Pollen-pistil Interaction:-

• It is a dynamic process involving pollen recognition followed by promotion or inhibition of the pollen.
• This interaction takes place through the chemical components produced by them.
• If the pollen is compatible (right type), the pistil accepts it and promotes post-pollination events. The pollen grain germinates on the stigma to produce a pollen tube through one of the germ pores. The contents of the pollen grain move into the pollen tube. Pollen tube grows through the tissues of the stigma and style and reaches the ovary.
• If the pollen is incompatible (wrong type), the pistil rejects the pollen by preventing pollen germination on the stigma or the pollen tube growth in the style.
• In some plants, pollen grains are shed at 2-celled condition (a vegetative cell & a generative cell). In such plants, the generative cell divides and forms the two male gametes during the growth of the pollen tube in the stigma.
• In plants which shed pollen in the 3-celled condition, pollen tubes carry 2 male gametes from the beginning. The pollen tube, after reaching the ovary, enters the ovule through the micropyle and then enters one of the synergids through the filiform apparatus. The filiform apparatus present at the micropylar part of the synergies guides the entry of the pollen tube.
• A plant breeder can manipulate pollen-pistil interaction, even in incompatible pollinations, to get desired hybrids.