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Jiri Friml - One of the best experts on this subject based on the ideXlab platform.
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cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in arabidopsis
New Phytologist, 2016Co-Authors: Jiri Friml, Tomasz Nodzyński, Marketa Pernisova, Tomas Prat, Peter Grones, Danka Harustiakova, Martina Matonohova, Lukas Spichal, Jan HejatkoAbstract:• Redirection of intercellular auxin fluxes via relocalization of the PIN3 and PIN7 auxin efflux carriers has been suggested to be necessary for the root gravitropic response. Cytokinins have also been proposed to play a role in controlling root gravitropism, but conclusive evidence is lacking. • We present a detailed study of the dynamics of root bending early after gravistimulation, which revealed a delayed gravitropic response in transgenic lines with depleted endogenous cytokinins (Pro35S:AtCKX) and cytokinin signaling mutants. Pro35S:AtCKX lines as well as a cytokinin receptor mutant ahk3 showed aberrations in the auxin response distribution in columella cells consistent with defects in the auxin transport machinery. • Using in vivo real-time imaging of PIN3-GFP and PIN7-GFP in AtCKX3 overexpression and ahk3 backgrounds, we observed wild type-like relocalization of PIN Proteins in columella early after gravistimulation, with gravity-induced relocalization of PIN7 faster than that of PIN3. Nonetheless, the cellular distribution of PIN3 and PIN7 and expression of PIN7 and the auxin influx carrier AUX1 was affected in AtCKX overexpression lines. • Based on the retained cytokinin sensitivity in PIN3 PIN4 PIN7 mutant, we propose the AUX1-mediated auxin transport rather than columella-located PIN Proteins as a target of endogenous cytokinins in the control of root gravitropism.
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Cytokinins influence root gravitropism via differential regulation of auxin transporter expression and localization in Arabidopsis
The New phytologist, 2016Co-Authors: Marketa Pernisova, Jiri Friml, Tomasz Nodzyński, Tomas Prat, Peter Grones, Danka Harustiakova, Martina Matonohova, Lukas Spichal, Jan HejatkoAbstract:Redirection of intercellular auxin fluxes via relocalization of the PIN-FORMED 3 (PIN3) and PIN7 auxin efflux carriers has been suggested to be necessary for the root gravitropic response. Cytokinins have also been proposed to play a role in controlling root gravitropism, but conclusive evidence is lacking. We present a detailed study of the dynamics of root bending early after gravistimulation, which revealed a delayed gravitropic response in transgenic lines with depleted endogenous cytokinins (Pro35S:AtCKX) and cytokinin signaling mutants. Pro35S:AtCKX lines, as well as a cytokinin receptor mutant ahk3, showed aberrations in the auxin response distribution in columella cells consistent with defects in the auxin transport machinery. Using in vivo real-time imaging of PIN3-GFP and PIN7-GFP in AtCKX3 overexpression and ahk3 backgrounds, we observed wild-type-like relocalization of PIN Proteins in the columella early after gravistimulation, with gravity-induced relocalization of PIN7 faster than that of PIN3. Nonetheless, the cellular distribution of PIN3 and PIN7 and expression of PIN7 and the auxin influx carrier AUX1 was affected in AtCKX overexpression lines. Based on the retained cytokinin sensitivity in PIN3 PIN4 PIN7 mutant, we propose the AUX1-mediated auxin transport rather than columella-located PIN Proteins as a target of endogenous cytokinins in the control of root gravitropism.
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Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport.
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding TangAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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arabidopsis root uvb sensitive2 weak auxin response1 is required for polar auxin transport
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding Tang, Mark EstelleAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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Polar PIN localization directs auxin flow in plants.
Science (New York N.Y.), 2006Co-Authors: Justyna Wisniewska, Eva Benkova, Ikram Blilou, Ben Scheres, Daniela Seifertová, Philip B. Brewer, Kamil Ruzicka, David Rouquié, Jiri FrimlAbstract:Polar flow of the phytohormone auxin requires plasma membrane-associated PIN Proteins and underlies multiple developmental processes in plants. Here we address the importance of the polarity of subcellular PIN localization for the directionality of auxin transport in Arabidopsis thaliana. Expression of different PINs in the root epidermis revealed the importance of PIN polar positions for directional auxin flow and root gravitropic growth. Interfering with sequence-embedded polarity signals directly demonstrates that PIN polarity is a primary factor in determining the direction of auxin flow in meristematic tissues. This finding provides a crucial piece in the puzzle of how auxin flow can be redirected via rapid changes in PIN polarity.
Wendy Ann Peer - One of the best experts on this subject based on the ideXlab platform.
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Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport.
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding TangAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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arabidopsis root uvb sensitive2 weak auxin response1 is required for polar auxin transport
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding Tang, Mark EstelleAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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arabidopsis p glycoprotein19 participates in the inhibition of gravitropism by gravacin
Chemistry & Biology, 2007Co-Authors: Marcela Rojaspierce, Wendy Ann Peer, Joshua J. Blakeslee, Boosaree Titapiwatanakun, Eun Ju Sohn, Fang Fang, Cynthia K Larive, Yan Cheng, Sean Cuttler, Angus S MurphyAbstract:Summary ATP-binding cassette (ABC) transporters have been implicated in a multitude of biological pathways. In plants, some ABC transporters are involved in the polar transport of the plant hormone auxin and the gravitropic response. We previously identified Gravacin as a potent inhibitor of gravitropism in Arabidopsis thaliana . We demonstrate that P-glycoprotein19 (PGP19) is a target for Gravacin and participates in its inhibition of gravitropism. Gravacin inhibited the auxin transport activity of PGP19 and PGP19-PIN complexes. Furthermore, we identified E1174 as an important residue for PGP19 activity and its ability to form active transport complexes with PIN1. Gravacin is an auxin transport inhibitor that inhibits PGPs, particularly PGP19, which can be used to further dissect the role of PGP19 without the inhibition of other auxin transporters, namely PIN Proteins.
Stéphanie Robert - One of the best experts on this subject based on the ideXlab platform.
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Cell polarity and patterning by PIN trafficking through early endosomal compartments in Arabidopsis thaliana.
PLoS genetics, 2013Co-Authors: Hirokazu Tanaka, Saeko Kitakura, Stéphanie Robert, Tatsuo Kakimoto, Hana Rakusová, Tomohiro Uemura, Mugurel I. Feraru, Riet De Rycke, Jiři FrimlAbstract:PIN-FORMED (PIN) Proteins localize asymmetrically at the plasma membrane and mediate intercellular polar transport of the plant hormone auxin that is crucial for a multitude of developmental processes in plants. PIN localization is under extensive control by environmental or developmental cues, but mechanisms regulating PIN localization are not fully understood. Here we show that early endosomal components ARF GEF BEN1 and newly identified Sec1/Munc18 family protein BEN2 are involved in distinct steps of early endosomal trafficking. BEN1 and BEN2 are collectively required for polar PIN localization, for their dynamic repolarization, and consequently for auxin activity gradient formation and auxin-related developmental processes including embryonic patterning, organogenesis, and vasculature venation patterning. These results show that early endosomal trafficking is crucial for cell polarity and auxin-dependent regulation of plant architecture.
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abp1 mediates auxin inhibition of clathrin dependent endocytosis in arabidopsis
Cell, 2010Co-Authors: Stéphanie Robert, Michael Sauer, Steffen Vanneste, Jing Zhang, Jurgen Kleinevehn, Elke Barbez, Tomasz Paciorek, Pawel Radoslaw Baster, Sibu Simon, Milada CovanovaAbstract:Spatial distribution of the plant hormone auxin regulates multiple aspects of plant development. These self-regulating auxin gradients are established by the action of PIN auxin transporters, whose activity is regulated by their constitutive cycling between the plasma membrane and endosomes. Here, we show that auxin signaling by the auxin receptor AUXIN-BINDING PROTEIN 1 (ABP1) inhibits the clathrin-mediated internalization of PIN Proteins. ABP1 acts as a positive factor in clathrin recruitment to the plasma membrane, thereby promoting endocytosis. Auxin binding to ABP1 interferes with this action and leads to the inhibition of clathrin-mediated endocytosis. Our study demonstrates that ABP1 mediates a nontranscriptional auxin signaling that regulates the evolutionarily conserved process of clathrin-mediated endocytosis and suggests that this signaling may be essential for the developmentally important feedback of auxin on its own transport.
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Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport.
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding TangAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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arabidopsis root uvb sensitive2 weak auxin response1 is required for polar auxin transport
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding Tang, Mark EstelleAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
Ding Tang - One of the best experts on this subject based on the ideXlab platform.
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Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXIN RESPONSE1 is required for polar auxin transport.
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding TangAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
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arabidopsis root uvb sensitive2 weak auxin response1 is required for polar auxin transport
The Plant Cell, 2010Co-Authors: Wendy Ann Peer, Jerry D Cohen, Angus S Murphy, Jiri Friml, Stéphanie Robert, Ranjan Swarup, Michael J. Prigge, Ding Tang, Mark EstelleAbstract:Auxin is an essential phytohormone that regulates many aspects of plant development. To identify new genes that function in auxin signaling, we performed a genetic screen for Arabidopsis thaliana mutants with an alteration in the expression of the auxin-responsive reporter DR5rev:GFP (for green fluorescent protein). One of the mutants recovered in this screen, called weak auxin response1 (wxr1), has a defect in auxin response and exhibits a variety of auxin-related growth defects in the root. Polar auxin transport is reduced in wxr1 seedlings, resulting in auxin accumulation in the hypocotyl and cotyledons and a reduction in auxin levels in the root apex. In addition, the levels of the PIN auxin transport Proteins are reduced in the wxr1 root. We also show that WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms. Our data indicate that RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN Proteins in the root.
Jiři Friml - One of the best experts on this subject based on the ideXlab platform.
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Directional auxin fluxes in plants by intramolecular domain-domain coevolution of PIN auxin transporters.
The New phytologist, 2020Co-Authors: Yuzhou Zhang, Corinna Hartinger, Xiaojuan Wang, Jiři FrimlAbstract:Morphogenesis and adaptive tropic growth in plants depend on gradients of the phytohormone auxin, mediated by the membrane-based PIN-FORMED (PIN) auxin transporters. PINs localize to a particular side of the plasma membrane (PM) or to the endoplasmic reticulum (ER) to directionally transport auxin and maintain intercellular and intracellular auxin homeostasis, respectively. However, the molecular cues that confer their diverse cellular localizations remain largely unknown. In this study, we systematically swapped the domains between ER- and PM-localized PIN Proteins, as well as between apical and basal PM-localized PINs from Arabidopsis thaliana, to shed light on why PIN family members with similar topological structures reside at different membrane compartments within cells. Our results show that not only do the N- and C-terminal transmembrane domains (TMDs) and central hydrophilic loop contribute to their differential subcellular localizations and cellular polarity, but that the pairwise-matched N- and C-terminal TMDs resulting from intramolecular domain-domain coevolution are also crucial for their divergent patterns of localization. These findings illustrate the complexity of the evolutionary path of PIN Proteins in acquiring their plethora of developmental functions and adaptive growth in plants.
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The lipid code-dependent phosphoswitch PDK1-D6PK activates PIN-mediated auxin efflux in Arabidopsis.
Nature plants, 2020Co-Authors: Shutang Tan, Jiři Friml, Jan Petrášek, Xixi Zhang, Wei Kong, Xiao-li Yang, Gergely Molnár, Zuzana Vondráková, Roberta Filepová, Hong-wei XueAbstract: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. The PDK1 lipid-dependent kinase controls PIN1 and auxin transport through a phosphorylation cascade that includes AGC-type kinase D6PK. The double pdk1 mutant reveals auxin-related phenotypes such as reduced gravitropism and lateral roots.
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Evolution of fast root gravitropism in seed plants.
Nature communications, 2019Co-Authors: Yuzhou Zhang, Xixi Zhang, Xiaojuan Wang, Guanghui Xiao, Jiři FrimlAbstract:An important adaptation during colonization of land by plants is gravitropic growth of roots, which enabled roots to reach water and nutrients, and firmly anchor plants in the ground. Here we provide insights into the evolution of an efficient root gravitropic mechanism in the seed plants. Architectural innovation, with gravity perception constrained in the root tips along with a shootward transport route for the phytohormone auxin, appeared only upon the emergence of seed plants. Interspecies complementation and protein domain swapPINg revealed functional innovations within the PIN family of auxin transporters leading to the evolution of gravitropism-specific PINs. The unique apical/shootward subcellular localization of PIN Proteins is the major evolutionary innovation that connected the anatomically separated sites of gravity perception and growth response via the mobile auxin signal. We conclude that the crucial anatomical and functional components emerged hand-in-hand to facilitate the evolution of fast gravitropic response, which is one of the major adaptations of seed plants to dry land.
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Antagonistic and auxin-dependent phosphoregulation of columella PIN Proteins controls lateral root gravitropic setpoint angle in Arabidopsis
2019Co-Authors: Suruchi Roychoudhry, Jiři Friml, Peter Grones, Katelyn Sageman-furnas, Chris Wolverton, Heather L. Goodman, Jack L. Mullen, Roger P. Hangarter, Stefan KepinskiAbstract:Abstract Lateral roots of many species are maintained at non-vertical angles with respect to gravity. These gravitropic setpoint angles (GSAs) are intriguing because their maintenance requires that roots are able to effect gravitropic response both with and against the gravity vector. Here we have used the Arabidopsis lateral root in order to investigate the molecular basis of the maintenance of non-vertical GSAs. We show that gravitropism in the lateral root is angle-dependent and that both upward and downward graviresponse requires auxin transport and the generation of auxin asymmetries consistent with the Cholodny-Went model. We show that the symmetry in auxin distribution in lateral roots growing at GSA can be traced back to a net, balanced polarization of PIN3 and PIN7 auxin transporters in the columella cells. Further, upward and downward graviresponse in lateral roots correlates with corresponding changes in PIN3 and PIN7 polar localisation. Finally, we show that auxin, in addition to driving tropic growth in the lateral root, acts within the columella to regulate GSA via the PIN phosphatase subunit RCN1 in a PIN3-dependent and PIN7-independent manner. Together, these findings provide a molecular framework for understanding gravity-dependent nonvertical growth in Arabidopsis lateral roots.
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A Forward Genetic Screen for New Regulators of Auxin-mediated Degradation of Auxin Transport Proteins in Arabidopsis thaliana
Journal of Plant Growth Regulation, 2015Co-Authors: Radka Zemová, Hélène S. Robert, Marta Zwiewka, Agnieszka Bielach, Jiři FrimlAbstract:The plant hormone auxin (indole-3-acetic acid) is a major regulator of plant growth and development including embryo and root patterning, lateral organ formation and growth responses to environmental stimuli. Auxin is directionally transported from cell to cell by the action of specific auxin influx [AUXIN-RESISTANT1 (AUX1)] and efflux [PIN-FORMED (PIN)] transport regulators, whose polar, subcellular localizations are aligned with the direction of the auxin flow. Auxin itself regulates its own transport by modulation of the expression and subcellular localization of the auxin transporters. Increased auxin levels promote the transcription of PIN2 and AUX1 genes as well as stabilize PIN Proteins at the plasma membrane, whereas prolonged auxin exposure increases the turnover of PIN Proteins and their degradation in the vacuole. In this study, we applied a forward genetic approach, to identify molecular components playing a role in the auxin-mediated degradation. We generated EMS-mutagenized Arabidopsis PIN2::PIN2:GFP, AUX1::AUX1:YFP eir1 aux1 populations and designed a screen for mutants with persistently strong fluorescent signals of the tagged PIN2 and AUX1 after prolonged treatment with the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D). This approach yielded novel auxin degradation mutants defective in trafficking and degradation of PIN2 and AUX1 Proteins and established a role for auxin-mediated degradation in plant development.