MUCILAGE-RELATED10 Produces Galactoglucomannan That Maintains Pectin and Cellulose Architecture in Arabidopsis Seed Mucilage
[1];
[1];
[3];
- Forschungszentrum Jülich, Juelich (Germany). Inst. for Biosciences and Geosciences
- Inst. National de la Recherche Agronomique and AgroParisTech, Versailles (France). Inst. Jean-Pierre Bourgin, ERL Centre National de la Recherche Scientifique
- RWTH Aachen Univ. (Germany). Inst. for Botany and Molecular Genetics, BioEconomy Science Center
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst. and Physical Biosciences Division
- Univ. of California, Berkeley, CA (United States). Dept. of Plant and Microbial Biology; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst. and Physical Biosciences Division
Plants invest a lot of their resources into the production of an extracellular matrix built of polysaccharides. While the composition of the cell wall is relatively well characterized, the functions of the individual polymers and the enzymes that catalyze their biosynthesis remain poorly understood. We exploited the Arabidopsis (Arabidopsis thaliana) seed coat epidermis (SCE) to study cell wall synthesis. SCE cells produce mucilage, a specialized secondary wall that is rich in pectin, at a precise stage of development. A coexpression search for MUCILAGE-RELATED (MUCI) genes identified MUCI10 as a key determinant of mucilage properties. MUCI10 is closely related to a fenugreek (Trigonella foenumgraecum) enzyme that has in vitro galactomannan α-1,6-galactosyltransferase activity. Our detailed analysis of the muci10 mutants demonstrates that mucilage contains highly branched galactoglucomannan (GGM) rather than unbranched glucomannan. Muci10 likely decorates glucomannan, synthesized by CELLULOSE SYNTHASE-LIKE A2, with galactose residues in vivo. The degree of galactosylation is essential for the synthesis of the GGM backbone, the structure of cellulose, mucilage density, as well as the adherence of pectin. We propose that GGM scaffolds control mucilage architecture along with cellulosic rays and show that Arabidopsis SCE cells represent an excellent model in which to study the synthesis and function of GGM. Arabidopsis natural varieties with defects similar to muci10 mutants may reveal additional genes involved in GGM synthesis. Since GGM is the most abundant hemicellulose in the secondary walls of gymnosperms, understanding its biosynthesis may facilitate improvements in the production of valuable commodities from softwoods.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); Natural Sciences and Engineering Research Council of Canada (NSERC)
- Grant/Contract Number:
- AC02-05CH11231; 313/323–400–00213
- OSTI ID:
- 1512244
- Journal Information:
- Plant Physiology (Bethesda), Vol. 169, Issue 1; ISSN 0032-0889
- Publisher:
- American Society of Plant BiologistsCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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