2,3-DIHYDROXYBENZOIC ACID AND RELATED COMPOUNDS AS STIMULANTS OF GERMINATION OF CONIDIA OF COLLETOTRICHUM-MUSAE (BERK AND CURT) ARX

Anthranilic acid, a stimulant of germination in leachates of banana fruits, was converted in replacement culture experiments to 2,3-dihydroxybenzoic acid, catechol and pyrogallol by mycelium of Colletotrichum musae. 3-Hydroxyanthranilic acid was not an intermediate in the formation of 2,3-dihydroxybenzoic acid. Both catechol and pyrogallol were produced when mycelium was incubated with 2,3-dihydroxybenzoic acid, but incubation of mycelium with catechol did not yield pyrogallol, suggesting that both of these compounds were derived from 2,3-dihydroxybenzoic acid. The same catabolites were detected when conidia were incubated with anthranilic acid. Concentrations of 2,3-dihydroxybenzoic acid and catechol were maximal after 8 h incubation, when under the conditions of the experiment approximately one-third of the conidia had germinated, and declined thereafter. In bioassay experiments the concentration of 2,3-dihydroxybenzoic acid required to stimulate 50% germination was significantly less (2·5 × 10-5m) than that of anthranilic acid (3·7 × 10-4m) or catechol (1·3 x 10-3m). Pyrogallol was not effective in the assay. The possibility that the mode of action of these and other compounds involves their chelating properties is discussed. © 1979.