title: The bean polygalacturonase-inhibiting protein 2 (PvPGIP2) is highly conserved in common bean (Phaseolus vulgaris L.) germplasm and related species.
abstract: Polygalacturonase-inhibiting proteins (PGIPs) are extracellular plant protein inhibitors of endo-polygalacturonases (PGs) that belong to the leucine-rich repeat (LRR) protein family. In bean, PGIP is encoded by a small gene family of four members among which Pvpgip2 encodes the most wide-spectrum and efficient inhibitor of fungal PGs. In order to evaluate the sequence polymorphism of Pvpgip2 and its functional significance, we have analyzed a number of wild and cultivated bean (P. vulgaris) accessions of Andean and Mesoamerican origin, and some genotypes from the related species P. coccineus, P. acutifolius, and P. lunatus. Our analyses indicate that the protein encoded by Pvpgip2 is highly conserved in the bean germplasm. The few detected polymorphic sites correspond to synonymous substitutions and only two wild genotypes contain a Pvpgip2 with a single non-synonymous replacement. Sequence comparison showed a slightly larger variation in the related bean species P. coccineus, P. acutifolius, and P. lunatus and confirmed the known phylogenetic relationships with P. vulgaris. The majority of the replacements were within the xxLxLxx region of the leucine rich repeat (LRR) domain and none of them affected residues contributing to structural features. The variant PGIPs were expressed in Nicotiana benthamiana using PVX as vector and their inhibitory activity compared to that of PvPPGIP2. All the variants were able to fully inhibit the four fungal PGs tested with minor differences. Taken together these results support the hypothesis that the overall sequence conservation of PGIP2 and minor variation at specific sites is necessary for high-affinity recognition of different fungal PGs.
authors.affiliation: Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Viterbo, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Farina
authors.forename: Valentina
authors.initials: V
authors.lastname: Rocchi
authors.forename: Michela
authors.initials: M
authors.lastname: Janni
authors.forename: Stefano
authors.initials: S
authors.lastname: Benedettelli
authors.forename: Giulia
authors.initials: G
authors.lastname: De Lorenzo
authors.forename: Renato
authors.initials: R
authors.lastname: D'Ovidio
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D004791:Enzyme Inhibitors; D007527:Isoenzymes / Q000145:classification / Q000235:genetics; D008969:Molecular Sequence Data; D027805:Phaseolus / Q000201:enzymology / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; C081479:PGIP protein, plant; D010940:Plant Proteins