Localization of Ribulose Bisphosphate Carboxylase in the Guard Cells by an Indirect, Immunofluorescence Technique

Abstract

Ribulose bisphosphate carboxylase [RuBPase], a key enzyme in the photosynthetic carboxylation process, was localized through an indirect immunofluorescent technique in the guard cells of some of the 41 spp. of plants examined. This sample includes 17 families of both dicotyledons and monocotyledons, 1 gymnosperm and 1 pteridophyte. Plants were selected to represent all of the 3 major photosynthetic categories, i.e., C3, C4 and crassulacean acid metabolism. Rabbit antibodies raised against tobacco (Nicotiana tabacum L.) RuBPase were used for this immunofluorescent study. A good degree of fluroescence was observed in the guard cells of 7 of 21 spp. exhibiting crassulacean acid metabolism. C3 plants exhibited a very low degree (almost negligible) of fluorescence, while the C4 species did not exhibit any fluorescence.