Induction of Resistance Against Sclerotinia sclerotiorum in Rapeseed by β-Ocimene Through Enhanced Production of Coniferyl Aldehyde

Rapeseed (<i>Brassica napus</i>) is an essential oil resource, but its yield can be significantly compromised by <i>Sclerotinia sclerotiorum</i> (<i>S. sclerotiorum</i>) infection. Due to the absence of rapeseed strains that are highly or completely immune to <i>S. sclerotiorum</i>, enhancing rapeseed resistance through genetic approaches is challenging. In this study, we developed a novel method to enhance rapeseed resistance to <i>S. sclerotiorum</i> using β-ocimene. Our results demonstrated that β-ocimene treatment significantly strengthened the defense capabilities of rapeseed. β-ocimene treatment can simultaneously activate multiple defense-related signaling pathways, including jasmonic acid signaling, salicylic acid signaling, and MAPK signaling, in rapeseed, while also inducing the accumulation of secondary metabolites coniferyl aldehyde-a key secondary metabolite in the phenylpropanoid pathway critical for plant defense responses. Furthermore, applying coniferyl aldehyde to the leaves of rapeseed can remarkably enhance its resistance to sclerotinia disease. Collectively, these findings confirm that β-ocimene activates the defense system of rapeseed, elevates the content of coniferyl aldehyde, and thereby enables rapeseed to effectively combat sclerotinia disease. The metabolomics data are available via MetaboLights under the identifier MTBLS12510. In conclusion, this study not only uncovers the mechanism by which β-ocimene induces rapeseed resistance to sclerotinia disease but also presents a novel approach for its prevention and control.