Cytokinin response factors regulate PIN-FORMED auxin transporters

Authors: Maria Šimášková, José Antonio O’Brien, Mamoona Khan, Giel Van Noorden, Krisztina Ötvös, Anne Vieten, Inge De Clercq, Johanna Maria Adriana Van Haperen, Candela Cuesta, Klára Hoyerová, Steffen Vanneste, Peter Marhavý, Krzysztof Wabnik, Frank Van Breusegem, Moritz K. Nowack, Angus Murphy, Jiřı́ Friml, Dolf Weijers, Tom Beeckman, Eva Benková - Nature Communications 2015 cited by 147

Auxin and cytokinin are key endogenous regulators of plant development. Although cytokinin-mediated modulation of auxin distribution is a developmentally crucial hormonal interaction, its molecular basis is largely unknown. Here we show a direct regulatory link between cytokinin signalling and the auxin transport machinery uncovering a mechanistic framework for cytokinin-auxin cross-talk. We show that the CYTOKININ RESPONSE FACTORS (CRFs), transcription factors downstream of cytokinin perception, transcriptionally control genes encoding PIN-FORMED (PIN) auxin transporters at a specific PIN CYTOKININ RESPONSE ELEMENT (PCRE) domain. Removal of this cis-regulatory element effectively uncouples PIN transcription from the CRF-mediated cytokinin regulation and attenuates plant cytokinin sensitivity. We propose that CRFs represent a missing cross-talk component that fine-tunes auxin transport capacity downstream of cytokinin signalling to control plant development. The concerted action of the hormones cytokinin and auxin is an important regulator of plant development. Here Šimášková et al. propose a mechanistic basis by which cytokinin-responsive transcription factors regulate transport of auxin in Arabidopsisroots.