GENETICS, BIOSYNTHESIS AND MOLECULAR BIOLOGY OF FLOWER COLOUR OF DIANTHUS CARYOPHYLLUS (CARNATION)

The present commercial carnation strains express a high variety of colours including white, yellow, orange and a number of different red hues.
In addition, unstable expression of flower colour is known leading to pigmented stripes or spots on an otherwise white, yellow or pale coloured background.

Pigmentation in carnation is caused by flavonoids and the closely related chalcones (Fig. 1). The main end products are anthocyanin glucosides based on pelargonidin (Pg) and cyanidin (Cy) and flavonol derivatives based on kaempferol (Km) and quercetin (Qu). In addition, in yellow and orange strains, the chalcone isosalipurposide is accumulated (Fig. 1).

The biosynthetic pathway to anthocyanins and flavonols is well-known (Heller and Forkmann, 1994). It starts with the condensation of 4-coumaroyl-CoA with 3 molecules malonyl-CoA, catalyzed by the enzyme chalcone synthase (CHS, Fig. 1). In carnation, this step is most probably controlled by the gene Y. Recessive alleles of this gene are known to reduce strongly flavonoid formation leading to very pale pink or pale yellow flower colour (Geissman and Mehlquist, 1947). Enzymatic measurements revealed that the respective lines (e.g. the strain "Maiella") only express very little CHS activity.

Ornamental Plant Improvement: Classical and Molecular

G. Forkmann, J. Dedio, J. Henkel, B. Min, M. Wassenegger

https://doi.org/10.17660/ActaHortic.1995.420.6