Question

Given that a male tobacco plant has genotype, $S_A{S}_B$, and the female plant has genotype, $S_C{S}_B$. Assuming that the pollen from the male flower gets dropped on the stigma of the female flower, predict the consequence after that.

• A. All of the pollen will germinate
• B. All pollen will die
• C. Fertilisation won't occur
• D. Half of the pollen will die and half of them will germinate on stigma

Answer 1

The correct option is D Half of the pollen will die and half of them will germinate on stigma

Self-incompatibility is the process in which the pollen grain with the same genotype as that of egg would not germinate. They will only germinate if the pollen grains and female plant have different genotypes.
Female reproductive parts will not contain $S_A$, hence, the pollen carrying $S_A$ will germinate but the one carrying $S_B$ will not germinate due to self incompatibility. Hence, half of the pollens will die and half of them will germinate on the stigma.