Caracterização de Fusarium oxysporum f. sp. cubense e controle alternativo do mal do Panamá.

Abstract

Brazil is the fifth largest producer of banana (Musa spp.), concentrating its great production in the northeast region of the country. Among the diseases that affect this crop, Panama caused by Fusarium oxysporum f. sp. cubense (Foc) stands out. In order to contain this disease, some sources of resistance have been applied. However, some alternative strategies, as natural products, must be verified to avoid selection pressure, which can preclude genetic control. Thus, this research aimed to characterize genetically and morphologically Foc isolated from states of Brazilian northeast region (Paraiba, Pernambuco, Rio Grande do Norte, Bahia and Alagoas) and evaluate an alternative method to control the disease using aqueous garlic extract (C1 = 0; C2 = 2.5; C3 = 5; C4 = 7.5 and C5 = 10%). Foc isolated in vitro were morphologically characterized by analyzing the color of both sides of colonies, mycelial diameter, mycelial growth speed index and sporulation. Phylogenetic analysis generated a tree for TEF and IGS genes using Neighbor-Joining (NJ) analysis with 21 sequences obtained from GenBank, by aligning eight Fusarium spp. The results obtained in the phylogenetic analysis identified four groups of F. oxysporum with distinct phylogenetic lines, with CMM 0807 grouped with F. oxysporum f. sp. cubense specie with 99% of bootstrap support. In in vitro experiments, the area under the disease progress curve (AUDPC) was analyzed using a note scale with cultivar Pacovan seedlings. The inoculation was made in the rhizome through its immersion and the pathogen suspension adjusted to 106

conidia mL-1

. The growing concentration of garlic extract significantly reduced mycelial F. oxysporum f. sp. cubense growth and the Panama disease.