What is the Difference Between Gametophytic and Sporophytic Self Incompatibility?

The main difference between gametophytic and sporophytic self-incompatibility lies in the determination of the pollen phenotype. Self-incompatibility is a mechanism that prevents pollen from one flower from fertilizing other flowers of the same plant, promoting cross-pollination.

Here are the key differences between the two types of self-incompatibility:

1. Gametophytic Self-Incompatibility (GSI): In this system, the pollen phenotype is determined by its own haploid genotype. The incompatibility reaction is determined by the genotype of the gametes. This system requires strict codominance, meaning that both alleles at a given locus must be expressed to the same extent.
2. Sporophytic Self-Incompatibility (SSI): In this system, the pollen phenotype is determined by the diploid genotype of the parent plant (sporophyte). The incompatibility reaction is determined by the genotype of the sporophyte (parent plant). This system allows for complex patterns of independent S allele dominance interactions, which introduces an additional level of mating system complexity relative to GSI.

In summary, the key difference between gametophytic and sporophytic self-incompatibility is that in gametophytic self-incompatibility, the pollen phenotype is determined by its gametophytic haploid genotype, while in sporophytic self-incompatibility, the pollen phenotype is determined by the diploid genotype of the plant.

Comparative Table: Gametophytic vs Sporophytic Self Incompatibility

Here is a table comparing Gametophytic and Sporophytic Self-Incompatibility:

Gametophytic self-incompatibility is the more common type and is determined by the genotype of gametes. In contrast, sporophytic self-incompatibility is determined by the genotype of the sporophyte (parent plant).