Chemical Dissolution of Cellulose Membranes as a Prerequisite for Penetration from Appressoria of Colletotrichum lagenarium

Abstract

The relationship between protein synthesis during appressorial formation and the ability of appressoria to form penetration hyphae in nitrocellulose membranes was investigated for the plant pathogenic fungus Colletotrichum lagenarium. Cycloheximide treatment before appressorial pigmentation inhibited the formation both of penetration hyphae and of haloes, the latter resulting from the partial degradation of cellulose membranes; but treatment after appressorial pigmentation did not inhibit halo formation. When spores were transferred to 32 °C before appressoria became pigmented, both pigmentation and penetration were prevented. In the presence of 1 mm-3,4-dihydroxyphenylalanine (DOPA) at 32 °C, pigmentation was restored, but the formation of haloes and penetration hyphae was still prevented. Penetration into cellulose membranes pretreated with cellulase was observed from 20–30 % of appressoria which had been formed in the presence of cycloheximide at 24 °C or in the presence of DOPA at 32 °C. The results suggest that there are two phases of protein synthesis following spore germination, only the first of which is involved in halo formation.