@article{kolbeck_casp_2022,
	title = {{CASP} microdomain formation requires cross cell wall stabilization of domains and non-cell autonomous action of {LOTR1}},
	volume = {11},
	issn = {2050-084X},
	url = {https://doi.org/10.7554/eLife.69602},
	doi = {10/gpjfdm},
	abstract = {Efficient uptake of nutrients in both animal and plant cells requires tissue-spanning diffusion barriers separating inner tissues from the outer lumen/soil. However, we poorly understand how such contiguous three-dimensional superstructures are formed in plants. Here, we show that correct establishment of the plant Casparian Strip (CS) network relies on local neighbor communication. We show that positioning of Casparian Strip membrane domains (CSDs) is tightly coordinated between neighbors in wild-type and that restriction of domain formation involves the putative extracellular protease LOTR1. Impaired domain restriction in lotr1 leads to fully functional CSDs at ectopic positions, forming ‘half strips’. LOTR1 action in the endodermis requires its expression in the stele. LOTR1 endodermal expression cannot complement, while cortex expression causes a dominant-negative phenotype. Our findings establish LOTR1 as a crucial player in CSD positioning acting in a directional, non-cell-autonomous manner to restrict and coordinate CS positioning.},
	urldate = {2022-02-17},
	journal = {eLife},
	author = {Kolbeck, Andreas and Marhavý, Peter and De Bellis, Damien and Li, Baohai and Kamiya, Takehiro and Fujiwara, Toru and Kalmbach, Lothar and Geldner, Niko},
	editor = {Benitez-Alfonso, Yoselin and Kleine-Vehn, Jürgen and Jallais, Yvon and Somssich, Marc},
	month = jan,
	year = {2022},
	keywords = {arabidopsis, casparian strip, endodermis, microdomains, neprosin, network},
	pages = {e69602},
}

Efficient uptake of nutrients in both animal and plant cells requires tissue-spanning diffusion barriers separating inner tissues from the outer lumen/soil. However, we poorly understand how such contiguous three-dimensional superstructures are formed in plants. Here, we show that correct establishment of the plant Casparian Strip (CS) network relies on local neighbor communication. We show that positioning of Casparian Strip membrane domains (CSDs) is tightly coordinated between neighbors in wild-type and that restriction of domain formation involves the putative extracellular protease LOTR1. Impaired domain restriction in lotr1 leads to fully functional CSDs at ectopic positions, forming ‘half strips’. LOTR1 action in the endodermis requires its expression in the stele. LOTR1 endodermal expression cannot complement, while cortex expression causes a dominant-negative phenotype. Our findings establish LOTR1 as a crucial player in CSD positioning acting in a directional, non-cell-autonomous manner to restrict and coordinate CS positioning.

@article{otvos_pickle_2021,
	title = {Pickle {Recruits} {Retinoblastoma} {Related} 1 to {Control} {Lateral} {Root} {Formation} in {Arabidopsis}},
	volume = {22},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	url = {https://www.mdpi.com/1422-0067/22/8/3862},
	doi = {10.3390/ijms22083862},
	abstract = {Lateral root (LR) formation is an example of a plant post-embryonic organogenesis event. LRs are issued from non-dividing cells entering consecutive steps of formative divisions, proliferation and elongation. The chromatin remodeling protein PICKLE (PKL) negatively regulates auxin-mediated LR formation through a mechanism that is not yet known. Here we show that PKL interacts with RETINOBLASTOMA-RELATED 1 (RBR1) to repress the LATERAL ORGAN BOUNDARIES-DOMAIN 16 (LBD16) promoter activity. Since LBD16 function is required for the formative division of LR founder cells, repression mediated by the PKL–RBR1 complex negatively regulates formative division and LR formation. Inhibition of LR formation by PKL–RBR1 is counteracted by auxin, indicating that, in addition to auxin-mediated transcriptional responses, the fine-tuned process of LR formation is also controlled at the chromatin level in an auxin-signaling dependent manner.},
	language = {en},
	number = {8},
	urldate = {2021-07-01},
	journal = {International Journal of Molecular Sciences},
	author = {Ötvös, Krisztina and Miskolczi, Pál and Marhavý, Peter and Cruz-Ramírez, Alfredo and Benková, Eva and Robert, Stéphanie and Bakó, László},
	month = jan,
	year = {2021},
	keywords = {\textit{de novo} organogenesis, auxin signaling, chromatin remodeling},
	pages = {3862},
}

Lateral root (LR) formation is an example of a plant post-embryonic organogenesis event. LRs are issued from non-dividing cells entering consecutive steps of formative divisions, proliferation and elongation. The chromatin remodeling protein PICKLE (PKL) negatively regulates auxin-mediated LR formation through a mechanism that is not yet known. Here we show that PKL interacts with RETINOBLASTOMA-RELATED 1 (RBR1) to repress the LATERAL ORGAN BOUNDARIES-DOMAIN 16 (LBD16) promoter activity. Since LBD16 function is required for the formative division of LR founder cells, repression mediated by the PKL–RBR1 complex negatively regulates formative division and LR formation. Inhibition of LR formation by PKL–RBR1 is counteracted by auxin, indicating that, in addition to auxin-mediated transcriptional responses, the fine-tuned process of LR formation is also controlled at the chromatin level in an auxin-signaling dependent manner.

@article{kubiasova_cytokinin_2020,
	title = {Cytokinin fluoroprobe reveals multiple sites of cytokinin perception at plasma membrane and endoplasmic reticulum},
	volume = {11},
	issn = {2041-1723},
	url = {http://www.nature.com/articles/s41467-020-17949-0},
	doi = {10.1038/s41467-020-17949-0},
	language = {en},
	number = {1},
	urldate = {2021-06-07},
	journal = {Nature Communications},
	author = {Kubiasová, Karolina and Montesinos, Juan Carlos and Šamajová, Olga and Nisler, Jaroslav and Mik, Václav and Semerádová, Hana and Plíhalová, Lucie and Novák, Ondřej and Marhavý, Peter and Cavallari, Nicola and Zalabák, David and Berka, Karel and Doležal, Karel and Galuszka, Petr and Šamaj, Jozef and Strnad, Miroslav and Benková, Eva and Plíhal, Ondřej and Spíchal, Lukáš},
	month = dec,
	year = {2020},
	pages = {4285},
}

@article{fujita_schengen_2020,
	title = {{SCHENGEN} receptor module drives localized {ROS} production and lignification in plant roots},
	volume = {39},
	issn = {0261-4189},
	url = {https://www.embopress.org/doi/full/10.15252/embj.2019103894},
	doi = {10/gjct3x},
	abstract = {Abstract Production of reactive oxygen species (ROS) by NADPH oxidases (NOXs) impacts many processes in animals and plants, and many plant receptor pathways involve rapid, NOX-dependent increases of ROS. Yet, their general reactivity has made it challenging to pinpoint the precise role and immediate molecular action of ROS. A well-understood ROS action in plants is to provide the co-substrate for lignin peroxidases in the cell wall. Lignin can be deposited with exquisite spatial control, but the underlying mechanisms have remained elusive. Here, we establish a kinase signaling relay that exerts direct, spatial control over ROS production and lignification within the cell wall. We show that polar localization of a single kinase component is crucial for pathway function. Our data indicate that an intersection of more broadly localized components allows for micrometer-scale precision of lignification and that this system is triggered through initiation of ROS production as a critical peroxidase co-substrate.},
	number = {9},
	urldate = {2021-06-21},
	journal = {The EMBO Journal},
	author = {Fujita, Satoshi and De Bellis, Damien and Edel, Kai H and Köster, Philipp and Andersen, Tonni Grube and Schmid-Siegert, Emanuel and Dénervaud Tendon, Valérie and Pfister, Alexandre and Marhavý, Peter and Ursache, Robertas and Doblas, Verónica G and Barberon, Marie and Daraspe, Jean and Creff, Audrey and Ingram, Gwyneth and Kudla, Jörg and Geldner, Niko},
	month = may,
	year = {2020},
	note = {Publisher: John Wiley \& Sons, Ltd},
	keywords = {Casparian strips, extracellular diffusion barriers, lignin, localized ROS production, polarized signaling},
	pages = {e103894},
}

Abstract Production of reactive oxygen species (ROS) by NADPH oxidases (NOXs) impacts many processes in animals and plants, and many plant receptor pathways involve rapid, NOX-dependent increases of ROS. Yet, their general reactivity has made it challenging to pinpoint the precise role and immediate molecular action of ROS. A well-understood ROS action in plants is to provide the co-substrate for lignin peroxidases in the cell wall. Lignin can be deposited with exquisite spatial control, but the underlying mechanisms have remained elusive. Here, we establish a kinase signaling relay that exerts direct, spatial control over ROS production and lignification within the cell wall. We show that polar localization of a single kinase component is crucial for pathway function. Our data indicate that an intersection of more broadly localized components allows for micrometer-scale precision of lignification and that this system is triggered through initiation of ROS production as a critical peroxidase co-substrate.

@article{marhava_re-activation_2019,
	title = {Re-activation of {Stem} {Cell} {Pathways} for {Pattern} {Restoration} in {Plant} {Wound} {Healing}},
	volume = {177},
	issn = {00928674},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0092867419304015},
	doi = {10/gfz9tc},
	language = {en},
	number = {4},
	urldate = {2021-06-07},
	journal = {Cell},
	author = {Marhava, Petra and Hoermayer, Lukas and Yoshida, Saiko and Marhavý, Peter and Benková, Eva and Friml, Jiří},
	month = may,
	year = {2019},
	pages = {957--969.e13},
}

@article{holbein_root_2019,
	title = {Root endodermal barrier system contributes to defence against plant‐parasitic cyst and root‐knot nematodes},
	volume = {100},
	issn = {0960-7412, 1365-313X},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/tpj.14459},
	doi = {10.1111/tpj.14459},
	language = {en},
	number = {2},
	urldate = {2021-06-07},
	journal = {The Plant Journal},
	author = {Holbein, Julia and Franke, Rochus B. and Marhavý, Peter and Fujita, Satoshi and Górecka, Mirosława and Sobczak, Mirosław and Geldner, Niko and Schreiber, Lukas and Grundler, Florian M. W. and Siddique, Shahid},
	month = oct,
	year = {2019},
	pages = {221--236},
}

@article{marhavy_singlecell_2019,
	title = {Single‐cell damage elicits regional, nematode‐restricting ethylene responses in roots},
	volume = {38},
	issn = {0261-4189, 1460-2075},
	url = {https://onlinelibrary.wiley.com/doi/10.15252/embj.2018100972},
	doi = {10/gf2hvf},
	language = {en},
	number = {10},
	urldate = {2021-06-07},
	journal = {The EMBO Journal},
	author = {Marhavý, Peter and Kurenda, Andrzej and Siddique, Shahid and Dénervaud Tendon, Valerie and Zhou, Feng and Holbein, Julia and Hasan, M Shamim and Grundler, Florian MW and Farmer, Edward E and Geldner, Niko},
	month = may,
	year = {2019},
}

@article{ursache_protocol_2018,
	title = {A protocol for combining fluorescent proteins with histological stains for diverse cell wall components},
	volume = {93},
	issn = {0960-7412, 1365-313X},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/tpj.13784},
	doi = {10/gkf56d},
	language = {en},
	number = {2},
	urldate = {2021-06-07},
	journal = {The Plant Journal},
	author = {Ursache, Robertas and Andersen, Tonni Grube and Marhavý, Peter and Geldner, Niko},
	month = jan,
	year = {2018},
	pages = {399--412},
}

@article{marhavy_targeted_2016,
	title = {Targeted cell elimination reveals an auxin-guided biphasic mode of lateral root initiation},
	volume = {30},
	issn = {0890-9369, 1549-5477},
	url = {http://genesdev.cshlp.org/lookup/doi/10.1101/gad.276964.115},
	doi = {10.1101/gad.276964.115},
	language = {en},
	number = {4},
	urldate = {2021-06-07},
	journal = {Genes \& Development},
	author = {Marhavý, Peter and Montesinos, Juan Carlos and Abuzeineh, Anas and Van Damme, Daniel and Vermeer, Joop E.M. and Duclercq, Jerôme and Rakusová, Hana and Nováková, Petra and Friml, Jiři and Geldner, Niko and Benková, Eva},
	month = feb,
	year = {2016},
	keywords = {auxin, lateral root organogenesis, mechanical forces, meristem proliferation activity},
	pages = {471--483},
}

@article{marhavy_real-time_2015,
	title = {Real-time {Analysis} of {Lateral} {Root} {Organogenesis} in {Arabidopsis}},
	volume = {5},
	issn = {2331-8325},
	url = {http://www.bio-protocol.org/e1446},
	doi = {10/ggsz3x},
	language = {en},
	number = {8},
	urldate = {2021-06-07},
	journal = {BIO-PROTOCOL},
	author = {Marhavý, Peter and Benkova, Eva},
	year = {2015},
}

@article{marhavy_cytokinin_2014,
	title = {Cytokinin {Controls} {Polarity} of {PIN1}-{Dependent} {Auxin} {Transport} during {Lateral} {Root} {Organogenesis}},
	volume = {24},
	issn = {09609822},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0960982214004023},
	doi = {10/f52zbg},
	language = {en},
	number = {9},
	urldate = {2021-06-08},
	journal = {Current Biology},
	author = {Marhavý, Peter and Duclercq, Jérôme and Weller, Benjamin and Feraru, Elena and Bielach, Agnieszka and Offringa, Remko and Friml, Jiří and Schwechheimer, Claus and Murphy, Angus and Benková, Eva},
	month = may,
	year = {2014},
	pages = {1031--1037},
}

@article{rosquete_auxin_2013,
	title = {An {Auxin} {Transport} {Mechanism} {Restricts} {Positive} {Orthogravitropism} in {Lateral} {Roots}},
	volume = {23},
	issn = {09609822},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0960982213003667},
	doi = {10/f4w5br},
	language = {en},
	number = {9},
	urldate = {2021-06-08},
	journal = {Current Biology},
	author = {Rosquete, Michel Ruiz and von Wangenheim, Daniel and Marhavý, Peter and Barbez, Elke and Stelzer, Ernst H.K. and Benková, Eva and Maizel, Alexis and Kleine-Vehn, Jürgen},
	month = may,
	year = {2013},
	pages = {817--822},
}

@article{pollier_protein_2013,
	title = {The protein quality control system manages plant defence compound synthesis},
	volume = {504},
	issn = {1476-4687},
	doi = {10/f5jcsn},
	abstract = {Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondary metabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Here we show that, in the legume Medicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD) quality control system to manage the production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membrane-anchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulation is prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.},
	language = {eng},
	number = {7478},
	journal = {Nature},
	author = {Pollier, Jacob and Moses, Tessa and González-Guzmán, Miguel and De Geyter, Nathan and Lippens, Saskia and Vanden Bossche, Robin and Marhavý, Peter and Kremer, Anna and Morreel, Kris and Guérin, Christopher J. and Tava, Aldo and Oleszek, Wieslaw and Thevelein, Johan M. and Campos, Narciso and Goormachtig, Sofie and Goossens, Alain},
	month = dec,
	year = {2013},
	pmid = {24213631},
	keywords = {Cells, Cultured, Endoplasmic Reticulum-Associated Degradation, Gene Expression Profiling, Gene Expression Regulation, Plant, Gene Silencing, Genetic Complementation Test, Medicago truncatula, Microscopy, Electron, Scanning, Molecular Sequence Data, Mutation, Plant Growth Regulators, Plant Roots, Saccharomyces cerevisiae, Saponins, Signal Transduction, Ubiquitin-Protein Ligases},
	pages = {148--152},
}

Jasmonates are ubiquitous oxylipin-derived phytohormones that are essential in the regulation of many development, growth and defence processes. Across the plant kingdom, jasmonates act as elicitors of the production of bioactive secondary metabolites that serve in defence against attackers. Knowledge of the conserved jasmonate perception and early signalling machineries is increasing, but the downstream mechanisms that regulate defence metabolism remain largely unknown. Here we show that, in the legume Medicago truncatula, jasmonate recruits the endoplasmic-reticulum-associated degradation (ERAD) quality control system to manage the production of triterpene saponins, widespread bioactive compounds that share a biogenic origin with sterols. An ERAD-type RING membrane-anchor E3 ubiquitin ligase is co-expressed with saponin synthesis enzymes to control the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the rate-limiting enzyme in the supply of the ubiquitous terpene precursor isopentenyl diphosphate. Thus, unrestrained bioactive saponin accumulation is prevented and plant development and integrity secured. This control apparatus is equivalent to the ERAD system that regulates sterol synthesis in yeasts and mammals but that uses distinct E3 ubiquitin ligases, of the HMGR degradation 1 (HRD1) type, to direct destruction of HMGR. Hence, the general principles for the management of sterol and triterpene saponin biosynthesis are conserved across eukaryotes but can be controlled by divergent regulatory cues.

@article{marhavy_auxin_2012,
	title = {Auxin reflux between the endodermis and pericycle promotes lateral root initiation},
	volume = {32},
	issn = {0261-4189, 1460-2075},
	url = {http://emboj.embopress.org/cgi/doi/10.1038/emboj.2012.303},
	doi = {10/gkgdj3},
	number = {1},
	urldate = {2021-06-08},
	journal = {The EMBO Journal},
	author = {Marhavý, Peter and Vanstraelen, Marleen and De Rybel, Bert and Zhaojun, Ding and Bennett, Malcolm J and Beeckman, Tom and Benková, Eva},
	month = nov,
	year = {2012},
	pages = {149--158},
}

@article{bielach_genetic_2012,
	title = {Genetic approach towards the identification of auxin–cytokinin crosstalk components involved in root development},
	volume = {367},
	url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2011.0233},
	doi = {10/f32frv},
	abstract = {Phytohormones are important plant growth regulators that control many developmental processes, such as cell division, cell differentiation, organogenesis and morphogenesis. They regulate a multitude of apparently unrelated physiological processes, often with overlapping roles, and they mutually modulate their effects. These features imply important synergistic and antagonistic interactions between the various plant hormones. Auxin and cytokinin are central hormones involved in the regulation of plant growth and development, including processes determining root architecture, such as root pole establishment during early embryogenesis, root meristem maintenance and lateral root organogenesis. Thus, to control root development both pathways put special demands on the mechanisms that balance their activities and mediate their interactions. Here, we summarize recent knowledge on the role of auxin and cytokinin in the regulation of root architecture with special focus on lateral root organogenesis, discuss the latest findings on the molecular mechanisms of their interactions, and present forward genetic screen as a tool to identify novel molecular components of the auxin and cytokinin crosstalk.},
	number = {1595},
	urldate = {2021-06-08},
	journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
	author = {Bielach, Agnieszka and Duclercq, Jérôme and Marhavý, Peter and Benková, Eva},
	month = jun,
	year = {2012},
	note = {Publisher: Royal Society},
	pages = {1469--1478},
}

Phytohormones are important plant growth regulators that control many developmental processes, such as cell division, cell differentiation, organogenesis and morphogenesis. They regulate a multitude of apparently unrelated physiological processes, often with overlapping roles, and they mutually modulate their effects. These features imply important synergistic and antagonistic interactions between the various plant hormones. Auxin and cytokinin are central hormones involved in the regulation of plant growth and development, including processes determining root architecture, such as root pole establishment during early embryogenesis, root meristem maintenance and lateral root organogenesis. Thus, to control root development both pathways put special demands on the mechanisms that balance their activities and mediate their interactions. Here, we summarize recent knowledge on the role of auxin and cytokinin in the regulation of root architecture with special focus on lateral root organogenesis, discuss the latest findings on the molecular mechanisms of their interactions, and present forward genetic screen as a tool to identify novel molecular components of the auxin and cytokinin crosstalk.

@article{bielach_spatiotemporal_2012,
	title = {Spatiotemporal {Regulation} of {Lateral} {Root} {Organogenesis} in \textit{{Arabidopsis}} by {Cytokinin}},
	volume = {24},
	issn = {1040-4651, 1532-298X},
	url = {https://academic.oup.com/plcell/article/24/10/3967-3981/6101532},
	doi = {10/f4ffx8},
	language = {en},
	number = {10},
	urldate = {2021-06-08},
	journal = {The Plant Cell},
	author = {Bielach, Agnieszka and Podlešáková, Kateřina and Marhavý, Peter and Duclercq, Jérôme and Cuesta, Candela and Müller, Bruno and Grunewald, Wim and Tarkowski, Petr and Benková, Eva},
	month = oct,
	year = {2012},
	pages = {3967--3981},
}

@article{marhavy_cytokinin_2011,
	title = {Cytokinin {Modulates} {Endocytic} {Trafficking} of {PIN1} {Auxin} {Efflux} {Carrier} to {Control} {Plant} {Organogenesis}},
	volume = {21},
	issn = {15345807},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S1534580711003522},
	doi = {10/bz65s4},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {Developmental Cell},
	author = {Marhavý, Peter and Bielach, Agnieszka and Abas, Lindy and Abuzeineh, Anas and Duclercq, Jerome and Tanaka, Hirokazu and Pařezová, Markéta and Petrášek, Jan and Friml, Jiří and Kleine-Vehn, Jürgen and Benková, Eva},
	month = oct,
	year = {2011},
	pages = {796--804},
}

@article{zadnikova_role_2010,
	title = {Role of {PIN}-mediated auxin efflux in apical hook development of \textit{{Arabidopsis} thaliana}},
	volume = {137},
	issn = {1477-9129, 0950-1991},
	url = {https://journals.biologists.com/dev/article/137/4/607/44209/Role-of-PIN-mediated-auxin-efflux-in-apical-hook},
	doi = {10/cs9rb3},
	abstract = {The apical hook of dark-grown Arabidopsis seedlings is a simple structure that develops soon after germination to protect the meristem tissues during emergence through the soil and that opens upon exposure to light. Differential growth at the apical hook proceeds in three sequential steps that are regulated by multiple hormones, principally auxin and ethylene. We show that the progress of the apical hook through these developmental phases depends on the dynamic, asymmetric distribution of auxin, which is regulated by auxin efflux carriers of the PIN family. Several PIN proteins exhibited specific, partially overlapping spatial and temporal expression patterns, and their subcellular localization suggested auxin fluxes during hook development. Genetic manipulation of individual PIN activities interfered with different stages of hook development, implying that specific combinations of PIN genes are required for progress of the apical hook through the developmental phases. Furthermore, ethylene might modulate apical hook development by prolonging the formation phase and strongly suppressing the maintenance phase. This ethylene effect is in part mediated by regulation of PIN-dependent auxin efflux and auxin signaling.},
	language = {en},
	number = {4},
	urldate = {2021-06-08},
	journal = {Development},
	author = {Žádníková, Petra and Petrášek, Jan and Marhavý, Peter and Raz, Vered and Vandenbussche, Filip and Ding, Zhaojun and Schwarzerová, Kateřina and Morita, Miyo T. and Tasaka, Masao and Hejátko, Jan and Van Der Straeten, Dominique and Friml, Jiří and Benková, Eva},
	month = feb,
	year = {2010},
	pages = {607--617},
}

The apical hook of dark-grown Arabidopsis seedlings is a simple structure that develops soon after germination to protect the meristem tissues during emergence through the soil and that opens upon exposure to light. Differential growth at the apical hook proceeds in three sequential steps that are regulated by multiple hormones, principally auxin and ethylene. We show that the progress of the apical hook through these developmental phases depends on the dynamic, asymmetric distribution of auxin, which is regulated by auxin efflux carriers of the PIN family. Several PIN proteins exhibited specific, partially overlapping spatial and temporal expression patterns, and their subcellular localization suggested auxin fluxes during hook development. Genetic manipulation of individual PIN activities interfered with different stages of hook development, implying that specific combinations of PIN genes are required for progress of the apical hook through the developmental phases. Furthermore, ethylene might modulate apical hook development by prolonging the formation phase and strongly suppressing the maintenance phase. This ethylene effect is in part mediated by regulation of PIN-dependent auxin efflux and auxin signaling.