ISHS Acta Horticulturae 177: IV International Symposium on Flower Bulbs
Acta Hortic. 177: 375-384 (1986)
THE IDENTIFICATION OF ANTHOCYANIN PIGMENTS IN THE PETALS AS AN AID TO THE BREEDING OF GLADIOLUS
A. Cohen, N. Akavia, N. Umiel

Abstract:

Six anthocyanidins were identified in the petals of cultivated gladiolus using HPLC and utilizing known anthocyanidin standards extracted from specific plants.

These anthocyanidins (Pelargonidin, Cyanidin, Peonidin, Delphinidin, Petunidin and Malvidin) can be divided into three groups based on the number of radicals others than Hydrogen attached to the B ring. Two kinds of sugars are attaced to the aglycon: glucose and rhamnose; and these could appear in four different configurations giving a total of 24 pigmental variations.

Pigments of each group may appear individually or in conjunction with pigments from either or both groups, all pigments contributing their share to the visible color in the petals. Flowers having a single pigment in their petals were also found.

The study of flower-pigment inheritance should consider (a) the genetic factors responsible for the differences between groups (at least two biochemical steps are involved in the pathway determining the number of hydroxyl residues on the B ring); (b) the substitution of OCH3 for the hydroxyl (at the level of flavonoid precursors of anthocyanidins); and (c) the different levels of glycosylation producing the anthocyanin pigments. At least 20 steps are recognized in the tentative biochemical pathway having quantitative and qualitative impact on pigment content. The presence and absence, and the relative amounts of specific pigments of each group, depend on (1) biosynthetic blocks in the pathway, (2) the relative abundance of precursors and/or (3) the differences in the efficiency of precursor utilization brought about by their genetic state (e.g. heterozygosity level in the tetraploid cultivars). All these factors affect the results of crosses between selected parents. Specific parental clones containing a single pigment produce offspring lines having no pigmental variation and little or no difference in the visible color. This opens the possibility for F1 hybrid production in gladiolus.