title: Brassica napus possesses an expanded set of polygalacturonase inhibitor protein genes that are differentially regulated in response to Sclerotinia sclerotiorum infection, wounding and defense hormone treatment.
abstract: Most plants encode a limited set of polygalacturonase inhibitor (PGIP) genes that may be involved in aspects of plant development, but more importantly in the inactivation of polygalacturonases (PG) secreted by pathogens. Previously, we characterized two Brassica napus PGIP genes, BnPgip1 and BnPgip2, which were differentially expressed in response to pathogen infection and wounding. Here we report that the B. napus genome encodes a set of at least 16 PGIP genes that are similar to BnPgip1 or BnPgip2. This is the largest Pgip gene family reported to date. Comparison of the BnPGIPs revealed several sites within the xxLxLxx region of leucine rich repeats that form beta-sheets along the interacting face of the PGIP that are hypervariable and represent good candidates for generating PGIP diversity. Characterization of the regulatory regions and RT-PCR studies with gene-specific primers revealed that individual genes were differentially responsive to pathogen infection, mechanical wounding and signaling molecules. Many of the BnPgip genes responded to infection by the necrotic pathogen, Sclerotinia sclerotiorum; however, these genes were also induced either by jasmonic acid, wounding and salicylic acid or some combination thereof. The large number of PGIPs and the differential manner in which they are regulated likely ensures that B. napus can respond to attack from a broad spectrum of pathogens and pests.
authors.affiliation: Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada. hegedusd@agr.gc.ca
authors.forename: Dwayne D
authors.initials: DD
authors.lastname: Hegedus
authors.forename: Rugang
authors.initials: R
authors.lastname: Li
authors.forename: Lone
authors.initials: L
authors.lastname: Buchwaldt
authors.forename: Isobel
authors.initials: I
authors.lastname: Parkin
authors.forename: Steve
authors.initials: S
authors.lastname: Whitwill
authors.forename: Cathy
authors.initials: C
authors.lastname: Coutu
authors.forename: Diana
authors.initials: D
authors.lastname: Bekkaoui
authors.forename: S Roger
authors.initials: SR
authors.lastname: Rimmer
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000502:physiology*; D029688:Brassica napus / Q000382:microbiology / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D005810:Multigene Family; D054883:Oxylipins / Q000378:metabolism; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; C081479:PGIP protein, plant; D010940:Plant Proteins; C011006:jasmonic acid; D020156:Salicylic Acid