GC-MS based metabolite profiling of medicinal plant-Catharanthus roseus under cadmium stress

Alteration in metabolite levels in response to heavy metal exposure plays an important role in sustaining metal stress in plants. The objective of the present study was to examine the change in metabolite profile of medicinal plant- Catharanthus roseus in response to heavy metal cadmium (Cd), using gas chromatography mass spectrometry (GC-MS). A total of 78 Cd responsive metabolites were identified in control and cadmium treated samples. These included fatty acids, alkaloids, terpenoids, phytosterols and other miscellaneous compounds. An increase in saturated fatty acids such as myristic acid, palmitic acid, adipic acid, stearic acid, decanoic acid, tridecanoic acid, pentadecanoic acid, octadecanoic acid and decrease in unsaturated fatty acids such as linoleic acid, 9-hexadecenoic acid and 9, 12-octadecadienoic acid indicated lipid peroxidation in treated plants. Higher malondialdehyde content and ultrastructural changes in chloroplasts in treated plants confirmed these results. Elevated levels of alkaloids vindolinine, catharanthine, vindoline, tabersonine, nicotine, coronaridine, vidorosine indicated effect on metabolic pathways including the monoterpenoid indole alkaloids pathway. Other responsive metabolites included terpenes like caryophyllene, campestrin, phytol, neophytadiene, cedrol and silicone oil in addition to isoprenoids and polyamines. These metabolites have known antioxidant properties and are employed by plants to overcome oxidative stress and maintain membrane integrity. Overall, metabolite profiling demonstrated that the Cd tolerance can be attributed to the differential accumulation of the secondary metabolites in C. roseus.