Abstract
Phytophthora infestans, the causal agent of late blight, is a major threat to commercial potato production worldwide. Significant costs are required for crop protection to secure yield. Many dominant genes for resistance (R-genes) to potato late blight have been identified, and some of these R-genes have been applied in potato breeding. However, the P. infestans population rapidly accumulates new virulent strains that render R-genes ineffective. Here we introduce a new class of resistance which is based on the loss-of-function of a susceptibility gene (S-gene) encoding a product exploited by pathogens during infection and colonization. Impaired S-genes primarily result in recessive resistance traits in contrast to recognition-based resistance that is governed by dominant R-genes. In Arabidopsis thaliana, many S-genes have been detected in screens of mutant populations. In the present study, we selected 11 A. thalianaS-genes and silenced orthologous genes in the potato cultivar Desiree, which is highly susceptible to late blight. The silencing of five genes resulted in complete resistance to the P. infestans isolate Pic99189, and the silencing of a sixth S-gene resulted in reduced susceptibility. The application of S-genes to potato breeding for resistance to late blight is further discussed.Electronic supplementary materialThe online version of this article (doi:10.1007/s11248-016-9964-2) contains supplementary material, which is available to authorized users.
Highlights
The plant immune system comprises an intricate network of active and passive mechanisms that successfully prevent the colonization of a host by a pathogen (Jones and Dangl 2006) (Fig. 1)
We showed that silencing Downy Mildew Resistant 1 (DMR1) and PMR4 orthologues resulted in resistance to the powdery mildew fungus Oidium neolycopersici (Huibers et al 2013), suggesting that susceptibility gene (S-gene), such as PMR4 and DMR1, are conserved among plant species and that impaired orthologues confer resistance to the associated pathogens in other plant species
To identify potato orthologues of the 11 S-genes listed in Table 1, we used the amino acid sequences of A. thaliana in a BLAST analysis of the potato sequence database
Summary
The plant immune system comprises an intricate network of active and passive mechanisms that successfully prevent the colonization of a host by a pathogen (Jones and Dangl 2006) (Fig. 1). We showed that silencing DMR1 and PMR4 orthologues resulted in resistance to the powdery mildew fungus Oidium neolycopersici (Huibers et al 2013), suggesting that S-genes, such as PMR4 and DMR1, are conserved among plant species and that impaired orthologues confer resistance to the associated pathogens in other plant species. This finding prompted us to identify potato orthologues of S-genes reported in other plant species
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