AtDSEL, an Arabidopsis cytosolic DAD1-like acylhydrolase, is involved in negative regulation of storage oil mobilization during seedling establishment |
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Authors: | Kim Eun Yu Seo Young Sam Kim Woo Taek |
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Institution: | Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea |
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Abstract: | Mobilization of seed storage reserves is essential for seed germination and seedling establishment. Here, we report that AtDSEL, an Arabidopsis thalianaDAD1-like Seedling Establishment-related Lipase, is involved in the mobilization of storage oils for early seedling establishment. AtDSEL is a cytosolic member of the DAD1-like acylhydrolase family encoded by At4g18550. Bacterially expressed AtDSEL preferentially hydrolyzed 1,3-diacylglycerol and 1-monoacylglycerol, suggesting that AtDSEL is an sn-1-specific lipase. AtDSEL-overexpressing transgenic Arabidopsis plants (35S:AtDSEL) were defective in post-germinative seedling growth in medium without an exogenous carbon source. This phenotype was rescued by the addition of sucrose to the growth medium. In contrast, loss-of-function mutant plants (atdsel-1 and atdsel-2) had a mildly fast-growing phenotype regardless of the presence of an exogenous carbon source. Electron microscopy revealed that 5-day-old 35S:AtDSEL cotyledons retained numerous peroxisomes and oil bodies, which were exhausted in wild-type and mutant cotyledons. The impaired seedling establishment of 35S:AtDSEL was not rescued by the addition of an exogenous fatty acid source, and 35S:AtDSEL seedling growth was insensitive to 2,4-dichlorophenoxybutyric acid, indicating that β-oxidation was blocked in AtDSEL-overexpressers. These results suggest that AtDSEL is involved in the negative regulation of seedling establishment by inhibiting the breakdown of storage oils. |
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Keywords: | 2 4-D 2 4-dichlorophenoxyacetic acid 2 4-DB 2 4-dichlorophenoxybutyric acid DAG diacylglycerol DGDG digalactosyldiacylglycerol GFP green fluorescent protein 1-LPC 1-lysophosphatidylcholine MAG monoacylglycerol MGDG monogalactosyldiacylglycerol PC phosphatidylcholine TAG triacylglycerol |
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