Taxonomic group: plant / Streptophyta
(Phylum: Streptophyta)
Publication DOI: 10.1104/pp.114.250050Journal NLM ID: 0401224Publisher: American Society of Plant Biologists
Correspondence: nakamura
gate.sinica.edu.tw, kkobayashi
bio.c.u-tokyo.ac.jp
Institutions: Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan, PRESTO, JST, Kawaguchi, Saitama 332-0012, Japan, CREST, JST, Kawaguchi, Saitama 332-0012, Japan, Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Tapei 11529, Taiwan
Monogalactosyldiacylglycerol (MGDG) is the major lipid constituent of thylakoid membranes and is essential for chloroplast biogenesis in plants. In Arabidopsis (Arabidopsis thaliana), MGDG is predominantly synthesized by inner envelope-localized MONOGALACTOSYLDIACYLGLYCEROL SYNTHASE1 (MGD1); its knockout causes albino seedlings. Because of the lethal phenotype of the null MGD1 mutant, functional details of MGDG synthesis at seedling development have remained elusive. In this study, we used an inducible gene-suppression system to investigate the impact of MGDG synthesis on cotyledon development. We created transgenic Arabidopsis lines that express an artificial microRNA targeting MGD1 (amiR-MGD1) under the control of a dexamethasone-inducible promoter. The induction of amiR-MGD1 resulted in up to 75% suppression of MGD1 expression, although the resulting phenotypes related to chloroplast development were diverse, even within a line. The strong MGD1 suppression by continuous dexamethasone treatment caused substantial decreases in galactolipid content in cotyledons, leading to severe defects in the formation of thylakoid membranes and impaired photosynthetic electron transport. Time-course analyses of the MGD1 suppression during seedling germination revealed that MGDG synthesis at the very early germination stage is particularly important for chloroplast biogenesis. The MGD1 suppression down-regulated genes associated with the photorespiratory pathway in peroxisomes and mitochondria as well as those responsible for photosynthesis in chloroplasts and caused high expression of genes for the glyoxylate cycle. MGD1 function may link galactolipid synthesis with the coordinated transcriptional regulation of chloroplasts and other organelles during cotyledon greening.
Structure type: monomer
Location inside paper: Figure 2
Trivial name: MGDG
Compound class: glycolipid, glycoside
Contained glycoepitopes: IEDB_136044,IEDB_137472,IEDB_141794,IEDB_190606,SB_165,SB_166,SB_187,SB_195,SB_7,SB_88
Methods: GC, biological assays, microscopy, genetic manipulations, lipid extraction
Comments, role: LIP is mixture of 16:3, 18:2, 18:3 aliphatic acids
Related record ID(s): 60940
NCBI Taxonomy refs (TaxIDs): 3702
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There is only one chemically distinct structure:
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