White marginal picotee formation in the petals of Camellia japonica 'Tamanoura'

Pigment and molecular analyses were carried out to elucidate how the white marginal picotee in the petals of Camellia japonica 'Tamanoura' is expressed. HPLC analyses showed that two major anthocyanins (cyanidin 3- glucoside and cyanidin 3-galactoside) were accumulated in the red part of the petals of 'Tamanoura', as found in those of wild type C. japonica, whereas no anthocyanins were detected in the white picotee part, indicating that the anthocyanin biosynthetic pathway might be blocked at some steps in the white part. Transcriptional levels of the genes involved in anthocyanin biosynthesis were investigated by RT-PCR. Most genes were equally expressed in both red and white parts of 'Tamanoura' petals, but the expression of chalcone synthase (CHS) was strongly suppressed only in the white picotee part. Full-length cDNA sequence of CjCHS was determined using the 5' and 3' RACE approach. The deduced amino acid sequence of CjCHS shared high homology with those of several woody plants. cDNA RT-PCR and genomic DNA PCR revealed no length differences in PCR products between red and white picotee parts in the petals of 'Tamanoura', suggesting that no insertion of transposable elements and DNA rearrangement occurred in CjCHS in the white part.