It has been known for quite some time that cytokinins, hormones typical of plants, are also produced and metabolized in bacteria. Most bacteria can only form the tRNA-bound cytokinins, but there are examples of plant-associated bacteria, both pathogenic and beneficial, that actively synthesize cytokinins to interact with their host. Similar to plants, bacteria produce diverse cytokinin metabolites, employing corresponding metabolic pathways. The identification of genes encoding the enzymes involved in cytokinin biosynthesis and metabolism facilitated their detailed characterization based on both classical enzyme assays and structural approaches. This review summarizes the present knowledge on key enzymes involved in cytokinin biosynthesis, modifications, and degradation in bacteria, and discusses their catalytic properties in relation to the presence of specific amino acid residues and protein structure.

• Klíčová slova
• CKX, LOG, cytochrome P450 monooxygenase, cytokinin, isopentenyl transferase, tRNA modification,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Isoprenoid and aromatic cytokinins occur in poplar as free compounds and constituents of tRNA, poplar isopentenyltransferases are involved in the production of isoprenoid cytokinins, while biosynthesis of their aromatic counterparts remains unsolved. Cytokinins are phytohormones with a fundamental role in the regulation of plant growth and development. They occur naturally either as isoprenoid or aromatic derivatives, but the latter are quite rare and less studied. Here, the spatial expression of all nine isopentenyl transferase genes of Populus × canadensis cv. Robusta (PcIPTs) as analyzed by RT-qPCR revealed a tissue preference and strong differences in expression levels for the different adenylate and tRNA PcIPTs. Together with their phylogeny, this result suggests a functional diversification for the different PcIPT proteins. Additionally, the majority of PcIPT genes were cloned and expressed in Arabidopsis thaliana under an inducible promoter. The cytokinin levels measured in the Arabidopsis-overexpressing lines as well as their phenotype indicate that the studied adenylate and tRNA PcIPT proteins are functional in vivo and thus will contribute to the cytokinin pool in poplar. We screened the cytokinin content in leaves of 12 Populus species by ultra-high performance-tandem mass spectrometry (UHPLC-MS/MS) and discovered that the capacity to produce not only isoprenoid, but also aromatic cytokinins is widespread amongst the Populus accessions studied. Important for future studies is that the levels of aromatic cytokinins transiently increase after daybreak and are much higher in older plants.

• Klíčová slova
• Cytokinin, Expression, Isopentenyltransferase, Poplar, Topolin, tRNA,
• MeSH
• alkyltransferasy a aryltransferasy genetika   metabolismus   MeSH
• Arabidopsis genetika   metabolismus   MeSH
• cytokininy biosyntéza   MeSH
• fylogeneze MeSH
• geneticky modifikované rostliny MeSH
• listy rostlin genetika   metabolismus   MeSH
• Populus genetika   metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenylate isopentenyltransferase MeSH Prohlížeč
• alkyltransferasy a aryltransferasy MeSH
• cytokininy MeSH
• regulátory růstu rostlin MeSH
• rostlinné proteiny MeSH

Cytokinins (CKs) and their metabolites and derivatives are essential for cell division, plant growth regulation and development. They are typically found at minute concentrations in plant tissues containing very complicated biological matrices. Therefore, defined standards labelled with stable isotopes are required for precise metabolic profiling and quantification of CKs, as well as in vivo elucidation of CK biosynthesis in various plant species. In this work, 11 [15N]-labelled C6-purine derivatives were prepared, among them 5 aromatic (4, 5, 6, 7, 8) and 3 isoprenoid (9, 10, 11) CKs. Compared to current methods, optimized syntheses of 6-amino-9H-[15N5]-purine (adenine) and 6-chloro-9H-[15N4]-purine (6-chloropurine) were performed to achieve more effective, selective and generally easier approaches. The chemical identity and purity of prepared compounds were confirmed by physico-chemical analyses (TLC; HRMS; HPLC-MS; 1H, 13C, 15N NMR). The presented approach is applicable for the synthesis of any other desired [15N4]-labelled C6-substituted purine derivatives.

• Klíčová slova
• 15N-labelled, cytokinin, purine, synthesis,
• Publikační typ
• časopisecké články MeSH

The present review summarizes current knowledge of the biosynthesis and biological importance of isoprenoid-derived plant signaling compounds. Cellular organisms use chemical signals for intercellular communication to coordinate their growth, development, and responses to environmental cues. The skeletons of majority of plant signaling molecules, mediators of plant intercellular 'broadcasting', are built from C5 units of isoprene and therefore belong to a huge and diverse group of natural substances called isoprenoids (terpenoids). They fill many important roles in nature. This review summarizes current knowledge of the biosynthesis and biological importance of a group of isoprenoid-derived plant signaling compounds.

• Klíčová slova
• Dimethylallyl diphosphate, Isopentenyl diphosphate, Isoprenoids, Phytoecdysteroids, Plant hormones, Terpenoids,
• MeSH
• brassinosteroidy biosyntéza   MeSH
• cytokininy biosyntéza   MeSH
• gibereliny biosyntéza   MeSH
• kyselina abscisová biosyntéza   MeSH
• metabolické sítě a dráhy MeSH
• regulátory růstu rostlin biosyntéza   MeSH
• rostliny metabolismus   MeSH
• signální transdukce * MeSH
• terpeny metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• brassinosteroidy MeSH
• cytokininy MeSH
• gibereliny MeSH
• kyselina abscisová MeSH
• regulátory růstu rostlin MeSH
• terpeny MeSH

Cytokinins, a class of phytohormones, are adenine derivatives common to many different organisms. In plants, these play a crucial role as regulators of plant development and the reaction to abiotic and biotic stress. Key enzymes in the cytokinin synthesis and degradation in modern land plants are the isopentyl transferases and the cytokinin dehydrogenases, respectively. Their encoding genes have been probably introduced into the plant lineage during the primary endosymbiosis. To shed light on the evolution of these proteins, the genes homologous to plant adenylate isopentenyl transferase and cytokinin dehydrogenase were amplified from the genomic DNA of cyanobacterium Nostoc sp. PCC 7120 and expressed in Escherichia coli. The putative isopentenyl transferase was shown to be functional in a biochemical assay. In contrast, no enzymatic activity was detected for the putative cytokinin dehydrogenase, even though the principal domains necessary for its function are present. Several mutant variants, in which conserved amino acids in land plant cytokinin dehydrogenases had been restored, were inactive. A combination of experimental data with phylogenetic analysis indicates that adenylate-type isopentenyl transferases might have evolved several times independently. While the Nostoc genome contains a gene coding for protein with characteristics of cytokinin dehydrogenase, the organism is not able to break down cytokinins in the way shown for land plants.

• MeSH
• biologická evoluce MeSH
• cytokininy metabolismus   MeSH
• Escherichia coli enzymologie   růst a vývoj   MeSH
• fylogeneze MeSH
• geneticky modifikované rostliny genetika   růst a vývoj   metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• mutace genetika   MeSH
• mutageneze cílená MeSH
• Nostoc enzymologie   genetika   MeSH
• oxidoreduktasy genetika   metabolismus   MeSH
• prenyltransferáza genetika   metabolismus   MeSH
• regulace genové exprese enzymů MeSH
• rekombinantní proteiny metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• tabák enzymologie   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytokinin oxidase MeSH Prohlížeč
• cytokininy MeSH
• oxidoreduktasy MeSH
• prenyltransferáza MeSH
• rekombinantní proteiny MeSH