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DEVELOPMENT AND HORMONE ACTION

Apyrases (Nucleoside Triphosphate-Diphosphohydrolases) Play a Key Role in Growth Control in Arabidopsis^1,[W],[OA]

Section of Molecular Cell and Developmental Biology, University of Texas, Austin, Texas 78712 (J.W., Y.S., T.B., J.T., D.A., A.G., S.R., S.J.R.); and Section of Molecular Biotechnology, Technical University of Dresden, 01069 Dresden, Germany (I.S., F.J.)

Expression of two Arabidopsis (Arabidopsis thaliana) apyrase (nucleoside triphosphate-diphosphohydrolase) genes with high similarity, APY1 and APY2, was analyzed during seedling development and under different light treatments using -glucuronidase fusion constructs with the promoters of both genes. As evaluated by -glucuronidase staining and independently confirmed by other methods, the highest expression of both apyrases was in rapidly growing tissues and/or tissues that accumulate high auxin levels. Red-light treatment of etiolated seedlings suppressed the protein and message level of both apyrases at least as rapidly as it inhibited hypocotyl growth. Adult apy1 and apy2 single mutants had near-normal growth, but apy1apy2 double-knockout plants were dwarf, due primarily to reduced cell elongation. Pollen tubes and etiolated hypocotyls overexpressing an apyrase had faster growth rates than wild-type plants. Growing pollen tubes released ATP into the growth medium and suppression of apyrase activity by antiapyrase antibodies or by inhibitors simultaneously increased medium ATP levels and inhibited pollen tube growth. These results imply that APY1 and APY2, like their homologs in animals, act to reduce the concentration of extracellular nucleotides, and that this function is important for the regulation of growth in Arabidopsis.

² These authors contributed equally to the article.

³ Present address: Carnegie Institution of Washington, 260 Panama Street, Stanford, CA 94305–4101.

⁴ Present address: University Hospital of Zurich, Raemistr. 100, 8091 Zurich, Switzerland.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Stanley J. Roux (sroux{at}uts.cc.utexas.edu).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.107.097568

^* Corresponding author; e-mail sroux{at}uts.cc.utexas.edu; fax 512–232–3402.

Received February 5, 2007; accepted April 2, 2007; published April 13, 2007.

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Plant Physiol. 2007 144: 535-536. [Full Text]