Abstract
MCA1 is identified candidates for the Ca2+-permeable mechanosensitive channel in Arabidopsis thaliana, and MCA2 is the only paralog of MCA1. In the roots, Ca2+ uptake activity is lower in the roots of mca2 than those of wild type, while there is no significant change in Ca2+ uptake activity between mca1 and wild type. MCA1 is expressed in the whole region of primary root, and MCA2 is expressed only in the elongation zone of primary root.
In this paper, we kinematically analyzed the root growth of mca1, mca2 and mca1mca2 double mutant. The analyses showed that there was no significant change in the root growth of mca1 compared to that of wild type plant, however the cell size and cell volume growth rate of mca2 is lower than those of wild type in root elongation zone. The region where the root growth of mca2 decreased is consistent with the expression pattern of MCA2. mca1mca2 also showed a decrease in cell size and cell volume growth rate in the same region, but the degree of decrease is less than that of mca2. These results suggest that the Ca2+ uptake by MCA2 directly affects the primary root growth, and MCA1 may mediate some signal by a slight Ca2+ uptake.
