Soil microbiome dynamics of Cannabis sativa L. under biotic stress induced by Tetranychus urticae

The microbiome 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 microbiome 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 16S rRNA gene sequencing data.The results revealed a decrease in plant growth-promoting genera such as Pseudomonas and members of the family Oxalobacteraceae in stressed plants, and a relative increase in members of the Gemmatimonadaceae family and SBR1031 genus ( Chloroflexota ), particularly during the late flowering stage. 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 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.