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


Author(s): Pernisová, Markéta; Prat, Tomas; Grones, Peter; Haruštiaková, Danka; Matonohova, Martina; Spíchal, Lukáš; Nodzyński, Tomasz; Friml, Jiří; Hejátko, Jan
Article Title: Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis
Affiliation IST Austria
Abstract: 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.
Keywords: Arabidopsis; Auxin; Cytokinins; AUX1; Root gravitropism; Pin-formed (PIN)
Journal Title: New Phytologist
Volume: 212
Issue 2
ISSN: 1469-8137
Publisher: Wiley-Blackwell  
Date Published: 2016-10-01
Start Page: 497
End Page: 509
URL:
DOI: 10.1111/nph.14049
Notes: Funded by Ministry of Education, Youth and Sports Czech Republic. Grant Numbers: CEITEC 2020, LQ1601, LO1204, LH14104 and The European Research Council. Grant Number: ERC-2011-StG-20101109-PSDP and The Czech Science Foundation. Grant Numbers: GAP501/11/1150, GA13-40637S, GP14-30004P
Open access: yes (repository)