Regulation of enzyme activities related to the biosynthesis of flavone glycosides in cell suspension culture of parsley ( Petroselinum hortense)

Abstract

1. 1. In cell suspension cultures of parsley ( Petroselinum hortense) the degree of increase of activity of phenylalanine ammonia-lyase caused by white light depends on the growth stage of the cultures. Maximum enzyme stimulation is observed at approximately the tenth day of growth. 2. 2. Changes in the activities of eight enzymes directly related to the biosynthesis of apiin ( 7-O-[β- D-apiofuranosyl -(1 → 2)-β- D-glucosyl ]-5,7,4′- trihydroxyflavone and graveobiosid B (3′-methoxyyapiin) were measured over a period of 24 h after illumination of cell suspension cultures of parsley. 3. 3. The enzymes investigated were phenylalanine ammonia-lyase, trans-cinnamic acid 4-hydroxylase, p-coumarete:CoA ligase, chalcone-flavanone isomerase, UDP-glucose:apigenin 7- O-glucosyltransferase, UDP-apiose:apigenin 7- O-glucoside-[1 → 2]-apiosyltransferase, UDP-apiose synthetasem and S-adenosylmethionine:luteolin3′- O-methyltransferase. 4. 4. Two groups of enzymes could be distinguished on the basis of their responses to light. The first group comprises the three enzymes acting on substrates of the phenylpropanoid type (phenylalanine, cinnamic acid and p-coumaric acid); the second group includes all those enzymes involved exclusively in the formation of flavonoid compounds and their glycosides. 5. 5. A hypothesis is discussed which would correlate three other enzymes assumed to take part in the same biosynthetic pathway with one of these groups of enzymes.