Genetic characterization of a dominant susceptible Rpp1 allele and analysis of quantitative resistance to Asian soybean rust
type: CreativeWork
description: Asian soybean rust (ASR), caused by fungal pathogen Phakopsora pachyrhizi, is a yield-threatening disease in soybean growing countries (Hartman et al. 2012; Godoy et al. 2016). The yield loss can reach as high as 80% if the conditions are conducive, and no control measures are taken (Yorinori et al. 2005; Walker et al. 2011; Hartman, Miles, and Frederick 2007). Soybean natural resistance to P. pachyrhizi has been identified as single R gene-conferred, and seven Rpp (Rpp1-Rpp7; Resistance to Phakopsora pachyrhizi 1-7) gene loci have been identified and mapped (Hartman et al. 2012). Although multiple Rpp genes have been mapped, none have been cloned and validated, and the molecular mechanisms of Rpp gene-mediated resistance remain largely elusive. A genotype was identified that could suppress resistance from Rpp1, resulting in dominant susceptibility (Garcia et al. 2011). The second chapter of this dissertation describes an exploration of a possible molecular mechanism of this dominant susceptible allele of the Rpp1 locus. To achieve that, genomic sequences of the Rpp1 locus were cloned from the dominant susceptible line (DS), as well as two Rpp1-harboring soybean accessions PI561356 and PI594760B, revealing three NBS-LRR genes in each resistance line and one (DS-R) in the DS line. Identification of the DS-R gene was verified through virus-induced gene silencing that led to resistance being partially restored in the susceptible Rpp1/DS-R heterozygous genotypes. The possible involvement of DS-derived small RNA, a potential mechanism for dominant repression of Rpp1 was explored. Rpp1 locus gene expression and small RNA abundances did not support this hypothesis. On the other hand, yeast two-hybrid assays, and more than 6x higher expression of DS-R than Rpp1 candidates, supported the hypothesis that an overly abundant DS-R protein could interact with and presumably disrupt the functional Rpp1 protein, probably leading to dominant susceptibility. In addition to exploring …
abstract: Asian soybean rust (ASR), caused by fungal pathogen Phakopsora pachyrhizi, is a yield-threatening disease in soybean growing countries (Hartman et al. 2012; Godoy et al. 2016). The yield loss can reach as high as 80% if the conditions are conducive, and no control measures are taken (Yorinori et al. 2005; Walker et al. 2011; Hartman, Miles, and Frederick 2007). Soybean natural resistance to P. pachyrhizi has been identified as single R gene-conferred, and seven Rpp (Rpp1-Rpp7; Resistance to Phakopsora pachyrhizi 1-7) gene loci have been identified and mapped (Hartman et al. 2012). Although multiple Rpp genes have been mapped, none have been cloned and validated, and the molecular mechanisms of Rpp gene-mediated resistance remain largely elusive. A genotype was identified that could suppress resistance from Rpp1, resulting in dominant susceptibility (Garcia et al. 2011). The second chapter of this dissertation describes an exploration of a possible molecular mechanism of this dominant susceptible allele of the Rpp1 locus. To achieve that, genomic sequences of the Rpp1 locus were cloned from the dominant susceptible line (DS), as well as two Rpp1-harboring soybean accessions PI561356 and PI594760B, revealing three NBS-LRR genes in each resistance line and one (DS-R) in the DS line. Identification of the DS-R gene was verified through virus-induced gene silencing that led to resistance being partially restored in the susceptible Rpp1/DS-R heterozygous genotypes. The possible involvement of DS-derived small RNA, a potential mechanism for dominant repression of Rpp1 was explored. Rpp1 locus gene expression and small RNA abundances did not support this hypothesis. On the other hand, yeast two-hybrid assays, and more than 6x higher expression of DS-R than Rpp1 candidates, supported the hypothesis that an overly abundant DS-R protein could interact with and presumably disrupt the functional Rpp1 protein, probably leading to dominant susceptibility. In addition to exploring …
author: Wei, Wei
language: en
keywords: Soybean, Asian Soybean Rust, Plant disease resistance, Plant-microbe interaction, Resistance gene, Dominant susceptibility, GWAS
date published: 2021-09-17T04:04:40Z
date modified: 2026-07-22T22:24:52Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/110838