Expression of a CYP76AB1 correlates with the sequential white-blue-white colour transition of Vanda coerulea petals

Abstract

The blue colour of Vanda coerulea petals is slowly produced during flower development but quickly disappears when the flowers are pollinated. To investigate the molecular basis of the phenomenon, we isolated a novel cytochrome P450 gene, CYP76AB1, from this plant by polymerase chain reaction (PCR) based on the conserved regions of flavonoid 3´,5´-hydroxylase amino acid sequences. CYP76AB1 transcripts were detectable at low level in the late phase of flower development when the petals were light blue, but became abundant in the subsequent opening flower stage, as the petals turned blue. When the flowers were pollinated they turned white, and the CYP76AB1 transcripts returned to low level. This indicates that the expression of CYP76AB1 may regulate petal colour of V. coerulea, and be a target for developing permanently blue flowers.

Identification of novel genes involved in petunia flower development using transcript profiling and reverse genetics

“…In P. hybrida, its member CYP76A4 has a role in lauric acid hydroxylation, although the physiological function of this activity has not been clarified yet (Tamaki et al, 2005). In Vanda coerulea petals, the expression of CYP76AB1 is correlated with the appearance of blue color in petals just before pollination (Ratanasut et al, 2011), therefore indicating that this gene may play a role in petals, although the biochemical function of the protein remains unknown. The function of the P. hybrida CYP76B9 involves metabolism of medium-chain fatty acids such as capric and lauric acids (Imaishi and Petkova-Andonova, 2007).…”