Manipulation, by nutrient limitation, of the biosynthetic activity of immobilized cells of Capsicum frutescens Mill. cv. annuum.
The relationship between the synthesis and accumulation of protein and capsaicin was investigated in cultured cells of Capsicum frutescens Mill. cv. annuum immobilized in reticulate polyurethane. Cells were cultured in media containing reduced concentrations of essential nutrients, in an attempt to manipulate the rates of protein synthesis. Cells cultured in the absence of orthophosphate for 7 d demonstrated no reduction in the incorporation of L-[U-(14)C]phenylalanine into soluble protein or an increase in incorporation into capsaicin, compared with controls supplied with orthophosphate. By day 15 of culture, however, a differential incorporation of label was observed. Over a 21-d culture period the intracellular phosphate did not completely disappear. Cells cultured in the absence of nitrate and phosphate combined, however, exhibited some reduction in incorporation of [(14)C]phenylalanine into protein and an increased incorporation into capsaicin after 7 d of culture, but the differences were greater at day 15, when increases in the total capsaicin content of the cultures were apparent. There was observed a relationship between the intracellular nitrate concentration, the culture growth index, and the incorporation of [(14)C]phenylalanine into soluble protein - each of these factors was inversely related to the incorporation of label into capsaicin and the total capsaicin content of the cultures.
Department of Botany, University of Edinburgh, The King's Buildings, Mayfield Road, EH9, Edinburgh, UK.
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Lindsey