Breeding system variation, genetics and evolution in the Turneraceae.

SHORE, J. S.; ARBO, M. M.; FERNÁNDEZ, A

NEW PHYTOLOGIST

Blackwell Publishing

Año: 2006 vol. 171 p. 539 - 551

0028-646X

We review the genetics and evolution of breeding systems in the Turneraceae. Distyly occurs in seven of 10 genera and 81% of species. The emaining 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 ‘ rimula -type’ supergene underlies distyly but does not prove this to be the case. A polygalacturonase, and an á -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 c M 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.