Diosgenin Biosynthesis in the Sprouts of Fenugreek as Influenced by Chitosan

Trigonella foenum-graecum L. (Fabaceae), known as Fenugreekis an annual herb, contains various secondary metabolites including steroidal saponins, flavonoids, phenolic compounds and alkaloids. This study was planned to investigate the effect of concentrations of chitosan on growth, expression of diosgenin biosynthetic genes and diosgenin accumulation in sprouts of T. foenum-graecum. Results revealed that there is no positive response of chitosan in any of the studied growth parameters i.e. shoot and root length, fresh and dry weight. In control treatment without any chitosan solution the highest values for all the parameters were observed. The results indicated that increasing concentrations of chitosan had no significant effect on shoot and root lengths. The fresh weight of sprouts treated with chitosan decreased markedly, but not significantly, compared with that of the control. However, the dry weight of sprouts treated with chitosan was almost similar to that of the control. Diosgenin biosynthetic pathway in response to different concentration of chitosan enhanced to an increasing level in the expression of all treated sprouts than those of no chitosan (control) treated sprouts. The highest expression level was detected when treated with 0.05 mg/mL chitosan in most of the genes except TfSQS. The expression of TfSQS was slightly higher in sprouts treated with 0.01 mg/mL chitosan than in those treated with 0.05 mg/mL chitosan. The highest expression level was in TfCAS at 0.05 mg/mL chitosan exhibiting 3 times higher expressing than that of control. The increasing expression trend for both TfSQLE and TfSTRL remained up to 0.05 mg/mL chitosan showing 1.7 times more expression in this concentration and then started to decrease the expression level. Diosgenin content in the T. foenum-graecum sprouts did not respond positively to chitosan treatment. Our findings could be potentially implemented for future studies in this arena.