AUTHOR=Page Rae , Huang Shuyi , Ronen Moshe , Sela Hanan , Sharon Amir , Shrestha Sandesh , Poland Jesse , Steffenson Brian J. 

TITLE=Genome-wide association mapping of rust resistance in Aegilops longissima

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1196486

DOI=10.3389/fpls.2023.1196486

ISSN=1664-462X

ABSTRACT=<p>The rust diseases, including leaf rust caused by <italic>Puccinia triticina</italic> (<italic>Pt</italic>), stem rust caused by <italic>P. graminis</italic> f. sp. <italic>tritici</italic> (<italic>Pgt</italic>), and stripe rust caused by <italic>P. striiformis</italic> f. sp. <italic>tritici</italic> (<italic>Pst</italic>), are major limiting factors in wheat production worldwide. Identification of novel sources of rust resistance genes is key to developing cultivars resistant to rapidly evolving pathogen populations. <italic>Aegilops longissima</italic> is a diploid wild grass native to the Levant and closely related to the modern bread wheat D subgenome. To explore resistance genes in the species, we evaluated a large panel of <italic>Ae. longissima</italic> for resistance to several races of <italic>Pt</italic>, <italic>Pgt</italic>, and <italic>Pst</italic>, and conducted a genome-wide association study (GWAS) to map rust resistance loci in the species. A panel of 404 <italic>Ae. longissima</italic> accessions, mostly collected from Israel, were screened for seedling-stage resistance to four races of <italic>Pt</italic>, four races of <italic>Pgt</italic>, and three races of <italic>Pst</italic>. Out of the 404 accessions screened, two were found that were resistant to all 11 races of the three rust pathogens screened. The percentage of all accessions screened that were resistant to a given rust pathogen race ranged from 18.5% to 99.7%. Genotyping-by-sequencing (GBS) was performed on 381 accessions of the <italic>Ae. longissima</italic> panel, wherein 125,343 single nucleotide polymorphisms (SNPs) were obtained after alignment to the <italic>Ae. longissima</italic> reference genome assembly and quality control filtering. Genetic diversity analysis revealed the presence of two distinct subpopulations, which followed a geographic pattern of a northern and a southern subpopulation. Association mapping was performed in the genotyped portion of the collection (n = 381) and in each subpopulation (n = 204 and 174) independently via a single-locus mixed-linear model, and two multi-locus models, FarmCPU, and BLINK. A large number (195) of markers were significantly associated with resistance to at least one of 10 rust pathogen races evaluated, nine of which are key candidate markers for further investigation due to their detection via multiple models and/or their association with resistance to more than one pathogen race. The novel resistance loci identified will provide additional diversity available for use in wheat breeding.</p>