The Brassica napus blackleg resistance gene LepR3 encodes a receptor‐like protein triggered by the Leptosphaeria maculans effector AVRLM1

Abstract

Summary LepR3, found in the Brassica napus cv ‘Surpass 400’, provides race‐specific resistance to the fungal pathogen Leptosphaeria maculans, which was overcome after great devastation in Australia in 2004. We investigated the LepR3 locus to identify the genetic basis of this resistance interaction. We employed a map‐based cloning strategy, exploiting collinearity with the Arabidopsis thaliana and Brassica rapa genomes to enrich the map and locate a candidate gene. We also investigated the interaction of LepR3 with the L. maculans avirulence gene AvrLm1 using transgenics. LepR3 was found to encode a receptor‐like protein (RLP). We also demonstrated that avirulence towards LepR3 is conferred by AvrLm1, which is responsible for both the Rlm1 and LepR3‐dependent resistance responses in B. napus. LepR3 is the first functional B. napus disease resistance gene to be cloned. AvrLm1's interaction with two independent resistance loci, Rlm1 and LepR3, highlights the need to consider redundant phenotypes in ‘gene‐for‐gene’ interactions and offers an explanation as to why LepR3 was overcome so rapidly in parts of Australia.

Host–pathogen interactions in relation to management of light leaf spot disease (caused by Pyrenopeziza brassicae) on Brassica species

“…With recent advances in Brassica genomics and understanding of the genetic basis of resistance against extracellular pathogens (i.e. B. napus resistance against Leptosphaeria maculans) (Larkan et al 2013(Larkan et al , 2015, rapid improvement in identifying novel sources of resistance against P. brassicae can be expected. Resistance genes mapped in previous studies can be further examined to characterise the genetic basis of resistance and they can be cloned.…”

Evolution of virulence in fungal plant pathogens: exploiting fungal genomics to control plant disease

“…For seedling resistance L. maculans has a gene for gene interaction with B. napus. Several resistance genes have been mapped, but only one, LepR3, has been cloned (Delourme et al 2006, van de Wouw et al 2009, Long et al 2011, Larkan et al 2013. Five avirulence genes have been cloned in L. maculans (AvrLm1, AvrLm4-7, AvrLm6, AvrLm11, AvrLmJ1) (Gout et al 2006, Parlange et al 2009, Balesdent et al 2013, van de Wouw et al 2014a).…”

New insights into receptor-like protein functions in Arabidopsis

“…It has been demonstrated that SOBIR1 physically interacted with Cf-4, Ve1, LepR3, Rlm2, AtRLP1, AtRLP23, AtRLP30 and AtRLP42, and was required for the proper function of these RLPs. 9,10,12,13,15,16,[24][25][26] However, it is unclear about the biological relevance of the physical interaction between SOBIR1 and two developmental RLPs CLV2 and TMM, respectively. It could postulate that SOBIR1 may involve in the CLV2-and/or TMM-mediated developmental processes.…”

“…The RLP disease resistance genes include the tomato Cf and Ve genes that provide resistance against Cladosporium fulvum and Verticillium spp., respectively, 5,6 LeEIX genes that combat against the ethylene-inducing xylanase produced from Trichoderma biocontrol fungi, 7 apple HcrVf genes that confer resistance to the scab fungus Venturia inaequalis, 8 the LepR3 and Rlm2 genes that render race-specific resistance to the fungal pathogen Leptosphaeria maculans. 9,10 Genome-wide sequence analyses identified a total of 57 AtRLPs in Arabidopsis. 11,12 Although the biological functions of most AtRLP genes still remain unknown, a number of AtRLP genes have been assigned functions.…”