Biocontrol potential and plant-growth-promoting effects of Bacillus amyloliquefaciens MBI 600 against Fusarium oxysporum f. sp. radicis-lycopersici on tomato

Fusarium oxysporum f. sp. radicis-lycopersici (Forl) is the causal agent of fusarium crown and root rot of tomato, a devastating disease causing extensive yield losses. Plant-growth-promoting rhizobacteria (PGPR) can be potential agents for biological control of plant pathogens. Among them, strains of Bacillus subtilis are well known for their ability to control foliar and soil-borne pathogens. In this study, we investigated the effects of a new Bacillus amyloliquefaciens strain (ΜΒΙ 600) on the growth of tomato and the control of Forl under both in-vitro and in-planta conditions. In the in-vitro experiments, the biological control agent reduced mycelial growth of Forl by 24.1%, while it also showed a weak antagonistic activity (antibiosis-inhibition zone <10mm). Dual applications of B. amyloliquefaciens MBI 600 on tomato seeds before sowing and on young seedlings before transplanting induced significant (P<0.05) increases in shoot height and root length. Similarly, dual applications of B. amyloliquefaciens MBI 600 resulted in significant (P<0.05) reductions in both disease severity and disease index (%), by 75% compared with untreated control plants.