Bacillus subtilis strain F62 against Fusarium oxysporum and promoting plant growth in the grapevine rootstock SO4.

Fusarium wilt is a fungal disease that causes economic losses to viticulture, whose causal agent Fusarium sp. has been associated with the decline and death of young vines. This work had the objective of evaluating the antagonistic potential of Bacillus subtilis F62 against F. oxysporum in vitro and in vivo, as well as the growth promotion in the grapevine rootstock SO4. In the in vitro assay, the antagonism by diffusible and volatile compounds of B. subtilis F62 and the inhibition of conidial germination of four Fusarium sp. isolates were evaluated. In the in vivo assay, cuttings and micropropagated plants of SO4 were submitted to four treatments: control, Bac (B. subtilis F62 inoculation), Fus (F. oxysporum inoculation) and Bac + Fus. We observed that inhibition of mycelial growth occurred mainly by diffusible compounds. B. subtilis F62 had a positive effect on the growth promotion and in the biocontrol of F. oxysporum, reducing the frequency of pathogen re-isolation in cuttings (18.1%) and in micropropagated plants (52.4%). These results demonstrate the ability of B. subtilis F62 to upgrade plant development and assist in controlling of the Fusarium wilt in the grapevine rootstock SO4.