A stretch-activated calcium-permeable channel in Arabidopsis

Abstract

Stretch-activated (SA) or mechanosensitive (MS) channels are important for sensing touch, stretch, compression and turgor in the development and physiology of plants. However, the molecular nature of plant SA channels has been unknown. In this symposium, we show the molecular identification of an SA channel in Arabidopsis thaliana. The Arabidopsis cDNA encoding this channel was isolated by functional complementation of the yeast mid1 mutant defective in a putative SA channel and the corresponding gene was designated AtMID1A. Patch-clamp analysis showed that AtMid1A had an SA channel activity. In addition, AtMid1A expressed in mammalian cells elicited a rise in cytosolic calcium concentration in response to membrane stretch. AtMid1A-overexpression plants were unable to grow on high-calcium media. The primary root of atmid1a-knockout plants was incapable to penetrating into a harder agar medium from a softer agar medium, suggesting that AtMid1A is required for touch sensing and response.