Question

Which molecular mechanism controls self-incompatibility?

Options

• Simple dominant and recessive alleles that control flower color

• S-alleles (S-locus genes) that match between pollen and stigma tissue trigger biochemical rejection

• Environmental factors that prevent pollen germination

• Structural differences in anther and stigma morphology

Answer 1

Self-incompatibility is controlled by S-alleles at the S-locus. When the S-allele carried by pollen matches that of the stigma tissue, the plant's biochemical system blocks fertilization, preventing self-fertilization and promoting outcrossing.