Characterization, molecular mapping and identification of candidates for a gene conferring high-temperature adult-plant resistance to wheat stripe rust originally from Aegilops ventricosa

Authors: LI, YUXIANG - Washington State University; LIU, L - Washington State University; WANG, MEINAN - Washington State University; TRAVIS, R - Washington State University; See, Deven; HU, XIAOPING - Northwest A&f University; Chen, Xianming

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2022
Publication Date: 2/20/2023
Citation: Li, Y., Liu, L., Wang, M., Travis, R., See, D.R., Hu, X., Chen, X. 2023. Characterization, molecular mapping and identification of candidates for a gene conferring high-temperature adult-plant resistance to wheat stripe rust originally from Aegilops ventricosa. Plant Disease. 107(2);431-442. https://doi.org/10.1094/PDIS-06-22-1419-RE.
DOI: https://doi.org/10.1094/PDIS-06-22-1419-RE

Interpretive Summary: Wheat gene Yr17, originally from Aegilops ventricosa, confers all-stage resistance to stripe rust, but the gene has become ineffective to most races of the stripe rust pathogen identified in the United States and other countries. However, wheat varieties with Yr17, including the near-isogenic line AvSYr17NIL that is used to differentiate Pst races, show non-race specific, high-temperature adult-plant (HTAP) resistance to stripe rust. To separate and identify the HTAP resistance gene, seeds of AvSYr17NIL were treated with ethyl methanesulfonate (EMS). Mutant lines with only HTAP resistance were obtained, and one of the lines, M1225, was crossed with the susceptible recurrent parent AvS. Genetic analyses of the progeny populations identified a single recessive gene, temporarily named yrM1225, for HTAP resistance, and the gene was mapped to the short arm of 2A in an interval of 8.7 cM. By dissecting chromosome 2A of the Chinese Spring genome and the 2NvS segment of Ae. ventricosa, six genes were considered candidates for the HTAP resistance gene. The separation of the HTAP resistance gene from Yr17 should improve the understanding of the different types of resistance and the host-pathogen interactions. The developed mutant lines and selected candidate genes will be useful in determining and cloning the novel HTAP resistance gene.

Technical Abstract: Wheat gene Yr17, originally from Aegilops ventricosa, confers all-stage resistance to stripe rust caused by Puccinia striiformis f. sp. tritici (Pst), but the gene has become ineffective to most Pst races identified in the United States and other countries. However, wheat varieties with Yr17, including the near-isogenic line AvSYr17NIL that is used to differentiate Pst races, show non-race specific, high-temperature adult-plant (HTAP) resistance to stripe rust. To separate and identify the HTAP resistance gene, seeds of AvSYr17NIL were treated with ethyl methanesulfonate (EMS). Mutant lines with only HTAP resistance were obtained, and one of the lines, M1225, was crossed with the susceptible recurrent parent Avocet S (AvS). Field responses of the F2 plants and F3 lines, together with the parents, were recorded at the adult-plant stage in Pullman and Mount Vernon, WA under natural Pst infection. The parents and the F4 population were phenotyped with an Yr17-virulent race at the adult-plant stage under the high temperature profile in the greenhouse. The phenotypic results were confirmed by testing the F5 population in the field under natural Pst infection. The F2 data indicated a single recessive gene, temporarily named yrM1225, for HTAP resistance. The F4 lines were genotyped with Kompetitive allele specific PCR (KASP) markers converted from single nucleotide polymorphism (SNP) markers selected from the short arm of wheat chromosome 2A on which Yr17 is located. The HTAP resistance gene was mapped on the short arm of 2A in an interval of 8.7 cM. By dissecting chromosome 2A of the Chinese Spring genome and the 2NvS segment of Ae. ventricosa, six genes were considered candidates for the HTAP resistance gene. The separation of the HTAP resistance gene from Yr17 should improve the understanding of the different types of resistance and the host plant-Pst interactions. The developed mutant lines and selected candidate genes will be useful in determining and cloning the novel HTAP resistance gene.