Comparative Evaluation of Different Phenolic Acids as Priming Agents for Mitigating Drought Stress in Wheat Seedlings

Abstract

The present investigation was designed to compare different phenolic acids viz. gallic acid (GA), ferulic acid (FA), p-coumaric acid (p-CA), caffeic acid (CF) and salicylic acid (SA) as priming agents for their stress alleviating effects. Pre-treatment with these phenolic acids augmented seedling growth of wheat grown under water deficit conditions as manifested by increased root length, shoot length and biomass of growing tissues. Out of different phenolic acids used in the present study, GA pre-treatment enhanced seedling growth of both wheat cultivars to the maximum extent which was accompanied by upregulation of superoxide dismutase, catalase (CAT) and peroxidase (POX) enzymes along with an increase in total phenolic and glycine betaine contents. This increase in endogenous antioxidants was further correlated with a decrease in H2O2 and malondialdehyde contents. Caffeic acid treated drought stressed seedlings also enhanced the activities of CAT and POX and content of proline as compared to the drought-stressed plants without CF treatment, with a concomitant decrease in H2O2 and lipid peroxidation level. This study also revealed that pre-treatments with GA, p-CA and SA have the potential to activate ascorbate glutathione cycle in stressed PBW 175 seedlings as revealed by ascorbate peroxidase and glutathione reductase enzymes. Although, p-CA, FA and SA showed stress alleviating effects against drought stress in wheat but the response was variable in two cultivars. These results suggest that GA with three hydroxyl groups could be most suitable priming agent for alleviating drought stress in wheat.