Coronatine, a Bacterial Phytotoxin, acts as a Stereospecific Analog of Jasmonate Type Signals in Tomato Cells and Potato Tißues

Coronatine was investigated in order to find its primary target in the biosynthesis of ethylene in cell suspension cultures of Lycopersicon peruvianum (L. p.) and Lycopersicon esculentum (L. e.). A stimulation of the ethylene forming enzyme (EFE) beginning after 30 to 60 minutes of the experiments and a decrease of the endogenous ACC-pool beginning after about 2 hours were detected, but could not be shown to be the primary effect of the toxin. Methyl jasmonate (Ja-Me) was tested in the same kind of experiments because of structural similarities with coronatine and gave effects similar to the toxin in contrast to auxin. Methyl (+)-epijasmonate was separated from its three other stereoisomers to confirm the structure activity relationship according to coronatine. Typical biotests for the toxin (hypertrophy of potato tuber tißue) as well as for the plant growth regulator (tuber induction at potato stolons) showed similar effects of coronatine and jasmonates in every case. Some structurally related compounds were tested in the cell culture system and implications for the mode of action are discußed.