Markus Geisler

Markus Geisler
Université de Fribourg · Department Biology

PD Dr. rer. nat.

About

135
Publications
33,560
Reads
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10,006
Citations
Additional affiliations
March 2011 - September 2016
Université de Fribourg
Position
  • Group Leader
March 2011 - September 2016
Université de Fribourg
Position
  • Group Leader
July 2002 - December 2010
University of Zurich
Position
  • Research Associate

Publications

Publications (135)
Preprint
Based on its proposed substrate preferences, the ABC transporter, ABCG36/PDR8/PEN3, from the model plant Arabidopsis stands at the cross-road between growth and defence. Recently, ABCG36 was shown to export a few indolic compounds, including the auxin precursor, indole-3-butyric acid (IBA), and to be implicated in the export of the major phytoalexi...
Article
Despite clear evidence that a local accumulation of auxin is likewise critical for male fertility, much less is known about the components that regulate auxin-controlled stamen development. In this study, we analyzed physiological and morphological parameters in mutants of key players of ABCB-mediated auxin transport and spatially and temporally di...
Article
Members of the B family of membrane-bound ATP-binding cassette (ABC) transporters represent key components of the auxin-efflux machinery in plants. Over the last two decades experimental studies have shown that modifying ABCB expression affects auxin distribution and plant phenotypes. However, precisely how ABCB proteins transport auxin in conjunct...
Article
Full-text available
Transmembrane (TM) proteins are major drug targets, but their structure determination, a prerequisite for rational drug design, remains challenging. Recently, the DeepMind’s AlphaFold2 machine learning method greatly expanded the structural coverage of sequences with high accuracy. Since the employed algorithm did not take specific properties of TM...
Preprint
Despite clear evidence that a local accumulation of auxin is likewise critical for male fertility, much less is known about the components that regulate auxin-controlled stamen development. In this study, we analyzed physiological and morphological parameters in mutants of key players of ABCB-mediated auxin transport and spatially and temporally di...
Article
Root architecture is one of the most important agronomic traits that determines rice crop yield. The primary root (PR) absorbs mineral nutrients and provides mechanical support; however, the molecular mechanisms of PR elongation remain unclear in rice. Here, the two loss-of-function T-DNA insertion mutants of root length regulator 4 (OsRLR4), osrlr...
Article
Full-text available
The effects of abscisic acid (ABA) on plant growth, development, and response to the environment depend on local ABA concentrations. Here, we show that in Arabidopsis, ABA homeostasis is regulated by two previously unknown ABA transporters. Adenosine triphosphate-binding cassette subfamily G member 17 (ABCG17) and ABCG18 are localized to the plasma...
Preprint
Despite clear evidence that a local accumulation of auxin is likewise critical for floral organ initiation than for vegetative tissues, much less is known about the molecular key players that regulate auxin-controlled flower development. Here, by an analysis of physiological and morphological parameters and by a spatial and temporal dissection of a...
Preprint
Full-text available
Transmembrane (TM) proteins are major drug targets, indicated by the high percentage of prescription drugs acting on them. For a rational drug design and an understanding of mutational effects on protein function, structural data at atomic resolution are required. However, hydrophobic TM proteins often resist experimental structure determination an...
Book
Full-text available
Fit for the Future. In the last two years, the Department of Biology continued its path of consolidation, removing the last administrative remains of the former “units”. We now have a uniform hierarchy, established minimally structured working groups that deal with diverse organizational tasks, and streamlined administration that gives us more fle...
Article
Grain size is one of the most import factors of controlling rice yield, as it is associated with grain weight (GW). To date, several rice genes that regulate grain size have been isolated; however, the regulatory mechanism underlying GW control is not fully understood. Herein, a quantitative trait locus qGL5 for grain length (GL) and GW was identif...
Preprint
The effects of abscisic acid (ABA) on plant growth, development and response to the environment depend on local ABA concentrations. Here, we exploited a genome-scale amiRNA screen, targeting the Arabidopsis transportome, to show that ABA homeostasis is regulated by two previously unknown ABA transporters. ABCG17 and ABCG18 are localized to the plas...
Article
Full-text available
Growing evidence has highlighted the essential role of plant hormones, notably, cytokinins (CKs), in nitrogen-fixing symbiosis, both at early and late nodulation stages1,2. Despite numerous studies showing the central role of CK in nodulation, the importance of CK transport in the symbiosis is unknown. Here, we show the role of ABCG56, a full-size...
Article
The plant cuticle is deposited on the surface of primary plant organs, such as leaves, fruits, and floral organs, forming a diffusion barrier and protecting the plant against various abiotic and biotic stresses. Cutin, the structural polyester of the plant cuticle, is synthesized in the apoplast. Plasma-membrane-localized ATP-binding cassette (ABC)...
Article
Full-text available
The plant hormone auxin is distributed in the plant by a sophisticated network of importers and exporters, including members of the ABCB subclass of ATP-binding cassette (ABC) transporters. ABCB-mediated auxin transport is controlled by Twisted Dwarf1, a member of the FK506-binding protein (FKBP) family. Here, we summarize current knowledge on ABC...
Article
Full-text available
The widely used non-steroidal anti-inflammatory drugs (NSAIDs) are derivatives of the phytohormone salicylic acid (SA). SA is well known to regulate plant immunity and development, whereas there have been few reports focusing on the effects of NSAIDs in plants. Our studies here reveal that NSAIDs exhibit largely overlapping physiological activities...
Article
Post‐transcriptional regulation of ATP‐binding cassette (ABC) proteins has been so far shown to encompass protein phosphorylation, maturation, and ubiquitination. Yet, recent accumulating evidence implicates FK506‐binding proteins (FKBPs), a type of peptidylprolyl cis–trans isomerase (PPIase) proteins, in ABC transporter regulation. In this perspec...
Article
Full-text available
The plant hormone auxin must be transported throughout plants in a cell-to-cell manner to affect its various physiological functions. ABCB transporters are critical for this polar auxin distribution, but the regulatory mechanisms controlling their function is not fully understood. The auxin transport activity of ABCB1 was suggested to be regulated...
Preprint
Full-text available
Root branching is an important strategy to explore efficiently large volumes of soil. To economize this process, lateral roots (LR) are formed along the growing root at discrete positions that are instructed by oscillating auxin signals derived from the lateral root cap (LRC). This assumes that auxin moves from the LRC across multiple layers to acc...
Preprint
Auxin transport activity of ABCB1 was suggested to be regulated by physical interaction with the FKBP42/Twisted Dwarf1 (TWD1), a bona fide peptidylprolyl cis-trans isomerase (PPIase), but all attempts to demonstrate such a PPIase activity on TWD1 have failed so far. By using a structure-based approach we have identified a series of surface-exposed...
Chapter
Polar growth is provided by rapid cell expansion that spatially focuses at the tip. The regulation and maintenance of polar growth requires two important intracellular events: intensive exocytosis in the tip region and a highly dynamic cytoskeleton system. The selective transport of secretory vesicles and their accumulation in the apical region, wh...
Article
Full-text available
The PDR-type ABCG transporter, ABCG36/PDR8/PEN3, is thought to be implicated in the export of a few structurally unrelated substrates, including the auxin precursor, indole-3-butyric acid (IBA), although a clear-cut proof of transport is lacking. An outward facing, lateral root (LR) location for ABCG36 fuelled speculations that it might secrete IBA...
Article
In order to survive under ever‐changing conditions plants must be able to adaptively respond to their environment. Plant hormones and the signaling cross‐talk among them play a key role in integrating external and internal cues, enabling the plants to acclimate accordingly. HSP90 and several of its co‐chaperones are known as pleiotropic factors inv...
Technical Report
Full-text available
Anticipating future challenges. The Department of Biology has changed greatly during these last years, notably in the disappearance of the former “units” to form a more flexible and hierarchically uniform structure, the reorganization of the administrative and technical staff, the establishment of platforms in bioinformatics, bioimaging, and proteo...
Article
Full-text available
Nonhost resistance of Arabidopsis thaliana against Phytophthora infestans, a filamentous eukaryotic microbe and the causal agent of potato late blight, is based on a multi-layered defense system. A. thaliana controls pathogen entry through the penetration-resistance genes PEN2 and PEN3, encoding an atypical myrosinase and an ABC transporter, respec...
Article
Full-text available
In rice, there are five members of the auxin carrier AUXIN1/LIKE AUX1 (AUX1/LAX) family, however, the biological functions of the other four members besides OsAUX1 remains unknown. Here, by using Crispr/cas9 we constructed two independent OsAUX3 knock‐down lines, osaux3‐1 and osaux3‐2, in wild‐type rice, Hwayoung (WT/HY) and Dongjin (WT/DJ). osaux3...
Article
Full-text available
Transport of signaling molecules is of major importance for regulating plant growth, development, and responses to the environment. A prime example is the spatial-distribution of auxin, which is regulated via transporters to govern developmental patterning. A critical limitation in our ability to identify transporters by forward genetic screens is...
Article
Recently, the plant transport field has shifted their research focus toward a more integrative investigation of transport networks thought to provide the basis for long-range transport routes. Substantial progress was provided by of a series of elegant techniques that allow for a visualization or prediction of substrate movements in plant tissues i...
Article
Full-text available
Plant ATP binding cassette (ABC) transporters are membrane proteins that are important for transporting a wide range of compounds, including secondary metabolites and phytohormones. In Arabidopsis, some members of the ABCB subfamily of ABC transporter, also known as Multi-Drug Resistance proteins (MDRs), have been implicated in auxin transport. How...
Article
Full-text available
The outermost cell layer of plant roots (epidermis) constantly encounters environmental challenges. The epidermal outer plasma membrane domain harbours the PENETRATION3 (PEN3)/ABCG36/PDR8 ATP-binding cassette transporter that confers non-host resistance to several pathogens. Here, we show that the Arabidopsis ENDOPLASMIC RETICULUM-ARRESTED PEN3 (EA...
Article
Full-text available
Hormone transporters are crucial for plant hormone action, which is underlined by severe developmental and physiological impacts caused by their loss-of-function mutations. Here, we summarize recent knowledge on the individual roles of plant hormone transporters in local and long-distance transport. Our inventory reveals that many hormones are tran...
Article
Different subclasses of ATP-binding cassette (ABC) transporters have been implicated in the transport of native variants of the phytohormone auxin. Here, the putative, individual roles of key members belonging to the ABCB, ABCD and ABCG families, respectively, are highlighted and the knowledge of their assumed expression and transport routes is rev...
Article
Full-text available
The phytohormone auxin is a major determinant and regulatory component important for plant development. Auxin transport between cells is mediated by a complex system of transporters such as AUX1/LAX, PIN, and ABCB proteins, and their localization and activity is thought to be influenced by phosphatases and kinases. Flavonols have been shown to alte...
Article
Full-text available
Article
The phytohormone auxin is involved in virtually every aspect of plant growth and development. Through polar auxin transport, auxin gradients can be established, which then direct plant differentiation and growth. Shade avoidance responses are well-known processes that require polar auxin transport. Here, we have identified a sav4 (shade avoidance 4...
Article
Morphogenetic signals control the patterning of multicellular organisms. Cytokinins are mobile signals that are perceived by subsets of plant cells. We found that the responses to cytokinin signaling during Arabidopsis development are constrained by the transporter PURINE PERMEASE 14 (PUP14). In our experiments, the expression of PUP14 was inversel...
Article
Full-text available
Plant growth and architecture is regulated by the polar distribution of the hormone auxin. Polarity and flexibility of this process is provided by constant cycling of auxin transporter vesicles along actin filaments, coordinated by a positive auxin-actin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin...
Article
Plant development and architecture are greatly influenced by the polar distribution of the essential hormone auxin. The directional influx and efflux of auxin from plant cells depends primarily on AUX1/LAX, PIN, and ABCB/PGP/MDR families of auxin transport proteins. The functional analysis of these proteins has progressed rapidly within the last de...
Article
Full-text available
Flavonols are a group of secondary metabolites that affect diverse cellular processes. They are considered putative negative regulators of the transport of the phytohormone auxin, by which they influence auxin distribution and concomitantly take part in the control of plant organ development. Flavonols are accumulating in a large number of glycosid...
Article
Full-text available
The ABC (ATP-binding cassette) transporter family in higher plants is highly expanded compared with those of mammalians. Moreover, some members of the plant ABC subfamily B (ABCB) display very high substrate specificity compared with their mammalian counterparts that are often associated with multi-drug resistance phenomena. In this review, we high...
Article
Auxin and cadmium (Cd) stress play critical roles during root development. There are only a few reports on the mechanisms how Cd stress influences auxin homeostasis and affects primary root (PR) and lateral root (LR) development, whereas there is almost nothing known how auxin and Cd interfere with root hair (RH) development. Here, we characterize...
Article
Full-text available
Polar auxin transport and the action of the actin cytoskeleton are tightly interconnected, which is documented by the finding that auxin transporters reach their final destination by active movement of secretory vesicles along F-actin tracks. Moreover, auxin transporter polarity and flexibility is thought to depend on transporter cycling that requi...
Article
Full-text available
Approximately 0.2 % of all angiosperms are classified as metal hyperaccumulators based on their extraordinarily high leaf metal contents, for example >1 % zinc, >0.1 % nickel or >0.01 % cadmium (Cd) in dry biomass. So far, metal hyperaccumulation has been considered to be a taxon-wide, constitutively expressed trait, the extent of which depends sol...
Article
Full-text available
Cyclophilin A is a conserved peptidyl-prolyl cis-trans isomerase (PPIase) best known as the cellular receptor of the immunosuppressant cyclosporine A. Despite significant effort, evidence of developmental functions of cyclophilin A in non-plant systems has remained obscure. Mutations in a tomato (Solanum lycopersicum) cyclophilin A ortholog, DIAGEO...
Article
Full-text available
The function of the extracytoplasmic AUXIN-BINDING-PROTEIN1 (ABP1) is largely enigmatic. We complemented a homozygous T-DNA insertion null mutant of ABP1 in Arabidopsis thaliana Wassilewskia with three mutated and one wild-type (wt) ABP1 cDNA, all tagged C-terminally with a strepII-FLAG tag upstream the KDEL signal. Based on in silico modelling, th...
Article
The emergence and radiation of multicellular land plants was driven by crucial innovations to their body plans [1]. The directional transport of the phytohormone auxin represents a key, plant-specific mechanism for polarization and patterning in complex seed plants [2, 3, 4 and 5]. Here, we show that already in the early diverging land plant lineag...
Article
Full-text available
The function of the extracytoplasmic AUXIN-BINDING-PROTEIN1 (ABP1) is largely enigmatic. We complemented a homozygous T-DNA insertion null mutant of ABP1 in Arabidopsis thaliana Wassilewskia with three mutated and one wild-type (wt) ABP1 cDNA, all tagged C-terminally with a strepII–FLAG tag upstream the KDEL signal. Based on in silico modelling, th...
Article
Recently, emission of volatile organic compounds (VOCs) has emerged as a mode of communication between bacteria and plants. Although some bacterial VOCs that promote plant growth have been identified, their underlying mechanism of action is unknown. Here we demonstrate that indole, which was identified using a screen for Arabidopsis growth promotio...
Article
Full-text available
Auxin and brassinosteroid (BR) are important phytohormones for controlling lamina inclination implicated in plant architecture and grain yield. But the molecular mechanism of auxin and BR crosstalk for regulating lamina inclination remains unknown. Auxin response factors (ARFs) control various aspects of plant growth and development. We here report...
Chapter
ABC transporters require a tight regulation of their transport activity as they often distribute substrates that are either toxic or of metabolic or developmental function. Moreover in contrast to secondary active transporters or channels they represent in energetic terms rather inefficient ATP-consuming nano-machines. The regulation of mammalian A...
Article
Full-text available
Members of the ATP Binding Cassette B/Multidrug-resistance/P-glycoprotein (ABCB/MDR/PGP) subfamily were shown to function primarily in auxin transport. However, none of rice ABCB transporters have been functionally characterized. Here, we describe that a knock-down of OsABCB14 confers decreased auxin concentrations and polar auxin transport rates,...