Diversity of cycloidea-like genes in Gesneriaceae in relation to floral symmetry

Homology assessment of cycloidea-like genes was carried out in Gesneriaceae, a predominantly zygomorphic family in which several independent reversals to actinomorphy have occurred, as a basis for further investigation of the control and evolution of floral symmetry. Phylogenetic analysis of Gesneriaceae cycloidea (Gcyc) suggests that independent duplication and gene loss events have occurred during the evolution of this family after the split from Scrophulariaceae. Comparison of Gcyc sequences between zygomorphic and naturally occurring actinomorphic taxa does not suggest that reversals to actinomorphy were caused in these cases by loss of function of cyc-like genes. Examination of floral development in the nearly actinomorphic Ramonda myconi did not reveal any evidence of residual unequal dorso-ventral differentiation indicative of expression of Gcyc. This suggests that Gcyc may be expressed before primordia initiation in R. myconi, or may have additional functions not directly related to floral symmetry. (C) 2000 Annals of Botany Company.