PEROXIDASE ISOENZYME GRADIENTS IN CAPSICUM-ANNUUM LEAVES AND THEIR EXPRESSION IN VEGETATIVE AND FLOWERING PLANTS

The expression of peroxidases (EC 1 11 1 7) during leaf development ha s been studied by horizontal discontinuous starch-gel electrophoresis in vegetative and flowering plants of Capsicum annuum (var annuum) to assess the nature, subcellular localization and gradients of the perox idase isoenzymes that characterize the floral state determining the be ginning of reproductive development. The results showed that the devel opment of the leaves in both vegetative and flowering plants is accomp anied by a significant increase in the level of the peroxidase isoenzy me group prx a, similar to that found along the aging axis of the stem and, therefore, non-organ-specific. An analysis of the subcellular lo calization of the peroxidase isoenzyme group prx a in flowering plants showed that this isoenzyme group is mainly located bound ionically to cell walls. These results differ from those obtained previously by is oelectric focusing, in which no peroxidase isoenzyme changes were foun d as a consequence of leaf development. These results, and the fact th at a-mannosidase increases in free spaces of the cell wall as a conseq uence of leaf development, suggest that the expression of the peroxida se isoenzyme group prx a may be caused by differences in the terminal alpha-linked mannose residues of the previously existing peroxidase is o-glycoproteins.