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Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tremendous strides have been made in the past year toward elucidating the ethylene-response pathway. Ethylene is perceived by a family of histidine kinase-like receptors, which negatively regulate ethylene responses. Binding of ethylene requires a copper cofactor, and proper receptor function relies on a copper transporter. Downstream, EIN2 is a structurally novel protein containing an integral membrane domain. In the nucleus, the EIN3 family of DNA-binding proteins regulates transcription in response to ethylene, and an immediate target of EIN3 is a DNA-binding protein of the AP2/EREBP family.
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PMID:The ethylene-response pathway: signal perception to gene regulation. 1050 61

In Arabidopsis thaliana, the immediate early response of plants to cytokinin is formulated as the multistep histidine kinase (AHK)-->histidine-containing phosphotransmitter (AHP)-->response regulator (ARR) phosphorelay signaling circuitry, which is initiated by the cytokinin receptor histidine protein kinases. In the hope of finding components (or genes) that function downstream of the cytokinin-mediated His-->Asp phosphorelay signaling circuitry, we carried out genome-wide microarray analyses. To this end, we used a combinatorial microarray strategy by employing not only wild-type plants, but also certain transgenic lines in which the cytokinin-mediated His-->Asp phosphorelay signaling circuitry has been genetically manipulated. These transgenic lines employed were ARR21-overexpressing and ARR22-overexpressing plants, each of which exhibits a characteristic phenotype with regard to the cytokinin-mediated His-->Asp phosphorelay. The results of extensive microarray analyses with these plants allowed us systematically to identify a certain number of genes that were up-regulated at the level of transcription in response to cytokinin directly or indirectly. Among them, some representatives were examined further in wild-type plants to support the idea that certain genes encoding transcription factors are rapidly and specifically induced at the level of transcription by cytokinin in a manner similar to that of the type-A ARR genes, which are the hallmarks of the His-->Asp phosphorelay signaling circuitry. Several interesting transcription factors were thus identified as being cytokinin responsive, including those belonging to the AP2/EREBP family, MYB family, GATA family or bHLH family. Including these, the presented list of cytokinin-up-regulated genes (214) will provide us with valuable bases for understanding the His-->Asp phosphorelay in A. thaliana.
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PMID:Combinatorial microarray analysis revealing arabidopsis genes implicated in cytokinin responses through the His->Asp Phosphorelay circuitry. 1569 62

Root growth and function are determined by the action of environmental stresses through specific genes that adapt root development to these restrictive conditions. We have defined in vitro conditions affecting the growth and recovery of Medicago truncatula roots after a salt stress. A dedicated macroarray containing 384 genes, based on a large-scale subtractive hybridization approach, was constructed and used to analyze gene expression during salt stress and recovery of root growth from this stress. Several potential regulatory genes were identified as being linked to this recovery process: a novel RNA-binding protein, a small G-protein homologous to ROP9, a receptor-like kinase, two TF IIIA-like and an AP2-like transcription factors (TF), MtZpt2-1, MtZpt2-2 and MtAp2, and a histidine kinase associated with cytokinin transduction pathways. The two ZPT2-type TFs were also rapidly induced by cold stress in roots. By analyzing transgenic M. truncatula plants showing reduced expression levels of both TFs and affected in their capacity to recover root growth after a salt stress, we identified potential target genes that were either activated or repressed in these plants. Overexpression of MtZpt2-1 in roots conferred salt tolerance and affected the expression of three putative targets in the predicted manner: a cold-regulated A (CORA) homolog, a flower-promoting factor (FPF1) homolog and an auxin-induced proline-rich protein (PRP) gene. Hence, regulatory networks depending on TFIIIA-like transcription factors are involved in the control of root adaptation to salt stress.
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PMID:Identification of regulatory pathways involved in the reacquisition of root growth after salt stress in Medicago truncatula. 1748 37

Cytokinin response factor 6 (CRF6) is an Arabidopsis AP2/ERF transcription factor which is transcriptionally induced by cytokinin. Cytokinin is known to delay leaf senescence in wild-type (WT) plants, for example in dark-incubated detached leaves. This response is mediated by the cytokinin receptor Arabidopsis histidine kinase receptor 3 (AHK3). Similar to ahk3 mutants, crf6 leaves show decreased sensitivity to this cytokinin effect. Leaves overexpressing CRF6 retain more Chl than those of the WT under these conditions without exogenous cytokinin. It therefore appears that an increase in expression of CRF6 downstream of the perception of cytokinin by AHK3 is involved in the delay of leaf senescence. Intact crf6 plants also begin to undergo monocarpic senescence sooner than WT plants. Interestingly, plants overexpressing CRF6 display a more extreme acceleration of development than crf6 mutants, suggesting that a specific expression level or localization of CRF6 is necessary to prevent premature senescence. Expression analyses indicate that CRF6 is highly expressed in the veins of mature leaves and that this expression decreases with age. CRF6 expression is shown to be induced by abiotic stress, in addition to increased cytokinin. Together, these findings suggest that CRF6 functions to regulate developmental senescence negatively and may have a similar role in response to stress. CRF6 may therefore be involved in fine-tuning the timing of developmental and stress-induced senescence. CRF6 functioning in negative regulation of senescence is significant in that it is the first process known to be regulated by cytokinin, in which a CRF can be placed specifically downstream of the cytokinin signaling pathway.
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PMID:Cytokinin response factor 6 negatively regulates leaf senescence and is induced in response to cytokinin and numerous abiotic stresses. 2353 44