Down-stream components of cytokinin signaling and the role of cytokinin throughout the plant

Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA.
Plant Cell Reports (Impact Factor: 3.07). 02/2012; 31(5):801-12. DOI: 10.1007/s00299-012-1233-0
Source: PubMed


Cytokinins constitute a class of plant hormones influencing numerous aspects of growth and development. These processes occur through the downstream components of the cytokinin signaling pathway after its perception and signal transduction. The importance of these downstream signaling components has been revealed through the use of both traditional genetic and advanced molecular approaches studying mutants and transgenic lines involving cytokinin and diverse plant growth and developmental processes. Interestingly, these effects are not always directly via cytokinin, but by interactions with other plants hormones or transcription factor cascades, which can involve regulatory loops that affect transcription as well as hormone concentrations. This review covers recent advancements in understanding the role of cytokinin via its signaling components, specifically the downstream responses regulators in controlling vital plant growth and developmental processes.

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Available from: Aaron Rashotte, Jul 16, 2015
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    • "Eventually these plants produce adventitious roots that appear to take over the role of the major root and allow further plant growth. This phenotype is similar to phenotypes in multiple mutants of the cytokinin signaling pathway in arabidopsis including the receptor AHKs and the phosphotransfer protein AHPs, suggesting that SlCRF5 is likely an essential step in a similar cytokinin signaling pathway in tomato regulating root growth (reviewed in Gupta and Rashotte, 2012). Additional developmental defects are found in aerial tissues, including reduced leaf size, flower, fruit, and seed number. "
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    ABSTRACT: Cytokinin is an influential hormone involved in numerous aspects of plant growth and development. A group of transcription factors-cytokinin response factors (CRFs) has been included as a side branch to cytokinin signaling pathway which also constitute a subset of the AP2/ERF family of transcription factor proteins. This study examined the expression patterns of two transcription factor genes SlCRF3 and SlCRF5 in tomato (Solanum lycopersicum) to determine their regulation in response to cytokinin and a variety of abiotic stress conditions. Analyses conducted during different developmental stages by RT-PCR or GUS reporter gene expression revealed that these genes are differentially expressed in vegetative and reproductive organs. qRT-PCR experiments were also performed to study regulation by the hormone cytokinin and abiotic stress conditions such as flooding, drought, osmotic, oxidative, and temperature. These showed that SlCRF3 and SlCRF5 have different patterns of regulation in leaf, stem, and roots with SlCRF5 showing greater induction in leaf or root tissue compared to SlCRF3 in most cases. Additionally, knockdown analysis for SlCRF5 revealed defects across development including leaf morphology, primary root growth, and lateral root formation. Together, these findings indicate that SlCRF3 and SlCRF5 are potential regulators of tomato developmental processes associated with cytokinin or abiotic stresses.
    Journal of plant physiology 10/2013; 171(3). DOI:10.1016/j.jplph.2013.09.003 · 2.56 Impact Factor
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    • "Cellular and sub-cellular localization of multi-step cytokinin signaling components Cytokinin receptors have been widely studied (Kieber and Schaller 2010; Dortay et al. 2008; Gupta and Rashotte 2012). Their biochemical properties and specific functions were examined, but their cellular localization is still not fully investigated. "
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    ABSTRACT: Cytokinins (CKs) are a large group of plant hormones which play a crucial role in many physiological processes in plants. One of the interesting functions of CKs is the control of programmed cell death (PCD). It seems that all CKs-dependent phenomena including PCD are accompanied by special multi-step phosphorelay signaling pathway. This pathway consists of three elements: histidine kinase receptors (HKs), histidine phosphotransfer proteins (HPs) and response regulators (RRs). This review shows the résumé of the latest knowledge about CKs signaling pathways in many physiological processes in plants with special attention paid to PCD process.
    Plant Cell Reports 04/2013; 32(6). DOI:10.1007/s00299-013-1436-z · 3.07 Impact Factor
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    • "In contrast, auxin facilitates the degradation of SHY2 protein via the SKP-Cullin-F-Box and transport inhibitor response1 (SCF TIR1 ) ubiquitin– ligase complex thus sustaining the activity of the PIN genes and root growth (Benjamins and Scheres 2008). In another mechanism, the involvement of SHY2 in CK biosynthesis through negative regulation of isopentyl transferase (IPT5) has been indicated (Fig. 3a) (Werner and Schmulling 2009; Gupta and Rashotte 2012). This provides a possible explanation of SHY2 role in maintaining the equilibrium of endogenous CK through a feedback loop (Chapman and Estelle 2009). "
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    ABSTRACT: The demand for increased crop productivity and the predicted challenges related to plant survival under adverse environmental conditions have renewed the interest in research in root biology. Various physiological and genetic studies have provided ample evidence in support of the role of plant growth regulators in root development. The biosynthesis and transport of auxin and its signaling play a crucial role in controlling root growth and development. The univocal role of auxin in root development has established it as a master regulator. Other plant hormones, such as cytokinins, brassinosteroids, ethylene, abscisic acid, gibberellins, jasmonic acid, polyamines and strigolactones interact either synergistically or antagonistically with auxin to trigger cascades of events leading to root morphogenesis and development. In recent years, the availability of biological resources, development of modern tools and experimental approaches have led to the advancement of knowledge in root development. Research in the areas of hormone signal perception, understanding network of events involved in hormone action and the transport of plant hormones has added a new dimension to root biology. The present review highlights some of the important conceptual developments in the interplay of auxin and other plant hormones and associated downstream events affecting root development.
    Plant Cell Reports 04/2013; 32(6). DOI:10.1007/s00299-013-1430-5 · 3.07 Impact Factor
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