Comparative Incompatibility in Angiosperms and Fungi

Abstract

Incompatibility in angiosperms is distinguished from other outbreeding mechanisms, but in fungi the distinction between separation of the sexes (dioecy) and incompatibility is a fine one. An incompatibility system is operating when all mating groups have the attributes and potentialities of both sexes. The most satisfactory method of classifying the different systems in angiosperms and fungi is by the genetic control—di-allelic or multi-allelic. With one possible exception, this division coincides with a morphological classification, heterohomomorphic in angiosperms, and with systematic orders in the fungi. The di-allelic system has developed a super gene that controls secondary characters such as morphological differences in angiosperms and nutritional or pathological characters in fungi. The di-allelic fungi with two monokaryons and one permanently heterozygous dikaryon develop a system of complementary genes—linked with the incompatibility gene—that are necessary for the dikaryon. The multi-allelic systems do not develop such secondary characters; this is a consequence of having a multiplicity of different heterozygotes.