Cytokinin is a phytohormone that is well known for its roles in numerous plant growth and developmental processes, yet it has also been linked to abiotic stress response in a less defined manner. Arabidopsis (Arabidopsis thaliana) Cytokinin Response Factor 6 (CRF6) is a cytokinin-responsive AP2/ERF-family transcription factor that, through the cytokinin signaling pathway, plays a key role in the inhibition of dark-induced senescence. CRF6 expression is also induced by oxidative stress, and here we show a novel function for CRF6 in relation to oxidative stress and identify downstream transcriptional targets of CRF6 that are repressed in response to oxidative stress. Analysis of transcriptomic changes in wild-type and crf6 mutant plants treated with H2O2 identified CRF6-dependent differentially expressed transcripts, many of which were repressed rather than induced. Moreover, many repressed genes also show decreased expression in 35S:CRF6 overexpressing plants. Together, these findings suggest that CRF6 functions largely as a transcriptional repressor. Interestingly, among the H2O2 repressed CRF6-dependent transcripts was a set of five genes associated with cytokinin processes: (signaling) ARR6, ARR9, ARR11, (biosynthesis) LOG7, and (transport) ABCG14. We have examined mutants of these cytokinin-associated target genes to reveal novel connections to oxidative stress. Further examination of CRF6-DNA interactions indicated that CRF6 may regulate its targets both directly and indirectly. Together, this shows that CRF6 functions during oxidative stress as a negative regulator to control this cytokinin-associated module of CRF6- dependent genes and establishes a novel connection between cytokinin and oxidative stress response.
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Zwack P, De Clercq I, Howton T, et al. Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress. Plant Physiology. 2016;172(2):1249-1258. doi:10.1104/pp.16.00415
Zwack, P., De Clercq, I., Howton, T., Hallmark, H. T., Hurny, A., Keshishian, E., … Rashotte, A. (2016). Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress. Plant Physiology. American Society of Plant Biologists. https://doi.org/10.1104/pp.16.00415
Zwack, Paul, Inge De Clercq, Timothy Howton, H Tucker Hallmark, Andrej Hurny, Erika Keshishian, Alyssa Parish, et al. “Cytokinin Response Factor 6 Represses Cytokinin-Associated Genes during Oxidative Stress.” Plant Physiology. American Society of Plant Biologists, 2016. https://doi.org/10.1104/pp.16.00415.
P. Zwack et al., “Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress,” Plant Physiology, vol. 172, no. 2. American Society of Plant Biologists, pp. 1249–1258, 2016.
Zwack P, De Clercq I, Howton T, Hallmark HT, Hurny A, Keshishian E, Parish A, Benková E, Mukhtar MS, Van Breusegem F, Rashotte A. 2016. Cytokinin response factor 6 represses cytokinin-associated genes during oxidative stress. Plant Physiology. 172(2), 1249–1258.
Zwack, Paul, et al. “Cytokinin Response Factor 6 Represses Cytokinin-Associated Genes during Oxidative Stress.” Plant Physiology, vol. 172, no. 2, American Society of Plant Biologists, 2016, pp. 1249–58, doi:10.1104/pp.16.00415.