The characterization of the soybean polygalacturonase-inhibiting proteins (Pgip) gene family reveals that a single member is responsible for the activity detected in soybean tissues

Abstract

Polygalacturonase-inhibiting proteins (PGIPs) are leucine-rich repeat (LRR) proteins that inhibit fungal endopolygalacturonases (PGs). They are encoded by multigene families whose members show functional redundancy and subfunctionalization for recognition of fungal PGs. In order to expand the information on the structure and functional features of legume PGIP, we have isolated and characterized four members of the soybean Pgip gene family and determined the properties of the encoded protein products. Sequence analysis showed that these genes form two clusters: one cluster of about 5 kbp containing Gmpgip1 and Gmpgip2, and the other containing Gmpgip3 and Gmpgip4 within a 60 kb fragment of a separate BAC clone. Sequence diversification of the four members resides mainly in the xxLxLxx region that includes residues forming the beta-sheet B1. When compared with other legume Pgip genes, Gmpgip3 groups with the bean genes Pvpgip1 and Pvpgip2, suggesting that these genes are closer to the ancestral gene. At the protein level, only GmPGIP3 shows the capability to inhibit fungal PGs. The spectrum of inhibition of GmPGIP3 against eight different fungal PGs mirrors that of the PGIP purified from soybean tissues and is similar to that of the bean PvPGIP2, one of the most efficient inhibitors so far characterized. We also report that the four Gmpgip genes are differentially regulated after wounding or during infection with the fungal pathogen Sclerotinia sclerotiorum. Following fungal infection Gmpgip3 is up regulated promptly, while Gmpgip2 is delayed.

Integration of evolutionary and desolvation energy analysis identifies functional sites in a plant immunity protein

“…The symbol ϱ indicates no inhibition; the asterisk indicates cases where inhibitory activities of PvPGIP2 and alanine variants are significantly different (P Ͻ 0.003). a This PG is the same as that indicated as F. moniliforme PG (FmPG) in previous articles (21,23,26,28,30,31,34).…”

“…PGIPs are apoplastic proteins that counteract the action of fungal and insect PGs (13,26,27). They exhibit 10 imperfect LRRs of the extracellular type [consensus motif: xxLxLxxNxLt/sGxIPxxLxxLxx (24)] and are encoded by small gene families of clustered paralogs that show different patterns of gene expression and specificity against PGs (26,(28)(29)(30). Single PGIP residues located in the concave surface of the LRR solenoid (i.e., the ␤-sheet B1) differentially affect the inhibition of fungal PGs (23,31).…”

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

“…In the soybean (Glycine max), GmPGIP3, which is the most highly expressed gene of this family in the species, is phylogenetically grouped with PvPGIP1 and PvPGIP2, suggesting that the duplication that originated the ancestors of PvPGIP1/PvPGIP2 and PvPGIP3/PvPGIP4 occurred before the separation of Glycine and Phaseolus (Kalunke et al, 2014). Among these genes, PvPGIP2 is the most efficient in inhibiting the largest number of fungal PGs (Manfredini et al, 2005;D'Ovidio et al, 2004bD'Ovidio et al, , 2006. In addition, the highly conserved nature of the nucleotide sequence of this gene in various lines and species of Phaseolus indicates high adaptive significance (Farina et al, 2009).…”

Identification of a partial oil palm polygalacturonase-inhibiting protein (EgPGIP) gene and its expression during basal stem rot infection caused by Ganoderma boninense

“…Similarly, the soybean Gmpgip1, Gmpgip3, Gmpgip4 are expressed in 7-day-old seedlings, whereas Gmpgip2 is expressed only following Sclerotinia sclerotiorum infection (D'Ovidio et al, 2006). In Arabidopsis, Atpgip1 and Atpgip2 are up regulated co-ordinately in response to B. cinerea infection, but through separate signal transduction pathways.…”