Question

Assertion : Self-incompatibility is a genetic mechanism which prevents self-pollination and thereby fertilisation by inhibiting either pollen germination or pollen tube growth in the pistil.
Reason: In gametophytic self-incompatibility, the incompatibility reaction is determined by the genotype of the sporophytic tissue of the plant from which the pollen is derived.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

Self-incompatibility refers to the inability of pollen from a flower to germinate on the stigma of the same flower (or other flower of same plant). Depending on the origin of factors determining the mating types two categories of self incompatibility have been recognised:
(i) Gametophytic self-incompatibility $(GSI)$.The incompati bility process is determined by the genotype of male gametophyte (pollen) itself, e.g., Liliaceae, Poaceae, Solanaceae.
(ii) Sporophytic self-incompatibility $(SSI)$. The incompatibility process is controlled by the genotype of the sporophytic tissue of the plant from which the pollen is derived, e.g., Asteraceae, Brassicaceae.