Seleção de bactérias endofíticas de bananeira para o biocontrole da murcha de fusarium

Abstract

The fusarium wilt caused by soil-dwelling phytopathogen Fusarium oxysporum f. sp. cubense (foc) is one of the main diseases affecting banana crop. In banana plants from susceptible materials the available control measures are inefficient. The adoption of new technologies in agriculture is essential, and in this context, biological disease control is an excellent alternative. Thus, two trials were established with the objective of evaluating in vitro (1) and in a greenhouse (2) the action of 40 endophytic isolates on foc and plant growth of “Prata Catarina” banana. The experiments were established in a completely randomized design with 41 treatments and three replications and 42 treatments and five replications for the first and second trials, respectively. In the in vitro assay (1) forty endophytic isolates of the genera Bacillus, Klebsiella, Paenibacillus, Stenotrophomonas, Lysinibacillus, Sporolactobacillus were challenged with foc. The experiments were in pairing system or in the presence of volatile compounds. Endophytic isolates significantly reduced foc mycelial growth in both tests, but less pronounced in the presence of volatiles. The maximum reductions in colony area in the pairing reached 76.40% and 54.62% in the presence of volatiles, respectively. Approximately 87.5% of bacterial isolates negatively affected sporulation. The principal component analysis indicated that the spore germination variable in the presence of bacterial cells better explains the data variation. The second experiment, in a greenhouse, was a randomized block design with 42 treatments (40 endophytic isolates and two controls (foc and control) and 5 replications. The incidence and severity of foc as well as the promotion of plant growth were evaluated. All endophytic isolates used reduced the severity of fusarium wilt, these values reached 91.33%. Regardless of the presence or absence of foc, endophytic isolates were able to promote increment for all morphological characteristics evaluated. Root dry matter increment values reached 1015% for the EB37 isolate.