Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis

Pernisová, Markéta and Prat, Tomas and Grones, Peter and Haruštiaková, Danka and Matonohova, Martina and Spíchal, Lukáš and Nodzyński, Tomasz and Friml, Jiří and Hejátko, Jan (2016) Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis. New Phytologist, 212 (2). pp. 497-509. ISSN 1469-8137

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Redirection of intercellular auxin fluxes via relocalization of the PIN-FORMED 3 (PIN3) and PIN7 auxin efflux carriers has been suggested to be necessary for the root gravitropic response. Cytokinins have also been proposed to play a role in controlling root gravitropism, but conclusive evidence is lacking. We present a detailed study of the dynamics of root bending early after gravistimulation, which revealed a delayed gravitropic response in transgenic lines with depleted endogenous cytokinins (Pro35S:AtCKX) and cytokinin signaling mutants. Pro35S:AtCKX lines, as well as a cytokinin receptor mutant ahk3, showed aberrations in the auxin response distribution in columella cells consistent with defects in the auxin transport machinery. Using in vivo real-time imaging of PIN3-GFP and PIN7-GFP in AtCKX3 overexpression and ahk3 backgrounds, we observed wild-type-like relocalization of PIN proteins in the columella early after gravistimulation, with gravity-induced relocalization of PIN7 faster than that of PIN3. Nonetheless, the cellular distribution of PIN3 and PIN7 and expression of PIN7 and the auxin influx carrier AUX1 was affected in AtCKX overexpression lines. Based on the retained cytokinin sensitivity in pin3 pin4 pin7 mutant, we propose the AUX1-mediated auxin transport rather than columella-located PIN proteins as a target of endogenous cytokinins in the control of root gravitropism.

Item Type: Article
DOI: 10.1111/nph.14049
Additional Information: This is the peer reviewed version of the following article: [FULL CITE], which has been published in final form at [ This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Uncontrolled Keywords: Arabidopsis, Auxin, Cytokinins, AUX1, Root gravitropism, Pin-formed (PIN)
Subjects: 500 Science > 580 Plants > 581 Botany
Research Group: Friml Group
SWORD Depositor: Sword Import User
Depositing User: Sword Import User
Date Deposited: 16 Apr 2018 12:28
Last Modified: 16 Apr 2018 12:28

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