Asymmetric gibberellin signaling regulates vacuolar trafficking of PIN auxin transporters during root gravitropism Journal Article


Author(s): Löfke, Christian; Zwiewka, Marta; Heilmann, Ingo; Van Montagu, Marc C; Teichmann, Thomas; Friml, Jiří
Article Title: Asymmetric gibberellin signaling regulates vacuolar trafficking of PIN auxin transporters during root gravitropism
Affiliation IST Austria
Abstract: Gravitropic bending of plant organs is mediated by an asymmetric signaling of the plant hormone auxin between the upper and lower side of the respective organ. Here, we show that also another plant hormone, gibberellic acid (GA), shows asymmetric action during gravitropic responses. Immunodetection using an antibody against GA and monitoring GA signaling output by downstream degradation of DELLA proteins revealed an asymmetric GA distribution and response with the maximum at the lower side of gravistimulated roots. Genetic or pharmacological manipulation of GA levels or response affects gravity-mediated auxin redistribution and root bending response. The higher GA levels at the lower side of the root correlate with increased amounts of PIN-FORMED2 (PIN2) auxin transporter at the plasma membrane. The observed increase in PIN2 stability is caused by a specific GA effect on trafficking of PIN proteins to lytic vacuoles that presumably occurs downstream of brefeldin A-sensitive endosomes. Our results suggest that asymmetric auxin distribution instructive for gravity-induced differential growth is consolidated by the asymmetric action of GA that stabilizes the PIN-dependent auxin stream along the lower side of gravistimulated roots.
Keywords: protein stability; protein trafficking; Hormone cross-talk
Journal Title: PNAS
Volume: 110
Issue 9
ISSN: 1091-6490
Publisher: National Academy of Sciences  
Date Published: 2013-02-26
Start Page: 3627
End Page: 3632
Sponsor: This research was supported by Deutsche Forschungsgemeinschaft Grant ERA-PD 045 and Central European Institute of Technology Project CZ.1.05/1.1.00/02.0068 from the European Regional Development Fund.
URL:
DOI: 10.1073/pnas.1300107110
Open access: yes (repository)