Role of LOTR1 in Nutrient Transport through Organization of Spatial Distribution of Root Endodermal Barriers

Baohai Li, Takehiro Kamiya, Lothar Kalmbach, Mutsumi Yamagami, Katsushi Yamaguchi, Shuji Shigenobu, Shinichiro Sawa, John M C Danku, David E. Salt, Niko Geldner, Toru Fujiwara*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

The formation of Casparian strips and suberin lamellae at the endodermis limits the free diffusion of nutrients and harmful substances via the apoplastic space between the soil solution and the stele in roots [1–3]. Casparian strips are ring-like lignin polymers deposited in the middle of anticlinal cell walls between endodermal cells and fill the gap between them [4–6]. Suberin lamellae are glycerolipid polymers covering the endodermal cells and likely function as a barrier to limit transmembrane movement of apoplastic solutes into the endodermal cells [7, 8]. However, the current knowledge on the formation of these two distinct endodermal barriers and their regulatory role in nutrient transport is still limited. Here, we identify an uncharacterized gene, LOTR1, essential for Casparian strip formation in Arabidopsis thaliana. The lotr1 mutants display altered localization of CASP1, an essential protein for Casparian strip formation [9], disrupted Casparian strips, ectopic suberization of endodermal cells, and low accumulation of shoot calcium (Ca). Degradation by expression of a suberin-degrading enzyme in the mutants revealed that the ectopic suberization at the endodermal cells limits Ca transport through the transmembrane pathway, thereby causing reduced Ca delivery to the shoot. Moreover, analysis of the mutants showed that suberin lamellae function as an apoplastic diffusion barrier to the stele at sites of lateral root emergence where Casparian strips are disrupted. Our findings suggest that the transmembrane pathway through unsuberized endodermal cells, rather than the sites of lateral root emergence, mediates the transport of apoplastic substances such as Ca into the xylem.

Original languageEnglish
Pages (from-to)758-765
Number of pages8
JournalCurrent Biology
Volume27
Issue number5
Early online date23 Feb 2017
DOIs
Publication statusPublished - 6 Mar 2017

Keywords

  • apoplast
  • calcium transport
  • Casparian strip
  • cell wall
  • lateral root
  • suberin
  • transmembrane pathway

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