Question

Write a short note on self-incompatibility.

Hint:

Think of a flower's own biochemical defence against fertilising itself with its own pollen.

Answer 1

Understanding the Question:
Self-incompatibility is a genetic mechanism in flowering plants that prevents self-pollen from fertilising the same flower or plant.

Detailed Explanation:
Even when self-pollen lands on the stigma of the same flower, a biochemical recognition system stops the pollen tube from growing properly or stops fertilisation from completing, so self-fertilisation is blocked.
Species belonging to the Brassicaceae and Solanaceae families are common examples that show this trait.
This mechanism forces cross-pollination between different plants, which increases genetic variation in the offspring and avoids the harmful effects of inbreeding.

Final Answer:
Self-incompatibility is a genetic barrier that stops self-pollen from fertilising the same plant, promoting cross-pollination and healthier genetic variation.