Alterations of Cor TFL1 and Cor AP1 expression correlate with major evolutionary shifts of inflorescence architecture in Cornus (Cornaceae) - a proposed model for variation of closed inflorescence forms.

TFL1-, AP1- and LFY-like genes are known to be key regulators of inflorescence development. However, it remains to be tested whether the evolutionary modifications of inflorescence morphology result from shifts in their expression patterns., We compared the spatiotemporal expression patterns of Cor TFL1, Cor AP1 and Cor LFY in six closely related Cornus species that display four types of closed inflorescence morphology using quantitative real-time polymerase chain reaction ( qRT- PCR) and RNA in situ hybridization. Character mapping on the phylogeny was conducted to identify evolutionary changes and to assess the correlation between changes in gene expression and inflorescence morphology., Results demonstrated variation of gene expression patterns among species and a strong correlation between Cor TFL1 expression and the branch index of the inflorescence type. Evolutionary changes in Cor TFL1 and Cor AP1 expression co-occurred on the phylogeny with the morphological changes underpinning inflorescence divergence., The study found a clear correlation between the expression patterns of Cor TFL1 and Cor AP1 and the inflorescence architecture in a natural system displaying closed inflorescences. The results suggest a role for the alteration in Cor TFL1 and Cor AP1 expression during the evolutionary modification of inflorescences in Cornus. We propose that a TFL1-like and AP1-like gene-based model may explain variation of closed inflorescences in Cornus and other lineages. [ABSTRACT FROM AUTHOR]