5 decades of terpenes research in the service of cannabis
In our research station at Israeli Agricultural Research Organization we made extensive work on plants aromatic compounds for the last 50 years. Our station delivers multidisciplinary approach, doing research in agricultural, biochemical, ecological, analytical and genetical subjects. This great experience enables us during these years to work on plant breeding, agro-techniques and physiology; growing for the fresh herbs market; study the factors affecting essential oil yield and composition; introduction, selection and breeding of wild plants from the Middle East as peculiar sources of essential oils and other secondary metabolites with biological activity. Some of the most common verities of Basil, Thyme, chives and other culinary herbs have been breed in our station.
So, when the research around medical cannabis began to emerge, and a multidisciplinary knowledge was needed to understand the biological processes of this plant and its assimilation as commercial growth, our research station was the best place to go forward.
To put this in context, we know for many years that plant contents of the volatile oil and its composition depend on the genotype, environmental conditions, developmental stage and breeding methods. One study has shown that by breed two different types of clary sage (Slavia sclarea), a Russian commercial type that is acclimated in Israel, with a high content of linalool and linalyl acetate, with an Israeli rare wild type habitat in the east Galilee, dominant with the terpenes – nerol, granyal, granyol and geranyl acetate, produced intermediate-type hybrids with a different terpene composition from their parents.
In other studies, with controlled growth conditions it was found that the volatile oil content depends on the level of radiation, temperature, and photoperiodic (light dark regime). We learned that in Salvias about seventy percent of the volatile oil is made at sepals, and most of the terpenes accumulation occurs after the petals ripening and dropout. We have shown that the relative composition of the volatiles varies with the development of the inflorescence. We found that the overall content of the terpenes increases as well as the relative contents of linalyl acetate.
The composition of the terpenes varies from older leaves to younger ones. Prof. Nativ Dudai and his colleagues have shown in two different works that the relative composition of terpenes is influenced by the location of the leaves on the stem. These studies focused on a hybrid strain of Common sage (Salvia officinalis) and Greek sage (Salvia fruticosa) and White micromeria (Micromeria fruticosa).
In another work done with Salvia sclarea, we showed that the level of mono terpenes such as linalool decreases with the age of flowering to a level of zero. Compared to them, the level of the diterpene sclareol remain significant in aging inflorescence. Sclareol is from the same chemical family of β-caryophyllene, highly abounded diterpene in cannabis.
This data gives us lots of advantages when producing new varieties of cannabis with desired cannabinoids and terpenes profile for different medical propose. We can easily implement our knowledge to protocols for better yield and quality.