Siliplant1 protein precipitates silica in sorghum silica cells

Santosh Kumar, Nurit Adiram-Filiba, Shula Blum, Javier Arturo Sanchez-Lopez, Oren Tzfadia, Ayelet Omid, Hanne Volpin, Yael Heifetz, Gil Goobes, Rivka Elbaum*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Silicon is absorbed by plant roots as silicic acid. The acid moves with the transpiration stream to the shoot, and mineralizes as silica. In grasses, leaf epidermal cells called silica cells deposit silica in most of their volume using an unknown biological factor. Using bioinformatics tools, we identified a previously uncharacterized protein in Sorghum bicolor, which we named Siliplant1 (Slp1). Slp1 is a basic protein with seven repeat units rich in proline, lysine, and glutamic acid. We found Slp1 RNA in sorghum immature leaf and immature inflorescence. In leaves, transcription was highest just before the active silicification zone (ASZ). There, Slp1 was localized specifically to developing silica cells, packed inside vesicles and scattered throughout the cytoplasm or near the cell boundary. These vesicles fused with the membrane, releasing their content in the apoplastic space. A short peptide that is repeated five times in Slp1 precipitated silica in vitro at a biologically relevant silicic acid concentration. Transient overexpression of Slp1 in sorghum resulted in ectopic silica deposition in all leaf epidermal cell types. Our results show that Slp1 precipitates silica in sorghum silica cells.

Original languageAmerican English
Pages (from-to)6830-6843
Number of pages14
JournalJournal of Experimental Botany
Volume71
Issue number21
DOIs
StatePublished - 2 Dec 2020

Bibliographical note

Publisher Copyright:
© 2020 The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Keywords

  • Biomineralization
  • Siliplant1 (Slp1)
  • Sorghum bicolor
  • phytolith
  • silica cell
  • silicification

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