Microbial secondary metabolites for modulating plant biotic stress resistance: Bridging the lab-field gap

• Biotic stress significantly reduces crop productivity. • Microbes have been demonstrated to enhance plant tolerance to biotic stress. • Microbial inoculants show promise in lab studies, but their efficacy remains inconsistent in the field. • Research is needed to bridge the gap between lab and field testing. • Combining microbial extracts and inoculants could enhance treatment effectiveness. Biotic stress, including pest attacks, plant diseases caused by pathogenic microbes, and competition from weeds, significantly limit the optimal crop productivity. The use of beneficial microorganisms has been shown to enhance plants' tolerance to these stressors. Numerous laboratory studies have investigated the effectiveness of microbial secondary metabolites as biological control agents against pests, diseases, and weeds. However, a critical challenge remains in determining whether microorganisms applied in the field will produce the same secondary metabolites as those observed in the laboratory, and whether their effectiveness will be comparable, better, or worse. This review examines the comparative effectiveness of microbial agents in producing secondary metabolites that enhance plant tolerance to biotic stress, considering both laboratory and field settings.