title: Cell death of Nicotiana benthamiana is induced by secreted protein NIS1 of Colletotrichum orbiculare and is suppressed by a homologue of CgDN3.
abstract: Colletotrichum orbiculare, the causal agent of cucumber anthracnose, infects Nicotiana benthamiana. Functional screening of C. orbiculare cDNAs in a virus vector-based plant expression system identified a novel secreted protein gene, NIS1, whose product induces cell death in N. benthamiana. Putative homologues of NIS1 are present in selected members of fungi belonging to class Sordariomycetes, Dothideomycetes, or Orbiliomycetes. Green fluorescent protein-based expression studies suggested that NIS1 is preferentially expressed in biotrophic invasive hyphae. NIS1 lacking signal peptide did not induce NIS1-triggered cell death (NCD), suggesting apoplastic recognition of NIS1. NCD was prevented by virus-induced gene silencing of SGT1 and HSP90, indicating the dependency of NCD on SGT1 and HSP90. Deletion of NIS1 had little effect on the virulence of C. orbiculare against N. benthamiana, suggesting possible suppression of NCD by C. orbiculare at the postinvasive stage. The CgDN3 gene of C. gloeosporioides was previously identified as a secreted protein gene involved in suppression of hypersensitive-like response in Stylosanthes guianensis. Notably, we found that NCD was suppressed by the expression of a CgDN3 homologue of C. orbiculare. Our findings indicate that C. orbiculare expresses NIS1 at the postinvasive stage and suggest that NCD could be repressed via other effectors, including the CgDN3 homologue.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
authors.forename: Kae
authors.initials: K
authors.lastname: Yoshino
authors.forename: Hiroki
authors.initials: H
authors.lastname: Irieda
authors.forename: Fumie
authors.initials: F
authors.lastname: Sugimoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yoshioka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Okuno
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Takano
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D016923:Cell Death / Q000502:physiology; D020231:Colletotrichum / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity* / Q000648:ultrastructure; D028462:Cucumis / Q000382:microbiology; D018076:DNA, Complementary / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D015723:Gene Library; D020868:Gene Silencing; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D025301:Hyphae / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D014774:Virulence / Q000235:genetics
chemical_list: C417975:DN3 protein, Colletotrichum gloeosporioides; D018076:DNA, Complementary; D005656:Fungal Proteins; D018841:HSP90 Heat-Shock Proteins; D010940:Plant Proteins