Functional characterization of a gene family encoding Polygalacturonases in Phytophthora parasitica.
Phytophthora parasitica is an oomycete plant pathogen that causes severe disease in a wide variety of plant species. In our previous study, we discovered a multigene family encoding endopolygalacturonases (endoPG) in Phytophthora parasitica. Here, we screened the genomic library of Phytophthora parasitica for the genes encoding endoPG named pppg2 through pppg10, and analyzed their functions. Results obtained by real-time quantitative reverse transcriptase-polymerase chain reaction demonstrated that some of these genes are highly induced during plant infection, which suggests their important roles in the pathogenesis of Phytophthora parasitica. Analysis by in-gel activity assay of recombinant proteins obtained from Pichia pastoris indicated that each of these genes encodes a functional endoPG. Investigation of the function of pppg genes in planta by a Potato virus X agroinfection system in tobacco revealed that each pppg caused specific effects, varying from no symptoms to dwarfism, necrosis, leaf curl, silvery leaf, and cracks in leaf stalks. Appearance of these effects depends on the expression of a pppg protein with a normal active site in the apoplast. These results indicated that each pppg plays a distinct role in the decomposition of plant cell wall.
Wu
Chih-Hang
CH
Department of Plant Pathology and Microbiology, National Taiwan University, Taipei 106, Taiwan.
Yan
Hao-Zhi
HZ
Liu
Li-Fei
LF
Liou
Ruey-Fen
RF
D020418:Algal Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008957:Models, Genetic; D005810:Multigene Family; D010838:Phytophthora / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D011096:Polygalacturonase / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000382:microbiology
D020418:Algal Proteins; D011096:Polygalacturonase