TY - JOUR AB - Clathrin-mediated endocytosis is the major route of entry of cargos into cells and thus underpins many physiological processes. During endocytosis, an area of flat membrane is remodeled by proteins to create a spherical vesicle against intracellular forces. The protein machinery which mediates this membrane bending in plants is unknown. However, it is known that plant endocytosis is actin independent, thus indicating that plants utilize a unique mechanism to mediate membrane bending against high-turgor pressure compared to other model systems. Here, we investigate the TPLATE complex, a plant-specific endocytosis protein complex. It has been thought to function as a classical adaptor functioning underneath the clathrin coat. However, by using biochemical and advanced live microscopy approaches, we found that TPLATE is peripherally associated with clathrin-coated vesicles and localizes at the rim of endocytosis events. As this localization is more fitting to the protein machinery involved in membrane bending during endocytosis, we examined cells in which the TPLATE complex was disrupted and found that the clathrin structures present as flat patches. This suggests a requirement of the TPLATE complex for membrane bending during plant clathrin–mediated endocytosis. Next, we used in vitro biophysical assays to confirm that the TPLATE complex possesses protein domains with intrinsic membrane remodeling activity. These results redefine the role of the TPLATE complex and implicate it as a key component of the evolutionarily distinct plant endocytosis mechanism, which mediates endocytic membrane bending against the high-turgor pressure in plant cells. AU - Johnson, Alexander J AU - Dahhan, Dana A AU - Gnyliukh, Nataliia AU - Kaufmann, Walter AU - Zheden, Vanessa AU - Costanzo, Tommaso AU - Mahou, Pierre AU - Hrtyan, Mónika AU - Wang, Jie AU - Aguilera Servin, Juan L AU - van Damme, Daniël AU - Beaurepaire, Emmanuel AU - Loose, Martin AU - Bednarek, Sebastian Y AU - Friml, Jiří ID - 9887 IS - 51 JF - Proceedings of the National Academy of Sciences TI - The TPLATE complex mediates membrane bending during plant clathrin-mediated endocytosis VL - 118 ER - TY - GEN AB - Raw data generated from the publication - The TPLATE complex mediates membrane bending during plant clathrin-mediated endocytosis by Johnson et al., 2021 In PNAS AU - Johnson, Alexander J ID - 14988 TI - Raw data from Johnson et al, PNAS, 2021 ER - TY - THES AB - Blood – this is what animals use to heal wounds fast and efficient. Plants do not have blood circulation and their cells cannot move. However, plants have evolved remarkable capacities to regenerate tissues and organs preventing further damage. In my PhD research, I studied the wound healing in the Arabidopsis root. I used a UV laser to ablate single cells in the root tip and observed the consequent wound healing. Interestingly, the inner adjacent cells induced a division plane switch and subsequently adopted the cell type of the killed cell to replace it. We termed this form of wound healing “restorative divisions”. This initial observation triggered the questions of my PhD studies: How and why do cells orient their division planes, how do they feel the wound and why does this happen only in inner adjacent cells. For answering these questions, I used a quite simple experimental setup: 5 day - old seedlings were stained with propidium iodide to visualize cell walls and dead cells; ablation was carried out using a special laser cutter and a confocal microscope. Adaptation of the novel vertical microscope system made it possible to observe wounds in real time. This revealed that restorative divisions occur at increased frequency compared to normal divisions. Additionally, the major plant hormone auxin accumulates in wound adjacent cells and drives the expression of the wound-stress responsive transcription factor ERF115. Using this as a marker gene for wound responses, we found that an important part of wound signalling is the sensing of the collapse of the ablated cell. The collapse causes a radical pressure drop, which results in strong tissue deformations. These deformations manifest in an invasion of the now free spot specifically by the inner adjacent cells within seconds, probably because of higher pressure of the inner tissues. Long-term imaging revealed that those deformed cells continuously expand towards the wound hole and that this is crucial for the restorative division. These wound-expanding cells exhibit an abnormal, biphasic polarity of microtubule arrays before the division. Experiments inhibiting cell expansion suggest that it is the biphasic stretching that induces those MT arrays. Adapting the micromanipulator aspiration system from animal scientists at our institute confirmed the hypothesis that stretching influences microtubule stability. In conclusion, this shows that microtubules react to tissue deformation and this facilitates the observed division plane switch. This puts mechanical cues and tensions at the most prominent position for explaining the growth and wound healing properties of plants. Hence, it shines light onto the importance of understanding mechanical signal transduction. AU - Hörmayer, Lukas ID - 9992 SN - 2663-337X TI - Wound healing in the Arabidopsis root meristem ER - TY - JOUR AB - Availability of the essential macronutrient nitrogen in soil plays a critical role in plant growth, development, and impacts agricultural productivity. Plants have evolved different strategies for sensing and responding to heterogeneous nitrogen distribution. Modulation of root system architecture, including primary root growth and branching, is among the most essential plant adaptions to ensure adequate nitrogen acquisition. However, the immediate molecular pathways coordinating the adjustment of root growth in response to distinct nitrogen sources, such as nitrate or ammonium, are poorly understood. Here, we show that growth as manifested by cell division and elongation is synchronized by coordinated auxin flux between two adjacent outer tissue layers of the root. This coordination is achieved by nitrate‐dependent dephosphorylation of the PIN2 auxin efflux carrier at a previously uncharacterized phosphorylation site, leading to subsequent PIN2 lateralization and thereby regulating auxin flow between adjacent tissues. A dynamic computer model based on our experimental data successfully recapitulates experimental observations. Our study provides mechanistic insights broadening our understanding of root growth mechanisms in dynamic environments. AU - Ötvös, Krisztina AU - Marconi, Marco AU - Vega, Andrea AU - O’Brien, Jose AU - Johnson, Alexander J AU - Abualia, Rashed AU - Antonielli, Livio AU - Montesinos López, Juan C AU - Zhang, Yuzhou AU - Tan, Shutang AU - Cuesta, Candela AU - Artner, Christina AU - Bouguyon, Eleonore AU - Gojon, Alain AU - Friml, Jiří AU - Gutiérrez, Rodrigo A. AU - Wabnik, Krzysztof T AU - Benková, Eva ID - 9010 IS - 3 JF - EMBO Journal SN - 02614189 TI - Modulation of plant root growth by nitrogen source-defined regulation of polar auxin transport VL - 40 ER - TY - JOUR AB - Auxin is a major plant growth regulator, but current models on auxin perception and signaling cannot explain the whole plethora of auxin effects, in particular those associated with rapid responses. A possible candidate for a component of additional auxin perception mechanisms is the AUXIN BINDING PROTEIN 1 (ABP1), whose function in planta remains unclear. Here we combined expression analysis with gain- and loss-of-function approaches to analyze the role of ABP1 in plant development. ABP1 shows a broad expression largely overlapping with, but not regulated by, transcriptional auxin response activity. Furthermore, ABP1 activity is not essential for the transcriptional auxin signaling. Genetic in planta analysis revealed that abp1 loss-of-function mutants show largely normal development with minor defects in bolting. On the other hand, ABP1 gain-of-function alleles show a broad range of growth and developmental defects, including root and hypocotyl growth and bending, lateral root and leaf development, bolting, as well as response to heat stress. At the cellular level, ABP1 gain-of-function leads to impaired auxin effect on PIN polar distribution and affects BFA-sensitive PIN intracellular aggregation. The gain-of-function analysis suggests a broad, but still mechanistically unclear involvement of ABP1 in plant development, possibly masked in abp1 loss-of-function mutants by a functional redundancy. AU - Gelová, Zuzana AU - Gallei, Michelle C AU - Pernisová, Markéta AU - Brunoud, Géraldine AU - Zhang, Xixi AU - Glanc, Matous AU - Li, Lanxin AU - Michalko, Jaroslav AU - Pavlovicova, Zlata AU - Verstraeten, Inge AU - Han, Huibin AU - Hajny, Jakub AU - Hauschild, Robert AU - Čovanová, Milada AU - Zwiewka, Marta AU - Hörmayer, Lukas AU - Fendrych, Matyas AU - Xu, Tongda AU - Vernoux, Teva AU - Friml, Jiří ID - 8931 JF - Plant Science KW - Agronomy and Crop Science KW - Plant Science KW - Genetics KW - General Medicine SN - 0168-9452 TI - Developmental roles of auxin binding protein 1 in Arabidopsis thaliana VL - 303 ER - TY - JOUR AB - The phytohormone auxin and its directional transport through tissues are intensively studied. However, a mechanistic understanding of auxin-mediated feedback on endocytosis and polar distribution of PIN auxin transporters remains limited due to contradictory observations and interpretations. Here, we used state-of-the-art methods to reexamine the auxin effects on PIN endocytic trafficking. We used high auxin concentrations or longer treatments versus lower concentrations and shorter treatments of natural (IAA) and synthetic (NAA) auxins to distinguish between specific and nonspecific effects. Longer treatments of both auxins interfere with Brefeldin A-mediated intracellular PIN2 accumulation and also with general aggregation of endomembrane compartments. NAA treatment decreased the internalization of the endocytic tracer dye, FM4-64; however, NAA treatment also affected the number, distribution, and compartment identity of the early endosome/trans-Golgi network (EE/TGN), rendering the FM4-64 endocytic assays at high NAA concentrations unreliable. To circumvent these nonspecific effects of NAA and IAA affecting the endomembrane system, we opted for alternative approaches visualizing the endocytic events directly at the plasma membrane (PM). Using Total Internal Reflection Fluorescence (TIRF) microscopy, we saw no significant effects of IAA or NAA treatments on the incidence and dynamics of clathrin foci, implying that these treatments do not affect the overall endocytosis rate. However, both NAA and IAA at low concentrations rapidly and specifically promoted endocytosis of photo-converted PIN2 from the PM. These analyses identify a specific effect of NAA and IAA on PIN2 endocytosis, thus contributing to its polarity maintenance and furthermore illustrate that high auxin levels have nonspecific effects on trafficking and endomembrane compartments. AU - Narasimhan, Madhumitha AU - Gallei, Michelle C AU - Tan, Shutang AU - Johnson, Alexander J AU - Verstraeten, Inge AU - Li, Lanxin AU - Rodriguez Solovey, Lesia AU - Han, Huibin AU - Himschoot, E AU - Wang, R AU - Vanneste, S AU - Sánchez-Simarro, J AU - Aniento, F AU - Adamowski, Maciek AU - Friml, Jiří ID - 9287 IS - 2 JF - Plant Physiology SN - 0032-0889 TI - Systematic analysis of specific and nonspecific auxin effects on endocytosis and trafficking VL - 186 ER - TY - THES AB - Plant motions occur across a wide spectrum of timescales, ranging from seed dispersal through bursting (milliseconds) and stomatal opening (minutes) to long-term adaptation of gross architecture. Relatively fast motions include water-driven growth as exemplified by root cell expansion under abiotic/biotic stresses or during gravitropism. A showcase is a root growth inhibition in 30 seconds triggered by the phytohormone auxin. However, the cellular and molecular mechanisms are still largely unknown. This thesis covers the studies about this topic as follows. By taking advantage of microfluidics combined with live imaging, pharmaceutical tools, and transgenic lines, we examined the kinetics of and causal relationship among various auxininduced rapid cellular changes in root growth, apoplastic pH, cytosolic Ca2+, cortical microtubule (CMT) orientation, and vacuolar morphology. We revealed that CMT reorientation and vacuolar constriction are the consequence of growth itself instead of responding directly to auxin. In contrast, auxin induces apoplast alkalinization to rapidly inhibit root growth in 30 seconds. This auxin-triggered apoplast alkalinization results from rapid H+- influx that is contributed by Ca2+ inward channel CYCLIC NUCLEOTIDE-GATED CHANNEL 14 (CNGC14)-dependent Ca2+ signaling. To dissect which auxin signaling mediates the rapid apoplast alkalinization, we combined microfluidics and genetic engineering to verify that TIR1/AFB receptors conduct a non-transcriptional regulation on Ca2+ and H+ -influx. This non-canonical pathway is mostly mediated by the cytosolic portion of TIR1/AFB. On the other hand, we uncovered, using biochemical and phospho-proteomic analysis, that auxin cell surface signaling component TRANSMEMBRANE KINASE 1 (TMK1) plays a negative role during auxin-trigger apoplast alkalinization and root growth inhibition through directly activating PM H+ -ATPases. Therefore, we discovered that PM H+ -ATPases counteract instead of mediate the auxintriggered rapid H+ -influx, and that TIR1/AFB and TMK1 regulate root growth antagonistically. This opposite effect of TIR1/AFB and TMK1 is consistent during auxin-induced hypocotyl elongation, leading us to explore the relation of two signaling pathways. Assisted with biochemistry and fluorescent imaging, we verified for the first time that TIR1/AFB and TMK1 can interact with each other. The ability of TIR1/AFB binding to membrane lipid provides a basis for the interaction of plasma membrane- and cytosol-localized proteins. Besides, transgenic analysis combined with genetic engineering and biochemistry showed that vi they do function in the same pathway. Particularly, auxin-induced TMK1 increase is TIR1/AFB dependent, suggesting TIR1/AFB regulation on TMK1. Conversely, TMK1 also regulates TIR1/AFB protein levels and thus auxin canonical signaling. To follow the study of rapid growth regulation, we analyzed another rapid growth regulator, signaling peptide RALF1. We showed that RALF1 also triggers a rapid and reversible growth inhibition caused by H + influx, highly resembling but not dependent on auxin. Besides, RALF1 promotes auxin biosynthesis by increasing expression of auxin biosynthesis enzyme YUCCAs and thus induces auxin signaling in ca. 1 hour, contributing to the sustained RALF1-triggered growth inhibition. These studies collectively contribute to understanding rapid regulation on plant cell growth, novel auxin signaling pathway as well as auxin-peptide crosstalk. AU - Li, Lanxin ID - 10083 SN - 2663-337X TI - Rapid cell growth regulation in Arabidopsis ER - TY - JOUR AB - Auxin plays a dual role in growth regulation and, depending on the tissue and concentration of the hormone, it can either promote or inhibit division and expansion processes in plants. Recent studies have revealed that, beyond transcriptional reprogramming, alternative auxincontrolled mechanisms regulate root growth. Here, we explored the impact of different concentrations of the synthetic auxin NAA that establish growth-promoting and -repressing conditions on the root tip proteome and phosphoproteome, generating a unique resource. From the phosphoproteome data, we pinpointed (novel) growth regulators, such as the RALF34-THE1 module. Our results, together with previously published studies, suggest that auxin, H+-ATPases, cell wall modifications and cell wall sensing receptor-like kinases are tightly embedded in a pathway regulating cell elongation. Furthermore, our study assigned a novel role to MKK2 as a regulator of primary root growth and a (potential) regulator of auxin biosynthesis and signalling, and suggests the importance of the MKK2 Thr31 phosphorylation site for growth regulation in the Arabidopsis root tip. AU - Nikonorova, N AU - Murphy, E AU - Fonseca de Lima, CF AU - Zhu, S AU - van de Cotte, B AU - Vu, LD AU - Balcerowicz, D AU - Li, Lanxin AU - Kong, X AU - De Rop, G AU - Beeckman, T AU - Friml, Jiří AU - Vissenberg, K AU - Morris, PC AU - Ding, Z AU - De Smet, I ID - 10015 JF - Cells KW - primary root KW - (phospho)proteomics KW - auxin KW - (receptor) kinase SN - 2073-4409 TI - The Arabidopsis root tip (phospho)proteomes at growth-promoting versus growth-repressing conditions reveal novel root growth regulators VL - 10 ER - TY - GEN AB - Growth regulation tailors plant development to its environment. A showcase is response to gravity, where shoots bend up and roots down1. This paradox is based on opposite effects of the phytohormone auxin, which promotes cell expansion in shoots, while inhibiting it in roots via a yet unknown cellular mechanism2. Here, by combining microfluidics, live imaging, genetic engineering and phospho-proteomics in Arabidopsis thaliana, we advance our understanding how auxin inhibits root growth. We show that auxin activates two distinct, antagonistically acting signalling pathways that converge on the rapid regulation of the apoplastic pH, a causative growth determinant. Cell surface-based TRANSMEMBRANE KINASE1 (TMK1) interacts with and mediates phosphorylation and activation of plasma membrane H+-ATPases for apoplast acidification, while intracellular canonical auxin signalling promotes net cellular H+-influx, causing apoplast alkalinisation. The simultaneous activation of these two counteracting mechanisms poises the root for a rapid, fine-tuned growth modulation while navigating complex soil environment. AU - Li, Lanxin AU - Verstraeten, Inge AU - Roosjen, Mark AU - Takahashi, Koji AU - Rodriguez Solovey, Lesia AU - Merrin, Jack AU - Chen, Jian AU - Shabala, Lana AU - Smet, Wouter AU - Ren, Hong AU - Vanneste, Steffen AU - Shabala, Sergey AU - De Rybel, Bert AU - Weijers, Dolf AU - Kinoshita, Toshinori AU - Gray, William M. AU - Friml, Jiří ID - 10095 SN - 2693-5015 T2 - Research Square TI - Cell surface and intracellular auxin signalling for H+-fluxes in root growth ER - TY - GEN AB - Plasmodesmata (PD) are crucial structures for intercellular communication in multicellular plants with remorins being their crucial plant-specific structural and functional constituents. The PD biogenesis is an intriguing but poorly understood process. By expressing an Arabidopsis remorin protein in mammalian cells, we have reconstituted a PD-like filamentous structure, termed remorin filament (RF), connecting neighboring cells physically and physiologically. Notably, RFs are capable of transporting macromolecules intercellularly, in a way similar to plant PD. With further super-resolution microscopic analysis and biochemical characterization, we found that RFs are also composed of actin filaments, forming the core skeleton structure, aligned with the remorin protein. This unique heterologous filamentous structure might explain the molecular mechanism for remorin function as well as PD construction. Furthermore, remorin protein exhibits a specific distribution manner in the plasma membrane in mammalian cells, representing a lipid nanodomain, depending on its lipid modification status. Our studies not only provide crucial insights into the mechanism of PD biogenesis, but also uncovers unsuspected fundamental mechanistic and evolutionary links between intercellular communication systems of plants and animals. AU - Wei, Zhuang AU - Tan, Shutang AU - Liu, Tao AU - Wu, Yuan AU - Lei, Ji-Gang AU - Chen, ZhengJun AU - Friml, Jiří AU - Xue, Hong-Wei AU - Liao, Kan ID - 7601 T2 - bioRxiv TI - Plasmodesmata-like intercellular connections by plant remorin in animal cells ER - TY - JOUR AU - Zhang, Yuzhou AU - Friml, Jiří ID - 6997 IS - 3 JF - New Phytologist SN - 0028-646x TI - Auxin guides roots to avoid obstacles during gravitropic growth VL - 225 ER - TY - JOUR AB - Plant root architecture dynamically adapts to various environmental conditions, such as salt‐containing soil. The phytohormone abscisic acid (ABA) is involved among others also in these developmental adaptations, but the underlying molecular mechanism remains elusive. Here, a novel branch of the ABA signaling pathway in Arabidopsis involving PYR/PYL/RCAR (abbreviated as PYLs) receptor‐protein phosphatase 2A (PP2A) complex that acts in parallel to the canonical PYLs‐protein phosphatase 2C (PP2C) mechanism is identified. The PYLs‐PP2A signaling modulates root gravitropism and lateral root formation through regulating phytohormone auxin transport. In optimal conditions, PYLs ABA receptor interacts with the catalytic subunits of PP2A, increasing their phosphatase activity and thus counteracting PINOID (PID) kinase‐mediated phosphorylation of PIN‐FORMED (PIN) auxin transporters. By contrast, in salt and osmotic stress conditions, ABA binds to PYLs, inhibiting the PP2A activity, which leads to increased PIN phosphorylation and consequently modulated directional auxin transport leading to adapted root architecture. This work reveals an adaptive mechanism that may flexibly adjust plant root growth to withstand saline and osmotic stresses. It occurs via the cross‐talk between the stress hormone ABA and the versatile developmental regulator auxin. AU - Li, Yang AU - Wang, Yaping AU - Tan, Shutang AU - Li, Zhen AU - Yuan, Zhi AU - Glanc, Matous AU - Domjan, David AU - Wang, Kai AU - Xuan, Wei AU - Guo, Yan AU - Gong, Zhizhong AU - Friml, Jiří AU - Zhang, Jing ID - 7204 IS - 3 JF - Advanced Science TI - Root growth adaptation is mediated by PYLs ABA receptor-PP2A protein phosphatase complex VL - 7 ER - TY - JOUR AB - The phytohormone auxin acts as an amazingly versatile coordinator of plant growth and development. With its morphogen-like properties, auxin controls sites and timing of differentiation and/or growth responses both, in quantitative and qualitative terms. Specificity in the auxin response depends largely on distinct modes of signal transmission, by which individual cells perceive and convert auxin signals into a remarkable diversity of responses. The best understood, or so-called canonical mechanism of auxin perception ultimately results in variable adjustments of the cellular transcriptome, via a short, nuclear signal transduction pathway. Additional findings that accumulated over decades implied that an additional, presumably, cell surface-based auxin perception mechanism mediates very rapid cellular responses and decisively contributes to the cell's overall hormonal response. Recent investigations into both, nuclear and cell surface auxin signalling challenged this assumed partition of roles for different auxin signalling pathways and revealed an unexpected complexity in transcriptional and non-transcriptional cellular responses mediated by auxin. AU - Gallei, Michelle C AU - Luschnig, Christian AU - Friml, Jiří ID - 7142 IS - 2 JF - Current Opinion in Plant Biology SN - 1369-5266 TI - Auxin signalling in growth: Schrödinger's cat out of the bag VL - 53 ER - TY - JOUR AB - Root system architecture (RSA), governed by the phytohormone auxin, endows plants with an adaptive advantage in particular environments. Using geographically representative arabidopsis (Arabidopsis thaliana) accessions as a resource for GWA mapping, Waidmann et al. and Ogura et al. recently identified two novel components involved in modulating auxin-mediated RSA and conferring plant fitness in particular habitats. AU - Xiao, Guanghui AU - Zhang, Yuzhou ID - 7219 IS - 2 JF - Trends in Plant Science SN - 13601385 TI - Adaptive growth: Shaping auxin-mediated root system architecture VL - 25 ER - TY - JOUR AB - The flexible development of plants is characterized by a high capacity for post-embryonic organ formation and tissue regeneration, processes, which require tightly regulated intercellular communication and coordinated tissue (re-)polarization. The phytohormone auxin, the main driver for these processes, is able to establish polarized auxin transport channels, which are characterized by the expression and polar, subcellular localization of the PIN1 auxin transport proteins. These channels are demarcating the position of future vascular strands necessary for organ formation and tissue regeneration. Major progress has been made in the last years to understand how PINs can change their polarity in different contexts and thus guide auxin flow through the plant. However, it still remains elusive how auxin mediates the establishment of auxin conducting channels and the formation of vascular tissue and which cellular processes are involved. By the means of sophisticated regeneration experiments combined with local auxin applications in Arabidopsis thaliana inflorescence stems we show that (i) PIN subcellular dynamics, (ii) PIN internalization by clathrin-mediated trafficking and (iii) an intact actin cytoskeleton required for post-endocytic trafficking are indispensable for auxin channel formation, de novo vascular formation and vascular regeneration after wounding. These observations provide novel insights into cellular mechanism of coordinated tissue polarization during auxin canalization. AU - Mazur, Ewa AU - Gallei, Michelle C AU - Adamowski, Maciek AU - Han, Huibin AU - Robert, Hélène S. AU - Friml, Jiří ID - 7465 IS - 4 JF - Plant Science SN - 01689452 TI - Clathrin-mediated trafficking and PIN trafficking are required for auxin canalization and vascular tissue formation in Arabidopsis VL - 293 ER - TY - JOUR AB - In plants, clathrin mediated endocytosis (CME) represents the major route for cargo internalisation from the cell surface. It has been assumed to operate in an evolutionary conserved manner as in yeast and animals. Here we report characterisation of ultrastructure, dynamics and mechanisms of plant CME as allowed by our advancement in electron microscopy and quantitative live imaging techniques. Arabidopsis CME appears to follow the constant curvature model and the bona fide CME population generates vesicles of a predominantly hexagonal-basket type; larger and with faster kinetics than in other models. Contrary to the existing paradigm, actin is dispensable for CME events at the plasma membrane but plays a unique role in collecting endocytic vesicles, sorting of internalised cargos and directional endosome movement that itself actively promote CME events. Internalized vesicles display a strongly delayed and sequential uncoating. These unique features highlight the independent evolution of the plant CME mechanism during the autonomous rise of multicellularity in eukaryotes. AU - Narasimhan, Madhumitha AU - Johnson, Alexander J AU - Prizak, Roshan AU - Kaufmann, Walter AU - Tan, Shutang AU - Casillas Perez, Barbara E AU - Friml, Jiří ID - 7490 JF - eLife TI - Evolutionarily unique mechanistic framework of clathrin-mediated endocytosis in plants VL - 9 ER - TY - JOUR AB - Endophytic fungi can be beneficial to plant growth. However, the molecular mechanisms underlying colonization of Acremonium spp. remain unclear. In this study, a novel endophytic Acremonium strain was isolated from the buds of Panax notoginseng and named Acremonium sp. D212. The Acremonium sp. D212 could colonize the roots of P. notoginseng, enhance the resistance of P. notoginseng to root rot disease, and promote root growth and saponin biosynthesis in P. notoginseng. Acremonium sp. D212 could secrete indole‐3‐acetic acid (IAA) and jasmonic acid (JA), and inoculation with the fungus increased the endogenous levels of IAA and JA in P. notoginseng. Colonization of the Acremonium sp. D212 in the roots of the rice line Nipponbare was dependent on the concentration of methyl jasmonate (MeJA) (2 to 15 μM) and 1‐naphthalenacetic acid (NAA) (10 to 20 μM). Moreover, the roots of the JA signalling‐defective coi1‐18 mutant were colonized by Acremonium sp. D212 to a lesser degree than those of the wild‐type Nipponbare and miR393b‐overexpressing lines, and the colonization was rescued by MeJA but not by NAA. It suggests that the cross‐talk between JA signalling and the auxin biosynthetic pathway plays a crucial role in the colonization of Acremonium sp. D212 in host plants. AU - Han, L AU - Zhou, X AU - Zhao, Y AU - Zhu, S AU - Wu, L AU - He, Y AU - Ping, X AU - Lu, X AU - Huang, W AU - Qian, J AU - Zhang, L AU - Jiang, X AU - Zhu, D AU - Luo, C AU - Li, S AU - Dong, Q AU - Fu, Q AU - Deng, K AU - Wang, X AU - Wang, L AU - Peng, S AU - Wu, J AU - Li, W AU - Friml, Jiří AU - Zhu, Y AU - He, X AU - Du, Y ID - 7497 IS - 9 JF - Journal of Integrative Plant Biology SN - 1672-9072 TI - Colonization of endophyte Acremonium sp. D212 in Panax notoginseng and rice mediated by auxin and jasmonic acid VL - 62 ER - TY - JOUR AB - In vitro propagation of the ornamentally interesting species Wikstroemia gemmata is limited by the recalcitrance to form adventitious roots. In this article, two strategies to improve the rooting capacity of in vitro microcuttings are presented. Firstly, the effect of exogenous auxin was evaluated in both light and dark cultivated stem segments and also the sucrose-content of the medium was varied in order to determine better rooting conditions. Secondly, different spectral lights were evaluated and the effect on shoot growth and root induction demonstrated that the exact spectral composition of light is important for successful in vitro growth and development of Wikstroemia gemmata. We show that exogenous auxin cannot compensate for the poor rooting under unfavorable light conditions. Adapting the culture conditions is therefore paramount for successful industrial propagation of Wikstroemia gemmata. AU - Verstraeten, Inge AU - Buyle, H. AU - Werbrouck, S. AU - Van Labeke, M.C. AU - Geelen, D. ID - 7540 IS - 1-2 JF - Israel Journal of Plant Sciences SN - 0792-9978 TI - In vitro shoot growth and adventitious rooting of Wikstroemia gemmata depends on light quality VL - 67 ER - TY - JOUR AB - Small RNAs (smRNA, 19–25 nucleotides long), which are transcribed by RNA polymerase II, regulate the expression of genes involved in a multitude of processes in eukaryotes. miRNA biogenesis and the proteins involved in the biogenesis pathway differ across plant and animal lineages. The major proteins constituting the biogenesis pathway, namely, the Dicers (DCL/DCR) and Argonautes (AGOs), have been extensively studied. However, the accessory proteins (DAWDLE (DDL), SERRATE (SE), and TOUGH (TGH)) of the pathway that differs across the two lineages remain largely uncharacterized. We present the first detailed report on the molecular evolution and divergence of these proteins across eukaryotes. Although DDL is present in eukaryotes and prokaryotes, SE and TGH appear to be specific to eukaryotes. The addition/deletion of specific domains and/or domain-specific sequence divergence in the three proteins points to the observed functional divergence of these proteins across the two lineages, which correlates with the differences in miRNA length across the two lineages. Our data enhance the current understanding of the structure–function relationship of these proteins and reveals previous unexplored crucial residues in the three proteins that can be used as a basis for further functional characterization. The data presented here on the number of miRNAs in crown eukaryotic lineages are consistent with the notion of the expansion of the number of miRNA-coding genes in animal and plant lineages correlating with organismal complexity. Whether this difference in functionally correlates with the diversification (or presence/absence) of the three proteins studied here or the miRNA signaling in the plant and animal lineages is unclear. Based on our results of the three proteins studied here and previously available data concerning the evolution of miRNA genes in the plant and animal lineages, we believe that miRNAs probably evolved once in the ancestor to crown eukaryotes and have diversified independently in the eukaryotes. AU - Moturu, Taraka Ramji AU - Sinha, Sansrity AU - Salava, Hymavathi AU - Thula, Sravankumar AU - Nodzyński, Tomasz AU - Vařeková, Radka Svobodová AU - Friml, Jiří AU - Simon, Sibu ID - 7582 IS - 3 JF - Plants TI - Molecular evolution and diversification of proteins involved in miRNA maturation pathway VL - 9 ER - TY - JOUR AB - Directional intercellular transport of the phytohormone auxin mediated by PIN FORMED (PIN) efflux carriers plays essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. Multilevel regulations of PIN activity under internal and external cues are complicated; however, the underlying molecular mechanism remains elusive. Here we demonstrate that 3’-Phosphoinositide-Dependent Protein Kinase1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub integrating the upstream lipid signalling and the downstream substrate activity through phosphorylation. Genetic analysis uncovers that loss-of-function Arabidopsis mutant pdk1.1 pdk1.2 exhibits a plethora of abnormalities in organogenesis and growth, due to the defective PIN-dependent auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 Protein Kinase to facilitate its activity towards PIN proteins. Our studies establish a lipid-dependent phosphorylation cascade connecting membrane composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes. AU - Tan, Shutang AU - Zhang, Xixi AU - Kong, Wei AU - Yang, Xiao-Li AU - Molnar, Gergely AU - Vondráková, Zuzana AU - Filepová, Roberta AU - Petrášek, Jan AU - Friml, Jiří AU - Xue, Hong-Wei ID - 7600 JF - Nature Plants TI - The lipid code-dependent phosphoswitch PDK1–D6PK activates PIN-mediated auxin efflux in Arabidopsis VL - 6 ER -