Polygalacturonase-inhibiting protein is a structural component of plant cell wall

Abstract

It is generally believed that plants "evolved a strategy of defending themselves from a phytopathogen attack" during evolution. This metaphor is used frequently, but it does not facilitate understanding of the mechanisms providing plant resistance to the invasion of foreign organisms and to other unfavorable external factors, as well as the role of these mechanisms in plant growth and development. Information on processes involving one of the plant resistance factors--polygalacturonase-inhibiting protein (PGIP)--is considered in this review. The data presented here indicate that PGIP, being an extracellular leucine-rich repeat-containing protein, performs important functions in the structure of plant cell wall. Amino acid residues participating in PGIP binding to homogalacturonan in the cell wall have been determined. The degree of methylation and the mode of distribution of homogalacturonan methyl groups are responsible for the formation of a complex structure, which perhaps determines the specificity of PGIP binding to pectin. PGIP is apparently one of the components of plant cell wall determining some of its mechanical properties; it is involved in biochemical processes related to growth, expansion, and maceration, and it influences plant morphology. Polygalacturonase (PG) is present within practically all plant tissues, but the manifestation of its activity varies significantly depending on physiological conditions in the tissue. Apparently, the regulation of PG functioning in apoplast significantly affects the development of processes associated with the modification of the structure of plant cell wall. PGIP can regulate PG activity through binding to homogalacturonan. The genetically determined structure of PGIP in plants determines the mode of its interaction with an invader and perhaps is one of the factors responsible for the set of pathogens causing diseases in a given plant species.

POLYGALACTURONASE INVOLVED IN EXPANSION1 Functions in Cell Elongation and Flower Development in Arabidopsis

“…Many plant species also express inhibitor proteins that bind to pectin/pectate lyases (Bugbee, 1993) or PGs (Ferrari et al, 2003(Ferrari et al, , 2012Protsenko et al, 2008;Maulik et al, 2012), although whether these inhibitors exclusively target enzymes produced by pathogens or might also interact with endogenous enzymes is currently unclear.…”

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

“…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). …”

Digestive pectinolytic activity in the Sunn pest,Eurygaster integricepsPuton (Hemiptera: Scutelleridae)

“…Wheat flour prepared from damaged seeds leads to sticky and weak dough and poor volume and texture of loaves (Aja et al 2004;Kinaci and Kinaci 2004). Several plant proteinaceous inhibitors of pectinases have been identified and characterised (Bulantseva et al 2005;Protsenko et al 2008). These inhibitors can be insecticidal and their function is to form complexes with digestive enzymes, which are stable and dissociate slowly.…”