Effects of the new plant growth retardants of quaternary ammonium iodides on gibberellin biosynthesis in Gibberella fujikuroi

The effects of twelve quaternary ammonium iodides, synthesizedas plant growth relardants, on the biosynthesis of gibberellinsin the culture of Gibberella fujikuroi were investigated. Ofthe two compounds with the strongest growth-retarding activity,N,N,N-trimethyl-1-methyl-(3',3',5'-trimethylcydohexyl)-2-propenylammonium iodide (1) was found to inhibit the biosynthesis, whileN,N,N-trimethyl-l-methyl-(3',3',5'5'- tetramethylcyclohexyl)-2-propenylammonium iodide (2) was not. The results on examination of thetwelve analogues indicate that their plant growth-retardingactivity is not related to the inhibition of gibberellin biosynthesis. (Received July 18, 1978; )