This chapter focuses on the gametophytic self-incompatibility—a prezygotic barrier to self-fertilization in plants that otherwise produce fully functional gametes. Two types of reproductive barriers operate in plants: interspecific and intraspecific. Interspecific reproductive barriers ensure the stability of each species, whereas intraspecific barriers permit a reasonable degree of variability within the species. Interspecific reproductive barriers are a consequence of evolutionary divergence among species, and the failure to cross-fertilize lies in the inability of pistil tissue to sustain the growth of pollen from other taxa, a phenomenon described as “incongruity.” Self-incompatibility is an intraspecific reproductive barrier. It is a system of cell-to-cell recognition allowing the pistil to recognize and reject pollen from genetically related individuals, thereby promoting outbreeding and heterozygosity in the population. Two main types of self-incompatibility systems exist: heteromorphic and homomorphic. New S alleles that appear in a population have a reproductive advantage over the extant S alleles because pollen bearing the new allele is less likely to land on stigma carrying the same allele and, thus, more likely to escape rejection.
All Science Journal Classification (ASJC) codes
- Cell Biology