Journal Article

Toxicity of Free Proline Revealed in an <i>Arabidopsis</i> T-DNA-Tagged Mutant Deficient in Proline Dehydrogenase

Tokihiko Nanjo, Miki Fujita, Motoaki Seki, Tomohiko Kato, Satoshi Tabata and Kazuo Shinozaki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 44, issue 5, pages 541-548
Published in print May 2003 | ISSN: 0032-0781
Published online May 2003 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcg066
Toxicity of Free Proline Revealed in an Arabidopsis T-DNA-Tagged Mutant Deficient in Proline Dehydrogenase

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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The toxicity of proline (Pro) to plant growth has raised questions despite its protective functions in response to environmental stresses. To evaluate Pro toxicity, we isolated an Arabidopsis T-DNA-tagged mutant, pdh, that had a defect in Pro dehydrogenase (AtProDH), which catalyzes the first step of Pro catabolism. The pdh mutant showed hypersensitivity to exogenous application of ≤10 mM l-Pro, at which wild-type plants grew normally. A dose-dependent increase in internal free Pro accumulation was observed in pdh plants during external Pro supply. These results do not just prove the toxicity of Pro, but also suggest that AtProDH is the only enzyme acting as a functional ProDH in Arabidopsis. To further analyze the targets of Pro toxicity, we compared the expression of thousands of genes by pdh plants with that by wild-type plants by cDNA microarray analysis. Most genes were unaffected. Here we demonstrate Pro toxicity by using the pdh mutant and discuss a cause-and-effect action between an excess of free Pro and growth inhibition in Arabidopsis.

Keywords: Keywords: cDNA microarray — Proline toxicity — Proline dehydrogenase — T-DNA-tagged mutant.; Abbreviations: Pro, proline; P5C, Δ1-pyrroline-5-carboxylate; P5CS, P5C synthase; ProDH/PDH, proline dehydrogenase; P5CDH, P5C dehydrogenase.

Journal Article.  4970 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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