Abstract
Two cell lines of Daucus carota were investigated. They differ in their capacity to synthesize cyanidin–gluco–xylosides.
One cell line is yellowish the other one is deep violet. This anthocyanin accumulation
can he inhibited by gibberellic acid A
3. The reaction is concentration dependent. The inhibitory effect cannot be ascribed
to a reduced capacity for precursor uptake. Both
14
C–acetate and
14
C–phenylalanine are incorporated at the same rate after GA3 treatment. The very important enzyme of the anthocyanin pathway, the phenylalanine-ammonia-lyase,
(PAL) is not inhibited directly in vitro.
The enzyme activity of the PAL is reduced drastically in the white cell line to 15 %
compared with the control. One of the following enzymes the hydroxycinnamate–CoA ligase
shows a similar reduction.
The alteration of the pathway described here are an example for a possible manipulation
of plant tissue cultures. The GA
3
has to be considered as a trigger and the anthocyanin synthesis has to be regarded
as a pointer for alterations of the pathway within the cell.
