Role of Diglycosyl Lipids in Photosynthesis and Membrane Lipid Homeostasis in Arabidopsis

• Published in: Plant physiology (Bethesda) Vol. 150; no. 3; pp. 1147 - 1159
• Main Authors: Hölzl, Georg, Witt, Sandra, Gaude, Nicole, Melzer, Michael, Schöttler, Mark Aurel, Dörmann, Peter
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.07.2009
• Subjects: Arabidopsis; Arabidopsis - metabolism; Arabidopsis - physiology; Arabidopsis - ultrastructure; Arabidopsis Proteins; Arabidopsis Proteins - physiology; Arabidopsis Proteins - radiation effects; Arabidopsis thaliana; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Biological Transport; Chloroflexus; Chloroflexus - metabolism; Chloroflexus aurantiacus; Chlorophylls; Chloroplasts; Chloroplasts - metabolism; Chloroplasts - ultrastructure; Cytochromes; Diglycerides; Diglycerides - metabolism; Fundamental and applied biological sciences. Psychology; Galactolipids; Galactolipids - genetics; Galactolipids - metabolism; Galactolipids - physiology; genetics; growth retardation; Homeostasis; light intensity; Lipid Metabolism; Lipids; Membrane Lipids; Membrane Lipids - metabolism; metabolism; mutants; Phenotype; Phosphates; Phosphates - metabolism; Photosynthesis; Photosynthesis - physiology; photosystem II; Photosystem II Protein Complex; Photosystem II Protein Complex - physiology; Photosystem II Protein Complex - radiation effects; physiology; Plant growth; Plant physiology and development; Plants; Plants, Genetically Modified; Plants, Genetically Modified - metabolism; Protein Stability; radiation effects; Thylakoids; Thylakoids - metabolism; Thylakoids - ultrastructure; ultrastructure; Arabidopsis thaliana; Plant physiology; Cruciferae; Dicotyledones; Angiospermae; Homeostasis; Lipids; Membrane; Spermatophyta; Experimental plant; Photosynthesis
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.109.139758

The galactolipid digalactosyldiacylglycerol (DGD) is an abundant thylakoid lipid in chloroplasts. The introduction of the bacterial lipid glucosylgalactosyldiacylglycerol (GGD) from Chloroflexus aurantiacus into the DGD-deficient Arabidopsis (Arabidopsis thaliana) dgd1 mutant was previously shown to result in complementation of growth, but photosynthetic efficiency was only partially restored. Here, we demonstrate that GGD accumulation in the double mutant dgd1dgd2, which is totally devoid of DGD, also complements growth at normal and high-light conditions, but photosynthetic efficiency in the GGD-containing dgd1dgd2 line remains decreased. This is attributable to an increased susceptibility of photosystem II to photodamage, resulting in reduced photosystem II accumulation already at normal light intensities. The chloroplasts of dgd1 and dgd1dgd2 show alterations in thylakoid ultrastructure, a phenotype that is restored in the GGD-containing lines. These data suggest that the strong growth retardation of the DGD-deficient lines dgd1 and dgd1dgd2 can be primarily attributed to a decreased capacity for chloroplast membrane assembly and proliferation and, to a smaller extent, to photosynthetic deficiency. During phosphate limitation, GGD increases in plastidial and extraplastidial membranes of the transgenic lines to an extent similar to that of DGD in the wild type, indicating that synthesis and transport of the bacterial lipid (GGD) and of the authentic plant lipid (DGD) are subject to the same mechanisms of regulation.