Plant mechanosensing and Ca2+ transport.

Mechanical stimuli generate Ca(2+) signals and influence growth and development in plants. Recently, candidates for Ca(2+)-permeable mechanosensitive (MS) channels have been identified. These channels are thought to be responsible for sensing osmotic shock, touch, and gravity. One candidate is the MscS-like (MSL) protein family, a homolog of the typical bacterial MS channels. Some of the MSL proteins are localized to plastids to maintain their shape and size. Another candidate is the mid1-complementing activity (MCA) protein family, which is structurally unique to the plant kingdom. MCA proteins are localized in the plasma membrane and are suggested to be involved in mechanosensing and to be functionally related to reactive oxygen species (ROS) signaling. Here, we review their structural features and role in planta.