Halotropism is a response of plant roots to avoid a saline environment

Carlos S. Galvan-Ampudia, Magdalena M. Julkowska, Essam Darwish, Jacinto Gandullo, Ruud A. Korver, Geraldine Brunoud, Michel A. Haring, Teun Munnik, Teva Vernoux, Christa Testerink*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

161 Citations (Scopus)


Tropisms represent fascinating examples of how plants respond to environmental signals by adapting their growth and development. Here, a novel tropism is reported, halotropism, allowing plant seedlings to reduce their exposure to salinity by circumventing a saline environment. In response to a salt gradient, Arabidopsis, tomato, and sorghum roots were found to actively prioritize growth away from salinity above following the gravity axis. Directionality of this response is established by an active redistribution of the plant hormone auxin in the root tip, which is mediated by the PIN-FORMED 2 (PIN2) auxin efflux carrier. We show that salt-induced phospholipase D activity stimulates clathrin-mediated endocytosis of PIN2 at the side of the root facing the higher salt concentration. The intracellular relocalization of PIN2 allows for auxin redistribution and for the directional bending of the root away from the higher salt concentration. Our results thus identify a cellular pathway essential for the integration of environmental cues with auxin-regulated root growth that likely plays a key role in plant adaptative responses to salt stress.

Original languageEnglish
Pages (from-to)2044-2050
Number of pages7
JournalCurrent Biology
Issue number20
Publication statusPublished - 21 Oct 2013
Externally publishedYes


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