Treatment of opium poppy (Papaver somniferum L.) cell cultures with au
toclaved mycelial homogenates of Botrytis sp. resulted in the accumula
tion of sanguinarine. Elicitor treatment also caused a rapid and trans
ient induction in the activity of tyrosine/dopa decarboxylase (TYDC, E
C 4.1.1.25), which catalyzes the conversion of L-tyrosine and L-dopa t
o tyramine and dopamine, respectively, the first steps in sanguinarine
biosynthesis. TYDC genes were differentially expressed in response to
elicitor treatment. TYDC1-like mRNA levels were induced rapidly but d
eclined to near baseline levels within 5 h. In contrast, TYDC2-like tr
anscript levels increased more slowly but were sustained for an extend
ed period. Induction of TYDC mRNAs preceded that of phenylalanine ammo
nia-lyase (PAL, EC 4.3.1.5) mRNAs. An elicitor preparation from Pythiu
m aphanidermatum was less effective in the induction of TYDC mRNA leve
ls and alkaloid accumulation; however, both elicitors equally induced
accumulation of PAL transcripts. In contrast, treatment with methyl ja
smonate resulted in an induction of TYDC but not PAL mRNAs. The calmod
ulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and
the protein kinase inhibitor staurosporine partially blocked the fung
al elicitor-induced accumulation of sanguinarine. However, only stauro
sporine and okadaic acid, an inhibitor of protein phosphatases 1 and 2
A, blocked the induction of TYDC1-like transcript levels, but they did
not block the induction of TYDC2-like or PAL transcript levels. These
data suggest that activation mechanisms for PAL, TYDC, and some later
sanguinarine biosynthetic enzymes are uncoupled.