Esterified carotenoids are synthesized in petals of carnation (Dianthus caryophyllus) and accumulate in differentiated chromoplasts.

Although yellow and orange petal colors are derived from carotenoids in many plant species, this has not yet been demonstrated for the order Caryophyllales, which includes carnations. Here, we identified a carnation cultivar with pale yellow flowers that accumulated carotenoids in petals. Additionally, some xanthophyll compounds were esterified, as is the case for yellow flowers in other plant species.

Carnation locus contains two chalcone isomerase genes involved in orange flower coloration.

Carnations carrying a recessive gene show accumulation of the yellow pigment chalcononaringenin 2'-glucoside (Ch2'G) in their flowers, whereas those with a dominant gene do accumulation the red pigment, anthocyanin. Although this metabolic alternative at the gene could explain yellow and red flower phenotypes, it does not explain the development of orange flower phenotypes which result from the simultaneous accumulation of both Ch2'G and anthocyanin. The carnation whole genome sequencing project recently revealed that two chalcone isomerase genes are present, one that is consistent with the gene (Dca60979) and another (Dca60978) that had not been characterized.

Repressed expression of a gene for a basic helix-loop-helix protein causes a white flower phenotype in carnation.

In a previous study, two genes responsible for white flower phenotypes in carnation were identified. These genes encoded enzymes involved in anthocyanin synthesis, namely, flavanone 3-hydroxylase (F3H) and dihydroflavonol 4-reductase (DFR), and showed reduced expression in the white flower phenotypes. Here, we identify another candidate gene for white phenotype in carnation flowers using an RNA-seq analysis followed by RT-PCR.