The function of seed fatty reducers in lower fatty acid storage in Arabidopsis and Oilseeds
Mingxun Chen, Xue Du, Lixi Jiang*

College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058
Corresponding Author：Tel: (+86 571) 8898 2905; Fax: (+86571) 8898 2904; E-mail: jianglx@zju.edu.cn

Abstract 
Previous studies based on microarray analysis have found that DELLAs downregulate several GDSL genes in unopened flowers and/or imbibed seeds. This suggests the role of DELLAs in seed fatty acid (FA) metabolism. In the present study, enhancement of GA signaling through DELLA mutation or exogenous GA₃ resulted in the upregulated expression of transcription factors for embryogenesis and seed development, genes involved in the FA biosynthesis pathway, and five GDSL-type Seed Fatty Acid Reducer (SFAR) genes. SFAR overexpression reduced the total seed FA content and led to a particular pattern of seed FA composition. This “SFAR footprint” can also be found in plants with enhanced GA₃ signaling. By contrast, the loss of SFAR function dramatically increases the seed FA content. The transgenic lines that overexpress SFAR were less sensitive to stressful environments, reflected by a higher germination rate and better seedling establishment compared with the WT plants. The GDSL-type hydrolyser is a family of proteins largely uncharacterized in Arabidopsis. Their biological function remains poorly understood. SFAR reduces seed FA storage and acts downstream of the GA signaling pathway. We provide the first evidence that some GDSL proteins are somehow involved in FA degradation in Arabidopsis seeds.

Key Words: GA signaling pathway; fatty acid; GDSL-type SFAR genes; Arabidopsis