Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in arabidopsis
Date
2011
Authors
Conn, S.
Gilliham, M.
Athman, A.
Schreiber, A.
Baumann, U.
Moller, I.
Cheng, N.
Stancombe, M.
Hirschi, K.
Webb, A.
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Advisors
Journal Title
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Volume Title
Type:
Journal article
Citation
The Plant Cell, 2011; 23(1):240-257
Statement of Responsibility
Simon J. Conn, Matthew Gilliham, Asmini Athman, Andreas W. Schreiber, Ute Baumann, Isabel Moller, Ning-Hui Cheng, Matthew A. Stancombe, Kendal D. Hirschi, Alex A. R. Webb, Rachel Burton, Brent N. Kaiser, Stephen D. Tyerman, and Roger A. Leigh
Conference Name
Abstract
The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca2+ transporters, CAX1 (Ca2+/H+-antiporter), ACA4, and ACA11 (Ca2+-ATPases), were identified as preferentially expressed in Ca-rich mesophyll. Analysis of respective loss-of-function mutants demonstrated that only a mutant that lacked expression of both CAX1 and CAX3, a gene ectopically expressed in leaves upon knockout of CAX1, had reduced mesophyll [Ca]. Reduced capacity for mesophyll Ca accumulation resulted in reduced cell wall extensibility, stomatal aperture, transpiration, CO2 assimilation, and leaf growth rate; increased transcript abundance of other Ca2+ transporter genes; altered expression of cell wall–modifying proteins, including members of the pectinmethylesterase, expansin, cellulose synthase, and polygalacturonase families; and higher pectin concentrations and thicker cell walls. We demonstrate that these phenotypes result from altered apoplastic free [Ca2+], which is threefold greater in cax1/cax3 than in wild-type plants. We establish CAX1 as a key regulator of apoplastic [Ca2+] through compartmentation into mesophyll vacuoles, a mechanism essential for optimal plant function and productivity.
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Data source: Supplementary information, http://www.plantcell.org/content/23/1/240/suppl/DC1
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© 2011 American Society of Plant Biologists