The PI/GLO-like locus in orchids: duplication and purifying selection at synonymous sites within Orchidinae (Orchidaceae).

Positive selection and relaxation of purifying constraints after duplication events have driven the functional diversification of gene families involved in development. One example of this occurred within the plant MADS-box genes. The evolution of the orchid flower was driven by duplication events followed by sub- and neo-functionalization of class B DEF-like MADS-box genes, which are present at three to four copies in the orchid genome.

Isolation and phylogenetic footprinting analysis of the 5'-regulatory region of the floral homeotic gene OrcPI from Orchis italica (Orchidaceae).

The nucleotide sequences of regulatory elements from homologous genes can be strongly divergent. Phylogenetic footprinting, a comparative analysis of noncoding regions, can detect putative transcription factor binding sites (TFBSs) shared among the regulatory regions of 2 or more homologous genes. These conserved motifs have the potential to serve the same regulatory function in distantly related taxa.

The OrcPI locus: genomic organization, expression pattern, and noncoding regions variability in Orchis italica (Orchidaceae) and related species.

OrcPI is a class B MADS-box gene of Orchis italica (Orchidaceae), homologous of the PISTILLATA/GLOBOSA gene isolated in Arabidopsis and Antirrhinum. Its role in determining petals and stamens is conserved in orchids, where it seems to be involved also in other functions, such as flower longevity and ovary development. The present study reports the genomic characterization of the OrcPI locus in O.