Silicification in grasses: Variation between different cell types

Santosh Kumar, Milan Soukup, Rivka Elbaum*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

116 Scopus citations

Abstract

Plants take up silicon as mono-silicic acid, which is released to soil by the weathering of silicate minerals. Silicic acid can be taken up by plant roots passively or actively, and later it is deposited in its polymerized form as amorphous hydrated silica. Major silica depositions in grasses occur in root endodermis, leaf epidermal cells, and outer epidermal cells of inflorescence bracts. Debates are rife about the mechanism of silica deposition, and two contrasting scenarios are often proposed to explain it. According to the passive mode of silicification, silica deposition is a result of silicic acid condensation due to dehydration, such as during transpirational loss of water from the aboveground organs. In general, silicification and transpiration are positively correlated, and continued silicification is sometimes observed after cell and tissue maturity. The other mode of silicification proposes the involvement of some biological factors, and is based on observations that silicification is not necessarily coupled with transpiration. Here, we review evidence for both mechanisms of silicification, and propose that the deposition mechanism is specific to the cell type. Considering all the cell types together, our conclusion is that grass silica deposition can be divided into three modes: spontaneous cell wall silicification, directed cell wall silicification, and directed paramural silicification in silica cells.

Original languageAmerican English
Article number438
JournalFrontiers in Plant Science
Volume8
DOIs
StatePublished - 28 Mar 2017

Bibliographical note

Publisher Copyright:
© 2017 Kumar, Soukup and Elbaum.

Keywords

  • Cell wall
  • Grasses
  • Inflorescence bracts
  • Root endodermis
  • Silica cells
  • Silicification mechanism
  • Transpiration
  • Trichomes

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