Present address: Graduate School of Science and Engineering, Saitama University, Saitama 338 8570, Japan.
Type-B monogalactosyldiacylglycerol synthases are involved in phosphate starvation-induced lipid remodeling, and are crucial for low-phosphate adaptation
Article first published online: 28 OCT 2008
© 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd
The Plant Journal
Volume 57, Issue 2, pages 322–331, January 2009
How to Cite
Kobayashi, K., Awai, K., Nakamura, M., Nagatani, A., Masuda, T. and Ohta, H. (2009), Type-B monogalactosyldiacylglycerol synthases are involved in phosphate starvation-induced lipid remodeling, and are crucial for low-phosphate adaptation. The Plant Journal, 57: 322–331. doi: 10.1111/j.1365-313X.2008.03692.x
- Issue published online: 13 JAN 2009
- Article first published online: 28 OCT 2008
- Received 17 June 2008; revised 29 August 2008; accepted 8 September 2008; published online 28 October 2008.
- phosphate starvation;
- MGDG synthase;
Mono- and digalactosyldiacylglycerol (MGDG and DGDG, respectively) constitute the bulk of membrane lipids in plant chloroplasts. Mutant analyses in Arabidopsis have shown that these galactolipids are essential for chloroplast biogenesis and photoautotrophic growth. Moreover, these non-phosphorous lipids are proposed to participate in low-phosphate (Pi) adaptations. Under Pi-limited conditions, a drastic accumulation of DGDG occurs concomitantly with a large reduction in membrane phospholipids, suggesting that plants substitute DGDG for phospholipids during Pi starvation. Previously, we reported that among the three MGDG synthase genes (MGD1, MGD2 and MGD3), the type-B MGD2 and MGD3 are upregulated in parallel with DGDG synthase genes during Pi starvation. Here, we describe the identification and characterization of T-DNA insertional mutants of Arabidopsis type-B MGD genes. Under Pi-starved conditions, the mgd3-1 mutant showed a drastic reduction in DGDG accumulation, particularly in the root, indicating that MGD3 is the main isoform responsible for DGDG biosynthesis in Pi-starved roots. Moreover, in the roots of mgd2 mgd3 plants, Pi stress-induced accumulation of DGDG was almost fully abolished, showing that type-B MGD enzymes are essential for membrane lipid remodeling in Pi-starved roots. Reductions in fresh weight, root growth and photosynthetic performance were also observed in these mutants under Pi-starved conditions. These results demonstrate that Pi stress-induced membrane lipid remodeling is important in plant growth during Pi starvation. The widespread distribution of type-B MGD genes in land plants suggests that membrane lipid remodeling mediated by type-B MGD enzymes is a potent adaptation to Pi deficiency for land plants.