INFECTION PROCESSES OF <em>COLLETOTRICHUM</em> ISOLATES FROM FOREST TREES IN THE TROPICS

Abstract

Several isolates of Colletotrichum obtained from forest trees were found to have wide host ranges. They infected both legumes and other forest trees. All the isolates examined penetrated the cuticle of inoculated plants through production of germ-tubes that arose from appressoria. However, some isolates also penetrated the host through open stomata, sometimes after the production of appressoria but on most occasions appressoria were not formed. Two types of infection process were observed. In the first, shown by isolates 634, 640 and 659, individual infected cells were dead upon infection but growth through adjacent cells and tissues caused no extensive degradation of cell walls. In the second process, shown by isolate 689, infected cells were also killed soon after infection, but as the pathogen began to grow through the tissues, cell walls in advance of the hyphae were extensively degraded. Typically, in both strategies the host cuticle remained unaltered even after complete dissolution of underlying epidermal cell walls