The response of terpenoids to exogenous gibberellic acid in Cannabis sativa L. at vegetative stage

Abstract

In this study the influence of gibberellic acid (GA 3 ) on plastidic and cytosolic terpenoids and on two key enzymes, 1-deoxy-D-xylulose-5-phosphate synthase (DXS) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), for terpenoid biosynthesis was compared in vegetative cannabis plants. Treatment with GA 3 resulted in a decrease of DXS activity in comparison with the control plants. The amount of chlorophylls a, b and total carotenoids declined when plants treated by GA 3 in a concentration dependent manner. The a-tocopherol content of cannabis plants decreased in 50 lM GA 3 treatment and increased in 100 lM GA 3 treatment. Exogenous GA 3 caused an increase in HMGR activity. Concomitant with this result, the amount of squalene and phytosterols increased with GA 3 treatment. The amount of THC and CBD did not change at 50 lM GA 3 treatment, but applying of 100 lM GA 3 increased THC and CBD content in leaf plant in comparison with control plants. GA 3 treatment declined number and percentage of monoterpenes in treated plants. Also the number of sesquiterpenes decreased in response to GA 3 treatment but among the remainder of them, the amount of some sesquiterpenes decreased and some sesquiterpenes increased with GA 3 treatment. Our results showed that GA 3 treatment had opposite effect on primary terpenoid biosynthesis by the plastidic 2C-methyl-D-erythritol 4-phosphate (MEP) and mevalonate (MVA) pathways. But secondary terpenoids showed different response to GA 3 treatment probably due to interference of two biosynthetic pathways in their formation.

Terpenoids and Gibberellic Acids Interaction in Plants

“…7 & 8. Reduction in chlorophyll content after GA 3 application has been reported in wheat (Misra & biswal, 1980), rice seedlings (Yim et al, 1997) and pea (Bora & Sarma, 2006) which are consistence with our results (Mansouri et al, 2011). The variation in the level of the cartenoids were similar to those observed for the chlorophylls.…”

“…13).The THC content was higher than those of CBD content ( Mansouri et al, 2011). Perhaps, the increase observed in the THC and CBD content at high level of GA 3 is not a direct effect of GA 3 treatment and could reflect the GA 3 interaction with other plant hormones.…”

Effects of Gibberellic Acid on Gene Expression of Menthol Biosynthesis Pathway In Peppermint (Mentha Piperita L.)

“…Furthermore, the number and percentage of mono and sesquiterpens -derived MEP pathway declined in treated plants. This finding tightly has confirmed new insights into limiting the role of the MEP pathway in the synthesis of plastidic isoprenoids by exogenous application of GA 3 [17]. The current study also demonstrated that transcript accumulation for the respective enzymes of early pathway steps remained unaffected under GA 3 treatment.…”

A comprehensive analysis of fifteen genes of steviol glycosides biosynthesis pathway in Stevia rebaudiana (Bertoni)

“…There is limited information on the effect of GA 3 in relation to terpenoid metabolism. The work on Cannabis sativa showed down-regulation of the DXS by the GA 3 (Mansouri et al, 2011). However, up-regulation of the genes of the SGs biosynthesis pathway in stevia suggests differential gene regulation.…”

“…Cuttings of six month old plants were transferred to a plant growth chamber (temperature 25 ± 3°C, light intensity 200 μE m − 2 s − 1 , RH 70-80%; Saveer Biotech, India) and placed in 100 μM GA 3 (Mansouri et al, 2011), 100 μM kinetin (Yi et al, 1999) and 100 μM MeJA (Bhardwaj et al, 2011), separately (Sigma-Aldrich, USA). Cuttings kept in water served as control.…”