Breeding system variation, genetics and evolution in the Turneraceae.
We review the genetics and evolution of breeding systems in the Turneraceae. Distyly occurs in seven of 10 genera and 81% of species. The remaining species are homostylous. Polyploid evolution has been significant in Turnera. Approximately 60% of species are polyploid ranging from diploid through decaploid. No relationship between breeding system and polyploidy is evident. The genetics of distyly involves a one-locus two-allele system (S and s). Evidence from crosses with homostylous species and mutants is consistent with the possibility that a "Primula-type" supergene underlies distyly but does not prove this to be the case. A polygalacturonase, and an alpha-dioxygenase specific to the transmitting tissue of short-styled plants both exhibit morph-limited expression in concert with predictions from an evolutionary model. The function of the proteins in distyly, if any, is unknown. We have begun constructing a fine-scale genetic map of Turnera. Two genetic markers lie within 0.2 cm of the distyly locus. This should provide a starting point for positional cloning of the distyly locus and reveal the genetic architecture and molecular basis of distyly.
Shore
Joel S
JS
Department of Biology, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada. shore@yorku.ca
Arbo
Maria M
MM
Fernández
Aveliano
A
D005075:Biological Evolution; D001947:Breeding; D032461:Chromosomes, Plant / Q000235:genetics; D014644:Genetic Variation; D011123:Polyploidy; D029647:Turnera / Q000145:classification / Q000235:genetics*