Evaluation of stress induced changes in selected metabolites in some varieties of ginger

Abstract

Ginger, which is considered as ‘Maha Aushadha’ since ancient times, is well known for its secondary metabolites. In the present study, response of two cultivars of ginger to different stress signals was evaluated. A comparative analysis of stress induced changes in morphological attributes and in the production of secondary metabolites in two selected cultivar varieties of ginger (Zingiber officinalec cv-Varada and Zingiber officinale cv- Mahima) was evaluated. All the data reported in this study were based on field experiments done under protective greenhouse condition. Under this controlled condition, the effect of applied stress signals on morphological characters as well as secondary metabolite production were precisely studied and analyzed. Solitary as well as combined foliar sprays of Salicylic Acid and Zinc Sulphate Heptahydrate in two different concentrations along with drought were also taken as one of the other stress factors was included in the present study. The present study gave an idea about the varied expression of two cultivars of ginger in terms of secondary metabolite production, volatile non-volatile composition of ginger in response to the different stressed environmental conditions, the present results were also found that some stress combinations may altered the production of secondary metabolites and other phytoconstituents in a significant level. The synergistic effect of stress combination had different results that are evaluated for the production of higher quantity of ginger volatiles and non-volatiles. The quantitative estimation of Total Phenolics Content (TPC), Total Flavonoid Content (TFC) and the comparative analysis of antioxidant assay by DPPH showed that stress signals increased the concentration of both TPC and TFC in both the varieties when comparing with the control plants which eventually resulted in the increase in antioxidant activity of the same. Increasing concentration of foliar spray of Salicylic Acid had a positive impact on the Total Phenolic Content when comparing with the foliar application of Zinc Sulphate of same concentration. HPLC analysis of 15 trials of both varieties were done to estimate the quantity of 6-gingerol in rhizomes. Here also, the results indicated that stress considerably increased the concentration of 6-gingerol in trials. The results were narrow down to perform the estimation of total chlorophyll content, to quantify the PAL enzyme activity and for GC-MS analysis to list down components and its concentration in different trials.GC-MS analysis of 5 trials of two varieties indicated that there was a total of 44 compounds identified at different retention times in both the varieties. GC-MS analysis of Zingiber officinale cv-Varada was found to have 38 compounds out of the identified 44 compounds. Out of 44 compounds 23 compounds were found unique to cv-Varada. For Zingiber officinale cv-Mahima out of 44 compounds 21 compounds were identified.