avirulence to 1 resistance gene were heterozygous. Based on the segregation of the virulence/avirulence phenotypes, the virulences to 4 resistance genes were controlled by a dominant gene; virulences to 3 resistance genes by two dominant genes; virulences to 2 resistance genes by one dominant and one recessive gene; and the avirulence to one resistance gene by two complementary dominant genes. Molecular mapping revealed the linkage of 10 avirulence/virulence genes corresponding to 10 resistance genes. Comparison of the virulence inheritance with previous studies showed complex interactions between the pathogen virulence and host resistance, which is useful for understanding the plant-pathogen interactions and stripe rust control.

Technical Abstract: Puccinia striiformis f. sp. tritici (Pst) is the causal agent of stripe (yellow) rust on wheat. It seriously threatens wheat production worldwide. The obligate biotrophic fungus is highly capable of producing new virulent races that can overcome resistance. Studying inheritance of Pst virulence using the classical genetic approach was not possible until the recent discovery of its sexual stage on barberry plants. In the present study, 127 progeny isolates were obtained by selfing a representative Chinese Yellow Rust (CYR) race, CYR32, on Berberis aggregate. The parental isolate and progeny isolates were characterized by testing on 25 wheat lines with different Yr genes for resistance and 10 simple sequence repeat (SSR) markers. The 127 isolates were classified into 27 virulence phenotypes, and 65 multi-locus genotypes. All progeny isolates and the parental isolates were avirulent to Yr5, Yr8, Yr10, Yr15, Yr24, Yr26, Yr32 and YrTr1; but virulent to Yr1, Yr2, Yr3, Yr4, Yr25, Yr44 and Yr76. Virulences of the parental isolate to nine Yr genes (Yr6, Yr7, Yr9, Yr17, Yr27, Yr28, Yr43, YrA and YrExp2) and the avirulence to YrSP were found to be heterozygous. Based on the segregation of the virulence/avirulence phenotypes, we found that the virulences to the Yr7, Yr28, Yr43 and YrExp2 lines were controlled by a dominant gene; virulences to the Yr6, Yr9 and YrA (Yr73, Yr74) lines by two dominant genes; virulences to the Yr17 and Yr27 lines by one dominant and one recessive gene; and the avirulence to the YrSP line by two complementary dominant genes. Molecular mapping revealed the linkage of 10 avirulence/virulence genes corresponding to 10 Yr genes. Comparison of the inheritance of virulence/avirulence to these Yr genes with previous studies indicated complex interactions between virulence genes in the pathogen and also with resistance genes in wheat lines. The results are useful for understanding the plant-pathogen interactions and developing wheat cultivars with effective and durable resistance.