Subcellular distribution of arabinogalactan proteins in pollen grains and tubes as revealed with a monoclonal antibody raised against stylar arabinogalactan proteins

Abstract

Monoclonal antibody PCBC3, raised against stylar extracts from Nicotiana alata flowers, was deduced from enzyme-linked immunosorbent assays and inhibition of immuno-gold labelling on tissue sections to bind specifically to carbohydrate epitopes on arabinogalactan proteins (AGPs) but not to other arabinose-containing cell wall polysaccharides. When pollen grains of N. tabacum were hydrated in fixative, PCBC3 bound to vesicles in the vicinity of the endoplasmic reticulum but, when grains were hydrated for 20 min in culture medium before fixation, binding was restricted to the plasma membrane. The generative-cell plasma membrane was also labelled in grains of Lycopersicon peruvianum. In pollen ..