RESUMO
BACKGROUNDS: Cannabis sativa L. produces at least 120 cannabinoids. Although genetic variation is the main factor in cannabinoid production, the effects of short-term environmental stresses in the early flowering stage remains largely unknown. METHODS: To investigate the effects of short-term environmental stresses on the onset of cannabinoid production in young immature flowers, a hemp variety, Green-Thunder (5-8% CBD/mg of dry weight), was treated with mechanical damage, insect herbivory, extreme heat, or drought stress for 5-7 days during the first 2 weeks of flowering. Three hemp tissues, including flowers, leaves, and stems, were collected from hemp grown under these stress conditions at multiple time points during the first 2 weeks after transition to the short photoperiod and analyzed using high pressure liquid chromatography to quantify phytocannabinoids including cannabigerolic acid (CBGA), cannabigerol (CBG), cannabidiolic acid (CBDA), cannabidiol (CBD), Δ-tetrahydrocannabinolic acid (THCA), Δ-tetrahydrocannabinol (THC), and cannabinol (CBN). RESULTS: The 5 days of mechanical wounding did not affect the production of any of the cannabinoids during the initial stage of flowering. However, after 5 days of herbivore treatment, there was a significant difference in concentration between day 1 and day 6 of CBGA (control: 308 µg/g; treatment - 24 µg/g), CBG (control: 69 µg/g; treatment: 52 µg/g), and CBD (control: 755 µg/g; treatment: 194 µg/g) between the control and treatment plants. The 7 days of heat treatment at 45-50 oC significantly reduced the production of CBGA during this observed window (control: 206 µg/g; treatment: 182 µg/g) and CBG (control: 21 µg/g; treatment: - 112 µg/g). Notably, the largest change was observed after 7 days of drought stress, when plants showed a 40% greater accumulation of CBG (control: 336 µg/g; treatment: 622 µg/g), and a significant decrease (70-80%) in CBD (control: 1182 µg/g; treatment: 297 µg/g) and THC amounts (control: 3927 µg/g; treatment: 580 µg/g). CONCLUSIONS: Although this observation is limited in the early flowering stage, the common field stresses are adequate to induce changes in the cannabinoid profiles, particularly drought stress being the most impactful stress for hemp flower initiation with the altering the cannabinoid production by decreasing CBD and THC accumulation while increasing CBG by 40%.
RESUMO
Cannabis sativa, also known as marijuana or hemp, produces a non-psychoactive compound cannabidiol (CBD). To investigate the defensive role of CBD, a feeding preference assay was performed with tobacco hornworm Manduca sexta. The larvae clearly show feeding preference towards the Cannabis tissue containing low CBD over high CBD. While the larva avoided the high CBD diet, we investigated detrimental effects of CBD in the insects' diet. Contrasted to the performance on low CBD-infused artificial diet (AD), larvae reared on the high CBD diet suffer significantly reduced growth and increased mortality. Through testing different carriers, we found that the increase of EtOH in the diet is negatively correlated with insect development and behaviors. Notably, CBD treatment significantly improved ethanol-intoxicated larval survival rate by 40% and also improved diet searching activity, resulting in increased diet consumption. Electrophysiology results revealed that the CBD-treated ganglia had delayed but much larger response with electric stimuli in comparison to the larvae reared on AD only and EtOH-added diet. Our results show CBDs' defensive role against pest insects, which suggests its possible use as an insecticide. We also provide evidence that CBD alleviates alcohol-induced stress; consequently, improving the performance and viability of M. sexta larvae.
