Establishment and characterization of a betaxanthin-producing cell culture from Portulaca grandiflora

Abstract

Cell cultures derived from three yellow flowering Portulaca grandiflora genotypes contained betacyanins rather than betaxanthins. A betaxanthin-producing cell culture was obtained by subculturing orange cell clusters isolated from the red-violet cell culture of a violet flowering P. grandiflora genotype. Selection of the most strongly yellow coloured cell material reduced the portion of betacyanins considerably and resulted in a P. grandiflora cell culture characterized by a high concentration of betaxanthins and the occurrence of free betalamic acid. Vulgaxanthin I was the main compound. Besides these pigments carotenoids and flavonoids were detectable.Betaxanthin biosynthesis strongly dependend on light. Product accumulation reached its maximum during the stationary phase of the growth cycle. Excretion of pigments, especially of betalains, could not be detected. Vulgaxanthin I as found in the cell culture was identical with one of two main betaxanthins in the yellow petals of P. grandiflora.The yellow P. grandiflora cells grew well on solid modified Murashige and Skoog medium but failed to grow in liquid medium after a few subcultures. In contrast, white P. grandiflora suspension cultures could be established repeatedly.

Isolation of Stable, Variously Colored Callus Lines in Portulaca sp. ‘Jewel’ and Analysis of Betalain Composition

“…However, different colors did only develop on media with different hormone contents. Yellow, betaxanthin-producing callus was also reported in Portulaca grandiflora (Bohm et al, 1991;Bohm and Bohm, 1996). In this communication, we report the isolation of diverse callus lines displaying yellow, orange and red colorization under identical culture conditions.…”

“…Reversion of betacyanin accumulation by methylation inhibitor treatment As summarized in Fig. 7, callus lines of different color could be isolated from a magenta line that (Bohm et al, 1991). It seems that cell cultures bring out of the all biosynthetic ability, not depend on original plant genotype.…”

Portulaca grandiflora Hook. and P. oleracea L.: Formation of Betalains and Unsaturated Fatty Acids

“…The following betaxanthins (the respective amino acid or amine residue in parentheses) were reported only in fiowers: portulaxanthin I (hydroxy proline, Fig. 3c), II (tyrosine), III (glycine), vulgaxanthin I (glutamine), II (glutamic acid), dopaxanthin (3,4 -dihydroxyphenylalanine), miraxanthin I (methionine sulfoxide), indicaxanthin (proline), and humulixanthin (5-hydroxynorvaline) (Piattelli et al 1965;Adachi and Nakatsukasa 1983;Strack et al 1987;Böhm et al 1991;Trezzini and Zryd 1991). Free betalamic acid could be detected in P. grandiflora petals, especia1ly together with betaxanthins (Kimler et al 1971;Reznik 1978;Adachi and Nakatsukasa 1983), but its presence obviously depends on the genotype (Adachi and Nakatsukasa 1983;Böhm et al 1991;Rink and Böhm 1991).…”

“…Mostly they led to callus formation, but cell cultures derived from this plant material could either not be obtained or were not studied in detail (Konar 1978;Böhm et al 1991).…”

Induction of Betacyanin Synthesis and Pigment Accumulation in Cell Suspension Cultures of Portulaca.

“…However, betalain producing cell suspension cultures have not been introduced to date. Betalainsynthesizing calli, when transferred to liquid medium, showed reduced growth with subsequent subcultures and eventually turned brown in colour and died (Bohm et al, 1991). Suspension cultures of P. oleracea subsp, sativa proved to be easily initiated and maintained but the cells remained colourless .…”