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Niko Geldner - One of the best experts on this subject based on the ideXlab platform.
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High-order mutants reveal an essential requirement for peroxidases but not laccases in Casparian Strip lignification
Proceedings of the National Academy of Sciences, 2020Co-Authors: Nelson Rojas-murcia, Kian Hématy, Damien De Bellis, Satoshi Fujita, Robertas Ursache, Yuree Lee, Aurélia Emonet, Niko GeldnerAbstract:Lignin has enabled plants to colonize land, grow tall, transport water within their bodies, and protect themselves against various stresses. Consequently, this polyphenolic polymer, impregnating cellulosic plant cell walls, is the second most abundant polymer on Earth. Yet, despite its great physiological, ecological, and economical importance, our knowledge of lignin biosynthesis in vivo, especially the polymerization steps within the cell wall, remains vague—specifically, the respective roles of the two polymerizing enzymes classes, laccases and peroxidases. One reason for this lies in the very high numbers of laccases and peroxidases encoded by 17 and 73 homologous genes, respectively, in Arabidopsis. Here, we have focused on a specific lignin structure, the ring-like Casparian Strips (CSs) within the root endodermis. By reducing candidate numbers using cellular resolution expression and localization data and by boosting stacking of mutants using CRISPR-Cas9, we mutated the majority of laccases in Arabidopsis in a nonuple mutant—essentially abolishing laccases with detectable endodermal expression. Yet, we were unable to detect even slight defects in CS formation. By contrast, we were able to induce a complete absence of CS formation in a quintuple peroxidase mutant. Our findings are in stark contrast to the strong requirement of xylem vessels for laccase action and indicate that lignin in different cell types can be polymerized in very distinct ways. We speculate that cells lignify differently depending on whether lignin is localized or ubiquitous and whether cells stay alive during and after lignification, as well as the composition of the cell wall.
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CASP microdomain formation requires cross cell wall stabilization of domains between neighbors and non-cell autonomous action of LOTR1 cell wall protein
2020Co-Authors: A. Kolbeck, Lothar Kalmbach, Peter Marhavy, D. De Bellis, Niko GeldnerAbstract: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 these contiguous three-dimensional superstructures are formed in plants. Here, we show that correct establishment of the plant Casparian Strip (CS) network requires 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 is associated with disrupted CSDs and establishment of fully functional CSD at ectopic positions, forming "half Strips". LOTR1 is expressed in stele and needs to be expressed there. Endodermal expression, by contrast, cannot complement, while cortex expression causes a dominant-negative phenotype. Our findings establish LOTR1 as a crucial player in CSD positioning acting in a non-cell-autonomous pathway to restrict and coordinate CS positioning.
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High-order mutants reveal an essential requirement for peroxidases but not laccases in Casparian Strip lignification
2020Co-Authors: Nelson Rojas-murcia, Kian Hématy, Damien De Bellis, Satoshi Fujita, Robertas Ursache, Yuree Lee, Aurélia Emonet, Niko GeldnerAbstract:ABSTRACT The invention of lignin has been at the heart of plants’ capacity to colonize land, allowing them to grow tall, transport water within their bodies and protect themselves against various stresses. Consequently, this polyphenolic polymer, that impregnates the cellulosic plant cell walls, now represents the second most abundant polymer on Earth, after cellulose itself. Yet, despite its great physiological, ecological and economical importance, our knowledge of lignin biosynthesis in vivo, especially the crucial last steps of polymerization within the cell wall, remains vague. Specifically, the respective roles and importance of the two main polymerizing enzymes classes, laccases and peroxidases have remained obscure. One reason for this lies in the very high numbers of laccases and peroxidases encoded by 17 and 73 homologous genes, respectively, in the Arabidopsis genome. Here, we have focused on a specific lignin structure, the ring-like Casparian Strips (CS) within the endodermis of Arabidopsis roots. By reducing the number of possible candidate genes using cellular resolution expression and localization data and by boosting the levels of mutants that can be stacked using CRISPR/Cas9, we were able to knock-out more than half of all laccases in the Arabidopsis genome in a nonuple mutant – abolishing the vast majority of laccases with detectable endodermal-expression. Yet, we were unable to detect even slight defects in CS formation. By contrast, we were able to induce a complete absence of CS formation in a quintuple peroxidase mutant. Our findings are in stark contrast to the strong requirement of xylem vessels for laccase action and indicate that lignin in different cell types can be polymerized in very distinct ways. We speculate that cells lignify differently depending on whether they deposit lignin in a localized or ubiquitous fashion, whether they stay alive during and after lignification as well as the composition of the cell wall.
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The Casparian Strip-one ring to bring cell biology to lignification?
Current Opinion in Biotechnology, 2019Co-Authors: Inês C. R. Barbosa, Nelson Rojas-murcia, Niko GeldnerAbstract:Lignin research has long been motivated by the outstanding importance of wood for human societies. The annual, non-woody Arabidopsis thaliana, has nevertheless contributed greatly to our understanding of lignification, due to its unrivalled genetic resources. Arabidopsis is also great for cell and developmental biology, allowing precise imaging and tracking of cell types. Root endodermis differentiation involves the precise lignification of the Casparian Strip, as an apoplastic barrier; while barrier damage triggers a less localized, compensatory lignification. Transcriptional reprogramming and peptide-induced signalling emerge as promising tools for the study of endodermal lignification. We argue that endodermis lignification is an attractive model complementary to equally powerful, cellular xylem differentiation systems, as it might better represent the restricted – often localized – lignification seen in non-vascular cells.
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Role of the endodermal bypass in radial substrate transport in roots.
2018Co-Authors: Fengying Duan, Niko Geldner, David E. Salt, Ricardo F. H. Giehl, Nicolaus Von WirénAbstract:(A) Schematic representation of radial transport pathways in roots with (WT, Columbia-0) or without (sgn3 mutant) functional CSs. (B–E) Normalized shoot accumulation as readout for radial transport rates of Sr2+ or 15NH4+ when supplied in the nutrient solution at low (200 μM) or high (4 mM) concentration. Bars represent means ± SD. P values were calculated using Student t test (n = 4 biological replicates). Underlying data can be found in S1 Data. 15NH4+, 15N-labeled ammonium; CS, Casparian Strip; DW, dry weight; sgn3, schengen 3; Sr2+, strontium ion; WT, wild-type.
Marie Barberon - One of the best experts on this subject based on the ideXlab platform.
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Regulation of a plant aquaporin by a Casparian Strip membrane domain protein-like.
Plant Cell & Environment, 2019Co-Authors: Chloé Champeyroux, Marie Barberon, Jorge Bellati, Christophe Maurel, Valerie Rofidal, Veronique SantoniAbstract:The absorption of soil water by roots allows plants to maintain their water status. At the endodermis, water transport can be affected by initial formation of a Casparian Strip and further deposition of suberin lamellas and regulated by the function of aquaporins. Four Casparian Strip membrane domain protein-like (CASPL; CASPL1B1, CASPL1B2, CASPL1D1, and CASPL1D2) were previously shown to interact with PIP2;1. The present work shows that CASPL1B1, CASPL1B2, and CASPL1D2 are exclusively expressed in suberized endodermal cells, suggesting a cell-specific role in suberization and/or water transport regulation. When compared with wild-type plants, and by contrast to caspl1b1*caspl1b2 double loss of function, caspl1d1*caspl1d2 double mutants showed, in some control or NaCl stress experiments and not upon abscisic acid (ABA) treatment, a weak enlargement of the continuous suberization zone. None of the mutants showed root hydraulic conductivity (Lpr ) phenotype, whether in control, NaCl, or ABA treatment conditions. The data suggest a slight negative role for CASPL1D1 and CASPL1D2 in suberization under control or salt stress conditions, with no major impact on whole root transport functions. At the molecular level, CASPL1B1 was able to physically interact with PIP2;1 and potentially could influence the regulation of aquaporins by acting on their phosphorylated form.
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Regulation of a plant aquaporin by a Casparian Strip membrane domain protein-like
Plant Cell and Environment, 2019Co-Authors: Chloé Champeyroux, Marie Barberon, Jorge Bellati, Christophe Maurel, Valerie Rofidal, Veronique SantoniAbstract:The absorption of soil water by roots allows plants to maintain their water status. At the endodermis, water transport can be affected by initial formation of a Casparian Strip, and further deposition of suberin lamellas and regulated by the function of aquaporins. Four Casparian Strip membrane domain protein-like (CASPL) (CASPL1B1, CASPL1B2, CASPL1D1 and CASPL1D2) were previously shown to interact with PIP2;1, (Bellati et al. 2016). The present work shows that CASPL1B1, CASPL1B2 and CASPL1D2 are exclusively expressed in suberized endodermal cells, suggesting a cell-specific role in suberization and/or water transport regulation. When compared to wild-type plants, and by contrast to caspl1b1*caspl1b2 double loss-of-function, caspl1d1*caspl1d2 double mutants showed, in some control or NaCl stress experiments and not upon ABA treatment a weak enlargement of the continuous suberization zone. None of the mutants showed root hydraulic conductivity (Lpr ) phenotype, whether in control, NaCl or ABA treatment conditions. The data suggest a slight negative role for CASPL1D1 and CASPL1D2 in suberization under control or salt stress conditions, with no major impact on whole root transport functions. At the molecular level, CASPL1B1 was able to physically interact with PIP2;1, and potentially could influence the regulation of aquaporins by acting on their phosphorylated form.
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Transient cell-specific EXO70A1 activity in the CASP domain and Casparian Strip localization.
Nature Plants, 2017Co-Authors: Lothar Kalmbach, Marie Barberon, Kian Hématy, Damien De Bellis, Satoshi Fujita, Robertas Ursache, Jean Daraspe, Niko GeldnerAbstract:In a striking case of evolutionary convergence, polarized cell layers with ring-like diffusion barriers have evolved in both plant and animal lineages independently. In plants, ring-like Casparian Strips become localized by the Casparian Strip MEMBRANE DOMAIN PROTEINS (CASPs). The mechanism of this striking localization, however, has remained enigmatic. Here we present a genetic screen aimed at isolating determinants of CASP localization. One of the mutants, lord of the rings 2 (lotr2)/exo70a1, displays dramatic de-localization of CASPs into randomly localized microdomains. EXO70A1 is a subunit of the exocyst complex, a central component of secretion in eukaryotes. Irradiation of EXO70 subunit genes in plants has suggested specialization of this conserved complex. Intriguingly, lotr2/exo70a1 does neither affect secretion of the CASPs, nor that of other membrane proteins in the endodermis, thus separating exocyst activity in localization from a general defect in secretion. Our results establish EXO70A1 as a central player in Casparian Strip formation, generating a transient positional information that will be translated into a precisely localized cell wall modification.
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root diffusion barrier control by a vasculature derived peptide binding to the sgn3 receptor
Science, 2017Co-Authors: Verónica G. Doblas, Marie Barberon, Julien Alassimone, Satoshi Fujita, Elwira Smakowskaluzan, Mathias Madalinski, Youssef Belkhadir, Niko GeldnerAbstract:The root endodermis forms its extracellular diffusion barrier by developing ringlike impregnations called Casparian Strips. A factor responsible for their establishment is the SCHENGEN3/GASSHO1 (SGN3/GSO1) receptor-like kinase. Its loss of function causes discontinuous Casparian Strips. SGN3 also mediates endodermal overlignification of other Casparian Strip mutants. Yet, without ligand, SGN3 function remained elusive. Here we report that schengen2 (sgn2) is defective in an enzyme sulfating peptide ligands. On the basis of this observation, we identified two stele-expressed peptides (Casparian Strip INTEGRITY FACTORS, CIF1/2) that complement sgn2 at nanomolar concentrations and induce Casparian Strip mislocalization as well as overlignification—all of which depend on SGN3. Direct peptide binding to recombinant SGN3 identifies these peptides as SGN3 ligands. We speculate that CIF1/2-SGN3 is part of a barrier surveillance system, evolved to guarantee effective sealing of the supracellular Casparian Strip network.
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The endodermis, a tightly controlled barrier for nutrients.
Current Opinion in Plant Biology, 2017Co-Authors: Verónica G. Doblas, Niko Geldner, Marie BarberonAbstract:Plant roots acquire nutrients from the soil and transport them upwards to the aerial parts. To reach the central vasculature of the root, water and nutrients radially cross all external cell layers. The endodermis surrounds the vascular tissues and forms diffusion barriers. It thereby compartmentalizes the root and allows control of nutrient transport from the soil to the vasculature, as well as preventing backflow of nutrients from the stele. To achieve this role, endodermal cells undergo two specialized differentiations states consisting of deposition of two impermeable polymers in the cell wall: lignin, forming the Casparian Strips, and suberin lamellae. Recent publications showed that endodermal barrier formation is not a hard-wired, irreversible process. Synthesis and degradation of suberin lamellae is highly regulated by plant hormones in response to nutrient stresses. Moreover, Casparian Strip continuity seems to be constantly checked by two small peptides produced in the vasculature that diffuse into the apoplastic space in order to test endodermal barrier integrity. This review discusses the recent understanding of endodermal barrier surveillance and plasticity and its role in plant nutrition.
Joop E.m. Vermeer - One of the best experts on this subject based on the ideXlab platform.
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Plant Biology: Journey to the Center of the Casparian Strip.
Current Biology, 2020Co-Authors: Dorothee Stöckle, Joop E.m. VermeerAbstract:Diffusion barriers in roots play an important role in regulating the movement of compounds between the soil environment and the vasculature. A new study provides new mechanistic insights into how a pair of copper-binding proteins facilitate the formation of a lignified nanodomain within Casparian Strips.
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Polarly localized kinase SGN1 is required for Casparian Strip integrity and positioning
Nature Plants, 2016Co-Authors: Julien Alassimone, Marie Barberon, Joop E.m. Vermeer, Lothar Kalmbach, Satoshi Fujita, Nelson Rojas-murcia, Verónica G. Doblas, Maritza Van Dop, Luca Santuari, Christian S. HardtkeAbstract:Casparian Strips are precisely localized and aligned ring-like cell wall modifications in the root of all higher plants. They set up an extracellular diffusion barrier analogous to animal tight junctions, and are crucial for maintaining the homeostatic capacity of plant roots. Casparian Strips become localized because of the formation of a highly stable plasma membrane domain, consisting of a family of small transmembrane proteins called Casparian Strip membrane domain proteins (CASPs). Here we report a large-scale forward genetic screen directly visualizing endodermal barrier function, which allowed us to identify factors required for the formation and integrity of Casparian Strips. We present the identification and characterization of one of the mutants, schengen1 (sgn1), a receptor-like cytoplasmic kinase that we show localizes in a strictly polar fashion to the outer plasma membrane of endodermal cells and is required for the positioning and correct formation of the centrally located CASP domain.
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Polarly localized kinase SGN1 is required for Casparian Strip integrity and positioning
Nature Plants, 2016Co-Authors: Julien Alassimone, Marie Barberon, Joop E.m. Vermeer, Lothar Kalmbach, Satoshi Fujita, Nelson Rojas-murcia, Verónica G. Doblas, Maritza Van Dop, Luca Santuari, Christian S. HardtkeAbstract:Casparian Strips are precisely localized and aligned ring-like cell wall modifications in the root of all higher plants. They set up an extracellular diffusion barrier analogous to animal tight junctions, and are crucial for maintaining the homeostatic capacity of plant roots. Casparian Strips become localized because of the formation of a highly stable plasma membrane domain, consisting of a family of small transmembrane proteins called Casparian Strip membrane domain proteins (CASPs). Here we report a large-scale forward genetic screen directly visualizing endodermal barrier function, which allowed us to identify factors required for the formation and integrity of Casparian Strips. We present the identification and characterization of one of the mutants, schengen1 ( sgn1 ), a receptor-like cytoplasmic kinase that we show localizes in a strictly polar fashion to the outer plasma membrane of endodermal cells and is required for the positioning and correct formation of the centrally located CASP domain. The Casparian Strip (CS) is a hydrophobic endodermal barrier isolating the cortex from the vasculature in the roots. A visual genetic screen identifies SCHENGEN1, a novel receptor-like kinase crucial for the integrity and positioning of the CS.
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A receptor-like kinase mutant with absent endodermal diffusion barrier displays selective nutrient homeostasis defects.
eLife, 2014Co-Authors: Alexandre Pfister, Marie Barberon, Julien Alassimone, Misako Yamazaki, Joop E.m. Vermeer, Lothar Kalmbach, Christophe Maurel, Yuree Lee, Junpei Takano, Takehiro KamiyaAbstract:The endodermis represents the main barrier to extracellular diffusion in plant roots, and it is central to current models of plant nutrient uptake. Despite this, little is known about the genes setting up this endodermal barrier. In this study, we report the identification and characterization of a strong barrier mutant, schengen3 (sgn3). We observe a surprising ability of the mutant to maintain nutrient homeostasis, but demonstrate a major defect in maintaining sufficient levels of the macronutrient potassium. We show that SGN3/GASSHO1 is a receptor-like kinase that is necessary for localizing Casparian Strip DOMAIN PROTEINS (CASPs)--major players of endodermal differentiation--into an uninterrupted, ring-like domain. SGN3 appears to localize into a broader band, embedding growing CASP microdomains. The discovery of SGN3 strongly advances our ability to interrogate mechanisms of plant nutrient homeostasis and provides a novel actor for localized microdomain formation at the endodermal plasma membrane.
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Functional and Evolutionary Analysis of the Casparian Strip MEMBRANE DOMAIN PROTEIN Family
Plant Physiology, 2014Co-Authors: Daniele Roppolo, Alexandre Pfister, Joop E.m. Vermeer, Brigitte Boeckmann, Emmanuel Boutet, Maria C. Rubio, Valérie Dénervaud-tendon, Jacqueline Gheyselinck, Ioannis Xenarios, Niko GeldnerAbstract:Casparian Strip MEMBRANE DOMAIN PROTEINS (CASPs) are four-membrane-span proteins that mediate the deposition of Casparian Strips in the endodermis by recruiting the lignin polymerization machinery. CASPs show high stability in their membrane domain, which presents all the hallmarks of a membrane scaffold. Here, we characterized the large family of CASP-like (CASPL) proteins. CASPLs were found in all major divisions of land plants as well as in green algae; homologs outside of the plant kingdom were identified as members of the MARVEL protein family. When ectopically expressed in the endodermis, most CASPLs were able to integrate the CASP membrane domain, which suggests that CASPLs share with CASPs the propensity to form transmembrane scaffolds. Extracellular loops are not necessary for generating the scaffold, since CASP1 was still able to localize correctly when either one of the extracellular loops was deleted. The CASP first extracellular loop was found conserved in euphyllophytes but absent in plants lacking Casparian Strips, an observation that may contribute to the study of Casparian Strip and root evolution. In Arabidopsis (Arabidopsis thaliana), CASPL showed specific expression in a variety of cell types, such as trichomes, abscission zone cells, peripheral root cap cells, and xylem pole pericycle cells.
Ichirou Karahara - One of the best experts on this subject based on the ideXlab platform.
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The pea stem: a unique experimental system to study the development of the Casparian Strip.
Plant Signaling & Behavior, 2012Co-Authors: Ichirou KaraharaAbstract:The Casparian Strip is commonly observed in the endodermis of roots of vascular plants and, in some cases, also in the stems. Pea stems develop the Casparian Strip, and its development has been reported to be regulated by blue light. In addition, for the purpose of photobiological studies, pea stems provide a unique experimental system for other physiological studies of the development of the Casparian Strip. In this article, I have briefly summarized (1) the effects of environmental factors on the development of the Casparian Strip, (2) the advantage of using pea stems for physiological studies of the development of the Casparian Strip, and (3) cellular events indicated to be involved in the development of the Casparian Strip, focusing on the studies using pea stems as well as other recent studies.
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Development of the Casparian Strip is delayed by blue light in pea stems
Planta, 2011Co-Authors: Ichirou Karahara, Eliko Takaya, Shigetaka Fujibayashi, Hiroshi Inoue, James L. Weller, James B. Reid, Michizo SugaiAbstract:To understand the regulatory mechanisms involved in tissue development by light, the kinetics of regulation of Casparian Strip (CS) development in garden pea stems was studied. We found that short-term irradiation with white light delayed the development of the CS and used this delay to assess the quantitative effect of light on CS development. We examined the effect of the duration and fluence rates of white light treatment on CS development and observed a significant relationship between fluence and the delay in CS development indicating that the Bunsen–Roscoe law of reciprocity holds for this response. The effect of white light irradiation was not inhibited in the presence of a photosynthetic inhibitor, DCMU, or a carotenoid biosynthesis inhibitor, Norflurazon, indicating that the delay in CS development by light is a photomorphogenetic response rather than a subsidiary effect mediated by photosynthetic activity. An action spectrum for the response displayed a major peak in the blue-light region, suggesting a dominant role for blue-light receptors. A minor peak in the red-light region also suggested the possible involvement of phytochromes. Although phytochromes are known to contribute to blue-light responses, phytochrome-deficient mutants showed a normal delay of CS development in response to blue light, indicating that the response is not mediated by phytochrome and suggesting a role for one or more specific blue-light receptors.
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Casparian Strip development and its potential function in salt tolerance.
Plant Signaling & Behavior, 2011Co-Authors: Tong Chen, Ichirou Karahara, Xia Cai, Lucas Schreiber, Jinxing LinAbstract:The root system is particularly affected by unfavourable conditions because it is in direct contact with the soil environment. Casparian Strips, a specialised structure deposited in anticlinal walls, are characterised by the impregnation of the primary wall pores with lignin and suberin. The Casparian Strips in the endo- and exodermis of vascular plant roots appear to play an important role in preventing the non-selective apoplastic bypass of salts into the stele along the apoplast under salt stress. However, only a few investigations have examined the deposition and function of these apoplastic barriers in response to salt stress in higher plants.
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Effects of ethylene on the production, elongation, and differentiation of endodermal cells in maize primary root: An integrative analysis of the developmental process of a particular cell type
Plant Root, 2008Co-Authors: Ichirou Karahara, Kaori Matsuda, Yoshihiro HonmaAbstract:A unique integrative analysis is proposed to monitor changes in the develop- mental processes of a particular cell type in the root, i.e. the rates of cell differentiation, produc- tion, and elongation. As a model case, effects of exogenous ethylene on differentiation, division and elongation of endodermal cells were ana- lyzed in maize primary roots. The distance from the lowest position of the Casparian Strip, a morphological marker for endodermal cell differentiation, to the root tip decreased in response to ethylene in a dose-dependent manner. The endodermal cell flux in a single cell file, an indicator for cell division, decreased in response to ethylene, although the estimated time required for an individual cell to complete the formation of the Casparian Strip, as an indicator for the cell differentiation rate, did not. As indicators for cell elongation, the mature cell length did not change in the presence of ethylene, although the period for cell elongation increased. The Casparian Strip formed after the endodermal cell had ceased elongation, irrespective of the presence of ethylene.
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Development of the Casparian Strip in primary roots of maize under salt stress.
Planta, 2004Co-Authors: Ichirou Karahara, Atsuo Ikeda, Takanori Kondo, Yuzo UetakeAbstract:The Casparian Strip in the endodermis of vascular plant roots appears to play an important role in preventing the influx of salts into the stele through the apoplast under salt stress. The effects of salinity on the development and morphology of the Casparian Strip in primary roots of maize (Zea mays L.) were studied. Compared to the controls, the Strip matured closer to the root tip with increase in the ambient concentration of NaCl. During growth in 200 mM NaCl, the number and the length of the endodermal cells in the region between the root tip and the lowest position of the endodermal Strip decreased, as did the apparent rate of production of cells in single files of endodermal cells (the rate of cell formation being equal to the rate at which cells are lost from the meristem). The estimated time required for an individual cell to complete the formation of the Strip after generation of the cell in the presence of 200 mM NaCl was not very different from that required in controls. Thus, salinity did not substantially affect the actual process of formation of the Strip in individual cells. The radial width of the Casparian Strip, a morphological parameter that should be related to the effectiveness of the Strip as a barrier, increased in the presence of 200 mM NaCl. The mean width of the lignified region was 0.92 μm in distilled water and 1.33 μm in 200 mM NaCl at the lowest position of the Strip. The mean width of the Strip relative to that of the radial wall at this position was significantly greater after growth in the presence of 200 mM NaCl than in the controls, namely, 20.5% in distilled water and 33.9% in 200 mM NaCl. These observations suggest that the function of the Strip is enhanced under salt stress.
Veronique Santoni - One of the best experts on this subject based on the ideXlab platform.
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Regulation of a plant aquaporin by a Casparian Strip membrane domain protein-like.
Plant Cell & Environment, 2019Co-Authors: Chloé Champeyroux, Marie Barberon, Jorge Bellati, Christophe Maurel, Valerie Rofidal, Veronique SantoniAbstract:The absorption of soil water by roots allows plants to maintain their water status. At the endodermis, water transport can be affected by initial formation of a Casparian Strip and further deposition of suberin lamellas and regulated by the function of aquaporins. Four Casparian Strip membrane domain protein-like (CASPL; CASPL1B1, CASPL1B2, CASPL1D1, and CASPL1D2) were previously shown to interact with PIP2;1. The present work shows that CASPL1B1, CASPL1B2, and CASPL1D2 are exclusively expressed in suberized endodermal cells, suggesting a cell-specific role in suberization and/or water transport regulation. When compared with wild-type plants, and by contrast to caspl1b1*caspl1b2 double loss of function, caspl1d1*caspl1d2 double mutants showed, in some control or NaCl stress experiments and not upon abscisic acid (ABA) treatment, a weak enlargement of the continuous suberization zone. None of the mutants showed root hydraulic conductivity (Lpr ) phenotype, whether in control, NaCl, or ABA treatment conditions. The data suggest a slight negative role for CASPL1D1 and CASPL1D2 in suberization under control or salt stress conditions, with no major impact on whole root transport functions. At the molecular level, CASPL1B1 was able to physically interact with PIP2;1 and potentially could influence the regulation of aquaporins by acting on their phosphorylated form.
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Regulation of a plant aquaporin by a Casparian Strip membrane domain protein-like
Plant Cell and Environment, 2019Co-Authors: Chloé Champeyroux, Marie Barberon, Jorge Bellati, Christophe Maurel, Valerie Rofidal, Veronique SantoniAbstract:The absorption of soil water by roots allows plants to maintain their water status. At the endodermis, water transport can be affected by initial formation of a Casparian Strip, and further deposition of suberin lamellas and regulated by the function of aquaporins. Four Casparian Strip membrane domain protein-like (CASPL) (CASPL1B1, CASPL1B2, CASPL1D1 and CASPL1D2) were previously shown to interact with PIP2;1, (Bellati et al. 2016). The present work shows that CASPL1B1, CASPL1B2 and CASPL1D2 are exclusively expressed in suberized endodermal cells, suggesting a cell-specific role in suberization and/or water transport regulation. When compared to wild-type plants, and by contrast to caspl1b1*caspl1b2 double loss-of-function, caspl1d1*caspl1d2 double mutants showed, in some control or NaCl stress experiments and not upon ABA treatment a weak enlargement of the continuous suberization zone. None of the mutants showed root hydraulic conductivity (Lpr ) phenotype, whether in control, NaCl or ABA treatment conditions. The data suggest a slight negative role for CASPL1D1 and CASPL1D2 in suberization under control or salt stress conditions, with no major impact on whole root transport functions. At the molecular level, CASPL1B1 was able to physically interact with PIP2;1, and potentially could influence the regulation of aquaporins by acting on their phosphorylated form.
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Regulation of root water transport by Casparian Strip domain-like proteins.
2016Co-Authors: Chloé Champeyroux, Jorge Bellati, Christophe Maurel, Veronique SantoniAbstract:Regulation of root water transport by Casparian Strip domain-like proteins. . Plant Biology Europe EPSO/FESPB 2016 Congress