Identificação de colletotrichum spp. e neopestalotiopsis spp., associadas a doenças foliares do cacaueiro

Abstract

The cacao (Theobroma cacao L.) is a tree plant, originated in South America, probably in the Amazon and Orinoco river basins. In the genus Theobroma, cocoa is one of the few species used for economic purposes, with potential for the production of a multitude of by-products, among them cocoa butter and chocolate. The culture is of great importance to more than 50 countries, among which Brazil represents the sixth largest production, with the bigger part concentrated in the state of Bahia. Although a crop of great importance, cocoa productivity has been limited by the occurrence of various phytosanitary problems. Among the pathogens that affect the crop, fungi of the genus Colletotrichum and Pestalotiopsis can pose a threat if dispersed under favorable conditions. Species of Colletototrichum have already been reported causing anthracnose in cacao in all crop producing countries. In this culture, Pestalotiopsis spp. are reported mainly as endophytic, having been observed causing leaf spot in Cuba. For a long time, species of Colletotrichum and Pestalotiopsis were characterized only by morpho-cultural characters, causing several overlaps and synonymy. Thus, the objectives of this study were to characterize isolates of Colletotrichum and Neopestalotiopsis associated with leaf diseases in cacao. For that, cocoa leaves presenting symptoms were collected in the municipalities of Igrapiúna-BA, Boca da Mata-AL and Maceió-AL. In the laboratory, were done indirect isolation and getting monosporic cultures for later identification. the Colletotrichum species were characterized was made from molecular techniques using the genomic regions, GAPDH, TUB2, CHS, ACT and CAL, together with morphocultural characterization techniques. Within this genus, it was possible to identify the species, C. fructicola, C. siamense, C. theobromicola, C. aeschynomenes, C. tropicale, C. karstii, C. limetticola and C. gigasporum causing anthracnose in cacao leaves. This is first report of these species in Brazilian cacauicultura and the first report of C. aeschynomenes, C. karstii and C. limetticola, in the cacao culture. For Neopestalotiopsis were used ITS, β-tub and EF1-α sequence data, which allowed grouping of 5 isolates into two species: N. surinamensis and N. brasiliensis sp. nov. This is the first report of N. surinamensis in cacao culture and the first occurrence of this species in Brazil, whereas N. brasiliensis its about a new species belonging to the genus Neopestalotiopsis.

Keywords: Malvaceae. Anthracnose. Leaf spot. Bayesian Inference.