Decapitation effects on some aspects of oxidative metabolism in senescing mungbean (Vigna radiata (L.) Wilczek cv. PDM-54) cotyledons were studied. There was gradual decrease in fresh weight, dry weight and soluble protein contents. However, pigment contents recorded increase till 7th day and a subsequent decline. On shoot decapitation even though fresh weight, dry weight and protein contents showed lesser depletion, the photosynthetic pigment contents declined further. The superoxide dismutase activity increased where as catalase activity decreased in senescing cotyledons which favoured the chances of accumulation of H2O2 as a result increase in lipid peroxidation was noticed. However, on reversal of senescence by decapitation, there was decline in superoxide dismutase and increase in catalase activities that could limit the oxidative corrosion in the tissues, as observed in the form of lowering lipid peroxidation in rejuvenated cotyledons. Thus, catalase (H2O2 - scavenging) activity seems to be one of the key regulatory aspect of oxidative metabolism in senescing mungbean cotyledons.
Catalase, cotyledon rejuvenation, lipid peroxidation, reactive oxygen species, superoxide dismutase
