Auxin glycosylation plays a fundamental role in the regulation of auxin homeostasis, activity, and transport, contributing to the dynamic control of plant growth and development. Glycosylation enhances auxin stability, solubility, and storage capacity, serving as a key mechanism for both temporary inactivation and long-term storage of auxin molecules. Specific glycosyltransferases are critical for this process, catalyzing glycosylation at either the carboxyl group or the nitrogen atom of the indole ring. The storage roles of glycosylated auxins, such as IAA-N-Glc, have been shown to be essential during embryogenesis and seed germination, while irreversible conjugation into catabolic products helps to maintain auxin homeostasis in vegetative tissues. This review highlights the diversity, enzymatic specificity, and physiological relevance of auxin glycosylation pathways, including a frequently overlooked N-glycosylation, underscoring its importance in the complex network of auxin metabolism.
The genomes of charophyte green algae, close relatives of land plants, typically do not show signs of developmental regulation by phytohormones. However, scattered reports of endogenous phytohormone production in these organisms exist. We performed a comprehensive analysis of multiple phytohormones in Viridiplantae, focusing mainly on charophytes. We show that auxin, salicylic acid, ethylene and tRNA-derived cytokinins including cis-zeatin are found ubiquitously in Viridiplantae. By contrast, land plants but not green algae contain the trans-zeatin type cytokinins as well as auxin and cytokinin conjugates. Charophytes occasionally produce jasmonates and abscisic acid, whereas the latter is detected consistently in land plants. Several phytohormones are excreted into the culture medium, including auxin by charophytes and cytokinins and salicylic acid by Viridiplantae in general. We note that the conservation of phytohormone biosynthesis and signaling pathways known from angiosperms does not match the capacity for phytohormone biosynthesis in Viridiplantae. Our phylogenetically guided analysis of established algal cultures provides an important insight into phytohormone biosynthesis and metabolism across Streptophyta.
- MeSH
- biologická evoluce MeSH
- Chlorophyta metabolismus genetika MeSH
- cyklopentany metabolismus MeSH
- cytokininy * metabolismus MeSH
- ethyleny metabolismus MeSH
- fylogeneze * MeSH
- kyselina abscisová metabolismus MeSH
- kyselina salicylová metabolismus MeSH
- kyseliny indoloctové * metabolismus MeSH
- oxylipiny metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- regulátory růstu rostlin * metabolismus MeSH
- signální transdukce MeSH
- Viridiplantae metabolismus genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklopentany MeSH
- cytokininy * MeSH
- ethylene MeSH Prohlížeč
- ethyleny MeSH
- jasmonic acid MeSH Prohlížeč
- kyselina abscisová MeSH
- kyselina salicylová MeSH
- kyseliny indoloctové * MeSH
- oxylipiny MeSH
- regulátory růstu rostlin * MeSH
BACKGROUND: Acidic phytohormones are small molecules controlling many physiological functions in plants. A comprehensive picture of their profiles including the active forms, precursors and metabolites provides an important insight into ongoing physiological processes and is essential for many biological studies performed on plants. RESULTS: A high-throughput sample preparation method for liquid chromatography-tandem mass spectrometry determination of 25 acidic phytohormones classed as auxins, jasmonates, abscisates and salicylic acid was optimised. The method uses a small amount of plant tissue (less than 10 mg fresh weight) and acidic extraction in 1 mol/L formic acid in 10% aqueous methanol followed by miniaturised purification on reverse phase sorbent accommodated in pipette tips organised in a 3D printed 96-place interface, capable of processing 192 samples in one run. The method was evaluated in terms of process efficiency, recovery and matrix effects as well as establishing validation parameters such as accuracy and precision. The applicability of the method in relation to the amounts of sample collected from distantly related plant species was evaluated and the results for phytohormone profiles are discussed in the context of literature reports. CONCLUSION: The method developed enables high-throughput profiling of acidic phytohormones with minute amounts of plant material, and it is suitable for large scale interspecies studies.
- Klíčová slova
- 3D printing, Evolutionarily distant plant species, High-throughput, In-tip microSPE, Liquid chromatography, Mass spectrometry, Miniaturisation, Plant hormones,
- Publikační typ
- časopisecké články MeSH
Shoot cultures of hypericin non-producing H. calycinum L. (primitive Ascyreia section), hypericin-producing H. perforatum L., H. tetrapterum Fries (section Hypericum) and H. richeri Vill. (the evolutionarily most advanced section Drosocarpium in our study) were developed and investigated for their growth, development, hypericin content and endogenous phytohormone levels. Hypericins in wild-growing H. richeri significantly exceeded those in H. perforatum and H. tetrapterum. H. richeri also had the highest hypericin productivity in vitro in medium supplemented with 0.2 mg/L N6-benzyladenine and 0.1 mg/L indole-3-butyric acid and H. tetrapterum-the lowest one in all media modifications. In shoot culture conditions, the evolutionarily oldest H. calycinum had the highest content of salicylic acid and total jasmonates in some of its treatments, as well as dominance of the storage form of abscisic acid (ABA-glucose ester) and lowest cytokinin ribosides and cytokinin O-glucosides as compared with the other three species. In addition, the evolutionarily youngest H. richeri was characterized by the highest total amount of cytokinin ribosides. Thus, both evolutionary development and the hypericin production capacity seemed to interact closely with the physiological parameters of the plant organism, such as endogenous phytohormones, leading to the possible hypothesis that hypericin productivity may have arisen in the evolution of Hypericum as a means to adapt to environmental changes.
- Klíčová slova
- Hypericum evolution, endogenous phytohormones, hypericin, in vitro culture, wild habitats,
- Publikační typ
- časopisecké články MeSH
Plant microgametogenesis involves stages leading to the progressive development of unicellular microspores into mature pollen. Despite the active and continuing interest in the study of male reproductive development, little is still known about the hormonomics at each ontogenetic stage. In this work, we characterized the profiles and dynamics of phytohormones during the process of microgametogenesis in four Nicotiana species (Nicotiana tabacum, Nicotiana alata, Nicotiana langsdorffii, and Nicotiana mutabilis). Taking advantage of advanced HPLC-ESI-MS/MS, twenty to thirty endogenous hormone derivatives were identified throughout pollen ontogenesis, including cytokinins, auxins, ABA and its derivatives, jasmonates, and phenolic compounds. The spectra of endogenous phytohormones changed dynamically during tobacco pollen ontogeny, indicating their important role in pollen growth and development. The different dynamics in the accumulation of endogenous phytohormones during pollen ontogenesis between N. tabacum (section Nicotiana) and the other three species (section Alatae) reflects their different phylogenetic positions and origin within the genus Nicotiana. We demonstrated the involvement of certain phytohormone forms, such as cis-zeatin- and methylthiol-type CKs, some derivatives of abscisic acid, phenylacetic and benzoic acids, in pollen development for the first time here. Our results suggest that unequal levels of endogenous hormones and the presence of specific derivatives may be characteristic for pollen development in different phylogenetic plant groups. These results represent the currently most comprehensive study of plant hormones during the process of pollen development.
- Klíčová slova
- Nicotiana spp., hormonome, male gametophyte, ontogeny, phytohormones, pollen development,
- Publikační typ
- časopisecké články MeSH
The spatial location and timing of plant developmental events are largely regulated by the well balanced effects of auxin and cytokinin phytohormone interplay. Together with transport, localized metabolism regulates the concentration gradients of their bioactive forms, ultimately eliciting growth responses. In order to explore the dynamics of auxin and cytokinin metabolism during early seedling growth in Theobroma cacao (cacao), we have performed auxin and cytokinin metabolite profiling in hypocotyls and root developmental sections at different times by using ultra-high-performance liquid chromatography-electrospray tandem mass spectrometry (UHPLC-MS/MS). Our work provides quantitative characterization of auxin and cytokinin metabolites throughout early root and hypocotyl development and identifies common and distinctive features of auxin and cytokinin metabolism during cacao seedling development.
- Klíčová slova
- Theobroma cacao, auxin, cytokinin, phytohormone metabolism, root development,
- Publikační typ
- časopisecké články MeSH
Cytokinins are plant hormones, derivatives of adenine with a side chain at the N6-position. They are involved in many physiological processes. While the metabolism of trans-zeatin and isopentenyladenine, which are considered to be highly active cytokinins, has been extensively studied, there are others with less obvious functions, such as cis-zeatin, dihydrozeatin, and aromatic cytokinins, which have been comparatively neglected. To help explain this duality, we present a novel hypothesis metaphorically comparing various cytokinin forms, enzymes of CK metabolism, and their signalling and transporter functions to the comics superheroes Hulk and Deadpool. Hulk is a powerful but short-lived creation, whilst Deadpool presents a more subtle and enduring force. With this dual framework in mind, this review compares different cytokinin metabolites, and their biosynthesis, translocation, and sensing to illustrate the different mechanisms behind the two CK strategies. This is put together and applied to a plant developmental scale and, beyond plants, to interactions with organisms of other kingdoms, to highlight where future study can benefit the understanding of plant fitness and productivity.
- Klíčová slova
- Hulk/Deadpool, aromatic cytokinins, cis-zeatin, cytokinin biosynthesis, cytokinin oxidase/dehydrogenase, cytokinin signalling, cytokinin transport, cytokinins, isopentenyl transferase,
- MeSH
- Arabidopsis metabolismus MeSH
- biologické modely MeSH
- biologický transport MeSH
- biotest MeSH
- cytokininy metabolismus MeSH
- fyziologie rostlin * MeSH
- glykosylace MeSH
- hydrolýza MeSH
- kinetika MeSH
- kinetin metabolismus MeSH
- oxidoreduktasy metabolismus MeSH
- regulátory růstu rostlin metabolismus MeSH
- rostliny metabolismus MeSH
- signální transdukce * MeSH
- vazba proteinů MeSH
- zeatin analogy a deriváty MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- cytokinin oxidase MeSH Prohlížeč
- cytokininy MeSH
- dihydrozeatin MeSH Prohlížeč
- kinetin MeSH
- oxidoreduktasy MeSH
- regulátory růstu rostlin MeSH
- zeatin MeSH
Cytokinins (CKs) are a class of phytohormones affecting many aspects of plant growth and development. In the complex process of CK homeostasis in plants, N-glucosylation represents one of the essential metabolic pathways. Its products, CK N7- and N9-glucosides, have been largely overlooked in the past as irreversible and inactive CK products lacking any relevant physiological impact. In this work, we report a widespread distribution of CK N-glucosides across the plant kingdom proceeding from evolutionary older to younger plants with different proportions between N7- and N9-glucosides in the total CK pool. We show dramatic changes in their profiles as well as in expression levels of the UGT76C1 and UGT76C2 genes during Arabidopsis ontogenesis. We also demonstrate specific physiological effects of CK N-glucosides in CK bioassays including their antisenescent activities, inhibitory effects on root development, and activation of the CK signaling pathway visualized by the CK-responsive YFP reporter line, TCSv2::3XVENUS. Last but not least, we present the considerable impact of CK N7- and N9-glucosides on the expression of CK-related genes in maize and their stimulatory effects on CK oxidase/dehydrogenase activity in oats. Our findings revise the apparent irreversibility and inactivity of CK N7- and N9-glucosides and indicate their involvement in CK evolution while suggesting their unique function(s) in plants.
- Klíčová slova
- Arabidopsis, N-glucosides, Zea mays, [2-3H]tZ9G, cis-zeatin, cytokinin, cytokinin oxidase/dehydrogenase, oat, senescence, trans-zeatin, β-D-glucosidase Zm-p60.1,
- MeSH
- Arabidopsis genetika metabolismus MeSH
- cytokininy genetika MeSH
- glukosidy genetika MeSH
- glukosyltransferasy genetika MeSH
- kukuřice setá genetika metabolismus MeSH
- molekulární evoluce * MeSH
- oxidoreduktasy genetika MeSH
- regulace genové exprese u rostlin genetika MeSH
- regulátory růstu rostlin genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cytokininy MeSH
- glukosidy MeSH
- glukosyltransferasy MeSH
- oxidoreduktasy MeSH
- regulátory růstu rostlin MeSH
Cytokinin (CK) N-glucosides are the most abundant group of CK metabolites in many species; however, their physiological role in planta was for a long time perceived as irreversible storage CK forms only. Recently, a comprehensive screen showed that only vascular plants form CK N-glucosides in contrast to mosses, algae, and fungi. The formation of CK N-glucosides as biologically inactive CK conjugates thus represents an evolutionarily young mechanism for deactivation of CK bases. Even though CK N-glucosides are not biologically active themselves due to their inability to activate the CK perception system, new data on CK N-glucoside metabolism show that trans-zeatin (tZ) N7- and N9-glucosides are metabolized in vivo, efficiently releasing free CK bases that are most probably responsible for the biological activities observed in a number of bioassays. Moreover, CK N-glucosides' subcellular localization as well as their abundance in xylem both point to their possible plasma membrane transport and indicate a role also as CK transport forms. Identification of the enzyme(s) responsible for the hydrolysis of tZ N7- and N9-glucosides, as well as the discovery of putative CK N-glucoside plasma membrane transporter, would unveil important parts of the overall picture of CK metabolic interconversions and their physiological importance.
Cytokinin is an indispensable phytohormone responsible for physiological processes ranging from root development to leaf senescence. The term "cytokinin" refers to several dozen adenine-derived compounds occurring naturally in plants. Cytokinins (CKs) can be divided into various classes and forms; base forms are generally considered to be active while highly abundant cytokinin-N-glucosides (CKNGs), composed of a CK base irreversibly conjugated to a glucose molecule, are considered inactive. However, results from early CK studies suggest CKNGs do not always lack activity despite the perpetuation over several decades in the literature that they are inactive. Here we show that exogenous application of trans-Zeatin-N-glucosides (tZNGs, a specific class of CKNGs) to Arabidopsis results in CK response comparable to the application of an active CK base. These results are most apparent in senescence assays where both a CK base (tZ) and tZNGs (tZ7G, tZ9G) delay senescence in cotyledons. Further experiments involving root growth and shoot regeneration revealed tZNGs do not always have the same effects as tZ, and have largely distinct effects on the transcriptome and proteome. These data are in contrast to previous reports of CKNGs being inactive and raise questions about the function of these compounds as well as their mechanism of action.
- MeSH
- Arabidopsis růst a vývoj metabolismus MeSH
- cytokininy metabolismus MeSH
- glukosidy metabolismus MeSH
- kořeny rostlin růst a vývoj metabolismus MeSH
- regulátory růstu rostlin MeSH
- zeatin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cytokininy MeSH
- glukosidy MeSH
- regulátory růstu rostlin MeSH
- zeatin MeSH
