Bioorganic chemistry of nyctinastic leaf-movement using synthetic probe compounds

Most legumes close their leaves in the evening, as if to sleep, and open them in the morning. This is called nyctinasty, and such a circadian rhythmic movement has been known to be controlled by their biological clocks. We have identified several bioactive substances that regulate this leaf-movement, and our recent studies revealed the mechanism for the control of nyctinasty by the biological clock. In this review, we will show two examples of our attempts for the bioorganic study of plant leaf-movement using synthetic probe compounds. One is the direct observation of the target cell for leaf-movement factor by fluorescence-labeled probe compounds and the other is the chemical studies on the historical problem, "Why does the plant sleep?", by artificial leaf-opening substance.