Role of phenylalanine in the biosynthesis of flavonoids and cinnamic acids in strawberry leaf disks

Abstract Alteration of the turnover of phenylalanine ammonia-lyase and cinnamic-4-hydroxylase in leaf disks actively synthesizing phenolics was accomplished by inhibition and by withholding substrate. Measurement of the result of these manipulations on the accumulation of cinnamic acids and flavonoids suggested that the ammonia-lyases are obligatory enzymes in phenolic synthesis but are not necessarily rate limiting.