Formation of root silica aggregates in sorghum is an active process of the endodermis

Milan Soukup, Victor M. Rodriguez Zancajo, Janina Kneipp, Rivka Elbaum*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Silica deposition in plants is a common phenomenon that correlates with plant tolerance to various stresses. Deposition occurs mostly in cell walls, but its mechanism is unclear. Here we show that metabolic processes control the formation of silica aggregates in roots of sorghum (Sorghum bicolor L.), a model plant for silicification. Silica formation was followed in intact roots and root segments of seedlings. Root segments were treated to enhance or suppress cell wall biosynthesis. The composition of endodermal cell walls was analysed by Raman microspectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis. Our results were compared with in vitro reactions simulating lignin and silica polymerization. Silica aggregates formed only in live endodermal cells that were metabolically active. Silicic acid was deposited in vitro as silica onto freshly polymerized coniferyl alcohol, simulating G-lignin, but not onto coniferyl alcohol or ferulic acid monomers. Our results show that root silica aggregates form under tight regulation by endodermal cells, independently of the transpiration stream. We raise the hypothesis that the location and extent of silicification are primed by the chemistry and structure of polymerizing lignin as it cross-links to the wall.

Original languageAmerican English
Pages (from-to)6807-6817
Number of pages11
JournalJournal of Experimental Botany
Volume71
Issue number21
DOIs
StatePublished - 2 Dec 2020

Bibliographical note

Publisher Copyright:
© 2019 The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Keywords

  • Cell wall
  • SEM-EDX
  • Sorghum bicolor (L.) Moench
  • lignin
  • root endodermis
  • silica

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