Chemical substances controlling the leaf-movement of the plants: How does biological clock control the plant movement?

Many plants close their leaves in the evening like sleeping and open early in the morning. Such a circadian rhythm has been known to be controlled by their internal clock. Moreover, rapid seismonastic movement was also observed in Mimosa pudica L. Since Ricca's ingenious experiments suggested that some chemicals play an important role in leaf-movement of Mimosa pudica, many biologists and chemists have attempted to search for leaf-closing substances, and a number of compounds have been obtained, particularly, by Schildknecht et al. But, we have now demonstrated that the genuine leaf-movement factor of Mimosa is the mixture of three chemical substances, two of the three were identified as potassium L-malate and magnesium trans-aconitate. The mixture of these substances was effective at 10(-8)-10(-9) M. On the other hand, we have isolated chemical substances that control the nyctinastic leaf-movement from several nyctinastic plants. Each substance was effective at 10(-6)-10(-7) M only for the original plant, but not for other nyctinastic species. Thus, different leaf-movement factors exist in every nyctinastic plants,. This is contrary to the old theory establised by Schildknecht. This movement is controlled by the change in the balance of two inversely effective factors, leaf-closing and opening factor. MeOH-extracts of a nyctinastic plant, Lespedeza cuneata G. Don. collected in the daytime and at night showed inverse bioactivity. Thus, the balance of concentration between two leaf-movement factors in this plant which is controlled by biological clock was really inversed through a day. This mechanism for the control of nyctinastic movement is common among all nyctinastic plants.