1. Hypersensitivity of an Arabidopsis sugar signaling mutant toward exogenous proline application.
- Author
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Hellmann H, Funck D, Rentsch D, and Frommer WB
- Subjects
- Arabidopsis genetics, Arabidopsis growth & development, Enzyme Inhibitors pharmacology, Gene Expression Regulation, Plant drug effects, Glucuronidase genetics, Phosphoprotein Phosphatases antagonists & inhibitors, Proline antagonists & inhibitors, Promoter Regions, Genetic, Sorbitol pharmacology, Arabidopsis metabolism, Carbohydrate Metabolism, Mutation, Proline pharmacology
- Abstract
In transgenic Arabidopsis a patatin class I promoter from potato is regulated by sugars and proline (Pro), thus integrating signals derived from carbon and nitrogen metabolism. In both cases a signaling cascade involving protein phosphatases is involved in induction. Other endogenous genes are also regulated by both Pro and carbohydrates. Chalcone synthase (CHS) gene expression is induced by both, whereas the Pro biosynthetic Delta(1)-pyrroline-5-carboxylate synthetase (P5CS) is induced by high Suc concentrations but repressed by Pro, and Pro dehydrogenase (ProDH) is inversely regulated. The mutant rsr1-1, impaired in sugar dependent induction of the patatin promoter, is hypersensitive to low levels of external Pro and develops autofluorescence and necroses. Toxicity of Pro can be ameliorated by salt stress and exogenously supplied metabolizable carbohydrates. The rsr1-1 mutant shows a reduced response regarding sugar induction of CHS and P5CS expression. ProDH expression is de-repressed in the mutant but still down-regulated by sugar. Pro toxicity seems to be mediated by the degradation intermediate Delta(1)-pyrroline-5-carboxylate. Induction of the patatin promoter by carbohydrates and Pro, together with the Pro hypersensitivity of the mutant rsr1-1, demonstrate a new link between carbon/nitrogen and stress responses.
- Published
- 2000
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