Biology subjects

Vossen, J.

Publications and source records attributed to Vossen, J..

5 recordsLinked to original sources

bioRxiv2020

Allelic variants of the NLR protein Rpi-chc1 differentially recognise members of the Phytophthora infestans PexRD12/31 effector superfamily through the leucine-rich repeat domain

O_LIPhytophthora infestans is a pathogenic oomycete that causes the infamous potato late blight disease. Resistance (R) genes from diverse Solanum species encode intracellular receptors that recognize P. infestans RXLR effector proteins and provide effective defence responses. To deploy these R genes in a durable fashion in agriculture, we need to understand the mechanism of effector recognition and the way the pathogen evades recognition. C_LIO_LIWe cloned sixteen allelic variants of the Rpi-chc1 gene from Solanum chacoense and other Solanum species, and identified the cognate P. infestans RXLR effectors. These tools were used to study receptor-ligand interactions and co-evolution. C_LIO_LIFunctional and non-functional alleles of Rpi-chc1 encode Coiled-Coil-Nucleotide Binding-Leucine-Rich-Repeat (CNL) proteins. Rpi-chc1.1 recognised multiple PexRD12 (AVRchc1.1) proteins while Rpi-chc1.2 recognised multiple PexRD31 (AVRchc1.2) proteins, both from the PexRD12/31 superfamily. Domain swaps between Rpi-chc1.1 and Rpi-chc1.2 revealed that overlapping subdomains in the LRR were responsible for the difference in effector recognition. C_LIO_LIThis study showed that Rpi-chc1.1 and Rpi-chc1.2, evolved to recognize distinct members of the same PexRD12/31 effector family via the LRR domain. The biased distribution of polymorphisms suggests that exchange of LRRs during host-pathogen co-evolution can lead to novel recognition specificities. These insights will help future strategies to breed for durable resistant varieties. C_LI

plant biology↗

bioRxiv2020

The Rpi-mcq1 resistance gene family recognizes Avr2 of Phytophthora infestans but is distinct from R2

Potato late blight, which is caused by the destructive oomycete pathogen Phytophthora infestans, is a major threat to global food security. Several nucleotide binding, leucine-rich repeat (NLR) Resistance to P. infestans (Rpi) genes have been introgressed into potato cultivars from wild Solanum species that are native to Mexico, but these were quickly defeated. Positional cloning in Solanum mochiquense, combined with allele mining in Solanum huancabambense, were used to identify a new family of Rpi genes from Peruvian Solanum species. Rpi-mcq1, Rpi-hcb1.1 and Rpi-hcb1.2 confer race-specific resistance to a panel of P. infestans isolates. Effector assays showed that the Rpi-mcq1 family mediates a hypersensitive response upon recognition of the RXLR effector AVR2, which had previously been found to be exclusively recognized by the family of R2 resistance proteins. The Rpi-mcq1 and R2 genes are distinct and reside on chromosome IX and IV, respectively. This is the first report of two unrelated R protein families that recognize the same AVR protein. We anticipate that this likely is a consequence of a geographically separated dynamic co-evolution of R gene families of Solanum with an important effector gene of P. infestans. Author summaryPotato is the largest non-grain staple crop and essential for food security world-wide. However, potato plants are continuously threatened by the notorious oomycete pathogen Phytophthora infestans that causes late blight. This devastating disease has led to the Irish famine more then 150 years ago, and is still a major threat for potato. Resistance against P. infestans can be found in wild relatives of potato, which carry resistance genes that belong to the nucleotide binding site-leucine-rich repeat (NLR) class. Known NLR proteins typically recognize a matching effector from Phytophthora, which leads to a hypersensitive resistance response (HR). For example, R2 from Mexican Solanum species recognizes AVR2 from P. infestans. So far, these R genes exclusively match to one Avr gene. Here, we identified a new class of NLR proteins that are different from R2, but also recognize the same effector AVR2. This new family of NLR occurs in South American Solanum species, and we anticipate that it is likely a product of a geographically separated co-evolution with AVR2. This is the first report of two unrelated R protein families that recognize the same AVR protein.

plant biology↗

bioRxiv2020

Host-interactor screens of Phytophthora infestans RXLR proteins reveal vesicle trafficking as a major effector-targeted process

Pathogens modulate plant cell structure and function by secreting effectors into host tissues. Effectors typically function by associating with host molecules and modulating their activities. This study aimed to identify the host processes targeted by the RXLR class of host-translocated effectors of the potato blight pathogen Phytophthora infestans. To this end, we performed an in planta protein-protein interaction screen by transiently expressing P. infestans RXLR effectors in Nicotiana benthamiana leaves followed by co-immunoprecipitation (co-IP) and liquid chromatography tandem mass spectrometry (LC-MS/MS). This screen generated an effector-host protein interactome matrix of 59 P. infestans RXLR effectors x 586 N. benthamiana proteins. Classification of the host interactors into putative functional categories revealed over 35 biological processes possibly targeted by P. infestans. We further characterized the PexRD12/31 family of RXLR-WY effectors, which associate and co-localize with components of the vesicle trafficking machinery. One member of this family, PexRD31, increased the number of FYVE positive vesicles in N. benthamiana cells. FYVE positive vesicles also accumulated in leaf cells near P. infestans hyphae, indicating that the pathogen may enhance endosomal trafficking during infection. We anticipate that the interactome dataset we generated will serve as a useful community resource for functional studies of P. infestans effectors and of effector-targeted host processes.

plant biology↗

bioRxiv2019

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 identified 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. The S. endobioticum 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, an extremely diverse yet underrepresented basal lineage of fungi.\n\nAuthor SummaryPlant pathogens can have a great social and economic impact, and are a continuous threat to food security. A clear example is Synchytrium endobioticum, the fungus causing potato wart disease. The impact of the pathogen, lack of effective chemical control agents and the longevity of resting spores produced by the pathogen led to a world-wide quarantine status for S. endobioticum. Strict phytosanitary measures and the use of resistance potato varieties are currently the only way to prevent the spread of the disease. The emergence of new pathotypes that overcome resistance urged to study the underlying molecular mechanisms of S. endobioticum recognition by the plant. Here we describe the identification of the first effector (AvrSen1) of S. endobioticum that is recognized by the Sen1 resistance gene product. Also, we report the loss of AvrSen1 in other pathotypes thus avoiding recognition by the plant and triggering immune responses. AvrSen1 represents the first effector to be identified in the basal fungal lineage Chytridiomycota. The discovery of AvrSen1 provides an important tool to manage potato wart disease. Moreover, knowledge about Chytridiomycota effectors will shed light on other (pathogenic) interactions and the co-evolution of Chytridiomycota species with their hosts.

plant biology↗

bioRxiv2018

Tracking disease resistance deployment in potato breeding by enrichment sequencing

Following the molecular characterisation of functional disease resistance genes in recent years, methods to track and verify the integrity of multiple genes in varieties are needed for crop improvement through resistance stacking. Diagnostic resistance gene enrichment sequencing (dRenSeq) enables the high-confidence identification and complete sequence validation of known functional resistance genes in crops. As demonstrated for tetraploid potato varieties, the methodology is more robust and cost-effective in monitoring resistances than whole-genome sequencing and can be used to appraise (trans)gene integrity efficiently. All currently known NB-LRRs effective against viruses, nematodes and the late blight pathogen Phytophthora infestans can be tracked with dRenSeq in potato and hitherto unknown polymorphisms have been identified. The methodology provides a means to improve the speed and efficiency of future disease resistance breeding in crops by directing parental and progeny selection towards effective combinations of resistance genes.

plant biology↗