CRFs form protein–protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain

Cutcliffe, James W.; Hellmann, Eva; Heyl, Alexander; Rashotte, Aaron M.

doi:10.1093/jxb/err199

Cited by 93 publications

(68 citation statements)

References 21 publications

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“…Microarray analysis showed that the CRFs overlap with the type B ARRs in activating many cytokinin target genes; single and multiple loss-of-function mutations in the CRFs led to defects in cotyledon and leaf development, as well as embryo lethality in the case of crf5 crf6. Recently, published work has shown that the CRFs can form both homo-and heterodimers with one another, and has identified the protein domain required for CRF-CRF interaction and interactions with other cytokinin signalling components (Cutcliffe et al, 2011).…”

Section: Response Regulatorsmentioning

confidence: 99%

Crossing paths: cytokinin signalling and crosstalk

2013

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SummaryCytokinins are a major class of plant hormones that are involved in various aspects of plant development, ranging from organ formation and apical dominance to leaf senescence. Cytokinin and auxin have long been known to interact antagonistically, and more recent studies have shown that cytokinins also interact with other plant hormones to regulate plant development. A growing body of research has begun to elucidate the molecular and genetic underpinnings of this extensive crosstalk. The rich interconnections between the synthesis, perception and transport networks of these plant hormones provide a wide range of opportunities for them to modulate, amplify or buffer one another. Here, we review this exciting and rapidly growing area of cytokinin research.

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Section: Response Regulatorsmentioning

confidence: 99%

Crossing paths: cytokinin signalling and crosstalk

2013

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“…CYTOKININ RESPONSE FACTORS (CRFs) are a subset of the plant specific AP2/ERF domaincontaining transcription factor family that function both downstream, and as a side branch, of the primary cytokinin signaling pathway (Rashotte et al, 2006;Cutcliffe et al, 2011). Arabidopsis CRF6 is transcriptionally induced by cytokinin and plays a role in delaying leaf senescence (Zwack et al, 2013).…”

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confidence: 99%

Cytokinin Response Factor 6 Represses Cytokinin-Associated Genes during Oxidative Stress

et al. 2016

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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 H 2 O 2 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 H 2 O 2 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.The frequent environmental changes to which a plant is subject can lead to physiological alterations and disruption of normal metabolism. In particular, the energetic reactions that take place in chloroplasts, peroxisomes, and mitochondria are susceptible to dysfunction, which results in production of excessive levels of reactive oxygen species (ROS). In fact, many common abiotic stress conditions encountered in agriculture, including temperature extremes, drought, soil salinity, and air pollution, are known to include an oxidative stress component (Gill and Tuteja, 2010). Cellular levels of ROS are carefully maintained at relatively low levels through a wide range of scavenging and detoxification mechanisms. However, if the balance between ROS production and removal is shifted too far toward production (e.g. under stress conditions), cellular damage can occur as a result of oxidation of macromolecules such as lipids, proteins, and nucleic acids (Mittler, 2002;Gill and Tuteja, 2010). Accumulation of ROS beyond some threshold triggers cell death as a response. Therefore, ROS are thought to serve as indicators of oxidative stress within a cell but may also

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“…The latter are negative feedback regulators of cytokinin signaling (Kiba et al, 2003;To et al, 2004;Dortay et al, 2006;Lee et al, 2008). Moreover, several CYTOKININ RESPONSE FACTORS (CRFs) were identified as immediate-early cytokinin response targets, which interact with the AHPs and in turn regulate the transcription of a large portion of cytokinin response genes, many of which are also differentially regulated by B-type ARRs (Rashotte et al, 2006;Cutcliffe et al, 2011;Brenner et al, 2012).…”

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confidence: 99%

GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity

et al. 2015

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Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase. In addition, cytokinins are known to be involved in chloroplast development, nitrogen signaling, and senescence. Evidence is provided that GRF5 and cytokinins synergistically enhance cell division and chlorophyll retention after darkinduced senescence, which suggests that they also cooperate to stimulate chloroplast division and nitrogen assimilation. Taken together with the increased leaf size, ectopic expression of GRF5 has great potential to improve plant productivity.

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CRFs form protein–protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain

Cited by 93 publications

References 21 publications

Crossing paths: cytokinin signalling and crosstalk

Crossing paths: cytokinin signalling and crosstalk

Cytokinin Response Factor 6 Represses Cytokinin-Associated Genes during Oxidative Stress

GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity

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