Elucidating the Role of Elevated CO2 in Regulating Ozone Induced Oxidative Stress: Age-Dependant Modulation in the Mechanistic Response in Rauwolfia serpentina.

The ongoing climate change scenario is characterised by unprecedented increase in the concentrations of tropospheric ozone (O3) and atmospheric CO2. The oxidative stress induced by O3, perturb the plant functioning, resulting in severe consequences on plant performance. The present study investigates the role of elevated CO2 in amelioration of O3 stress in Rauwolfia serpentina, a well-documented medicinal plant, by exposing the plants to single treatments of elevated O3 (EO), elevated CO2 (EC), and a combination of elevated doses of O3 and CO2 (ECO), in open top chambers. The objective of the study was to investigate the role of elevated CO2 in modulating the mechanistic response of the plants in manoeuvring their disarrayed metabolic pathways due to elevated O3 stress. The results of the present study suggest that elevated CO2 was associated with changes in antioxidant and metabolic profiles in O3 stressed plants, indicating coordinated biochemical responses that may contribute to enhanced resilience towards the O3 induced oxidative stress. Under elevated CO2, whereas the plant's defense was more inclined towards strengthening the antioxidant pool during the vegetative stage, reproductive stage of plants relied more upon secondary metabolite production to cope with elevated O3 stress. The results support the positive effect of elevated CO2 in management of elevated O3 stress in R. serpentina, and explore the mechanistic modulation induced by elevated CO2 on the plant metabolism under elevated O3 stress.