Bacterial microbiota dynamics of Cannabis sativa L. under biotic stress induced by Tetranychus urticae

The microbiota associated with Cannabis sativa L. plays a crucial role in plant growth and health, although the mechanisms by which it is modulated in response to different types of stress during cultivation remains under investigation. In this study, the bacterial microbiota of both rhizospheric and bulk soil associated with a therapeutic C. sativa variety was characterized across three stages of the cultivation cycle (early vegetative, late vegetative, and late flowering), comparing healthy plants and those under stress induced by Tetranychus urticae. In addition to microbial profiling, plant physiological parameters were assessed, along with the analysis of cannabinoid and terpene profiles in floral tissues. Analyses of alpha diversity, community structure, discriminant taxa (LEfSe), and functional predictions (PICRUSt2) were performed using 16 S rRNA gene sequencing data. The results revealed stress-associated shifts in the rhizospheric bacterial community, characterized by changes in the dominance of several genera across plant developmental stages, including a reduced representation of taxa commonly associated with plant growth promotion. Functional predictions further indicated that in control conditions the rhizosphere community exhibited higher metabolic activity, enriched in pathways related to replication, transcription and protein synthesis, whereas under stress, functions shifted toward resource recycling and metabolic flexibility. These findings suggest that biotic stress triggers a functional and structural reorganization of the soil bacterial microbiota, favoring more resilient yet less beneficial communities for plant development.This study provides novel evidence of the interaction between insect, plant, and microbiota, with both agronomic and biotechnological implications.