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Functional screening of an Arabidopsis cDNA library enabled the identification of a novel cDNA, ESR1 (for Enhancer of Shoot Regeneration), that can confer cytokinin-independent shoot formation when overexpressed in Arabidopsis root explants. Neither callus induction nor root formation was affected by ESR1 overexpression. ESR1 encodes a putative(More)
The tobacco mitogen-activated protein kinase kinase kinase NPK1 regulates lateral expansion of the cell plate at cytokinesis. Here, we show that the kinesin-like proteins NACK1 and NACK2 act as activators of NPK1. Biochemical analysis suggests that direct binding of NACK1 to NPK1 stimulates kinase activity. NACK1 is accumulated specifically in M phase and(More)
Cytokinins stimulate shoot regeneration in tissue culture but the genes required for this developmental process are not well understood. Here we show that the Arabidopsis gene, ENHANCER OF SHOOT REGENERATION 2 (ESR2), encoding an AP2-domain transcriptional factor, functions in the regeneration of shoots in tissue culture. ESR2 overexpression conferred(More)
A cDNA (cNPK2) that encodes a protein of 518 amino acids was isolated from a library prepared from poly(A)+ RNAs of tobacco cells in suspension culture. The N-terminal half of the predicted NPK2 protein is similar in amino acid sequence to the catalytic domains of kinases that activate mitogen-activated protein kinases (designated here MAPKKs) from various(More)
A partial cDNA encoding an Arabidopsis thaliana FH (Formin Homology) protein (AFH1) was used as a probe to clone a full length AFH1 cDNA. The deduced protein encoded by the cDNA contains a FH1 domain rich in proline residues and a C-terminal FH2 domain which is highly conserved amongst FH proteins. In contrast to FH proteins of other organisms, the(More)
A cDNA clone (cNPK15) was isolated from tobacco cells in suspension culture, which encodes a predicted protein kinase of 422 amino acids. The predicted NPK15 protein consists of a hydrophobic region near the amino-terminus, a linker domain and the catalytic domain of a protein-serine/threonine kinase in the carboxyl-half. NPK15 was not found to be closely(More)
The Arabidopsis ENHANCER OF SHOOT REGENERATION (ESR)1 and ESR2 genes are thought to play critical roles in in vitro shoot regeneration. In this study, we investigated the functions and expression patterns of ESR1 and ESR2 during shoot regeneration by using their mutants and promoter-reporter systems. Shoot regeneration efficiencies of esr1 esr2 double(More)
The Arabidopsis Enhancer of Shoot Regeneration 1 (ESR1) gene regulates initiation of in vitro shoot regeneration. In this study, we investigated the transcription-modulating potential of ESR1. ESR1 induced reporter gene expression when overexpressed transiently in Arabidopsis leaf cells. Experiments using a fusion protein with the GAL4 DNA-binding domain(More)
The tobaccoNPK1 gene encodes a homolog of mitogenactivated protein kinase kinase kinases. We have recently identified tobacco kinesin-like proteins (NACK1/2) as activators for NPK1. Immunochemical analyses of NPK1 and NACK1 proteins suggest that NPK1 is involved in the regulation of some process in the M phase of the plant cell cycle.
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