Effect on phenylalanine ammonia-lyase

The presence or absence of phosphate ions plays an important role in the expression and accumulation of some secondary products. Zenk et al. (47) have demonstrated a 50% increase in anthraquinone accumulation in cell cultures of Morinda citrofolia when phosphate was increased to a concentration of 5g7h In suspension cultures of Catharanthus roseus, the overall accumulation of secondary metabolites like tryptamine and indole alkaloids has been shown to occur rapidly when cells were shifted to a medium devoid of phosphate (48,49). A study on the uptake of phosphate and its effect on phenylalanine ammonia lyase and the subsequent accumulation of cinnamoyl putrescine in cell suspension cultures of Nicotiana tabacum demonstrated marked sensitivity to phosphate concentration (5DX Enhanced phenylalanine ammonia lyase activity and increased production of cinnamoyl putrescine was induced by subculture onto phosphate-free medium while suppression of these effects and stimulation of growth was observed with phosphate concentrations of 0.02-0.5uM. Interestingly, phenylalanine ammonia lyase activity is stimulated by increasing phosphate concentrations in cell suspension of Catharanthus roseus (51). 

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