The endophytic fungal complex of Catharanthus roseus (L.) G. Don

Catharanthus roseus (L.) is well known for its production of several anticancerous vinca alkaloids such as vincristine, vindesine, vinorelbine, vinblastin, and the recently discovered vinflunine. This plant is a host to a plethora of endophytic fungi. A total 183 endophytic fungi representing 13 fungal taxa were isolated from leaf, stem and root tissues of C. roseus from two sites representing two different ecosystems in North India. Interestingly, with two exceptions (one coelomycete and one ascomycete), all of the isolates were Hyphomycetes. Root tissues were heavily colonized by genera such as Alternaria, Cladosporium and Aspergillus. However, leaf tissues showed a greater diversity of endophytes and Drechslera, Curvularia, Bipolaris, Alternaria and Aspergillus spp. were the dominant fungi isolated. Interestingly, a fungus producing no fruiting structures was the most prevalent, isolated from C. roseus. On the basis of its partial ITS-5.8 S rDNA sequences, it was identified as Chaetomium globossum, with 99% sequence similarity (537/540). The species richness as well as frequency of colonization of endophytic fungi were pronounced in the root tissues at both sites (Loc 1, 38.6%; Loc 2, 33.7%). This study suggests that endophytes are both host- and tissue-specific. It also confirms that despite ecological variations, there were little differences in the species richness of fungal endophytes recovered from plants in the two different ecological sites.