Mechanism of silica deposition in sorghum silica cells

Santosh Kumar*, Yonat Milstein, Yaniv Brami, Michael Elbaum, Rivka Elbaum

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

95 Scopus citations

Abstract

Grasses take up silicic acid from soil and deposit it in their leaves as solid silica. This mineral, comprising 1–10% of the grass dry weight, improves plants' tolerance to various stresses. The mechanisms promoting stress tolerance are mostly unknown, and even the mineralization process is poorly understood. To study leaf mineralization in sorghum (Sorghum bicolor), we followed silica deposition in epidermal silica cells by in situ charring and air-scanning electron microscopy. Our findings were correlated to the viability of silica cells tested by fluorescein diacetate staining. We compared our results to a sorghum mutant defective in root uptake of silicic acid. We showed that the leaf silicification in these plants is intact by detecting normal mineralization in leaves exposed to silicic acid. Silica cells were viable while condensing silicic acid into silica. The controlled mineral deposition was independent of water evapotranspiration. Fluorescence recovery after photobleaching suggested that the forming mineral conformed to the cellulosic cell wall, leaving the cytoplasm well connected to neighboring cells. As the silicified wall thickened, the functional cytoplasm shrunk into a very small space. These results imply that leaf silica deposition is an active, physiologically regulated process as opposed to a simple precipitation.

Original languageAmerican English
Pages (from-to)791-798
Number of pages8
JournalNew Phytologist
Volume213
Issue number2
DOIs
StatePublished - 1 Jan 2017

Bibliographical note

Publisher Copyright:
© 2016 The Authors. New Phytologist © 2016 New Phytologist Trust

Keywords

  • Sorghum bicolor
  • airSEM
  • biomineralization
  • cell viability
  • lsi1 mutant
  • silica cell
  • silicification

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