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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #357308
Research Project: Cereal Rust: Pathogen Biology and Host Resistance

Location: Cereal Disease Lab

Title: Bulked segregant analysis RNA-seq (BSR-Seq) validated a stem resistance locus in Aegilops umbellulata, a wild relative of wheat

Author
item EDAE, ERENA - University Of Minnesota
item Rouse, Matthew

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2019
Publication Date: 9/20/2019
Citation: Edae, E.A., Rouse, M.N. 2019. Bulked segregant analysis RNA-seq (BSR-Seq) validated a stem resistance locus in Aegilops umbellulata, a wild relative of wheat. PLoS One. 14(9):e0215492. https://doi.org/10.1371/journal.pone.0215492.
DOI: https://doi.org/10.1371/journal.pone.0215492

Interpretive Summary: Stem rust of wheat, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating foliar disease. The emerging Ug99 race group has combined virulence to most stem rust (Sr) resistance genes currently deployed in wheat and is a threat to global wheat production. Many disease resistance genes that have been transferred from wild relatives to cultivated wheat have played a significant role in wheat production worldwide. Ae. umbellulata is one of the species within the genus Aegilops that have been successfully used as sources of resistance genes to leaf rust, stem rust and powdery mildew. Most recently, a major QTL conferred resistance to the stem rust pathogen races Ug99 (TTKSK) and TTTTF was mapped on chromosome 2U using genotyping-by-sequencing SNP markers. The objective of the current work was to validate the mapping of this gene with an independent bi-parental mapping population and refine the QTL region with a bulk segregant analysis approach. The stem rust resistance QTL that was previously detected on chromosome 2U of Ae. umbellulata was mapped in the same region in both populations in this study. With bulk segregant analysis, we were also able to fine map the position of the QTL within 3.2 Mbp on chromosome 2U. Although there were a large number of genes in the orthologous region of chromosome 2D of Ae. tauschii, we detected only two Ae. umbellulata genes which can be considered as a potential candidate genes.

Technical Abstract: Many disease resistance genes that have been transferred from wild relatives to cultivated wheat have played a significant role in wheat production worldwide. Ae. umbellulata is one of the species within the genus Aegilops that have been successfully used as sources of resistance genes to leaf rust, stem rust and powdery mildew. Most recently, a major QTL conferred resistance to the stem rust pathogen races Ug99 (TTKSK) and TTTTF was mapped on chromosome 2U using genotyping-by-sequencing SNP markers. The objective of the current work was to validate the mapping of this gene with an independent bi-parental mapping population and refine the QTL region with a bulk segregant analysis approach. A bi-parental population of 154 F3 families was developed from stem rust resistant Ae. umbellulata accession (PI 5422375) and stem rust susceptible accession (PI 554395) for independently mapping the previously mapped QTL. For bulk segregant analysis, RNA was extracted from a bulk of leaf tissues of 12 homozygous resistant F3 families, and a separate bulk of 11 susceptible homozygous F3 families. The RNA samples of two bulks and the two parents were sequenced for SNPs identification. The stem rust resistance QTL that was previously detected on chromosome 2U of Ae. umbellulata was mapped in the same region in both populations. With bulk segregant analysis, we were also able to fine map the position of the QTL within 3.2 Mbp on chromosome 2U. Although there were a large number of genes in the orthologous region of chromosome 2D of Ae. tauschii, we detected only two Ae. umbellulata NLR genes which can be considered as a potential candidate genes.