Ms. Tian et al., RECOVERY OF ETHYLENE BIOSYNTHESIS IN DIAZOCYCLOPENTADIENE (DACP)-TREATED TOMATO FRUIT, Plant growth regulation, 22(2), 1997, pp. 73-78
Diazocyclopentadiene (DACP), a competitive ethylene action inhibitor b
inds irreversibly to the ethylene receptor to reduce tissue responses
to ethylene. Tomato fruit (Lycopersicon esculentum Mill cv 'Rondello')
were treated with DACP at the mature green stage. Ethylene biosynthes
is and respiration rate were depressed. Color changes from green to re
d were delayed. Compared to the control, ACC content increased and ACC
oxidase activity in vivo decreased in DACP-treated fruit. Thus, decre
ase of ethylene production caused by DACP treatment was due to the red
uction of ACC oxidase activity. The decline in ripening subsequently r
ecovered after DACP treatment. Results from the Northern analysis for
gene expression of ACC synthase and ACC oxidase, showed that expressio
n of both genes declined in DACP-treated fruit, and then recovered. Th
erefore the recovery of ethylene production was due to the recovery in
gene expression and activity of ACC oxidase. We conclude that the eff
ects of DACP on ethylene biosynthesis are on expression of ACC synthas
e and ACC oxidase genes, and/or regulation of ACC oxidase activity.