Molecular responses of plants to natural phytotoxins comprise more general and compound-specific mechanisms. How phytotoxic chalcones and other flavonoids inhibit seedling growth was widely studied, but how they interfere with seed germination is largely unknown. The dihydrochalcone and putative allelochemical myrigalone A (MyA) inhibits seed germination and seedling growth. Transcriptome (RNAseq) and hormone analyses of Lepidium sativum seed responses to MyA were compared to other bioactive and inactive compounds. MyA treatment of imbibed seeds triggered the phased induction of a detoxification programme, altered gibberellin, cis-(+)-12-oxophytodienoic acid and jasmonate metabolism, and affected the expression of hormone transporter genes. The MyA-mediated inhibition involved interference with the antioxidant system, oxidative signalling, aquaporins and water uptake, but not uncoupling of oxidative phosphorylation or p-hydroxyphenylpyruvate dioxygenase expression/activity. MyA specifically affected the expression of auxin-related signalling genes, and various transporter genes, including for auxin transport (PIN7, ABCG37, ABCG4, WAT1). Responses to auxin-specific inhibitors further supported the conclusion that MyA interferes with auxin homeostasis during seed germination. Comparative analysis of MyA and other phytotoxins revealed differences in the specific regulatory mechanisms and auxin transporter genes targeted to interfere with auxin homestasis. We conclude that MyA exerts its phytotoxic activity by multiple auxin-dependent and independent molecular mechanisms.

• Klíčová slova
• ATP-binding cassette (ABC) transporter, PIN auxin efflux carrier, WRKY transcription factors, allelochemical and allelopathy, aquaporin-mediated water transport, auxin transport and homeostasis, cis-(+)-12-oxophytodienoic acid (OPDA) reductase, gibberellin metabolism, phytotoxin detoxification programme, seed germination,
• MeSH
• chalkonoidy MeSH
• homeostáza MeSH
• hormony metabolismus   MeSH
• klíčení * genetika   MeSH
• kyseliny indoloctové metabolismus   MeSH
• Lepidium sativum * metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• semena rostlinná genetika   MeSH
• semenáček metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chalkonoidy MeSH
• hormony MeSH
• kyseliny indoloctové MeSH
• myrigalone A MeSH Prohlížeč
• regulátory růstu rostlin MeSH

Spontaneously arising channels that transport the phytohormone auxin provide positional cues for self-organizing aspects of plant development such as flexible vasculature regeneration or its patterning during leaf venation. The auxin canalization hypothesis proposes a feedback between auxin signaling and transport as the underlying mechanism, but molecular players await discovery. We identified part of the machinery that routes auxin transport. The auxin-regulated receptor CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) together with CANAR (Canalization-related Receptor-like kinase) interact with and phosphorylate PIN auxin transporters. camel and canar mutants are impaired in PIN1 subcellular trafficking and auxin-mediated PIN polarization, which macroscopically manifests as defects in leaf venation and vasculature regeneration after wounding. The CAMEL-CANAR receptor complex is part of the auxin feedback that coordinates polarization of individual cells during auxin canalization.

• MeSH
• Arabidopsis enzymologie   genetika   MeSH
• biologický transport MeSH
• kyseliny indoloctové metabolismus   MeSH
• mapování interakce mezi proteiny MeSH
• membránové transportní proteiny metabolismus   MeSH
• proteinkinasy genetika   metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• membránové transportní proteiny MeSH
• PIN1 protein, Arabidopsis MeSH Prohlížeč
• proteinkinasy MeSH
• proteiny huseníčku MeSH
• transkripční faktory MeSH
• WRKY23 protein, Arabidopsis MeSH Prohlížeč

Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor- and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration.

• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• heterocyklické sloučeniny tricyklické metabolismus   MeSH
• hrách setý genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• laktony metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin genetika   fyziologie   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• GR24 strigolactone MeSH Prohlížeč
• heterocyklické sloučeniny tricyklické MeSH
• kyseliny indoloctové MeSH
• laktony MeSH
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH

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

Cell polarity is a fundamental feature of all multicellular organisms. PIN auxin transporters are important cell polarity markers that play crucial roles in a plethora of developmental processes in plants. Here, to identify components involved in cell polarity establishment and maintenance in plants, we performed a forward genetic screening of PIN2:PIN1-HA;pin2 Arabidopsis (Arabidopsis thaliana) plants, which ectopically express predominantly basally localized PIN1 in root epidermal cells, leading to agravitropic root growth. We identified the regulator of PIN polarity 12 (repp12) mutation, which restored gravitropic root growth and caused a switch in PIN1-HA polarity from the basal to apical side of root epidermal cells. Next Generation Sequencing and complementation experiments established the causative mutation of repp12 as a single amino acid exchange in Aminophospholipid ATPase3 (ALA3), a phospholipid flippase predicted to function in vesicle formation. repp12 and ala3 T-DNA mutants show defects in many auxin-regulated processes, asymmetric auxin distribution, and PIN trafficking. Analysis of quintuple and sextuple mutants confirmed the crucial roles of ALA proteins in regulating plant development as well as PIN trafficking and polarity. Genetic and physical interaction studies revealed that ALA3 functions together with the ADP ribosylation factor GTPase exchange factors GNOM and BIG3 in regulating PIN polarity, trafficking, and auxin-mediated development.

• MeSH
• ADP-ribosylační faktory metabolismus   MeSH
• Arabidopsis účinky léků   metabolismus   MeSH
• biologický transport účinky léků   MeSH
• brefeldin A farmakologie   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• genetická epistáze účinky léků   MeSH
• GTP-fosfohydrolasy metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mutace genetika   MeSH
• proteiny huseníčku metabolismus   MeSH
• proteiny přenášející fosfolipidy metabolismus   MeSH
• tabák metabolismus   MeSH
• trans-Golgiho síť účinky léků   metabolismus   MeSH
• vazba proteinů účinky léků   MeSH
• výměnné faktory guaninnukleotidů metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ADP-ribosylační faktory MeSH
• brefeldin A MeSH
• GTP-fosfohydrolasy MeSH
• kyseliny indoloctové MeSH
• proteiny huseníčku MeSH
• proteiny přenášející fosfolipidy MeSH
• výměnné faktory guaninnukleotidů MeSH

Directional intercellular transport of the phytohormone auxin mediated by PIN-FORMED (PIN) efflux carriers has essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. PIN activity is therefore regulated by multiple internal and external cues, for which the underlying molecular mechanisms are not fully elucidated. Here, we demonstrate that 3'-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub that perceives upstream lipid signalling and modulates downstream substrate activity through phosphorylation. Using genetic analysis, we show that the loss-of-function Arabidopsis pdk1.1 pdk1.2 mutant exhibits a plethora of abnormalities in organogenesis and growth due to defective polar auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 protein kinase, a well-known upstream activator of PIN proteins. We uncover a lipid-dependent phosphorylation cascade that connects membrane-composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.

• MeSH
• Arabidopsis metabolismus   MeSH
• buněčná membrána metabolismus   MeSH
• fosfolipidy metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• membránové transportní proteiny metabolismus   fyziologie   MeSH
• proteinkinasy PDK fyziologie   MeSH
• proteiny huseníčku fyziologie   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosfolipidy MeSH
• kyseliny indoloctové MeSH
• membránové transportní proteiny MeSH
• proteinkinasy PDK MeSH
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH

Polar auxin transport plays a pivotal role in plant growth and development. PIN-FORMED (PIN) auxin efflux carriers regulate directional auxin movement by establishing local auxin maxima, minima, and gradients that drive multiple developmental processes and responses to environmental signals. Auxin has been proposed to modulate its own transport by regulating subcellular PIN trafficking via processes such as clathrin-mediated PIN endocytosis and constitutive recycling. Here, we further investigated the mechanisms by which auxin affects PIN trafficking by screening auxin analogs and identified pinstatic acid (PISA) as a positive modulator of polar auxin transport in Arabidopsis (Arabidopsis thaliana). PISA had an auxin-like effect on hypocotyl elongation and adventitious root formation via positive regulation of auxin transport. PISA did not activate SCFTIR1/AFB signaling and yet induced PIN accumulation at the cell surface by inhibiting PIN internalization from the plasma membrane. This work demonstrates PISA to be a promising chemical tool to dissect the regulatory mechanisms behind subcellular PIN trafficking and auxin transport.

• MeSH
• Arabidopsis účinky léků   metabolismus   MeSH
• biologický transport účinky léků   MeSH
• buněčná membrána účinky léků   metabolismus   MeSH
• endocytóza * účinky léků   MeSH
• fenotyp MeSH
• fenylacetáty farmakologie   MeSH
• gravitropismus účinky léků   MeSH
• hypokotyl účinky léků   růst a vývoj   MeSH
• kořeny rostlin účinky léků   růst a vývoj   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• signální transdukce MeSH
• výhonky rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fenylacetáty MeSH
• kyseliny indoloctové MeSH
• phenylacetic acid MeSH Prohlížeč
• pinstatic acid MeSH Prohlížeč
• proteiny huseníčku MeSH

Cell polarity, manifested by the localization of proteins to distinct polar plasma membrane domains, is a key prerequisite of multicellular life. In plants, PIN auxin transporters are prominent polarity markers crucial for a plethora of developmental processes. Cell polarity mechanisms in plants are distinct from other eukaryotes and still largely elusive. In particular, how the cell polarities are propagated and maintained following cell division remains unknown. Plant cytokinesis is orchestrated by the cell plate-a transient centrifugally growing endomembrane compartment ultimately forming the cross wall1. Trafficking of polar membrane proteins is typically redirected to the cell plate, and these will consequently have opposite polarity in at least one of the daughter cells2-5. Here, we provide mechanistic insights into post-cytokinetic re-establishment of cell polarity as manifested by the apical, polar localization of PIN2. We show that the apical domain is defined in a cell-intrinsic manner and that re-establishment of PIN2 localization to this domain requires de novo protein secretion and endocytosis, but not basal-to-apical transcytosis. Furthermore, we identify a PINOID-related kinase WAG1, which phosphorylates PIN2 in vitro6 and is transcriptionally upregulated specifically in dividing cells, as a crucial regulator of post-cytokinetic PIN2 polarity re-establishment.

• MeSH
• Arabidopsis cytologie   genetika   fyziologie   MeSH
• buněčná membrána metabolismus   MeSH
• buněčné dělení * MeSH
• cytokineze MeSH
• endocytóza MeSH
• fenotyp MeSH
• fosforylace MeSH
• kořeny rostlin cytologie   genetika   fyziologie   MeSH
• polarita buněk * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• rekombinantní fúzní proteiny MeSH
• reportérové geny MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• PIN2 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• rekombinantní fúzní proteiny MeSH

The angiosperm seed is composed of three genetically distinct tissues: the diploid embryo that originates from the fertilized egg cell, the triploid endosperm that is produced from the fertilized central cell, and the maternal sporophytic integuments that develop into the seed coat1. At the onset of embryo development in Arabidopsis thaliana, the zygote divides asymmetrically, producing a small apical embryonic cell and a larger basal cell that connects the embryo to the maternal tissue2. The coordinated and synchronous development of the embryo and the surrounding integuments, and the alignment of their growth axes, suggest communication between maternal tissues and the embryo. In contrast to animals, however, where a network of maternal factors that direct embryo patterning have been identified3,4, only a few maternal mutations have been described to affect embryo development in plants5-7. Early embryo patterning in Arabidopsis requires accumulation of the phytohormone auxin in the apical cell by directed transport from the suspensor8-10. However, the origin of this auxin has remained obscure. Here we investigate the source of auxin for early embryogenesis and provide evidence that the mother plant coordinates seed development by supplying auxin to the early embryo from the integuments of the ovule. We show that auxin response increases in ovules after fertilization, due to upregulated auxin biosynthesis in the integuments, and this maternally produced auxin is required for correct embryo development.

• MeSH
• Arabidopsis růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové farmakologie   MeSH
• semena rostlinná účinky léků   růst a vývoj   MeSH
• vývoj rostlin účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH

Intercellular distribution of the plant hormone auxin largely depends on the polar subcellular distribution of the plasma membrane PIN-FORMED (PIN) auxin transporters. PIN polarity switches in response to different developmental and environmental signals have been shown to redirect auxin fluxes mediating certain developmental responses. PIN phosphorylation at different sites and by different kinases is crucial for PIN function. Here we investigate the role of PIN phosphorylation during gravitropic response. Loss- and gain-of-function mutants in PINOID and related kinases but not in D6PK kinase as well as mutations mimicking constitutive dephosphorylated or phosphorylated status of two clusters of predicted phosphorylation sites partially disrupted PIN3 phosphorylation and caused defects in gravitropic bending in roots and hypocotyls. In particular, they impacted PIN3 polarity rearrangements in response to gravity and during feed-back regulation by auxin itself. Thus PIN phosphorylation, besides regulating transport activity and apical-basal targeting, is also important for the rapid polarity switches in response to environmental and endogenous signals.

• MeSH
• Arabidopsis účinky léků   fyziologie   MeSH
• fosforylace MeSH
• gravitropismus * MeSH
• kořeny rostlin účinky léků   fyziologie   MeSH
• kyseliny indoloctové farmakologie   MeSH
• percepce tíhy MeSH
• polarita buněk * MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulátory růstu rostlin farmakologie   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny indoloctové MeSH
• PIN3 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH