Journal Article

Expression of an <i>Oncidium</i> Gene Encoding a Patatin-Like Protein Delays Flowering in Arabidopsis by Reducing Gibberellin Synthesis

Chih-Ching Lin, Chung-Fu Chu, Pu-Huan Liu, Hsin-Hung Lin, Shih-Chien Liang, Wei-En Hsu, Jeng-Shane Lin, Hsin-Mei Wang, Ling-Lan Chang, Ching-Te Chien and Shih-Tong Jeng

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 52, issue 2, pages 421-435
Published in print February 2011 | ISSN: 0032-0781
Published online January 2011 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcq206
Expression of an Oncidium Gene Encoding a Patatin-Like Protein Delays Flowering in Arabidopsis by Reducing Gibberellin Synthesis

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

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The involvement of lipase in flowering is seldom studied, and this research provides evidence that fatty acids produced by lipase affect flowering. OSAG78 encoding a patatin-like protein was isolated from Oncidium Gower Ramsey. OSAG78 fused with green fluorescent protein was found to localize at the cell membrane. Transgenic Arabidopsis overexpressing OSAG78 demonstrated higher lipase activity than the wild-type control. In addition, the amount of free linoleic acid and linolenic acid in transgenic Arabidopsis was found to be higher than that in the wild type. Transgenics overexpressing OSAG78 exhibited altered phenotypes, including smaller leaves and rounder flowers, and also demonstrated a late flowering phenotype that could be rescued by gibberellin A3 (GA3) application. Several flowering-related genes were analyzed, indicating that the expression of gibberellin-stimulated genes was decreased in the plants overexpressing OSAG78. Also, the expression of AtGA2ox1, AtGA3ox1 and AtGA20ox1 genes encoding GA2-, GA3- and GA20-oxidases, respectively, which are mainly responsible for gibberellin metabolism, was decreased, and the level of GA4, a bioactive gibberellin, measured by gas chromatography–mass spectrometry was also reduced in the overexpressing lines. Furthermore, the expression levels of AtGA3ox1 and AtGA20ox1 were significantly decreased in wild-type Arabidopsis treated with linoleic acid, linolenic acid or methyl jasmonate. The membrane-bound OSAG78 might hydrolyze phospholipids to release linoleic acid and linolenic acid, and then depress the expression of genes encoding GA3- and GA20-oxidase. These changes reduced the bioactive gibberellin level, and, finally, late flowering occurred. Our results indicate that a patatin-like membrane protein with lipase activity affects flowering through the regulation of gibberellin metabolism.

Keywords: Flowering; Gibberellin; Lipase; Methyl jasmonate; Oncidium; Patatin

Journal Article.  8338 words.  Illustrated.

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

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