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.

Molecular cloning, functional analysis and localization of a novel gene encoding polygalacturonase-inhibiting protein in Chorispora bungeana

“…Abiotic stresses, such as SA, low temperature, jasmonate (JA), and oligogalacturonides, can also induce the PGIP expression (Li et al 2003;Hegedus et al 2008). For example, in Arabidopsis, cold induces the expression of AtPGIP1 but not AtPGIP2 (Ferrari et al 2003).…”

“…PGs degrade plant cell wall, which make other hydrolyzation enzymes to degrade cell wall more easily (Karr and Albersheim 1970). Poylgalacturonase-inhibiting proteins (PGIPs) are cell wall proteins that inhibit the activity of fungal PGs and retard the invasion of plant tissues by pathogens (Ferrari et al 2006;Spadoni et al 2006;Joubert et al 2007;Cheng et al 2008;Hegedus et al 2008;Janni et al 2008;Protsenko et al 2008). …”

Expression and validation of PvPGIP genes for resistance to white mold (Sclerotinia sclerotiorum) in common beans (Phaseolus vulgaris L.)

“…Genes that encode these proteins have been characterized in both monocotyledons and dicotyledons. Genomic analyses have shown that PGIP genes may exist as a single gene, for example in diploid wheat species (Di Giovanni et al, 2008), or are organized into gene families whose members are tandemarranged and may vary from two, as in Arabidopsis thaliana (Ferrari et al, 2003), to 16, as in Brassica napus (Hegedus et al, 2008). The overexpression of PGIP genes in transgenic plants such as wheat, tomato, tobacco, and A. thaliana limits fungal colonization (Powell et al, 2000;Ferrari et al, 2003;Manfredini et al, 2005;Janni et al, 2008).…”

Characterization of the dry bean polygalacturonase-inhibiting protein (PGIP) gene family during Sclerotinia sclerotiorum (Sclerotiniaceae) infection

“…(Ferrari et al, 2003) and Brassica napus L. (Li et al, 2003;Hegedus et al, 2008). In P. vulgaris, four genes code for proteins that show sequence variation from 3 to 24%.…”