Question

Give an account of pollen pistil interaction in detail.

Answer 1

Pollen-Pistil interaction:

1. All the events from the deposition of pollen grain on stigma to the entry of pollen tube in the ovule (through synergid) are referred to as pollen pistil interaction.
2. It is the interaction of pollen grains with sporophytic tissue (stigma).
3. It begins with pollination and ends with fertilization.
4. Pollination does not guarantee the transfer of the right type of pollen, sometimes the wrong type of pollen may also land on stigma.
5. The pistil has the ability to recognize and accept the right or compatible pollen of the same species. Thus the wrong type of pollen is discarded by the pistil.
6. Compatibility and incompatibility of the pollen-pistil are determined by special proteins.
7. The stigmatic surface of flowers refuses other wrong types of incompatible pollen grains. It ensures that only intraspecific pollen germinates successfully.
8. The compatible pollen absorbs water and nutrients from the surface of the stigma, germinates, and produces a pollen tube. Its growth through the style is determined by specific chemicals.
9. The stigmatic surface provides the essential prerequisites for successful germination, which are absent in the pollen.
10. The pollen tube, after reaching the ovary, is pushed through the ovule and reaches the embryo sac.
11. The tip of the pollen tube enters one of the synergids and then ruptures to release the contents. xii. Significance of pollen-pistil interaction: Due to pollen pistil interaction, intense competition develops even in the compatible pollen grains (gametes).