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|Title:||Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in arabidopsis|
|Citation:||Plant Cell, 2011; 23(1):240-257|
|Publisher:||Amer Soc Plant Physiologists|
|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|
|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.|
|Keywords:||Cell Wall; Vacuoles; Arabidopsis; Plant Leaves; Calcium; Antiporters; Cation Transport Proteins; Arabidopsis Proteins; RNA, Plant; Oligonucleotide Array Sequence Analysis; Gene Expression Profiling; Mutagenesis, Insertional; Gene Expression Regulation, Plant; Phenotype; Mutation; Plant Stomata; Single-Cell Analysis|
|Rights:||© 2011 American Society of Plant Biologists|
|Appears in Collections:||Agriculture, Food and Wine publications|
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