AtBGAL10 Is the Main Xyloglucan β-Galactosidase in Arabidopsis, and Its Absence Results in Unusual Xyloglucan Subunits and Growth Defects

In growing cells, xyloglucan is thought to connect cellulose microfibrils and regulate their separation during wall extension. In Arabidopsis (Arabidopsis thaliana), a significant proportion of xyloglucan side chains contain β-galactose linked to α-xylose at O2. In this work, we identified AtBGAL10...

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Published in:Plant physiology (Bethesda) 2012-03, Vol.158 (3), p.1146-1157
Main Authors: Sampedro, Javier, Gianzo, Cristina, Iglesias, Natalia, Guitián, Esteban, Revilla, Gloria, Zarra, Ignacio
Format: Article
Language:English
Subjects:
Abscission
Agrobacterium tumefaciens - genetics
Arabidopsis - enzymology
Arabidopsis - genetics
Arabidopsis - growth & development
Arabidopsis Proteins - genetics
Arabidopsis Proteins - metabolism
beta-Galactosidase - genetics
beta-Galactosidase - metabolism
BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES
Biological and medical sciences
Cell growth
Cell Wall - enzymology
Cell Wall - genetics
Cell walls
Enzyme Activation
Enzymes
Flowers - growth & development
Fundamental and applied biological sciences. Psychology
Gene Expression Regulation, Plant
Genes, Plant
Genes, Reporter
Glucans - metabolism
Mutagenesis, Insertional
Oligosaccharides
Peas
Phenotype
Phenotypes
Phylogeny
Pichia - genetics
Plant cells
Plant Leaves - enzymology
Plant Leaves - genetics
Plant Leaves - growth & development
Plant physiology and development
Plant Stems - enzymology
Plant Stems - genetics
Plant Stems - growth & development
Plants
Polysaccharides
Promoter Regions, Genetic
Xylans - metabolism
Xylosidases - genetics
Xylosidases - metabolism
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Summary:In growing cells, xyloglucan is thought to connect cellulose microfibrils and regulate their separation during wall extension. In Arabidopsis (Arabidopsis thaliana), a significant proportion of xyloglucan side chains contain β-galactose linked to α-xylose at O2. In this work, we identified AtBGAL10 (At5g63810) as the gene responsible for the majority of β-galactosidase activity against xyloglucan. Xyloglucan from bgal10 insertional mutants was found to contain a large proportion of unusual subunits, such as GLG and GLLG. These subunits were not detected in a bgal10 xyl1 double mutant, deficient in both ß-galactosidase and a-xylosidase. Xyloglucan from bgal10 xyl1 plants was enriched instead in XXLG/XLXG and XLLG subunits. In both cases, changes in xyloglucan composition were larger in the endoglucanase-accessible fraction. These results suggest that glycosidases acting on nonreducing ends digest large amounts of xyloglucan in wild-type plants, while plants deficient in any of these activities accumulate partly digested subunits. In both bgal10 and bgal10 xyl1, siliques and sepals were shorter, a phenotype that could be explained by an excess of nonreducing ends leading to a reinforced xyloglucan network. Additionally, AtBGAL10 expression was examined with a promoter-reporter construct. Expression was high in many cell types undergoing wall extension or remodeling, such as young stems, abscission zones, or developing vasculature, showing good correlation with a-xylosidase expression.
ISSN:0032-0889
1532-2548
1532-2548
DOI:10.1104/pp.111.192195