Identificação de Fusarium spp. associadas à mancha marrom da palma forrageira miúda no nordeste do Brasil

Abstract

The small forage palm (Nopalea cochenillifera) is a crop of great importance for many countries. In Brazil, it is more widely cultivated in the Northeast region, with greater exploitation in the states of Bahia, Paraíba, Pernambuco, Sergipe, Alagoas, Rio Grande do Norte and Ceará, where it is mainly used as a food source for animals, providing nutrients and supplying their needs water resources. With the expansion of this culture, many diseases began to be observed, such as the brown spot that is considered the most important for culture. The genus Fusarium is one of the causative agents, but to date no species of the genus has been identified associated with the disease. For the correct identification of the species belonging to this genus it is necessary to use molecular techniques, due to the high rate of genetic variability. In view of the above, this study aimed to identify and characterize Fusarium species associated with the brown spot of the small forage palm in Northeast Brazil. For this, 26 isolates from the states of Alagoas and Pernambuco were obtained from the Collection of Culture of Phytopathogens of UFAL (COUFAL). For the correct taxonomic positioning of the isolates, morphobacterial and molecular analyzes (phylogenies based on partial nucleotide sequences of the EF1-α and RPB2 genes) were performed. According to morphological and molecular analyzes, six species of Fusarium belonging to four different complexes were identified: F. proliferatum, F. verticillioides, F. pseudocircinatum (C. fujikuroi); F. oxysporum (C. oxysporum); Fusarium sp. (C. incarnatum-equiseti) and F. lunatum (C. dimerum). The species F. verticillioides and F. lunatum were the most aggressive. This is the first report of these species associated with the brown spot on the small forage palm in the world.