期刊
PLANT PHYSIOLOGY
卷 158, 期 3, 页码 1146-1157出版社
OXFORD UNIV PRESS INC
DOI: 10.1104/pp.111.192195
关键词
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资金
- Ministerio de Educacion y Ciencia [BFU2005-08770-C02-01]
- Ministerio de Ciencia y Tecnologia [BFI2003-03626]
- Xunta de Galicia [PGIDITOPXIC20002PN, 10PXIB200305PR]
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 beta-galactose linked to alpha-xylose at O2. In this work, we identified AtBGAL10 (At5g63810) as the gene responsible for the majority of beta-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 beta-galactosidase and alpha-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 alpha-xylosidase expression.
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