The paradigm of disease resistance through a dysfunctional variant of an essential gene may be applicable to other plant–pathogen interactions.Ī dynamic endomembrane system is a universal trait of eukaryotic cells that enables the transfer of vesicular cargoes throughout the cell and with the cell exterior ( 1). Immunoblots and electron microscopy immunolocalization revealed that resistance-type α-SNAPs specifically hyperaccumulate relative to wild-type α-SNAPs at the nematode feeding site, promoting the demise of this biotrophic interface. For successful growth and reproduction, SCN dramatically reprograms a set of plant root cells and must sustain this sedentary feeding site for 2–4 weeks. Expression of these α-SNAPs counteracted the cytotoxicity of resistance-type Rhg1 α-SNAPs. Soybean, due to ancient genome duplication events, carries other loci that encode canonical (wild-type) α-SNAPs. Elevated in planta expression of resistance-type Rhg1 α-SNAPs depleted the abundance of SNARE-recycling 20S complexes, disrupted vesicle trafficking, induced elevated abundance of NSF, and caused cytotoxicity.
In the present study, we found that the resistance-type Rhg1 α-SNAP is defective in interaction with NSF. Rhg1 is widely used in agriculture, but the mechanisms of Rhg1 disease resistance have remained unclear. glycines), the most economically damaging pathogen of soybeans worldwide. These Rhg1 loci mediate resistance to soybean cyst nematode (SCN H. However, certain haplotypes of the Rhg1 (resistance to Heterodera glycines 1) locus of soybean possess multiple repeat copies of an α-SNAP gene ( Glyma.18G022500) that encodes atypical amino acids at a highly conserved functional site. If (!(audioElement = document.Powdery mildews, ubiquitous obligate biotrophic plant pathogens, are often attacked in the field by mycoparasitic fungi belonging to the genus Ampelomyces.ġ if not exists audio control, then create it: Var uri = e.attributes.getNamedItem('data-uri').Α-SNAP and NSF proteins are conserved across eukaryotes and sustain cellular vesicle trafficking by mediating disassembly and reuse of SNARE protein complexes, which facilitate fusion of vesicles to target membranes. Some Ampelomyces strains are commercialized biocontrol agents of crop pathogenic powdery mildews. Using Agrobacterium tumefaciens-mediated transformation (ATMT), we produced stable Ampelomyces transformants that constitutively expressed green fluorescent protein (GFP) to (i) improve the visualization of the mildew– Ampelomyces interaction and (ii) decipher the environmental fate of Ampelomyces fungi before and after acting as a mycoparasite. Detection of Ampelomyces structures, and especially hyphae, was greatly enhanced when diverse powdery mildew, leaf, and soil samples containing GFP transformants were examined with fluorescence microscopy compared with brightfield and differential interference contrast optics.
We showed for the first time, to our knowledge, that Ampelomyces strains can persist up to 21 days on mildew-free host plant surfaces, where they can attack powdery mildew structures as soon as these appear after this period. As saprobes in decomposing, powdery mildew-infected leaves on the ground and also in autoclaved soil, Ampelomyces strains developed new hyphae but did not sporulate. These results indicate that Ampelomyces strains occupy a niche in the phyllosphere where they act primarily as mycoparasites of powdery mildews. Our work has established a framework for a molecular genetic toolbox for the genus Ampelomyces using ATMT.