THE GREENING PROCESS IN CRESS SEEDLINGS .5. POSSIBLE INTERFERENCE OF CHLOROPHYLL PRECURSORS, ACCUMULATED AFTER THUJAPLICIN TREATMENT, WITH LIGHT-REGULATED EXPRESSION OF LHC GENES
U. Oster et al., THE GREENING PROCESS IN CRESS SEEDLINGS .5. POSSIBLE INTERFERENCE OF CHLOROPHYLL PRECURSORS, ACCUMULATED AFTER THUJAPLICIN TREATMENT, WITH LIGHT-REGULATED EXPRESSION OF LHC GENES, Journal of photochemistry and photobiology.B, Biology, 36(3), 1996, pp. 255-261
Dark-grown cress seedlings were treated with beta-thujaplicin alone or
in combination with 5-aminolevulinate (ALA). This treatment induced a
nearly complete inhibition of protochlorophyllide (Pchlide) synthesis
and a significant accumulation of magnesium protoporphyrin monomethyl
ester (MgPPMe). Other porphyrins accumulated only in 48-h-old seedling
s but not in 72-h-old seedlings. Levels of several mRNAs were differen
tially affected by the pretreatment. The level of psbA and FOR transcr
ipts was either not affected in the dark (48-h-old seedlings) or only
slightly decreased (72-h-old seedlings) by thujaplicin treatment. The
moderate increase of the psbA transcript level by farred light was par
tly inhibited by thujaplicin in 48-h and 72-h-old seedlings. The level
of the Lhc mRNA was increased by thujaplicin treatment in the dark in
48-h-old seedlings, comparable with the level achieved by light induc
tion in the water controls. In contrast, the Lhc mRNA level in 72-h-ol
d seedlings was slightly decreased by thujaplicin and the subsequent l
ight induction was inhibited by about 50%. This inhibition of light in
duction was found for all investigated single Lhc genes. Differential
interference by Chl precursors other than Pchlide with Lhc gene expres
sion is discussed.