Plant nyctinasty – who will decode the ‘Rosetta Stone’?

Nyctinasty is the circadian rhythmic nastic movement of leguminous plants in response to the onset of darkness, a unique and intriguing phenomenon that has attracted attention for centuries. The movement itself is caused by the asymmetric volume change of motor cells between the adaxial and abaxial sides of the leaflet. Recently, we identified the ion channels responsible for the volume change of motor cells during the leaf-opening process of Samanea saman; the asymmetric expression of SsSLAH1, which is under the control of SsCCA1, was found to play a key role in this process. Here, we summarize the history of the study of nyctinasty, our current results and several insights for further study.