Farnesol inhibits growth and development of <i>Ustilaginoidea virens</i>

Abstract Rice false smut disease, caused by the pathogen Ustilaginoidea viren s, specifically infects rice panicles. This disease leads to significant quantitative and qualitative losses in the rice industry. Farnesol, a naturally occurring terpene produced by plants, exhibits diverse toxic potentials against various fungi. Here, we investigate the in vitro inhibitory effects of farnesol on U. virens isolates. The results indicate that farnesol could retard conidial germination at a concentration of 20 μM and inhibit germination at concentrations exceeding 40 μM. Additionally, farnesol demonstrates inhibitory activity on the mycelial growth and adhesion of U. virens in a dose‐dependent manner. RNA‐seq data show that farnesol treatment results in the misregulation of a subset of genes involved in oxidoreductase activity, membrane components, molecular function, and transcription factor activity. Furthermore, farnesol induces a significant accumulation of reactive oxygen species, including superoxide anions, which may subsequently trigger cell death. Notably, farnesol also induces the expression of genes encoding GTPase activity of UvRas1 and UvRas2 , leading to the expression of genes encoding adenylate cyclase, which promotes the synthesis of intracellular cAMP, and activates genes involved in MAPK pathway. Collectively, this study proposes a mechanism by which farnesol affects the growth and development of U. virens .