Cloning and sequence analysis of the endopolygalacturonase gene from the pitch canker fungus, Fusarium circinatum

The fungus Fusarium circinatum causes pitch canker disease on mature pine trees and root rot and damping-off of pine seedlings. Endopolygalacturonases (endo-PGs) play a major role during penetration of plants by fungi. Digestion of the pectic polysaccharides in the plant primary cell walls is one of the earliest functions of endoPGs during infection. The research objective was to clone and characterize the gene encoding endopolygalacturonase in F. circinatum. A 970-bp DNA fragment was cloned by using degenerate PCR amplification from F. circinatum DNA. Sequence data for this fragment were used to design specific primers for use in genome walking to amplify and sequence the remaining portion of the F. circinatum endoPG gene (Fcpg). The amino acid sequence predicted from this gene showed 90% and 87% similarity to Fusarium oxysporum and Fusarium moniliforme endoPGs, respectively.