Drought, one of the most largely experienced stresses causing dehydration of cells, affects the acres of agricultural lands and individual production, especially in agriculture and forest land. Plants develop resistance mechanisms to cope with water scarcity. However, rising reactive oxygen species (ROS) production coincides with rising stress-specific secondary metabolite accumulation in response to abiotic stimuli.
Upon abiotic stress, the plant elite produces reactive oxygen, which triggers the transcription of defence gene processes, bringing about an improved production of transcripts for some transcription reducers and protective genes as a part of the primary defense system. During these events, the primary abundant antioxidants (enzymes that include CAT, SOD, APX, DHAR, and GR) raise the activity of the defence processes to quickly trigger the plant's secondary metabolic pathways. This study focuses on the positive effects of inducing drought stress using PEG on Vitex agnus-castus callus culture. Nodal shoot explants were used to establish callus tissue, with 2,4-D and NAA inducing callus. The highest callus weight was seen at 3 mg/1 2,4-D and 0.5 mg/1 BA. The production of secondary metabo1ites in response to stress was achieved with MS medium containing 4% PEG 6000, showing improvements in growth and pharmaceutical compounds. Maximum rutin and chlorogenic acid contents were obtained at 2% and 3% PEG concentrations. Drought stress negatively affected various traits, but tolerance to PEG improved, with enhanced PAL and CAT activity regulating ROS levels. This study suggests that bioreactors can increase under stress condition the content of essential compounds in the pharmaceutical market.