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 has 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 peroxidase isoenzymes that characterize the floral state determining the beginning of reproductive development. The results showed that the development of the leaves in both vegetative and flowering plants is accompanied by a significant increase in the level of the peroxidase isoenzyme group prx a, similar to that found along the aging axis of the stem and, therefore, non-organ-specific. An analysis of the subcellular localization 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 isoelectric focusing, in which no peroxidase isoenzyme changes were found as a consequence of leaf development. These results, and the fact that a-mannosidase increases in free spaces of the cell wall as a consequence of leaf development, suggest that the expression of the peroxidase isoenzyme group prx a may be caused by differences in the terminal alpha-linked mannose residues of the previously existing peroxidase iso-glycoproteins.