| Summary: | Several
elevated levels of nitrogen and phosphate at varying pH of the medium which
impart a major influence on callus and biomass development and subsequent
production of alkaloids was investigated using suspension culture system of Catharanthus roseus in the present
study. The B5 medium was buffered at pH 4.51, 5.82 and 7.32 by addition of
different levels of (A) diammonium hydrogen phosphate (NH4)2HPO4
and (B) ammonium dihydrogen orthophosphate (NH4H2PO4)
representing the enhanced and varied supply of total nitrogen (NH4++NO3ˉ)
and phosphate compared to MS medium (as control) for cell biomass production
and alkaloid yield. The pH of the medium have shown significant effects with
maximum biomass fresh wt., dry wt. and total alkaloid yield at 5.82 medium pH
with elevated phosphate levels and total nitrogen concentration of 3710.10 mg/L
compared to control MS medium with 2850 mg/L total nitrogen. At 3667.33 and
3752.48 mg/L of total nitrogen with enhanced phosphate supply showed reduced
biomass fresh wt., dry wt. and total alkaloid yield at lower (4.51) and higher
(7.32) medium pH respectively. Inclusion of 200 mg/L of tryptophan or
phenylalanine as reduced nitrogen source in B5 medium buffered at 5.82 ± 0.2 pH
showed enhanced biomass and alkaloid production. Hence, addition of nitrogen,
phosphate, tryptophan, phenylalanine as nutrient in suspension culture
stimulate their uptake to enhance cell biomass and total alkaloids production
but as a function of pH of the medium.
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