LIPASE, A FUNGAL ENZYME ASSOCIATED IN THE EARLY STAGES OF PLANT INFECTION?
P BERTO1, P COMMÉNIL2, L BELINGHERI2 and B DEHORTER2
1Unité de Phytopathologie, FUSAGX, 2, Passage des Déportés, B-5030 Gembloux, Belgium; 2Laboratoire de Physiologie des Parois Végétales, USTL, SN2 2eme étage, F-59655 Villeneuve d'Ascq Cedex, France
Background and objectives
Results and conclusions
The lipase and the cutinase produced by B. cinerea were found to have different biochemical and serological properties. Purified polyclonal antibodies raised against the lipase specifically reacted with the lipase, and not with the cutinase. In vivo, the addition of antibodies to spore suspensions of B. cinerea completely suppressed lesion formation on the tomato leaves. Although B. cinerea conidia germinated in the presence of the anti-lipase antibody, the spore germ tubes did not penetrate the leaf cuticle. Thus, specific anti-lipase antibodies applied with an inoculum protect the leaves against attack.
These results suggest that B. cinerea lipase activity is required in the infection of tomato leaves. An 80-kDa lipase was detected on ungerminated spores of A. brassicicola. This lipolytic enzyme showed in vitro cutinolytic activity. Antibodies raised against the B. cinerea lipase cross-react with the 80-kDa lipase produced by A. brassicicola. No immunological cross- reactivity with anti-lipase antibodies was detected between cutinases produced when apple cutin was used as the sole carbon source. In vitro, lipase activity was inhibited by the antibody solution. In vivo, the addition of anti-lipase antibodies in spore suspensions of A. brassicicola delayed but did not prevent lesion formation on cauliflower leaves. However, the effect of the antibody was overcome when leaves were previously wiped with chloroform-soaked cotton wool to remove epicuticular waxes. In situ microscopic observations revealed that spore germination was not inhibited by anti-lipase antibodies. These results again suggest that A. brassicicola lipase could be involved in the first interactions with the plant cuticle.
Lipase appears as a novel enzyme associated in the early steps of plant infection. Athough its role in pathogenicity is not yet clear, it seems to differ according to plant-fungal pathogen system.