SELF AND CROSS-COMPATIBILITY IN 3 SPECIES OF THE HEMIPARASITE TRIPHYSARIA (SCROPHULARIACEAE)

The genus Triphysaria is comprised of both self-compatible and self-in compatible species, all of which are hemiparasites. Pollen tube growth experiments indicate that self-incompatibility is governed by a homom orphic, gametophytic mechanism typical of Scrophulariaceae and Solanac eae. While the autogamous and allogamous Triphysaria species are morph ologically quite distinct, interspecific hybrids between them were rea dily obtained with no evidence of unilateral compatibility. Self-compa tibility was dominant in interspecific Fl hybrids. Since several of th e morphological traits that distinguish the self-compatible and -incom patible species segregate in the F2 generation, the F2 population will be useful for mapping mating trait loci. The results are consistent w ith self-compatibility being derived from self-incompatibility relativ ely recently in evolution. (C) 1998 Elsevier Science B.V. All rights r eserved.