Chloroplast pigments, proteins, lipid peroxidation and activities of antioxidative enzymes during maturation and senescence of leaves and reproductive organs of Cajanus cajan L.

A comparative investigation was undertaken with pigeon pea leaves and attached flower buds/flowers/pods during their developmental stages including senescence in a natural system in experimental plots. Alterations in chloroplast pigments, total soluble proteins, lipid peroxidation, malondialdehyde (MDA) content and activities of guaiacol peroxidase (POD, EC 1.11.1.7) and superoxide dismutase (SOD, EC 1.15.1.1) were studied at 5-day interval from initial to 40-day stage. Chloroplast pigments and proteins of leaves increased upto 15 and 20-day stages respectively followed by a steady decline. Reproductive parts, however, exhibited rise in chloroplast pigments upto 25-day and protein till last stage as developing pods gain the amount from the senescing leaves which are nearest to them. Senescing leaves show very high POD activity than the developing and senescing pods and POD appears to be associated with chlorophyll degradation. Considerably higher activity and amount of LOX and MDA respectively have been noticed in senescing leaves than in flowers and pods. Increase in SOD activity during early stage of leaf growth and maturation indicates protective role that declined at senescent stages. Pods are unique in having very high SOD activity, only last stage of senescence does show a decline.