Glucosylation of anthocyanin in carnations (Dianthus caryophyllus) and delphiniums (Delphinium grandiflorum) involves novel sugar donors, aromatic acyl-glucoses, in a reaction catalyzed by the enzymes acyl-glucose-dependent anthocyanin 5 (7)-O-glucosyltransferase (AA5GT and AA7GT). The AA5GT enzyme was purified from carnation petals, and cDNAs encoding carnation Dc AA5GT and the delphinium homolog Dg AA7GT were isolated. Recombinant Dc AA5GT and Dg AA7GT proteins showed AA5GT and AA7GT activities in vitro. Although expression of Dc AA5GT in developing carnation petals was highest at early stages, AA5GT activity and anthocyanin accumulation continued to increase during later stages. Neither Dc AA5GT expression nor AA5GT activity was observed in the petals of mutant carnations; these petals accumulated anthocyanin lacking the glucosyl moiety at the 5 position. Transient expression of Dc AA5GT in petal cells of mutant carnations is expected to result in the transfer of a glucose moiety to the 5 position of anthocyanin. The amino acid sequences of Dc AA5GT and Dg AA7GT showed high similarity to glycoside hydrolase family 1 proteins, which typically act as b-glycosidases. A phylogenetic analysis of the amino acid sequences suggested that other plant species are likely to have similar acylglucose-dependent glucosyltransferases.

The whole-genome sequence of carnation (Dianthus caryophyllus L.) cv. ‘Francesco’ was determined using a combination of different new-generation multiplex sequencing platforms. The total length of the non-redundant sequences was 568 887 315 bp, consisting of 45 088 scaffolds, which covered 91% of the 622 Mb carnation genome estimated by k-mer analysis. The N50 values of contigs and scaffolds were 16 644 bp and 60 737 bp, respectively, and the longest scaffold was 1 287 144 bp. The average GC content of the contig sequences was 36%. A total of 1050, 13, 92 and 143 genes for tRNAs, rRNAs, snoRNA and miRNA, respectively, were identified in the assembled genomic sequences. For protein-encoding genes, 43 266 complete and partial gene structures excluding those in transposable elements were deduced. Gene coverage was ∼98%, as deduced from the coverage of the core eukaryotic genes. Intensive characterization of the assigned carnation genes and comparison with those of other plant species revealed characteristic features of the carnation genome. The results of this study will serve as a valuable resource for fundamental and applied research of carnation, especially for breeding new carnation varieties. Further information on the genomic sequences is available at .

In the "Rhapsody" cultivar of the carnation, which bears white flowers variegated with red flecks and sectors, a transposable element, dTdic1, belonging to the Ac/Ds superfamily, was found within the dihydroflavonol 4-reductase (DFR) gene. The red flecks and sectors of "Rhapsody" may be attributable to a reversion to DFR activity after the excision of dTdic1. The yellow color of the carnation petals is attributed to the synthesis and accumulation of chalcone 2'-glucoside. In several of the carnation cultivars that bear yellow flowers variegated with white flecks and sectors, both the chalcone isomerase (CHI) and DFR genes are disrupted by dTdic1.

Expression of a carrot phenylalanine ammonia-lyase (PAL) gene (DcPAL1) in suspension-cultured carrot cells is induced by treatment with a fungal elicitor, ultraviolet B (UV-B) irradiation, and by transferring and diluting cells with fresh medium (the dilution effect). Box-L-like sequences are known as important cis-elements of genes for enzymes involved in the phenylpropanoid biosynthetic pathway. Six sequences, box-L0 to box-L5, exist in the DcPAL1 gene promoter region. In this study, we isolated cDNA encoding the R2R3 type of MYB transcription factor, DcMYB1, using yeast one-hybrid screening with box-L1 or box-L5 as target elements. DcMYB1 bound to boxes-L0, L1, L3/4, and L5 sequences (ACC(A/T)(A/T)CC) in vitro, and in yeast cells and carrot protoplasts. Transient expression of DcMYB1 could up-regulate DcPAL1 promoter activity in carrot protoplasts. Results of the transient expression experiment for the deletion-mutated promoters of boxes-L0, L1, L3, and L5 suggest that these box-L-like sequences were required for the complete activation of the DcPAL1 promoter by DcMYB1. Expression of DcMYB1 transcripts was induced 0.5 h after elicitor treatment or UV-B irradiation, and 2 h after the dilution effect. Induction of DcPAL1 expression occurred 1 h after DcMYB1 expression in all stress treatments, and repression of DcMYB1 expression by RNA interference caused cessation of the up-regulation of DcPAL1 expression in the elicitor treatment or with UV-B irradiation. These results suggest that DcMYB1 is the main regulatory factor acting on box-L sequences in the DcPAL1 gene that respond to environmental cues.

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