Light-inducible pigmentation in Portulaca callus; selection of a high betalain producing cell line

Abstract

We have established a unique betalain pigmentation system in callus cultures that originated from seedlings of Portulaca sp. 'Jewel'. Within three different 'Jewel' lines examined, one line (JR) was clearly superior with regard to callus growth rate and pigment formation. Furthermore, after ten cycles of selection of deeply colored callus patches, the selected clones contained on an average four times the amount of betalain as compared to the non-selected mother line. The colorization was induced by light, but disappeared in the dark. Pigment synthesis was detectable within 30 h after irradiation and showed positive correlation with irradiation periods.

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

“…Explants from seedlings and developed plants of P. grandifiora genotypes rich in betacyanins produced primary calli with red-violet and white cell clusters on suitable media under the influence oflight (Adachi 1970;Endress 1976;Liebisch and Böhm 1981;Kishima et al 1991a). Corresponding to general experience (Böhm 1981), colored cells occurred on explants with and without betacyanins, e.g., hypocotyls and cotyledons, respectively (Fig.…”

“…6) grew twice as much on the latter medium than on the former during three to four subcultures after the removal of explants Böhm 1984, 1995). MS and B5 media were recently confirmed to be useful for the initiation of cell cultures from P. grandifiora seedlings (Kishima et al 1991a).…”

“…The quantification of betacyanins and betaxanthins in cultivated cells was carried out by calculating the extinctions of extracts on a fresh weight (Kishima et al 1991a), dry weight, or protein basis (Endress 1976;Böhm 1984, 1995;Böhm et al 1991). Absolute betalain concentrations are seldom determined since it is difficult to crystallize individual substances and to prevent their decomposition.…”

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

“…Betalain accumulation has been demonstrated in cultured cells of P. grandiflora (Schroder and Bohm, 1984;Trezzini and Zryd, 1990) and Portulaca sp. 'Jewel' (Adachi, 1970;Kishima et al, 1991) by using callus cultures. However, betalain producing cell suspension cultures have not been introduced to date.…”

“…Suspension cultures of P. oleracea subsp, sativa proved to be easily initiated and maintained but the cells remained colourless . In the present study, we used the variety `Jewel' of Portulaca sp., a genotype that can be induced to produce betalain in callus cultures (Adachi, 1970;Kishima et al, 1991), to establish cell suspension and, for the first time, …”