Glucanolytic Rhizobacteria Produce Antifungal Metabolites and Elicit ROS Scavenging System in Sugarcane

Plant growth-promoting bacteria have broad range usage in agriculture as an alternative to chemical fertilizers and fungicides. Their survival and persistency in the plant vicinity depend upon the production of secondary metabolites. In present study, 45 bacteria were isolated from the rhizosphere and endosphere of different sugarcane varieties growing at the different farmer’s fields of Punjab, Pakistan. Out of 45 isolates, 3 were able to produce hydrolytic enzyme glucanase. The glucanase-producing ability of bacterial strains was variable with solubilization zone 5.5–13.8 mm of different substrates. Dinitrosalicylic acid (DNS) quantification depicted the production of glucanase (0.1–0.3 U/mL of culture filtrate) by the antagonistic strains. All the glucanase-producing bacteria significantly inhibited the economically important pathogens of sugarcane, i.e., Fusarium moniliforme (45–56%) and Colletotrichum falcatum (52–63%), and pathogens of other crops, i.e., Fusarium oxysporum (58–63%), Rhizoctonia solani (42–53%) and Macrophomina phaseolina (53–61%). The glucanase-producing bacteria significantly induced the activities of enzymes involved in ROS scavenging, viz. SOD, POD, CAT and PPO by 1.4–2.0-fold. The glucanase-producing bacteria MAZ-3SR was identified as Bacillus amyloliquefaciens , while MAZ-10SR and MAZ-29SR were identified as Bacillus subtilis by 16S rDNA sequence comparision. These glucanolytic bacteria could be effectively used in sugarcane disease management and provide an effective way of enumerating the bioantagonists from sugarcane rhizosphere.