Pollen-pistil interaction in wheat

General organization and ultrastructure of pistil transmitting tract (PTT) for pollen tube pathway in wheat (Triticum aestivum L.) and pollen tube growth were studied. The peculiar features of cell ultrastructure in different parts of the PTT were shown and point to heterogeneous pollen tube pathway. Stylodia TT cells show protein and carbohydrate secretion. In stylar TT cells dark globules are secreted. In the ovarian cavity fibrillar material is present. The organization of pollen tube cytoplasm also changes during its growth towards the ovule. The thickness of the callose layer of the pollen tube wall decreases in the direction of the ovule. In the stylar TT the pollen tube plasma membrane forms finger-like protrusions, or plasmotubules, which can connect the neighbouring pollen tubes. The role of these plasmodesmata-like formations in the pollen tube and their role in the interaction of pollen tubes with PTT in different parts of pollen tube pathway in wheat are discussed.