Xylans Provide the Structural Driving Force for Mucilage Adhesion to the Arabidopsis Seed Coat

Arabidopsis (Arabidopsis thaliana) seed coat epidermal cells produce large amounts of mucilage that is released upon imbibition. This mucilage is structured into two domains: an outer diffuse layer that can be easily removed by agitation and an inner layer that remains attached to the outer seed coa...

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Vydáno v:Plant physiology (Bethesda) Ročník 171; číslo 1; s. 165
Hlavní autoři: Ralet, Marie-Christine, Crépeau, Marie-Jeanne, Vigouroux, Jacqueline, Tran, Joseph, Berger, Adeline, Sallé, Christine, Granier, Fabienne, Botran, Lucy, North, Helen M
Médium: Journal Article
Jazyk:angličtina
Vydáno: United States 01.05.2016
Témata:
Arabidopsis - enzymology
Arabidopsis - genetics
Arabidopsis - metabolism
Arabidopsis Proteins - genetics
Arabidopsis Proteins - metabolism
Cell Wall - chemistry
Cell Wall - metabolism
Cellulose - metabolism
Cluster Analysis
Gene Expression Regulation, Plant
Genes, Plant
Genetic Linkage
Glucosyltransferases - genetics
Glucosyltransferases - metabolism
Hexuronic Acids - metabolism
Mutation
Pectins - chemistry
Pectins - metabolism
Plant Extracts - chemistry
Plant Mucilage - chemistry
Plant Mucilage - genetics
Plant Mucilage - metabolism
Rhamnose - metabolism
Seeds - enzymology
Seeds - metabolism
Sequence Analysis, DNA
Staining and Labeling
Xylans - chemistry
Xylans - metabolism
Xylose - metabolism
ISSN:1532-2548, 1532-2548
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Shrnutí:Arabidopsis (Arabidopsis thaliana) seed coat epidermal cells produce large amounts of mucilage that is released upon imbibition. This mucilage is structured into two domains: an outer diffuse layer that can be easily removed by agitation and an inner layer that remains attached to the outer seed coat. Both layers are composed primarily of pectic rhamnogalacturonan I (RG-I), the inner layer also containing rays of cellulose that extend from the top of each columella. Perturbation in cellulosic ray formation has systematically been associated with a redistribution of pectic mucilage from the inner to the outer layer, in agreement with cellulose-pectin interactions, the nature of which remained unknown. Here, by analyzing the outer layer composition of a series of mutant alleles, a tight proportionality of xylose, galacturonic acid, and rhamnose was evidenced, except for mucilage modified5-1 (mum5-1; a mutant showing a redistribution of mucilage pectin from the inner adherent layer to the outer soluble one), for which the rhamnose-xylose ratio was increased drastically. Biochemical and in vitro binding assay data demonstrated that xylan chains are attached to RG-I chains and mediate the adsorption of mucilage to cellulose microfibrils. mum5-1 mucilage exhibited very weak adsorption to cellulose. MUM5 was identified as a putative xylosyl transferase recently characterized as MUCI21. Together, these findings suggest that the binding affinity of xylose ramifications on RG-I to a cellulose scaffold is one of the factors involved in the formation of the adherent mucilage layer.
Bibliografie:ObjectType-Article-1
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content type line 23
ISSN:1532-2548
1532-2548
DOI:10.1104/pp.16.00211