LOCALIZATION AND EXPRESSION OF ARABINOGALACTAN-PROTEINS IN THE OVARIES OF NICOTIANA-ALATA LINK AND OTTO

The transmitting-tissue cells of the style of flowering plants secrete a complex extracellular matrix through which pollen tubes grow to the ovary to effect fertilisation. This matrix is particularly rich in a class of proteoglycans, the arabinogalactan-proteins (AGPs). AGPs from the ovary of Nicotiana alata were found to be developmentally regulat ed, as the different charge classes of AGPs altered during floral deve lopment. The AGPs from the mature ovary had charge characteristics tha t were distinct from those previously reported for the stigma and styl e. However, the concentration of AGP (0.6 mu g/ml fresh weight) in the ovary did not change during development, or in response to either com patible or incompatible pollination. The AGPs of the ovary are mainly associated with the epidermis of the placenta.