@article{1284, abstract = {Brassinosteroids (BRs) are growth-promoting plant hormones that play a role in abiotic stress responses, but molecular modes that enable this activity remain largely unknown. Here we show that BRs participate in the regulation of freezing tolerance. BR signaling-defective mutants of Arabidopsis thaliana were hypersensitive to freezing before and after cold acclimation. The constitutive activation of BR signaling, in contrast, enhanced freezing resistance. Evidence is provided that the BR-controlled basic helix-loop-helix transcription factor CESTA (CES) can contribute to the constitutive expression of the C-REPEAT/DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR (CBF) transcriptional regulators that control cold responsive (COR) gene expression. In addition, CBF-independent classes of BR-regulated COR genes are identified that are regulated in a BR- and CES-dependent manner during cold acclimation. A model is presented in which BRs govern different cold-responsive transcriptional cascades through the post-translational modification of CES and redundantly acting factors. This contributes to the basal resistance against freezing stress, but also to the further improvement of this resistance through cold acclimation.}, author = {Eremina, Marina and Unterholzner, Simon and Rathnayake, Ajith and Castellanos, Marcos and Khan-Djamei, Mamoona and Kügler, Karl and May, Sean and Mayer, Klaus and Rozhon, Wilfried and Poppenberger, Brigitte}, journal = {PNAS}, number = {40}, pages = {E5982 -- E5991}, publisher = {National Academy of Sciences}, title = {{Brassinosteroids participate in the control of basal and acquired freezing tolerance of plants}}, doi = {10.1073/pnas.1611477113}, volume = {113}, year = {2016}, } @article{1640, abstract = {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.}, author = {Šimášková, Mária and O'Brien, José and Khan-Djamei, Mamoona and Van Noorden, Giel and Ötvös, Krisztina and Vieten, Anne and De Clercq, Inge and Van Haperen, Johanna and Cuesta, Candela and Hoyerová, Klára and Vanneste, Steffen and Marhavy, Peter and Wabnik, Krzysztof T and Van Breusegem, Frank and Nowack, Moritz and Murphy, Angus and Friml, Jiřĺ and Weijers, Dolf and Beeckman, Tom and Benková, Eva}, journal = {Nature Communications}, publisher = {Nature Publishing Group}, title = {{Cytokinin response factors regulate PIN-FORMED auxin transporters}}, doi = {10.1038/ncomms9717}, volume = {6}, year = {2015}, }