Alterations in lipid peroxidation, electrolyte leakage, and proline metabolism in Catharanthus roseus under treatment with triadimefon, a systemic fungicide

Triadimefon (TDM), a systemic fungicide with non-traditional plant-growth regulator properties, was administered to Catharanthus roseus (L.) G. Don. plants in order to determine its effects on oxidative injury in terms of H2O2 content, lipid peroxidation (LPO), electrolyte leakage (EL), protein and amino acid contents, as well as proline metabolism. The LPO, estimated as thiobarbituric acid-reactive substances (TBARS), decreased under TDM treatment. It was found that H2O2 and EL were reduced under TDM treatment when compared to control. TDM treatment caused a significant increase in the protein and amino acid contents. Glycine betaine (GB) and proline (PRO) significantly accumulated in C. roseus under stress arisen from fungicide applications. Proline oxidase (PROX) activities reduce the PRO content and gamma-glutamyl kinase (gamma-GK) accelerates the synthesis of PRO. Under TDM treatment, the activity of PROX decreased and the gamma-GK activity increased. From our results, it is suggested that fungicide triadimefon causes activation of metabolic processes in the medicinal plant Catharanthus roseus. These findings are of great significance for the cultivation of this medicinal plant, as it was previously reported that TDM causes an enhancement of antioxidant metabolism and ajmalicine production in C. roseus.