Interactions of S Alleles in Diploid Pollen

Abstract

SELF-INCOMPATIBILITY (S) alleles in the pollen of autotetraploids show either independent action or one or other of two types of interaction—‘dominance’ and ‘competition’. While dominance interaction is common, competitive interaction is rare. When two S alleles compete for a presumably limited amount of substrate, a competitive interaction occurs which leads to self-compatibility owing to the lack of full expression of either of the S alleles¹. A theory is proposed to explain the physiology of the different types of S allele behaviour in autotetraploids.