ABSTRACT The overuse of synthetic pesticides has raised concerns about environmental and health risks, prompting interest in eco‐friendly alternatives. In this study, we evaluated the biocontrol efficacy of Bacillus subtilis mutant 320 (BSM320) cultured in an extract of composted Lentinula edodes spent mushroom substrate (LeCSMS), termed LeG320. LeG320 showed strong antifungal activity against major soil‐borne pathogens and effectively suppressed powdery mildew ( Sphaerotheca fusca ) in cucumber. It outperformed uncultured LeCSMS and LB‐grown BSM320 in both in vitro and in planta assays. Gene expression analysis indicated that LeG320 activated salicylic acid and jasmonic acid signalling pathways by upregulating PR1 , PR3 , Lox1 , Lox23 , LecRK6.1 and WRKY20 . Additionally, LeG320 enhanced seedling growth without affecting germination. These findings suggest LeG320 is a growth‐compatible, disease‐suppressive agent that supports sustainable agriculture through the valorization of mushroom waste.
Kim et al. (Sun,) studied this question.