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Arabidopsis plasma membrane protein crucial for Ca²⁺ influx and touch sensing in roots

Author:
Nakagawa, Yuko, Katagiri, Takeshi, Shinozaki, Kazuo, Qi, Zhi, Tatsumi, Hitoshi, Furuichi, Takuya, Kishigami, Akio, Sokabe, Masahiro, Kojima, Itaru, Sato, Shusei, Kato, Tomohiko, Tabata, Satoshi, Iida, Kazuko, Terashima, Asuka, Nakano, Masataka, Ikeda, Mitsunobu, Yamanaka, Takuya, Iida, Hidetoshi
Source:
Proceedings of the National Academy of Sciences of the United States of America 2007 v.104 no.9 pp. 3639-3644
ISSN:
0027-8424
Subject:
Arabidopsis thaliana, roots, root growth, thigmotropism, membrane proteins, plasma membrane, calcium channels, calcium, physiological transport, complementary DNA, nucleotide sequences, gene expression, messenger RNA
Abstract:
Plants can sense and respond to mechanical stimuli, like animals. An early mechanism of mechanosensing and response is speculated to be governed by as-yet-unidentified sensory complexes containing a Ca²⁺-permeable, stretch-activated (SA) channel. However, the components or regulators of such complexes are poorly understood at the molecular level in plants. Here, we report the molecular identification of a plasma membrane protein (designated Mca1) that correlates Ca²⁺ influx with mechanosensing in Arabidopsis thaliana. MCA1 cDNA was cloned by the functional complementation of lethality of a yeast mid1 mutant lacking a putative Ca²⁺-permeable SA channel component. Mca1 was localized to the yeast plasma membrane as an integral membrane protein and mediated Ca²⁺ influx. Mca1 also increased [Ca²⁺]cyt upon plasma membrane distortion in ARABIDOPSIS: The growth of MCA1-overexpressing plants was impaired in a high-calcium but not a low-calcium medium. The primary roots of mca1-null plants failed to penetrate a harder agar medium from a softer one. These observations demonstrate that Mca1 plays a crucial role in a Ca²⁺-permeable SA channel system that leads to mechanosensing in ARABIDOPSIS: We anticipate our findings to be a starting point for a deeper understanding of the molecular mechanisms of mechanotransduction in plants.
Agid:
2351828