Histopathology of the infection process of Colletotrichum truncatum in papaya and pea leaves

Abstract

Colletotrichum truncatum is a pathogenic fungus causing anthracnose in several hosts; the infection process of this pathogen in papaya leaf as well as studies of the same strain of C. truncatum in different hosts is unknown. The aim of this study was to describe the infection process of a Colletotrichum truncatum strain by histological techniques in papaya and pea leaves. In both hosts, direct penetration occurred through appressoria around 20 h after inoculation (hai). In papaya, intercellular hyphae grew at 24-60 hai; the necrotrophic colonization began at 60 hai; intracellular hyphae grew in mesophyll cells causing extensive cellular degradation; in contrast, in pea primary infection hyphae began at 36 hai, secondary infection hyphae (necrotrophic state) began at 72 hai. In both hosts, the acervuli were observed at 96 hai, which was associated with typical anthracnose lesions. C. truncatum behaved as intramural subcuticular pathogen in papaya and as intracellular pathogen in pea; so that, the infection strategy is dependent on the host.