XTH31, encoding an in vitro XEH/XET-active enzyme, regulates aluminum sensitivity by modulating in vivo XET action, cell wall xyloglucan content, and aluminum binding capacity in Arabidopsis

Xiao Fang Zhu, Yuan Zhi Shi, Gui Jie Lei, Stephen C Fry, Bao Cai Zhang, Yi Hua Zhou, Janet Braam, Tao Jiang, Xiao Yan Xu, Chuan Zao Mao, Yuan Jiang Pan, Jian Li Yang, Ping Wu, Shao Jian Zheng

Research output: Contribution to journalArticlepeer-review

Abstract

Xyloglucan endohydrolase (XEH) and xyloglucan endotransglucosylase (XET) activities, encoded by xyloglucan endotransglucosylase-hydrolase (XTH) genes, are involved in cell wall extension by cutting or cutting and rejoining xyloglucan chains, respectively. However, the physiological significance of this biochemical activity remains incompletely understood. Here, we find that an XTH31 T-DNA insertion mutant, xth31, is more Al resistant than the wild type. XTH31 is bound to the plasma membrane and the encoding gene is expressed in the root elongation zone and in nascent leaves, suggesting a role in cell expansion. XTH31 transcript accumulation is strongly downregulated by Al treatment. XTH31 expression in yeast yields a protein with an in vitro XEH:XET activity ratio of >5000:1. xth31 accumulates significantly less Al in the root apex and cell wall, shows remarkably lower in vivo XET action and extractable XET activity, has a lower xyloglucan content, and exhibits slower elongation. An exogenous supply of xyloglucan significantly ameliorates Al toxicity by reducing Al accumulation in the roots, owing to the formation of an Al-xyloglucan complex in the medium, as verified by an obvious change in chemical shift of (27)Al-NMR. Taken together, the data indicate that XTH31 affects Al sensitivity by modulating cell wall xyloglucan content and Al binding capacity.
Original languageEnglish
Pages (from-to)4731-4747
Number of pages17
JournalPlant Cell
Volume24
Issue number11
DOIs
Publication statusPublished - 30 Nov 2012

Keywords

  • Aluminum
  • Amino Acid Sequence
  • Arabidopsis
  • Arabidopsis Proteins
  • Cell Wall
  • Chelating Agents
  • Down-Regulation
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Plant
  • Glucans
  • Glycosyltransferases
  • Mutagenesis, Insertional
  • Organ Specificity
  • Phenotype
  • Phylogeny
  • Plant Leaves
  • Plant Roots
  • Plants, Genetically Modified
  • Polysaccharides
  • Recombinant Fusion Proteins
  • Seedling
  • Sequence Analysis, DNA
  • Xylans

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