Calcium binding by arabinogalactan polysaccharides is important for normal plant development.
Lopez Hernandez, Federico
The Plant Cell
American Society of Plant Biologists
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Lopez Hernandez, F., Tryfona, T., Rizza, A., Yu, x., Harris, M., Webb, A., Kotake, T., & et al. (2020). Calcium binding by arabinogalactan polysaccharides is important for normal plant development.. The Plant Cell, 32 (8) https://doi.org/10.1105/tpc.20.00027
Arabinogalactan proteins (AGPs) are a family of plant extracellular proteoglycans involved in many physiological events. AGPs are often anchored to the extracellular side of the plasma membrane and are highly glycosylated with arabinogalactan (AG) polysaccharides, but the molecular function of this glycosylation remains largely unknown. The β-linked glucuronic acid (GlcA) residues in AG polysaccharides have been shown in vitro to bind to calcium in a pH-dependent manner. Here, we used Arabidopsis mutants in four AG β-glucuronyltransferases (GlcAT14A, B, D and E) to understand the role of glucuronidation of AG. AG isolated from glcat14 triple mutants had a strong reduction in glucuronidation. AG from a glcat14a/b/d triple mutant had lower calcium binding capacity in vitro than AG from wild-type plants. Some mutants had multiple developmental defects such as reduced trichome branching. glcat14a/b/e triple mutant plants had severely limited seedling growth, were sterile, and the propagation of calcium waves was perturbed in roots. Several of the developmental phenotypes were suppressed by increasing the calcium concentration in the growth medium. Our results show that AG glucuronidation is crucial for multiple developmental processes in plants and suggest that a function of AGPs might be to bind and release cell-surface apoplastic calcium.
This study was funded in part by Consejo Nacional de Ciencia y Tecnología (grant to F.L.H), by the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant-in-Aid for Scientific Research on Innovative Areas “Plant-Structure Optimization Strategy” Grant Number 18H05495 to T.K.) and by the BBSRC Cell Wall Sugars programme BB/G016240/1 to P.D)
Biotechnology and Biological Sciences Research Council (BB/G016240/1)
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External DOI: https://doi.org/10.1105/tpc.20.00027
This record's URL: https://www.repository.cam.ac.uk/handle/1810/309176