Plant survival depends on vascular tissues, which originate in a self-organizing manner as strands of cells co-directionally transporting the plant hormone auxin. The latter phenomenon (also known as auxin canalization) is classically hypothesized to be regulated by auxin itself via the effect of this hormone on the polarity of its own intercellular transport. Correlative observations supported this concept, but molecular insights remain limited. In the current study, we established an experimental system based on the model Arabidopsis thaliana, which exhibits auxin transport channels and formation of vasculature strands in response to local auxin application. Our methodology permits the genetic analysis of auxin canalization under controllable experimental conditions. By utilizing this opportunity, we confirmed the dependence of auxin canalization on a PIN-dependent auxin transport and nuclear, TIR1/AFB-mediated auxin signaling. We also show that leaf venation and auxin-mediated PIN repolarization in the root require TIR1/AFB signaling. Further studies based on this experimental system are likely to yield better understanding of the mechanisms underlying auxin transport polarization in other developmental contexts.

• Klíčová slova
• Arabidopsis thaliana, PIN1, TIR1/AFB, auxin, auxin canalization, cell polarity,
• MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• F-box proteiny * genetika   MeSH
• kyseliny indoloctové MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• receptory buněčného povrchu genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• F-box proteiny * MeSH
• kyseliny indoloctové MeSH
• proteiny huseníčku * MeSH
• receptory buněčného povrchu MeSH
• regulátory růstu rostlin MeSH
• TIR1 protein, Arabidopsis MeSH Prohlížeč

Plants, in contrast to animals, are unique in their capacity to postembryonically develop new organs due to the activity of stem cell populations, located in specialized tissues called meristems. Above ground, the shoot apical meristem generates aerial organs and tissues throughout plant life. It is well established that auxin plays a central role in the functioning of the shoot apical meristem. Auxin distribution in the meristem is not uniform and depends on the interplay between biosynthesis, transport, and degradation. Auxin maxima and minima are created, and result in transcriptional outputs that drive the development of new organs and contribute to meristem maintenance. To uncover and understand complex signaling networks such as the one regulating auxin responses in the shoot apical meristem remains a challenge. Here, we will discuss our current understanding and point to important research directions for the future.

• MeSH
• kyseliny indoloctové * metabolismus   MeSH
• meristém * fyziologie   MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• kyseliny indoloctové * MeSH

As non-photosynthesizing organs, roots are dependent on diffusion of oxygen from the external environment and, in some instances, from the shoot for their aerobic metabolism. Establishment of hypoxic niches in the developing tissues of plants has been postulated as a consequence of insufficient diffusion of oxygen to satisfy the demands throughout development. Here, we report that such niches are established at specific stages of lateral root primordia development in Arabidopsis thaliana grown under aerobic conditions. Using gain- and loss-of-function mutants, we show that ERF-VII transcription factors, which mediate hypoxic responses, control root architecture by acting in cells with a high level of auxin signaling. ERF-VIIs repress the expression of the auxin-induced genes LBD16, LBD18, and PUCHI, which are essential for lateral root development, by binding to their promoters. Our results support a model in which the establishment of hypoxic niches in the developing lateral root primordia contributes to the shutting down of key auxin-induced genes and regulates the production of lateral roots.

• Klíčová slova
• Arabidopsis, ERF-VII, auxin, hypoxia, lateral root, root development,
• MeSH
• Arabidopsis cytologie   genetika   metabolismus   MeSH
• hypoxie buňky MeSH
• kořeny rostlin cytologie   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• proteiny huseníčku MeSH

Plant adjustment to environmental changes involves complex crosstalk between extrinsic and intrinsic cues. In the past two decades, extensive research has elucidated the key roles of PHYTOCHROME-INTERACTING FACTOR4 (PIF4) and the phytohormone auxin in thermomorphogenesis. In this study, we identified a previously unexplored role of jasmonate (JA) signaling components, the Mediator complex, and their integration with auxin signaling during thermomorphogenesis in Arabidopsis (Arabidopsis thaliana). Warm temperature induces expression of JA signaling genes including MYC2, but, surprisingly, this transcriptional activation is not JA dependent. Warm temperature also promotes accumulation of the JA signaling receptor CORONATINE INSENSITIVE1 (COI1) and degradation of the JA signaling repressor JASMONATE-ZIM-DOMAIN PROTEIN9, which probably leads to de-repression of MYC2, enabling it to contribute to the expression of MEDIATOR SUBUNIT17 (MED17). In response to warm temperature, MED17 occupies the promoters of thermosensory genes including PIF4, YUCCA8 (YUC8), INDOLE-3-ACETIC ACID INDUCIBLE19 (IAA19), and IAA29. Moreover, MED17 facilitates enrichment of H3K4me3 on the promoters of PIF4, YUC8, IAA19, and IAA29 genes. Interestingly, both occupancy of MED17 and enrichment of H3K4me3 on these thermomorphogenesis-related promoters are dependent on PIF4 (or PIFs). Altered accumulation of COI1 under warm temperature in the med17 mutant suggests the possibility of a feedback mechanism. Overall, this study reveals the role of the Mediator complex as an integrator of JA and auxin signaling pathways during thermomorphogenesis.

• MeSH
• Arabidopsis * metabolismus   MeSH
• cyklopentany metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mediátorový komplex metabolismus   MeSH
• oxylipiny metabolismus   MeSH
• proteiny huseníčku * metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyklopentany MeSH
• jasmonic acid MeSH Prohlížeč
• kyseliny indoloctové MeSH
• mediátorový komplex MeSH
• oxylipiny MeSH
• proteiny huseníčku * MeSH

Arabidopsis PIN2 protein directs transport of the phytohormone auxin from the root tip into the root elongation zone. Variation in hormone transport, which depends on a delicate interplay between PIN2 sorting to and from polar plasma membrane domains, determines root growth. By employing a constitutively degraded version of PIN2, we identify brassinolides as antagonists of PIN2 endocytosis. This response does not require de novo protein synthesis, but involves early events in canonical brassinolide signaling. Brassinolide-controlled adjustments in PIN2 sorting and intracellular distribution governs formation of a lateral PIN2 gradient in gravistimulated roots, coinciding with adjustments in auxin signaling and directional root growth. Strikingly, simulations indicate that PIN2 gradient formation is no prerequisite for root bending but rather dampens asymmetric auxin flow and signaling. Crosstalk between brassinolide signaling and endocytic PIN2 sorting, thus, appears essential for determining the rate of gravity-induced root curvature via attenuation of differential cell elongation.

• MeSH
• Arabidopsis účinky léků   metabolismus   MeSH
• biologický transport účinky léků   MeSH
• brassinosteroidy metabolismus   farmakologie   MeSH
• endocytóza účinky léků   MeSH
• gravitropismus účinky léků   fyziologie   MeSH
• kořeny rostlin účinky léků   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• meristém účinky léků   metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• signální transdukce MeSH
• steroidy heterocyklické metabolismus   farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• brassinolide MeSH Prohlížeč
• brassinosteroidy MeSH
• kyseliny indoloctové MeSH
• PIN2 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH
• steroidy heterocyklické MeSH

• Klíčová slova
• AUX/IAA transcriptional regulators, Arabidopsis, Auxin F-Box (AFB), Auxin Response Factors (ARFs), Transport Inhibitor Response 1 (TIR1), auxin, canonical auxin signalling pathway, indole-3-acetic acid (IAA), kinase, receptor, TIR1/AFB co-receptor, non-canonical auxin signalling pathway, ubiquitination,
• MeSH
• fyziologie rostlin * MeSH
• kyseliny indoloctové metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH

Among the most fascinated properties of the plant hormone auxin is its ability to promote formation of its own directional transport routes. These gradually narrowing auxin channels form from the auxin source toward the sink and involve coordinated, collective polarization of individual cells. Once established, the channels provide positional information, along which new vascular strands form, for example, during organogenesis, regeneration, or leave venation. The main prerequisite of this still mysterious auxin canalization mechanism is a feedback between auxin signaling and its directional transport. This is manifested by auxin-induced re-arrangements of polar, subcellular localization of PIN-FORMED (PIN) auxin exporters. Immanent open questions relate to how position of auxin source and sink as well as tissue context are sensed and translated into tissue polarization and how cells communicate to polarize coordinately. Recently, identification of the first molecular players opens new avenues into molecular studies of this intriguing example of self-organizing plant development.

• Klíčová slova
• Auxin canalization, Auxin signaling, Auxin transport, PIN polarity, PIN trafficking, Vasculature formation,
• MeSH
• Arabidopsis * metabolismus   MeSH
• biologický transport MeSH
• kyseliny indoloctové MeSH
• proteiny huseníčku * metabolismus   MeSH
• regulátory růstu rostlin MeSH
• vývoj rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• proteiny huseníčku * MeSH
• regulátory růstu rostlin MeSH

De novo shoot organogenesis (DNSO) is a procedure commonly used for the in vitro regeneration of shoots from a variety of plant tissues. Shoot regeneration occurs on nutrient media supplemented with the plant hormones cytokinin (CK) and auxin, which play essential roles in this process, and genes involved in their signaling cascades act as master regulators of the different phases of shoot regeneration. In the last 20 years, the genetic regulation of DNSO has been characterized in detail. However, as of today, the CK and auxin signaling events associated with shoot regeneration are often interpreted as a consequence of these hormones simply being present in the regeneration media, whereas the roles for their prior uptake and transport into the cultivated plant tissues are generally overlooked. Additionally, sucrose, commonly added to the regeneration media as a carbon source, plays a signaling role and has been recently shown to interact with CK and auxin and to affect the efficiency of shoot regeneration. In this review, we provide an integrative interpretation of the roles for CK and auxin in the process of DNSO, adding emphasis on their uptake from the regeneration media and their interaction with sucrose present in the media to their complex signaling outputs that mediate shoot regeneration.

• Klíčová slova
• DNSO, auxin, cytokinin, de novo shoot organogenesis, gene regulatory network, hormone uptake, shoot regeneration, sucrose, transport,
• MeSH
• cytokininy metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• organogeneze rostlin * MeSH
• regulátory růstu rostlin metabolismus   MeSH
• výhonky rostlin cytologie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• cytokininy MeSH
• kyseliny indoloctové MeSH
• regulátory růstu rostlin MeSH

Postembryonic de novo organogenesis represents an important competence evolved in plants that allows their physiological and developmental adaptation to changing environmental conditions. The phytohormones auxin and cytokinin (CK) are important regulators of the developmental fate of pluripotent plant cells. However, the molecular nature of their interaction(s) in control of plant organogenesis is largely unknown. Here, we show that CK modulates auxin-induced organogenesis (AIO) via regulation of the efflux-dependent intercellular auxin distribution. We used the hypocotyl explants-based in vitro system to study the mechanism underlying de novo organogenesis. We show that auxin, but not CK, is capable of triggering organogenesis in hypocotyl explants. The AIO is accompanied by endogenous CK production and tissue-specific activation of CK signaling. CK affects differential auxin distribution, and the CK-mediated modulation of organogenesis is simulated by inhibition of polar auxin transport. CK reduces auxin efflux from cultured tobacco cells and regulates expression of auxin efflux carriers from the PIN family in hypocotyl explants. Moreover, endogenous CK levels influence PIN transcription and are necessary to maintain intercellular auxin distribution in planta. Based on these findings, we propose a model in which auxin acts as a trigger of the organogenic processes, whose output is modulated by the endogenously produced CKs. We propose that an important mechanism of this CK action is its effect on auxin distribution via regulation of expression of auxin efflux carriers.

• MeSH
• Arabidopsis účinky léků   růst a vývoj   metabolismus   MeSH
• biologický transport MeSH
• cytokininy farmakologie   MeSH
• kořeny rostlin účinky léků   růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• signální transdukce MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytokininy MeSH
• kyseliny indoloctové MeSH

The phytohormone auxin is a master regulator of plant growth and development in response to many endogenous and environmental signals. The underlying coordination of growth is mediated by the formation of auxin maxima and concentration gradients. The visualization of auxin dynamics and distribution can therefore provide essential information to increase our understanding of the mechanisms by which auxin orchestrates these growth and developmental processes. Several auxin reporters have been developed to better perceive the auxin distribution and signaling machinery in vivo. This review focuses on different types of auxin reporters and biosensors used to monitor auxin distribution and its dynamics, as well as auxin signaling, at the cellular and tissue levels in different plant species. We provide a brief history of each reporter and biosensor group and explain their principles and utilities.

• MeSH
• kyseliny indoloctové * MeSH
• regulátory růstu rostlin * MeSH
• rostliny MeSH
• signální transdukce MeSH
• vývoj rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• kyseliny indoloctové * MeSH
• regulátory růstu rostlin * MeSH