Ethylene treatment improves diosgenin accumulation in in vitro cultures of Dioscorea zingiberensis via up-regulation of CAS and HMGR gene expression

Abstract

Background:The perennial medicinal herb Dioscorea zingiberensis is a very important plant used for steroid drug manufacturing for its high level of diosgenin in rhizome. Although the stimulation of diosgenin accumulation by ethylene has been reported in a few of plant species, its regulation is not yet characterized at the molecular level, the underlying molecular mechanism remains elusive. Results: In this study, the effects of ethylene on diosgenin biosynthesis in in vitro cultures of D. zingiberensis were described. The results showed that, in samples treated with ethylene at concentration E3 (10 4 dilution of 40% ethephon), the diosgenin biosynthesis was significantly promoted in comparison with the control samples. Treatment with high concentrations of ethylene had inhibitory effect, whereas with low concentration of the gas elicitor brought about no detectable deleterious effect on the growth rate and diosgenin content of the cultures. The considerable increase of diosgenin level in in vitro cultured Dioscorea zingiberensis by ethylene application is accompanied by the concomitant increase of soluble proteins and chlorophyll content. The gene expressions of cycloartenol synthase and 3-hydroxy-3-methylglutaryl-CoA reductase but not of squalene synthase or farnesyl pyrophosphate synthase were up-regulated by applied ethylene. Conclusions: Our results suggest that ethylene treatment enhanced diosgenin accumulation via upregulation of the gene expressions of cycloartenol synthase and 3-hydroxy-3-methylglutaryl-CoA reductase.

In vitro culture of sweet basil: gas exchanges, growth, and rosmarinic acid production

“…Ethylene may either stimulate or inhibit growth (Biddington 1992) and secondary metabolism in various plant tissue and cell cultures. For instance, ethylene promotes the production of alkaloids in cell suspension cultures of Coffea arabica and Thalictrum rugosum (Cho et al 1988) and of Thalictrum minus (Kobayashi et al 1991 a,b), and diosgenin in in vitro plantlets of Dioscorea zingiberensis (Diarra et al 2013). The influence of plant growth regulators on production of secondary metabolites was also demonstrated in other studies (Patnaik et al 1999, Lucchesini et al 2009, Kiferle et al 2011.…”

Biotic elicitors enhance diosgenin production in Helicteres isora L. suspension cultures via up-regulation of CAS and HMGR genes

“…Increased CAS expression was observed in cell cultures of Withania somnifera treated with different fungal cell-homogenates (3% P. indica, 5% V. dahlia, 3% A. alternate and 3% F. solani). Along with HMGR, CAS also exhibited higher expression in Dioscorea zingiberensis (Diarra et al 2013) under the influence of ethylene treatment resulting in elicited diosgenin content. CAS is one of the important branch point involved in triterpenoid biosynthesis (Phillips et al 2006;Morlacchi et al 2009;Xue et al 2012).…”

“…MTN22 and Streptomyces sp. MTN14) (Gupta et al 2017), Artemisia annua with enhanced artemisinin biosynthesis under cadmium stress (Zhou et al 2017) and D. zingiberensis cultures treated with ethylene for enhanced levels of diosgenin (Diarra et al 2013). In the current work, highest fold-increment in the HMGR activity was observed in the samples harvested from bioreactor (10.28-fold increase), followed by suspension cultures treated with 1.5% E. coli (8.67-fold increase).…”

Exogenous 24-epibrassinolide ameliorates tolerance to high-temperature by adjusting the biosynthesis of pigments, enzymatic, non-enzymatic antioxidants, and diosgenin content in fenugreek

“…Therefore, the application of abiotic stresses in medicinal plants according to the purpose of their use (vegetative tissue or secondary metabolism) requires special expertise, particularly in identifying the intensity of this stress, and the plant growth stage as well as using various stimulants 26 , 57 , 58 . Numerous approaches have previously been utilized aimed at enhancing the secondary metabolites qualitatively and quantitatively in plants 1 , 10 , 56 , 59 . The conflicting results regarding how plant secondary metabolites contents vary following the application of different stimuli may highlight the prominent role of plant types in this matter.…”