Cell wall glucomannan in Arabidopsis is synthesised by CSLA glycosyltransferases, and influences the progression of embryogenesis

Mannans are hemicellulosic polysaccharides that have previously been implicated as structural constituents of cell walls and as storage reserves but which may serve other functions during plant growth and development. Several members of the Arabidopsis cellulose synthase-like A (CSLA) family have pr...

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Published in:	The Plant journal : for cell and molecular biology Vol. 60; no. 3; pp. 527 - 538
Main Authors:	Goubet, Florence, Barton, Christopher J, Mortimer, Jennifer C, Yu, Xiaolan, Zhang, Zhinong, Miles, Godfrey P, Richens, Jenny, Liepman, Aaron H, Seffen, Keith, Dupree, Paul
Format:	Journal Article
Language:	English
Published:	Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-11-2009 Blackwell Publishing Ltd Blackwell
Subjects:	Arabidopsis Arabidopsis - embryology Arabidopsis - enzymology Arabidopsis - genetics Biological and medical sciences Cell differentiation, maturation, development, hematopoiesis Cell physiology cell wall Cell Wall - enzymology Cells Chemical synthesis CSLA embryogenesis Embryos Fundamental and applied biological sciences. Psychology Gene Expression Regulation, Plant Genes glucomannan Glucosyltransferases - genetics Glucosyltransferases - metabolism mannan Mannans - biosynthesis Molecular and cellular biology Embryonic development glucomannan Enzyme Arabidopsis Transferases Glycosyltransferases Mannan Cell wall Arabidopsis thaliana Synthesis embryogenesis Cruciferae Dicotyledones Angiospermae Spermatophyta CSLA
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Summary:	Mannans are hemicellulosic polysaccharides that have previously been implicated as structural constituents of cell walls and as storage reserves but which may serve other functions during plant growth and development. Several members of the Arabidopsis cellulose synthase-like A (CSLA) family have previously been shown to synthesise mannan polysaccharides in vitro when heterologously expressed. It has also been found that CSLA7 is essential for embryogenesis, suggesting a role for the CSLA7 product in development. To determine whether the CSLA proteins are responsible for glucomannan synthesis in vivo, we characterised insertion mutants in each of the nine Arabidopsis CSLA genes and several double and triple mutant combinations. csla9 mutants showed substantially reduced glucomannan, and triple csla2csla3csla9 mutants lacked detectable glucomannan in stems. Nevertheless, these mutants showed no alteration in stem development or strength. Overexpression of CSLA2, CSLA7 and CSLA9 increased the glucomannan content in stems. Increased glucomannan synthesis also caused defective embryogenesis, leading to delayed development and occasional embryo death. The embryo lethality of csla7 was complemented by overexpression of CSLA9, suggesting that the glucomannan products are similar. We conclude that CSLA2, CSLA3 and CSLA9 are responsible for the synthesis of all detectable glucomannan in Arabidopsis stems, and that CSLA7 synthesises glucomannan in embryos. These results are inconsistent with a substantial role for glucomannan in wall strength in Arabidopsis stems, but indicate that glucomannan levels affect embryogenesis. Together with earlier heterologous expression studies, the glucomannan deficiency observed in csla mutant plants demonstrates that the CSLA family encodes glucomannan synthases.
Bibliography:	http://dx.doi.org/10.1111/j.1365-313X.2009.03977.x Quotient Bioresearch, Newmarket CB7 5WW, UK. US Department of Agriculture – Agricultural Research Service, Wapato, WA 98951, USA. Present addresses: Bayer BioScience NV, TechnologiePark 58, Gent 9052, Belgium. Department of Disease and Stress Biology, John Innes Centre, Norwich NR4 7UH, UK. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0960-7412 1365-313X
DOI:	10.1111/j.1365-313X.2009.03977.x