title: The pathogenic development of Sclerotinia sclerotiorum in soybean requires specific host NADPH oxidases.
abstract: The plant membrane-localized NADPH oxidases, also known as respiratory burst oxidase homologues (RBOHs), play crucial roles in various cellular activities, including plant disease responses, and are a major source of reactive oxygen species (ROS). Sclerotinia sclerotiorum is a cosmopolitan fungal pathogen that causes Sclerotinia stem rot (SSR) in soybean. Via a key virulence factor, oxalic acid, it induces programmed cell death (PCD) in the host plant, a process that is reliant on ROS generation. In this study, using protein sequence similarity searches, we identified 17 soybean RBOHs (GmRBOHs) and studied their contribution to SSR disease development, drought tolerance and nodulation. We clustered the soybean RBOH genes into six groups of orthologues based on phylogenetic analysis with their Arabidopsis counterparts. Transcript analysis of all 17 GmRBOHs revealed that, of the six identified groups, group VI (GmRBOH-VI) was specifically and drastically induced following S. sclerotiorum challenge. Virus-induced gene silencing (VIGS) of GmRBOH-VI using Bean pod mottle virus (BPMV) resulted in enhanced resistance to S. sclerotiorum and markedly reduced ROS levels during disease development. Coincidently, GmRBOH-VI-silenced plants were also found to be drought tolerant, but showed a reduced capacity to form nodules. Our results indicate that the pathogenic development of S. sclerotiorum in soybean requires the active participation of specific host RBOHs, to induce ROS and cell death, thus leading to the establishment of disease.
authors.affiliation: Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Ashish
authors.initials: A
authors.lastname: Ranjan
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Dhileepkumar
authors.initials: D
authors.lastname: Jayaraman
authors.affiliation: Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Grau
authors.affiliation: Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Hill
authors.affiliation: Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Whitham
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA.|Department of Agronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Ané
authors.affiliation: Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Damon L
authors.initials: DL
authors.lastname: Smith
authors.affiliation: Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Kabbage
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity*; D055864:Droughts; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013025:Glycine max / Q000378:metabolism* / Q000382:microbiology*
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases
keywords: NADPH oxidases; ROS; Sclerotinia sclerotiorum; Sclerotinia stem rot; drought; soybean