Harnessing the multifunctional bioagent Streptomyces sp. SP5 for Fusarium wilt suppression, metabolite-mediated antioxidant activity, and plant growth promotion

Streptomyces species are valuable allies in sustainable agriculture due to their ability to produce a diverse range of bioactive metabolites. This current study aimed to investigate the antioxidant, plant growth-promoting, and biocontrol potential of Streptomyces sp. SP5 against Fusarium wilt in Capsicum annuum. SP5 acetone precipitates and Et₂O extract exhibited strong dose-dependent antioxidant activity in multiple radical scavenging assays. In vitro seed bioassays with Vigna radiata revealed that SP5-derived indole-3-acetic acid markedly enhanced germination and early seedling growth, which was further supported by improved vegetative growth in pot experiments with Solanum lycopersicum. Furthermore, SP5 displayed remarkable biocontrol efficacy against Fusarium solani in Capsicum annuum. Under in vivo conditions, SP5 significantly reducing wilt incidence while simultaneously improving plant vigor and agronomic traits. SP5 treatments also enhanced photosynthetic pigment levels and stimulated the accumulation of phenolic and flavonoid compounds, indicating activation of plant defense responses under both stressed and non-stressed conditions. Overall, Streptomyces sp. SP5 functions as a multifunctional strain with combined antioxidant, growth-promoting, and biocontrol properties, highlighting its potential as an eco-friendly strategy for improving crop productivity and disease management.