Abstract
The sequence comparison revealed PEONY (PN), an Ipomoea nil MADS box gene, is most likely to be a counterpart of snapdragon class C gene, PLENA, not FARINELLI. To investigate the functions of PN in vivo, transgenic petunias constitutively expressing PN were generated. PN overexpressors (PNox) showed homeotic changes that are similar to blind(a petunia class A mutant) indicating that PN acts as a class C gene. In order to understand the relationship between floral organ identity and flower coloration, the effects of disordered floral organ identity on the transcription of anthocyanin biosynthetic structural genes were investigated in Pnox. ANTHOCYANIN1 (AN1) and ANTHOCYANIN2 (AN2), transcriptional activators of the structural genes, were drastically down-regulated in Pnox. Subsequently DIHYDROFLAVONOL 4-REDUCTASE was transcriptionally suppressed, whereas CHALCONE SYNTHASE-A remained unchanged. Further analysis of petunia homeotic mutants is underway. The relationship of floral organ identity and anthocyanins biosynthetic pathway will be discussed.
