Plant growth-promoting endophytic bacteria versus pathogenic infections: an example ofBacillus amyloliquefaciensRWL-1 andFusarium oxysporumf. sp.lycopersiciin tomato

Abstract

Fungal pathogenic attacks are one of the major threats to the growth and productivity of crop plants. Currently, instead of synthetic fungicides, the use of plant growth-promoting bacterial endophytes has been considered intriguingly eco-friendly in nature. Here, we aimed to investigate the in vitro and in vivo antagonistic approach by using seed-borne endophyticBacillus amyloliquefaciensRWL-1 against pathogenicFusarium oxysporumf. sp.lycopersici. The results revealed significant suppression of pathogenic fungal growth byBacillus amyloliquefaciensin vitro. Further to this, we inoculated tomato plants with RWL-1 andF. oxysporumf. sp.lycopersiciin the root zone. The results showed that the growth attributes and biomass were significantly enhanced by endophytic-inoculation during disease incidence as compared toF. oxysporumf. sp.lycopersiciinfected plants. Under pathogenic infection, the RWL-1-applied plants showed increased amino acid metabolism of cell wall related (e.g., aspartic acid, glutamic acid, serine (Ser), and proline (Pro)) as compared to diseased plants. In case of endogenous phytohormones, significantly lower amount of jasmonic acid (JA) and higher amount of salicylic acid (SA) contents was recorded in RWL-1-treated diseased plants. The phytohormones regulation in disease incidences might be correlated with the ability of RWL-1 to produce organic acids (e.g., succinic acid, acetic acid, propionic acid, and citric acid) during the inoculation and infection of tomato plants. The current findings suggest that RWL-1 inoculation promoted and rescued plant growth by modulating defense hormones and regulating amino acids. This suggests that bacterial endophytes could be used for possible control ofF. oxysporumf. sp.lycopersiciin an eco-friendly way.