Secondary metabolism in cultured red beet (Beta vulgaris L.) cells: Differential regulation of betaxanthin and betacyanin biosynthesis

Abstract

Red beet cell lines exhibiting a range of cell colours were generated from secondary callus via specific induction methods. Phenotype colour ranged from white/green through yellow, orange and red to deep violet, representing all types of pigments found in red beet plant. Specific phenotypes could only be obtained through specific induction sequences and once established were stabilised by cultivation on a maintenance medium. The ratio of auxin (2, 4-D) to cytokinin (6-BAP) was an important factor in the control of these processes. All coloured phenotypes were linked, but could be classified into two main groups, one yellow-red and the other orange-violet, according to their different cellular morphologies. A certain amount of instability still existed within each group. Modification of the growth regulator composition could be used to interchange specific combinations of coloured phenotypes, depending upon the initial state of cellular differentiation. Use of the DNA-methylation inhibitor 5-azacytidine demonstrated that methylation plays a key role in the repression of genes encoding enzymes involved in betacyanin biosynthesis. Furthermore, the poly(ADP-ribose) polymerase inhibitor 3-methoxybenzamide blocked the induction of the same gene set in a concentration dependent manner without affecting cell growth.

Phenotypic Plasticity of Vegetable Amaranth, Amaranthus tricolor L. under a Natural Climate

“…Betacyanins and betaxanthins were extracted from fresh amaranth leaves using 80% methanol containing 50 mM ascorbic acid according to Wyler et al (1959) and Girod and Zryd (1991), respectively, were measured spectrophotometrically at 540 and 475 nm, respectively. The quantifications were done using mean molar extinction coefficient (ε), which were 62 × 10 6 cm 2 mol -1 for betacyanin and 48 × 10 6 cm 2 mol -1 for betaxanthins.…”

Characterization and Functional Identification of a Novel Plant 4,5-Extradiol Dioxygenase Involved in Betalain Pigment Biosynthesis in Portulaca grandiflora

“…Pg buds (6-8 mm) were collected from vegetatively propagated clones obtained from quasi-isogenic lines established in our lab (Trezzini and Zrÿ d, 1990), their basal part were cut-off, and petals were extracted and frozen in liquid N 2 . Beet root calli cell cultures displaying different colors were selected from red beet (Beta vulgaris) Bikores monogerm (Girod and Zrÿ d, 1991b) and cultivated on a maintenance medium at 26°C with a 16-h photoperiod (light from GRO-LUX WSSYLVANIA, 6 mW m Ϫ2 ). We collected samples for the RNA extraction by vacuum filtration of suspension cultures; these samples were stored frozen at Ϫ80°C and ground in liquid N 2 just before extraction.…”

UV‐B‐ and oxidative stress‐induced increase in nicotinamide and trigonelline and inhibition of defensive metabolism induction by poly(ADP‐ribose)polymerase inhibitor in plant tissue

“…There are indications that PADPRP may influence secondary metabolism in plant tissues; when pigment-producing callus culture of red beet (Beta vulgaris) was treated with 3-AB (1 mM), there was a block in the pigment production [43]. Furthermore, it has been suggested that there is a connection between PADPRP and the expression of cytochrome P450 genes [44], because their expression was inhibited by PADPRP-inhibitor.…”