Biological potential of Bacillus subtilis V26 for the control of Fusarium wilt and tuber dry rot on potato caused by Fusarium species and the promotion of plant growth

Abstract

Fusariosis of potato caused by the Fusarium spp. is one of the most destructive soil-borne diseases throughout the world. This study aimed to investigate the growth-promoting and biocontrol potential of Bacillus subtilis V26 against the causal agents of Fusarium wilt and Fusarium dry rot diseases on potato. Characterization of plant growth promoting traits was assessed in vitro. The strain V26 was able to fix nitrogen, to produce indole-3-acetic acid, siderophore, hydrolytic enzymes and to solubilize inorganic phosphate. The PCR detection of ituC, fenA, fenB, fenD, srfAA, bmy, mnlA, bae and bac genes coding for iturin, fengycin, surfactin, bacyllomicin, macrolactin, bacillaene and bacilysin indicated a potential for lipopeptides, polyketides and dipeptide production, respectively by the strain V26. In vitro antagonism test showed that this strain can effectively inhibit F. oxysporum, F. solani, F. gramineaurum and F. sambucinum growth by 54.7 to 85.3% as compared to the untreated control, in a dual method. Antifungal activity was demonstrated against the dry rot potato tubers caused by Fusarium species. The preventive application of V26 significantly decreased the Fusarium dry rot disease severity at 42.8–63.8%, after 21 days of fungi inoculation. After 15 days of seedling emergence, plants were irrigated with V26 spore suspensions (108 CFU/mL), prior infection by Fusaium species, Fusarium wilt severity were reduced by 54.8 to 60.8% and plant growth parameters were improved, compared to the untreated ones, 60 days post-inoculation. Therefore, this strain could be a promising candidate to be developed as commercial biofertilizer and biocontrol formulation in sustainable agriculture.