Endopolygalacturonase is not required for pathogenicity of Cochliobolus carbonum on maize

• Published in: The Plant cell Vol. 2; no. 12; pp. 1191 - 1200
• Main Authors: Scott-Craig, J.S. (Michigan State University, East Lansing, MI), Panaccione, D.G, Cervone, F, Walton, J.D
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Physiologists 01.12.1990
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Amino Acid Sequence; Amino acids; Ascomycota - enzymology; Ascomycota - genetics; Ascomycota - pathogenicity; Base Sequence; Cell walls; Cloning, Molecular; COCHLIOBOLUS; Corn; DNA; DNA, Single-Stranded - genetics; Enzymes; EXPRESION GENICA; EXPRESSION DES GENES; Gels; GENE; GENES; GENETICA; GENETIQUE; Genome; Molecular Sequence Data; MUTACION INDUCIDA; Mutagenesis; Mutation - genetics; MUTATION PROVOQUEE; NUCLEOTIDE; NUCLEOTIDOS; Oligonucleotides; Plant cells; Plants; PODER PATOGENO; POLIGALACTURONASA; POLYGALACTURONASE; Polygalacturonase - genetics; POUVOIR PATHOGENE; Restriction Mapping; RNA; Sequence Homology; Transformation, Genetic; Virulence; ZEA MAYS; Zea mays - microbiology
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.2.12.1191

A gene (PGN1) encoding extracellular endopolygalacturonase was isolated from the fungal maize pathogen Cochliobolus carbonum race 1. A probe was synthesized by polymerase chain reaction using oligonucleotides based on the endopolygalacturonase amino acid sequence. Genomic and cDNA copies of the gene were isolated and sequenced. The corresponding mRNA was present in C. carbonum grown on pectin but not on sucrose as carbon source. The single copy of PGN1 in C. carbonum was disrupted by homologous integration of a plasmid containing an internal fragment of the gene. Polygalacturonase activity in one transformant chosen for further analysis was 10% or 35% of the wild-type activity based on viscometric or reducing sugar assays, respectively. End product analysis indicated that the residual activity in the mutant was due to an exopolygalacturonase. Pathogenicity on maize of the mutant lacking endopolygalacturonase activity was qualitatively indistinguishable from the wild-type strain, indicating that in this disease interaction endopolygalacturonase is not required. Either pectin degradation is not critical to this interaction or exopolygalacturonase alone is sufficient