Snapdragon, Antirrhinum

SMARTWEED Pofygonum lapathifoUum) SNAPDRAGON Antirrhinum majus L.) SORGHUM Sorghum vulgare Pers.)... 

Flavone synthase (FNS EC 1.14.11.22) introduces a double bond between C2 and C3 of a flavanone to produce the corresponding flavone. This activity was initially identified in parsley cell suspension cultures and subsequently shown to be encoded by a 2-oxoglutarate-dependent dioxygenase [67, 78, 79], This enzyme, now known as FNS-I, appears to have very limited distribution. To date, it has only been identified in the Apiaceae family (Umbellifers). The more widely occurring FNS-II (CYP93B) was initially identified from snapdragon (Antirrhinum majus) flowers [80] and was subsequently shown to be a P450 enzyme. FNS-I, FNS-II, and the various roles flavones play in plant species have recently been reviewed by Martens and Mithofer [81], Subsequent to this review, Yu et al. [82] demonstrated that the characteristic lack of natural accumulation of flavones in Brassicaceae could not be overcome in A. thaliana even by overexpression of recombinant parsley FNS-I. 

Maize mutants with altered flavonoid metabolism can also be identified based on variation in color, either of the seeds, the vegetative parts of the plant, or the floral structures (anthers and silks). Petunia (Petunia hybrida) and snapdragon (Antirrhinum majus) have also been widely used as model species for the elucidation of flavonoid biosynthesis (reviewed by Winkel-Shirley, 2001). In the description of genes involved in flavonoid biosynthesis presented in this section, the emphasis will be on maize and Arabidopsis. 

ODELL, E., RAGUSO, R. A., JONES, K. N., Bumblebee foraging responses to variation in floral scent and color in snapdragons (Antirrhinum Scrophulariaceae)., Am. Midi. Nat., 1999,142,257-265. 

Rose-of-Sharon, Hibiscus Salvia, Salvia Sapphire flower, Browallia Sedum, Sedum Shrub verbena, Lantana Silk tree, Albizia Snakeroot, Cimicifuga Snapdragon, Antirrhinum Speedwell, Veronica Spindle tree, Euonymus Spirea. Spiraea Spruce, Picea Spurge, Euphorbia, Pachysandra Stonecrop, Sedum Strawflower, Helichrysum Sunflower, Helianthus... 

However, the flavanone naringenin (10) [but not dihydro-kaempferol (13)] is the substrate for flavone formation in snapdragons. Antirrhinum majus (Scrophulariaceae) (flavone synthase II) (Fig. 11.10). In this plant, flavones arise from dehydrogenation of flavanones and not from dehydration of dihydroflavonols (Britsch et al., 1981). A similar enzyme system converts dihydroflavonols to flavonols (Britsch et al., 1981). In other work, the enzyme responsible for oxidation of flavanones to flavones in snapdragon Antirrhinum majus) was isolated from a microsomal fraction and shown to require NADPH and molecular oxygen (Britsch et al., 1981 Dewick, 1989 Forkmann and Stotz, 1981). The system appears to be a cytochrome P-450-dependent monooxygenase. This system also is known from Glycine max... 

Aurones are found in a number of flowers of some Scrophulariaceae (e.g., snapdragon [Antirrhinum majus]) and Compositae (e.g.. Coreopsis, Cosmos, and Dahlia). The yellow snapdragon flower is probably one of the best sources of aurones in the vacuoles of the epidermal cells of the flowers. In some other plant species, however, aurones are also found in the bark, wood, leaves, seedlings, and nectar. In 2001, the occurrence of aurone (4 -chloroaurone) in marine organisms has been reported [187]. However, its stmcture was revised to 3-(4 -chloroisocoumarin) later [188]. 

Chalcones, dihydrochalcones and aurones are not particularly important components of plant food materials, but they occur as notable pigments of flowers of many ornamental plants, such as the common snapdragon Antirrhinum spp., Scrophulariaceae) (Asteraceae), cosmos Cosmos spp.) and dahlia Dahlia spp.) from the Asteraceae family. Chalcones are also pigments of legume seeds (9-99) and woods. Prenylated chalcones are found in hop cones (10-98). 

Stotz G, Forkmann G (1981) Oxidation of flavanones to flavones with flower extracts of Antirrhinum majus (snapdragon). Z Naturforsch 36C 737-741... 

WRIGHT, G. A., SKINNER, B. D., SMITH, B. H., Ability of honeybee, Apis mellifera, to detect and discriminate odors of varieties of canola (Brassica rapa and Brassica napus) and snapdragon flowers (Antirrhinum majus)., J. Chem. Ecol., 2002,28, 721-740. 

Snapdragon. See Antirrhinum Soap sprays, 463,464,483-84 Sod crops, pests and, 418... 

Forkmann, G. and G. Stotz, Genetic control of flavanone 3-hydroxylase activity and flavonoid 3 -hydroxylase activity in Antirrhinum majus (snapdragon), Z. Naturforsch., 36c, 411-416 (1981). 

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