University of Hertfordshire

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Original languageEnglish
Publication statusPublished - 2013
EventBritish Society for Plant Pathology - UK, United Kingdom
Duration: 17 Dec 2013 → …

Conference

ConferenceBritish Society for Plant Pathology
CountryUnited Kingdom
CityUK
Period17/12/13 → …

Abstract

Phoma stem canker (Leptosphaeria maculans) is a major disease on oilseed rape (Brassica napus) in the UK. B. napus R gene-mediated resistance against L. maculans is associated with a gene-for-gene interaction but is often not durable since pathogen populations change from avirulent to virulent (Sprague et al., 2006). A single L. maculans gene AvrLm4-7 interacts with two B. napus R genes, Rlm4 and Rlm7 (Parlange et al., 2009). It has been suggested that Rlm7 is more durable than other R genes (Clarke, pers. comm.). The fitness cost of virulence
against Rlm1 and Rlm4 has been used to investigate durability of these R
genes (Huang et al., 2010). This work aims to investigate durability of
Rlm7.
Twenty isolates from cultivars carrying the Rlm7 gene (Roxet and Excel) obtained in 2011/2012 and were characterised at the AvrLm4-7 locus using cotyledon inoculation tests on cultivars carrying Rlm4 or Rlm7 genes. All isolates obtained from Excel and most isolates from Roxet produced resistant phenotypes on cultivars carrying the Rlm7 gene. To investigate changes in fitness and aggressiveness associated with changes from avirulent to virulent at the AvrLm4-7 locus, four isolates from Excel and four from Roxet that had produced resistant or intermediate phenotypes were characterised by inoculation onto
cotyledons of a susceptible cultivar (Drakkar) and several cultivars carrying the Rlm7 gene (Excel, Roxet and Hearty).
Future work will include molecular characterisation of theses isolates. UK
isolates for testing will be obtained in the cropping season 2012/2013
from cultivars carrying the Rlm7 and Rlm4 genes.

ID: 2684129