Journal Article

Disorganized distribution of homogalacturonan epitopes in cell walls as one possible mechanism for aluminium-induced root growth inhibition in maize

Ya Ying Li, Jian Li Yang, Yue Jiao Zhang and Shao Jian Zheng

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 104, issue 2, pages 235-241
Published in print August 2009 | ISSN: 0305-7364
Published online May 2009 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcp123
Disorganized distribution of homogalacturonan epitopes in cell walls as one possible mechanism for aluminium-induced root growth inhibition in maize

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

Aluminium (Al) toxicity is one of the most severe limitations to crop production in acid soils. Inhibition of root elongation is the primary symptom of Al toxicity. However, the underlying basis of the process is unclear. Considering the multiple physiological and biochemical functions of pectin in plants, possible involvement of homogalacturonan (HG), one of the pectic polysaccharide domains, was examined in connection with root growth inhibition induced by Al.

Methods

An immunolabelling technique with antibodies specific to HG epitopes (JIM5, unesterified residues flanked by methylesterifed residues; JIM7, methyl-esterified residues flanked by unesterified residues) was used to visualize the distribution of different types of HG in cell walls of root apices of two maize cultivars differing in Al resistance.

Key Results

In the absence of Al, the JIM5 epitope was present around the cell wall with higher fluorescence intensity at cell corners lining the intercellular spaces, and the JIM7 epitope was present throughout the cell wall. However, treatment with 50 µm Al for 3 h produced 10 % root growth inhibition in both cultivars and caused the disappearance of fluorescence in the middle lamella of both epitopes. Prolonged Al treatment (24 h) with 50 % root growth inhibition in ‘B73’, an Al-sensitive cultivar, resulted in faint and irregular distribution of both epitopes. In ‘Nongda3138’, an Al-resistant cultivar, the distribution of HG epitopes was also restricted to the lining of intercellular spaces when a 50 % inhibition to root growth was induced by Al (100 µm Al, 9 h). Altered distribution of both epitopes was also observed when of roots were exposed to 50 µm LaCl3 for 24 h, resulting in 40 % inhibition of root growth.

Conclusions

Changes in HG distribution and root growth inhibition were highly correlated, indicating that Al-induced perturbed distribution of HG epitopes is possibly involved in Al-induced inhibition of root growth in maize.

Keywords: Al toxicity; cell wall; homogalacturnonan; immunofluorescence; methylesterification; pectin

Journal Article.  3878 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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