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Fluorescent Immunolocalization of Arabinogalactan Proteins and Pectins in the Cell Wall of Plant Tissues
Published on: February 27, 2021
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Calcium Binding by Arabinogalactan Polysaccharides Is Important for Normal Plant Development
Federico Lopez-Hernandez1, Theodora Tryfona1, Annalisa Rizza2
1Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
The Plant Cell
|August 10, 2020
Summary
Arabinogalactan proteins (AGPs) glucuronidation is vital for plant development. Reduced glucuronidation impairs calcium binding, leading to growth defects, suggesting AGPs regulate cell-surface calcium.
Area of Science:
- Plant Biology
- Molecular Biology
- Biochemistry
Background:
- Arabinogalactan proteins (AGPs) are key plant extracellular proteoglycans.
- Their extensive glycosylation with arabinogalactan (AG) polysaccharides suggests functional importance, but remains unclear.
- β-linked glucuronic acid (GlcA) residues in AG bind calcium pH-dependently.
Purpose of the Study:
- Investigate the role of AG glucuronidation in plant development.
- Determine the function of AG β-glucuronyltransferases (GlcATs).
- Understand the link between AG structure, calcium binding, and plant physiology.
Main Methods:
- Utilized Arabidopsis mutants in four AG β-glucuronyltransferases (GlcAT14A, -B, -D, -E).
- Analyzed AG composition and glucuronidation levels in mutants.
- Assessed in vitro calcium binding capacity of isolated AG.
- Observed plant developmental phenotypes and calcium wave propagation.
Main Results:
- Triple mutants (e.g., glcat14a/b/d) showed significantly reduced AG glucuronidation.
- Reduced glucuronidation correlated with decreased in vitro calcium binding.
- Mutants exhibited developmental defects like reduced trichome branching and limited seedling growth.
- Phenotypes were often rescued by increased calcium in the growth medium.
Conclusions:
- AG glucuronidation is essential for multiple plant developmental processes.
- AGPs may function to bind and release cell-surface apoplastic calcium.
- Glucuronidation is a critical modification for AGP-mediated calcium signaling.
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