Question
What does an interaction between pollen grain and its compatible stigma result in, after pollination? List two steps in sequence that follow after the process.
✓
Answer
Events in pollen-pistil interaction:
- A compatible pollen grain starts its germination on the stigma.
- The intine grows out through one of the germ pores to form a pollen tube; the contents of the pollen grain move into the pollen tube.
- In those species, where the pollen grains are shed at the two-celled stage, the generative cell divides to form two male gametes.
- The pollen tube grows through the tissues of style and stigma and reaches the ovary.
- It enters the ovule through the micropyle and then enters the embryo sac through the filiform apparatus of one of the synergids.
- All these events, from the deposition of pollen grains on the stigma till the entry of pollen tube into the ovule, are collectively called pollen-pistil interaction.
- Syngamy, i.e., fusion of male and female gametes to form a zygote.
- Triple fusion, i.e., fusion of two polar nuclei (secondary nucleus) and a male gamete, to form the primary endosperm nucleus (PEN).
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