Plants growth and production of secondary metabolites can be influenced by external factors, both abiotic (non-living) and biotic (living). Even if technological advancements have been made for cannabis breeding and many different varieties with different phenotypic traits have been cultivated, there is still lack of systematic studies about the effect of soil microbiota on cannabis secondary metabolites, which plays an important role in plant survival in its environment. Microbiota refers to the collection of microorganisms that reside within a given habitat.
Within secondary metabolites, cannabinoids are the main compounds responsible for the vast majority of cannabis medicinal activity, with cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) generally present in higher concentrations. For medical and pharmaceutical purposes, it is important that the ratio of CBD and THC remains stable for the same cannabis chemovar.
Cannabinoid content in plants can variate greatly depending on abiotic factors such as light, temperature, humidity, water availability and nutrients. [1] Nevertheless, it’s not only climatic conditions that influence cannabinoid biosynthesis but also cultivation practices, plant genotypes, and the plethora of microorganisms present in the soil.
Biostimulant substances, plant growth promoting rhizobacteria (PGPR), and mycorrhizal fungi have been employed by growers in the attempt to maximize the yield of cannabis plants and stabilize their chemical composition. However, scientific research related to manipulation of soil microorganisms’ taxonomic composition and cannabis plant-microbiota interactions have been addressed mainly on well-known PGPR genera such as Pseudomonas and Bacillus, investigating their beneficial functions, pathogen tolerance, secondary metabolites biosynthesis, and stress response.
The microbiota is genotype-specific and using high-throughput sequencing technology and bioinformatics, it is possible to study the microbial genera present in a given natural sample that have been recruited by the plant variety to explore the mutual beneficial symbiotic effects. The importance of studying the natural microbial composition of microbe-rich organic soil is linked to the possibility of having a worthless or antagonistic effect if an unspecified microbiota is introduced into the native soil microorganisms’ community.
The study of the core microbiota community of bacteria and fungi grown around the roots of a specific plant variety can enhance plant health and growth, below-ground nutrient cycling, and the biosynthetic production of pharmaceutically- and agronomically-relevant chemical compounds. Through metagenomics and metabolomics, it is possible to identify the core microbiota of each cannabis chemovar and the influence of microorganisms on secondary metabolites production. Studies to reveal the microbial communities and their interactions with cannabis plants are crucial to develop new bioinoculants to improve cannabis overall quality and stabilize cannabinoid biosynthesis in a sustainable way.
References:
[1] Ahmed B, Hijri M. Potential impacts of soil microbiota manipulation on secondary metabolites production in cannabis. J Cannabis Res. 2021;3(1):25. [journal impact factor = 5.800; times cited = 4]image: https://www.pexels.com/it-it/foto/natura-secco-trama-astratto-6044629/
