Simultaneous Boosting of Plant Growth and Immunity by <i>Bacillus</i> volatiles Through GLK‐Mediated Enhancement of Chloroplast Functions

Microbial volatile organic compounds (mVOCs) offer significant benefits to plants, such as promoting growth and activating immune responses, positioning them as promising tools for crop productivity. However, the mechanisms driving mVOCs-mediated plant growth promotion (PGP) and immunity remain unclear. Here, we demonstrated that VOCs produced by the rapeseed (Brassica napus)-derived endophyte Bacillus velezensis CanL-30 (BvVOCs) simultaneously stimulate PGP and immunity in both Arabidopsis thaliana and rapeseed under controlled and field conditions. Gas chromatography-mass spectrometry analysis revealed that 2-heptanone and 2-nonanone in BvVOCs exhibit plant-growth-promoting activity, whereas decane and undecane possess disease resistance-inducing activity in plants. Using metabolomics and transcriptomics, along with genetic and chemical methodologies, we reveal that BvVOCs enhance photosynthetic capacity to promote growth, while jasmonic acid-dependent signalling underpins immunity activation. Furthermore, light intensity significantly influenced BvVOCs effects on PGP and immunity. Crucially, BvVOCs upregulate expression of the GOLDEN2-LIKE (GLK) transcription factors GLK1 and GLK2, and BvVOCs-driven PGP and immunity were lost in glk1glk2 double mutant plants. These findings clarify the molecular basis of Bacillus-based VOCs in boosting growth and disease resistance, underscoring their potential for sustainable pest management in agriculture.