The Solanum demissumR8 late blight resistance gene is an Sw-5 homologue that has been deployed worldwide in late blight resistant varieties

<p> The potato late blight resistance geneR8has been cloned.R8is found in five late blight resistant varieties deployed in three different continents. R8 recognises Avr8 and is homologous to the NB-LRR protein Sw-5 from tomato.Abstract: The broad spectrum late blight resistance gene R8 from Solanum demissum was cloned based on a previously published coarse map position on the lower arm of chromosome IX. Fine mapping in a recombinant population and bacterial artificial chromosome (BAC) library screening resulted in a BAC contig spanning 170 kb of the R8 haplotype. Sequencing revealed a cluster of at least ten R gene analogues (RGAs). The seven RGAs in the genetic window were subcloned for complementation analysis. Only one RGA provided late blight resistance and caused recognition of Avr8. From these results, it was concluded that the newly cloned resistance gene was indeed R8. R8 encodes a typical intracellular immune receptor with an N-terminal coiled coil, a central nucleotide binding site and 13 C-terminal leucine rich repeats. Phylogenetic analysis of a set of representative Solanaceae R proteins shows that R8 resides in a clearly distinct clade together with the Sw-5 tospovirus R protein from tomato. It was found that the R8 gene is present in late blight resistant potato varieties from Europe (Sarpo Mira), USA (Jacqueline Lee, Missaukee) and China (PB-06, S-60). Indeed, when tested under field conditions, R8 transgenic potato plants showed broad spectrum resistance to the current late blight population in the Netherlands, similar to Sarpo Mira.</p

The Synchytrium endobioticum AvrSen1 triggers a Hypersensitive Response in Sen1 potatoes while natural variants evade detection

Synchytrium endobioticum is an obligate biotrophic fungus of the phylum Chytridiomycota. It causes potato wart disease, has a world-wide quarantine status and is included on the HHS and USDA Select Agent list. S. endobioticum isolates are grouped in pathotypes based on their ability to evade host-resistance in a set of differential potato varieties. So far, thirty-nine pathotypes are reported. A single dominant gene (Sen1) governs pathotype 1 resistance and we anticipated that the underlying molecular model would involve a pathogen effector (AvrSen1) that is recognized by the host.The S. endobioticum specific secretome of fourteen isolates representing six different pathotypes was screened for effectors specifically present in pathotype 1(D1) isolates but absent in others. We discovered a single AvrSen1 candidate. Expression of this candidate in potato Sen1 plants showed a specific hypersensitive response, which co-segregated with the Sen1 resistance in potato populations. No HR was obtained with truncated genes found in pathotypes that evaded recognition by Sen1. These findings established that our candidate gene was indeed Avrsen1. AvrSen1 is a single copy gene and encodes a 376 amino acid protein without predicted function or functional domains, and is the first effector gene identified in Chytridiomycota

The Synchytrium endobioticum AvrSen1 triggers a Hypersensitive Response in Sen1 potatoes while natural variants evade detection

Synchytrium endobioticum is an obligate biotrophic fungus of the phylum Chytridiomycota. It causes potato wart disease, has a world-wide quarantine status and is included on the HHS and USDA Select Agent list. S. endobioticum isolates are grouped in pathotypes based on their ability to evade host-resistance in a set of differential potato varieties. So far, thirty-nine pathotypes are reported. A single dominant gene (Sen1) governs pathotype 1 resistance and we anticipated that the underlying molecular model would involve a pathogen effector (AvrSen1) that is recognized by the host.The S. endobioticum specific secretome of fourteen isolates representing six different pathotypes was screened for effectors specifically present in pathotype 1(D1) isolates but absent in others. We discovered a single AvrSen1 candidate. Expression of this candidate in potato Sen1 plants showed a specific hypersensitive response, which co-segregated with the Sen1 resistance in potato populations. No HR was obtained with truncated genes found in pathotypes that evaded recognition by Sen1. These findings established that our candidate gene was indeed Avrsen1. AvrSen1 is a single copy gene and encodes a 376 amino acid protein without predicted function or functional domains, and is the first effector gene identified in Chytridiomycota