Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: May 19, 2006
Publication Date: June 5, 2006
Citation: Mcevoy, J.L., Conway, W.S., Janisiewicz, W.J. 2006. Virulence factors associated with penicillium expansum and p. solitum during decay of apple fruit. Phytopathology. 96:S75
Both P. expansum and P. solitum cause blue mold of apple fruit during storage. P. expansum, however, is the more aggressive pathogen. Dependent upon the apple variety, P. expansum lesions generally reach 30 mm in size within 7 d at 20 C while P. solitum induced lesions 14 d to reach a comparable size. Isoelectric focusing profiles of pectinases, as detected by activity overlays, indicate that both pathogens produce multiple, medium-dependent polygalacturonases in vitro. P. expansum, but not P. solitum, produces detectable levels of polygalacturonase in apple tissue. Unlike P. expansum, P. solitum produces a detectable cellulase activity in vitro. Both pathogens induce a lowering of the pH of the host tissue, likely due to the production of organic acids. Since polygalacturonase transcripts have previously been shown to accumulate in response to acidification of host tissue local pH modulation by these pathogens may be a mechanism for increasing virulence.