First report of Colletotrichum capsici causing anthracnose in Jatropha curcas in Yucatan, Mexico

Colletotrichum capsici (Syd.) E. J. Butler & Bisby is an important pathogen with a worldwide distribution and is involved in diseases of economically important hosts such as pepper (Than et al., 2008) and papaya (Tapia-Tussell et al., 2008). In August 2008, symptoms of foliar necrosis were observed in fields of physic nut (Jatropha curcas) located in the Yucatan Peninsula in Mexico. The observed symptoms were crown canker and apical death of seedlings, and leaf blight causing 70% defoliation (Fig. 1). Physic nut is a native crop of Mexico and Central America that has gained a significant worldwide economic importance as a biofuel and this disease is affecting about 25% of the production in Yucatan.

Fungal isolates with morphological characteristics similar to those of C. capsici were collected from diseased plants and seedlings, cultured on Richard's V8 medium (RV8) and incubated at 28°C. After seven days, black sporodochia with conidia and setae were formed on the surface of RV8 plates. The isolates were evaluated for their pathogenicity on J. curcas leaves. Three plants per isolate were inoculated by spraying the leaves with a conidial suspension (1.0 x10conidia/ml). Lesions typical of C. capsici infection were observed in all three plants 12 days post inoculation. No symptoms were observed on non-inoculated plants. Koch´s postulates were confirmed by re-isolation of the fungus from inoculated plants. To confirm the identity of the isolates, the internal transcribed spacer (ITS) regions were amplified with the ITS1/ITS4 universal primers (White et al., 1990) and deposited in GenBank (Accession Nos. HM450126 and HM562708). Both sequences were 99% identical to sequences of C. capsici isolates (HM114276 and HM231266). In order to confirm the results, RFLP-PCR analyses were performed using restriction enzymes AluI and HaeIII. The restriction profiles generated with the reference strains C. capsici ATCC 48574 and C. capsici HM450132 were identical to all C. capsici isolates from J. curcas and those obtained by re-isolation of incoculated plants (Fig. 2). To our knowledge, this is the first report of Colletotrichum capsici affecting Jatropha curcas fields in Mexico.