Resumo

VARGAS DIAZ, Arely A. et al. Evaluation of Native Yucatecan Plant Extracts Against Alternaria chrysanthemi and Antifungal Activity Spectrum of Acalypha gaumeri. Rev. mex. fitopatol [online]. 2014, vol.32, n.1, pp.01-11. ISSN 2007-8080.

A total of 24 extracts (aqueous and ethanolic) from nine plant species were evaluated against Alternaria chrysanthemi, the causal agent of leaf spot of chrysanthemum. The highest antifungal activity was shown by ethanolic and aqueous extracts of Acalypha gaumeri root (Growth inhibition, GI = 75 and 69%, respectively), and by the aqueous extracts of Bonellia flammea stem and leaf (GI = 63 and 50%, respectively). These active extracts were subsequently assessed by agar dilution assay, where ethanolic extract (EE) of A. gaumeri root caused the highest inhibition of mycelial growth and sporulation, with a median Inhibitory Concentration (IC₅₀) of 0.53 mg/mL against A. chrysanthemi GI. This extract was partitioned and the highest activity was observed in the medium polarity fraction (ACR-1E), where an IC₅₀ of 0.13 mg/mL was recorded. This fraction completely inhibited A. chrysanthemi infection in chrysanthemum leaf, at concentrations of 85μg/cm². Also, A. gaumeri extract was able to inhibit the fungal strains Alternaria sp. (ITC02), Colletotrichum capsici, Colletotrichum gloeosporioides, Corynespora cassiicola, Curvularia sp. (ITC10), and Helminthosporium sp. (ITC04). The EE of A. gaumeri root may be a potential source of botanical fungicide to control phytopathogens.

Palavras-chave : Acalypha gaumeri; Alternaria chrysanthemi; antifungal assays; microdilution assay; natural fungicides; plant extracts.