title: The 50 distal amino acids of the 2AHPhoming protein of Grapevine fanleaf virus elicit a hypersensitive reaction on Nicotiana occidentalis.
abstract: Avirulence factors are critical for the arm's race between a virus and its host in determining incompatible reactions. The response of plants to viruses from the genus Nepovirus in the family Secoviridae, including Grapevine fanleaf virus (GFLV), is well characterized, although the nature and characteristics of the viral avirulence factor remain elusive. By using infectious clones of GFLV strains F13 and GHu in a reverse genetics approach with wild-type, assortant and chimeric viruses, the determinant of necrotic lesions caused by GFLV-F13 on inoculated leaves of Nicotiana occidentalis was mapped to the RNA2-encoded protein 2AHP, particularly to its 50 C-terminal amino acids. The necrotic response showed hallmark characteristics of a genuine hypersensitive reaction, such as the accumulation of phytoalexins, reactive oxygen species, pathogenesis-related protein 1c and hypersensitivity-related (hsr) 203J transcripts. Transient expression of the GFLV-F13 protein 2AHPfused to an enhanced green fluorescent protein (EGFP) tag in N. occidentalis by agroinfiltration was sufficient to elicit a hypersensitive reaction. In addition, the GFLV-F13 avirulence factor, when introduced in GFLV-GHu, which causes a compatible reaction on N. occidentalis, elicited necrosis and partially restricted the virus. This is the first identification of a nepovirus avirulence factor that is responsible for a hypersensitive reaction in both the context of virus infection and transient expression.
authors.affiliation: Université de Strasbourg, INRA, SVQV UMR-A 1131, Colmar, 68000, France.
authors.forename: Isabelle R
authors.initials: IR
authors.lastname: Martin
authors.affiliation: Université de Strasbourg, INRA, SVQV UMR-A 1131, Colmar, 68000, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Vigne
authors.affiliation: Université de Strasbourg, CNRS, IBMP UPR 2357, Strasbourg, 67000, France.
authors.forename: François
authors.initials: F
authors.lastname: Berthold
authors.affiliation: Université de Strasbourg, INRA, SVQV UMR-A 1131, Colmar, 68000, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Komar
authors.affiliation: Université de Strasbourg, INRA, SVQV UMR-A 1131, Colmar, 68000, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Lemaire
authors.affiliation: Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY, 14456, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Fuchs
authors.affiliation: Université de Strasbourg, CNRS, IBMP UPR 2357, Strasbourg, 67000, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Schmitt-Keichinger
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000276:immunology*; D016679:Genome, Viral / Q000235:genetics; D017860:Nepovirus / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D014026:Nicotiana / Q000276:immunology* / Q000821:virology*; D014764:Viral Proteins / Q000737:chemistry / Q000276:immunology*
chemical_list: D000596:Amino Acids; D014764:Viral Proteins
keywords: Nepovirus; Secoviridae; avirulence factor; defence; hypersensitive reaction; reverse genetics; symptom determinant