Unveiling the plant growth promotion and the antifungal potency against maize pathogen Fusarium verticillioides by desert-derived endophytes Bacillus subtilis RA15 and Bacillus tequilensis FC6 and their lipopeptides

Abstract

This study explores the potential of two novel bacteria Bacillus subtilis RA15 and Bacillus tequilensis FC6 screened in vivo for their ability to protect maize plants against Fusarium verticillioides and to enhance plant growth. Both bacterial strains demonstrated significant growth inhibition of F. verticillioides in vitro, as evidenced by inhibition zones and mycelial morphology changes. Additionally, cyclic lipopeptides, including iturin and fengycin, known for their antimicrobial properties, were detected in purified extracts from cell-free supernatants of strain cultures and from treated maize plants. Interestingly, in vivo experiments on maize seeds using lipopeptide extracts at the lower concentration tested (10 mg/L), especially from FC6 not only provided significant protection against the disease comparable to that of the chemical control (55 % and 51 % for strain FC6 and the control, respectively), but also significantly improved maize shoot and root lengths (660 % and 191 %) and weights (371 % and 205 %, respectively). These findings suggest a direct relationship between the produced lipopeptides and the biocontrol and growth promotion capacity of RA15 and FC6 strains. Overall, B. subtilis RA15, B. tequilensis FC6, and their antifungal compounds hold great promise as biocontrol agents for managing Fusarium ear and root rot disease.