Botrytis cinerea infection modulates trichome development and secondary metabolite biosynthesis in Cannabis sativa

Botrytis cinerea , the causal agent of gray mold or bud rot, is one of the most devastating necrotrophic fungal pathogens of Cannabis sativa L.. Its impact on trichome morphology and secondary metabolism is not well studied. The research aimed to characterize the B. cinerea infecting C. sativa in India and to determine the optimal temperature and humidity for sporulation, as well as its effect on plant trichome morphology and cannabinoid and terpene metabolic profiles. The pathogen was identified using both morphological and molecular methods using ITS and GAPDH. There was the most conidial production at 20°C and 94% relative humidity with a strong correlation of r = 0.87, P < 0.001. Scanning electron microscopy depicted the pathogen effect on the internal tissue parts, distinguishing prolific colonization and deformation of glandular capitate trichomes. GC-FID/MS and HPLC indicated important biochemical alterations in infected plants. Notably, infected plants exhibited a significant decrease in cannabidiol (CBD) levels (from 1.870% to 0.163%) and myrcene (from 5.788% to 1.206%), and, conversely, an increase in tetrahydrocannabinol (THC) (from 1.037% to 2.253%). Principal component analysis demonstrated the distant differences between infected and non-infected samples, indicating that the pathogen induces metabolic reprogramming. This study, the first report of B. cinerea on C. sativa in India, reported the pathogen adverse impact on trichome development and secondary metabolite profiling, which ultimately compromises the pharmaceutical quality of cannabis. The findings emphasize the need for integrated disease management and the development of resistant cultivars for sustainable medicinal cannabis production.