Functional analysis of Pcipg2 from the straminopilous plant pathogen Phytophthora capsici

Abstract Phytophthora capsici causes serious diseases in numerous crop plants. Polygalacturonases (PGs) are cell wall‐degrading enzymes that play an important role in pathogenesis in straminopilous pathogens. To understand PGs as they relate to the virulence of P. capsici , Pcipg 2 was identified from a genomic library of a highly virulent P. capsici strain. Pcipg 2 was strongly expressed during symptom development after the inoculation of pepper leaves with P. capsici . The wild protein (PCIPGII) was obtained from the expression of pcipg 2 and found that increasing activity of PGs in PCIPGII‐treated pepper leaves was consistent with increasing symptom development. Asp residues in active sites within pcipg 2 affected PCIPGII activity or its virulence on pepper leaves. Results show that pcipg 2 is an important gene among pcipg genes, and illustrate the benefit of analyzing mechanisms of pathogenicity during the period of host/parasite interaction. genesis 47:535–544, 2009. © 2009 Wiley‐Liss, Inc.