Eventos do processo de infecção de colletotrichum gloeosporioides inoculados em folhas de coffea arabica L.

Abstract

The present study was carried out with the objective to provide information on the pre-penetration, penetration and colonization events of isolates of Colletotrichum gloeosporioides from mango and coffee, when inoculated in coffee leaves. The cultivar Catucaí Vermelho was used in all experiments. Coffee leaves were selected, standardized and washed in sterile water. After that, circular areas of 0.5 cm in diameter were marked on the undersurface of the leaves. In the center of each circular area, 20 µL of spore suspension was deposited. One isolate from mango and two from coffee presenting blister spot were used in all trials. The time course of the experiments was 3, 6, 8, 12, 24, 36, 48, 72, 96, 144 and 240 hours after inoculation (h.a.i.). All materials were analyzed in scanning electron microscopy. The conidia of all isolates adhered more frequently on the plant tissue depressions and guard-cells forming septum before germination. The most common penetration via was the direct, although some penetration through stomata also occurred. Isolates obtained from blister spot symptoms germinated on coffee leaves after 6 to 8 h.a.i., producing appressoria after 12 h.a.i., and acervuli after 96 to 144 h.a.i. The isolate from mango germinated on the coffee leaves after 6 to 8 h.a.i. and formed appressoria after 8 to 12 h.a.i., but was unable to form acervuli, bearing conidia directly from conidiogenous hypha on the mycelium.