Calcium-permeable stretch-activated channel component. Involved in mechano-stimulated calcium uptake mechanism and in mechanosensing in the primary root. Inhibited by GdCl(3), but not by verapamil. Expressed in roots, leaves, stems, flowers and siliques. Expressed in vascular tissues of cotyledons, leaves and primary root, in the promeristem and adjacent elongation zone of the primary root and in the shoot apical meristem. Detected in the stele and endodermis, but not in the cortex, epidermis or root cap, including the columella. Not expressed in root hairs or in mesophyll cells of leaves and cotyledons. No visible phenotype when grown under normal conditions; due to partial redundancy with MCA2. The roots are unable to sense a change in the hardness of the growth medium. Mca1 and mca2 double mutant shows a strong growth defect.