INTERACTION BETWEEN HEMIPARASITIC- DENDROPHTHOE FALCATA (L.) ETTING. ON MANGIFERA INDICA LINN. - SOME OBSERVATIONS

Dendrophthoe, a perennial flowering plant, face several interesting physiological challenges. It is an evergreen, sturdy, hemiparasite belongs to Loranthaceae, distributed in the tropical and sub-tropical regions of the world. An attempt was made to unravel the physiological and biochemical defense of mango plant (host) against the invasion of the parasite Dendrophthoe falcata (L.) Etting. The methodologies adapted include microscopic, analytical and biochemical. Chlorophyll pigments showed a decrease possibly the reduction in availability of water and minerals. Reduction in soluble sugar contents was noted in the infected mango plant by the parasite. Significant increase in amino acids content was observed. Proline, a stress amino acid also increased during parasite invasion. Alpha amylase activity showed a higher profile corroborating with the sugar content. Total phenols also showed a reduction substantiated by localization studies meanwhile, flavonoids displayed an increased profile. Parasite invasion created an oxidative stress environment in the host tissue by producing the superoxide anion radical and hydrogen peroxide. Phenolic acids also showed variation among the plants corroborating with phenolic content. Elevated level of hydrogen peroxidase in the infected mango suggests the oxidative stress in the plant. Infected host tissue showed a preliminary defense strategy by inducing its antioxidant machinery of enzymes and compounds. The activities of total superoxide dismutases (SODs) as well as ascorbate peroxidase (APX) showed consistent increases with stress, however catalase activity declined. Biotic stressed mango plants also had higher guaiacol peroxidase (GPX) activity than control plants.