The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Zhiyong Wang - One of the best experts on this subject based on the ideXlab platform.

  • a triple helix loop helix basic helix loop helix cascade controls Cell Elongation downstream of multiple hormonal and environmental signaling pathways in arabidopsis
    The Plant Cell, 2012
    Co-Authors: Mingyi Bai, Min Fan, Zhiyong Wang
    Abstract:

    Environmental and endogenous signals, including light, temperature, brassinosteroid (BR), and gibberellin (GA), regulate Cell Elongation largely by influencing the expression of the paclobutrazol-resistant (PRE) family helix-loop-helix (HLH) factors, which promote Cell Elongation by interacting antagonistically with another HLH factor, IBH1. However, the molecular mechanism by which PREs and IBH1 regulate gene expression has remained unknown. Here, we show that IBH1 interacts with and inhibits a DNA binding basic helix-loop-helix (bHLH) protein, HBI1, in Arabidopsis thaliana. Overexpression of HBI1 increased hypocotyl and petiole Elongation, whereas dominant inactivation of HBI1 and its homologs caused a dwarf phenotype, indicating that HBI1 is a positive regulator of Cell Elongation. In vitro and in vivo experiments showed that HBI1 directly bound to the promoters and activated two EXPANSIN genes encoding Cell wall–loosening enzymes; HBI1’s DNA binding and transcriptional activities were inhibited by IBH1, but the inhibitory effects of IBH1 were abolished by PRE1. The results indicate that PREs activate the DNA binding bHLH factor HBI1 by sequestering its inhibitor IBH1. Altering each of the three factors affected plant sensitivities to BR, GA, temperature, and light. Our study demonstrates that PREs, IBH1, and HBI1 form a chain of antagonistic switches that regulates Cell Elongation downstream of multiple external and endogenous signals.

  • transcriptome profiling molecular biological and physiological studies reveal a major role for ethylene in cotton fiber Cell Elongation
    The Plant Cell, 2006
    Co-Authors: Jianxun Feng, Liang Zhang, Jing Cheng, Zhiyong Wang
    Abstract:

    Upland cotton (Gossypium hirsutum) produces the most widely used natural fibers, yet the regulatory mechanisms governing fiber Cell Elongation are not well understood. Through sequencing of a cotton fiber cDNA library and subsequent microarray analysis, we found that ethylene biosynthesis is one of the most significantly upregulated biochemical pathways during fiber Elongation. The 1-Aminocyclopropane-1-Carboxylic Acid Oxidase1-3 (ACO1-3) genes responsible for ethylene production were expressed at significantly higher levels during this growth stage. The amount of ethylene released from cultured ovules correlated with ACO expression and the rate of fiber growth. Exogenously applied ethylene promoted robust fiber Cell expansion, whereas its biosynthetic inhibitor l-(2-aminoethoxyvinyl)-glycine (AVG) specifically suppressed fiber growth. The brassinosteroid (BR) biosynthetic pathway was modestly upregulated during this growth stage, and treatment with BR or its biosynthetic inhibitor brassinazole (BRZ) also promoted or inhibited, respectively, fiber growth. However, the effect of ethylene treatment was much stronger than that of BR, and the inhibitory effect of BRZ on fiber Cells could be overcome by ethylene, but the AVG effect was much less reversed by BR. These results indicate that ethylene plays a major role in promoting cotton fiber Elongation. Furthermore, ethylene may promote Cell Elongation by increasing the expression of sucrose synthase, tubulin, and expansin genes.

Yuxian Zhu - One of the best experts on this subject based on the ideXlab platform.

  • saturated very long chain fatty acids promote cotton fiber and arabidopsis Cell Elongation by activating ethylene biosynthesis
    The Plant Cell, 2007
    Co-Authors: Yong-mei Qin, Yu Pang, Alexander J Kastaniotis, Kalervo J Hiltunen, Yuxian Zhu
    Abstract:

    Fatty acids are essential for membrane biosynthesis in all organisms and serve as signaling molecules in many animals. Here, we found that saturated very-long-chain fatty acids (VLCFAs; C20:0 to C30:0) exogenously applied in ovule culture medium significantly promoted cotton (Gossypium hirsutum) fiber Cell Elongation, whereas acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methyl-phenyl]-acetamide; ACE), which inhibits VLCFA biosynthesis, abolished fiber growth. This inhibition was overcome by lignoceric acid (C24:0). Elongating fibers contained significantly higher amounts of VLCFAs than those of wild-type or fuzzless-lintless mutant ovules. Ethylene nullified inhibition by ACE, whereas C24:0 was inactive in the presence of the ethylene biosynthesis inhibitor (l-[2-aminoethoxyvinyl]-glycine), indicating that VLCFAs may act upstream of ethylene. C24:0 induced a rapid and significant increase in ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) transcript levels that resulted in substantial ethylene production. C24:0 also promoted Ser palmitoyltransferase expression at a later stage, resulting in increased sphingolipid biosynthesis. Application of C24:0 not only stimulated Arabidopsis thaliana root Cell growth but also complemented the cut1 phenotype. Transgenic expression of Gh KCS13/CER6, encoding the cotton 3-ketoacyl-CoA synthase, in the cut1 background produced similar results. Promotion of Arabidopsis stem Elongation was accompanied by increased ACO transcript levels. Thus, VLCFAs may be involved in maximizing the extensibility of cotton fibers and multiple Arabidopsis Cell types, possibly by activating ethylene biosynthesis.

Herman Hofte - One of the best experts on this subject based on the ideXlab platform.

  • interaction between wall deposition and Cell Elongation in dark grown hypocotyl Cells in arabidopsis
    Plant Physiology, 2004
    Co-Authors: Guislaine Refregier, Sandra Pelletier, Danielle Jaillard, Herman Hofte
    Abstract:

    A central problem in plant biology is how Cell expansion is coordinated with wall synthesis. We have studied growth and wall deposition in epidermal Cells of dark-grown Arabidopsis hypocotyls. Cells elongated in a biphasic pattern, slowly first and rapidly thereafter. The growth acceleration was initiated at the hypocotyl base and propagated acropetally. Using transmission and scanning electron microscopy, we analyzed walls in slowly and rapidly growing Cells in 4-d-old dark-grown seedlings. We observed thick walls in slowly growing Cells and thin walls in rapidly growing Cells, which indicates that the rate of Cell wall synthesis was not coupled to the Cell Elongation rate. The thick walls showed a polylamellated architecture, whereas polysaccharides in thin walls were axially oriented. Interestingly, innermost Cellulose microfibrils were transversely oriented in both slowly and rapidly growing Cells. This suggested that transversely deposited microfibrils reoriented in deeper layers of the expanding wall. No growth acceleration, only slow growth, was observed in the Cellulose synthase mutant cesA6prc1-1 or in seedlings, which had been treated with the Cellulose synthesis inhibitor isoxaben. In these seedlings, innermost microfibrils were transversely oriented and not randomized as has been reported for other Cellulose-deficient mutants or following treatment with dichlorobenzonitrile. Interestingly, isoxaben treatment after the initiation of the growth acceleration in the hypocotyl did not affect subsequent Cell Elongation. Together, these results show that rapid Cell Elongation, which involves extensive remodeling of the Cell wall polymer network, depends on normal Cellulose deposition during the slow growth phase.

  • procuste1 encodes a Cellulose synthase required for normal Cell Elongation specifically in roots and dark grown hypocotyls of arabidopsis
    The Plant Cell, 2000
    Co-Authors: Mathilde Fagard, Maureen C Mccann, Guislaine Refregier, Thierry Desnos, Thierry Desprez, Florence Goubet, Gregory Mouille, Catherine Rayon, Samantha Vernhettes, Herman Hofte
    Abstract:

    Mutants at the PROCUSTE1 (PRC1) locus show decreased Cell Elongation, specifically in roots and dark-grown hypocotyls. Cell Elongation defects are correlated with a Cellulose deficiency and the presence of gapped walls. Map-based cloning of PRC1 reveals that it encodes a member (CesA6) of the Cellulose synthase catalytic subunit family, of which at least nine other members exist in Arabidopsis. Mutations in another family member, RSW1 (CesA1), cause similar Cell wall defects in all Cell types, including those in hypocotyls and roots, suggesting that Cellulose synthesis in these organs requires the coordinated expression of at least two distinct Cellulose synthase isoforms.

  • a plasma membrane bound putative endo 1 4 β d glucanase is required for normal wall assembly and Cell Elongation in arabidopsis
    The EMBO Journal, 1998
    Co-Authors: Frederic Nicol, Samantha Vernhettes, Isabelle His, A Jauneau, Herve Canut, Herman Hofte
    Abstract:

    Endo‐1,4‐β‐d‐glucanases (EGases) form a large family of hydrolytic enzymes in prokaryotes and eukaryotes. In higher plants, potential substrates in vivo are xyloglucan and non‐crystalline Cellulose in the Cell wall. Gene expression patterns suggest a role for EGases in various developmental processes such as leaf abscission, fruit ripening and Cell expansion. Using Arabidopsis thaliana genetics, we demonstrate the requirement of a specialized member of the EGase family for the correct assembly of the walls of elongating Cells. KORRIGAN ( KOR ) is identified by an extreme dwarf mutant with pronounced architectural alterations in the primary Cell wall. The KOR gene was isolated and encodes a membrane‐anchored member of the EGase family, which is highly conserved between mono‐ and dicotyledonous plants. KOR is located primarily in the plasma membrane and presumably acts at the plasma membrane–Cell wall interface. KOR mRNA was found in all organs examined, and in the developing dark‐grown hypocotyl, mRNA levels were correlated with rapid Cell Elongation. Among plant growth factors involved in the control of hypocotyl Elongation (auxin, gibberellins and ethylene) none significantly influenced KOR ‐mRNA levels. However, reduced KOR ‐mRNA levels were observed in det2 , a mutant deficient for brassinosteroids. Although the in vivo substrate remains to be determined, the mutant phenotype is consistent with a central role for KOR in the assembly of the Cellulose–hemiCellulose network in the expanding Cell wall.

Yong-mei Qin - One of the best experts on this subject based on the ideXlab platform.

  • Saturated Very-Long-Chain Fatty Acids Promote Cotton Fiber and Arabidopsis Cell Elongation by Activating
    2013
    Co-Authors: Ethylene Biosynthesis W, Yong-mei Qin, Yu Pang, A Alex, Er J. Kastaniotis, B Kalervo J. Hiltunen, Yu-xian Zhua
    Abstract:

    Fatty acids are essential for membrane biosynthesis in all organisms and serve as signaling molecules in many animals. Here, we found that saturated very-long-chain fatty acids (VLCFAs; C20:0 to C30:0) exogenously applied in ovule culture medium significantly promoted cotton (Gossypium hirsutum) fiber Cell Elongation, whereas acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methyl-phenyl]-acetamide; ACE), which inhibits VLCFA biosynthesis, abolished fiber growth. This inhibition was overcome by lignoceric acid (C24:0). Elongating fibers contained significantly higher amounts of VLCFAs than those of wildtype or fuzzless-lintless mutant ovules. Ethylene nullified inhibition by ACE, whereas C24:0 was inactive in the presence of the ethylene biosynthesis inhibitor (L-[2-aminoethoxyvinyl]-glycine), indicating that VLCFAs may act upstream of ethylene. C24:0 induced a rapid and significant increase in ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) transcript levels that resulted in substantial ethylene production. C24:0 also promoted Ser palmitoyltransferase expression at a later stage, resulting in increased sphingolipid biosynthesis. Application of C24:0 not only stimulated Arabidopsis thaliana root Cell growth but also complemented the cut1 phenotype. Transgenic expression of Gh KCS13/CER6, encoding the cotton 3-ketoacyl-CoA synthase, in the cut1 background produced similar results. Promotion of Arabidopsis stem Elongation was accompanied by increased ACO transcript levels. Thus, VLCFAs may be involved in maximizing the extensibility of cotton fibers and multiple Arabidopsis Cell types, possibly by activating ethylene biosynthesis

  • saturated very long chain fatty acids promote cotton fiber and arabidopsis Cell Elongation by activating ethylene biosynthesis
    The Plant Cell, 2007
    Co-Authors: Yong-mei Qin, Yu Pang, Alexander J Kastaniotis, Kalervo J Hiltunen, Yuxian Zhu
    Abstract:

    Fatty acids are essential for membrane biosynthesis in all organisms and serve as signaling molecules in many animals. Here, we found that saturated very-long-chain fatty acids (VLCFAs; C20:0 to C30:0) exogenously applied in ovule culture medium significantly promoted cotton (Gossypium hirsutum) fiber Cell Elongation, whereas acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methyl-phenyl]-acetamide; ACE), which inhibits VLCFA biosynthesis, abolished fiber growth. This inhibition was overcome by lignoceric acid (C24:0). Elongating fibers contained significantly higher amounts of VLCFAs than those of wild-type or fuzzless-lintless mutant ovules. Ethylene nullified inhibition by ACE, whereas C24:0 was inactive in the presence of the ethylene biosynthesis inhibitor (l-[2-aminoethoxyvinyl]-glycine), indicating that VLCFAs may act upstream of ethylene. C24:0 induced a rapid and significant increase in ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) transcript levels that resulted in substantial ethylene production. C24:0 also promoted Ser palmitoyltransferase expression at a later stage, resulting in increased sphingolipid biosynthesis. Application of C24:0 not only stimulated Arabidopsis thaliana root Cell growth but also complemented the cut1 phenotype. Transgenic expression of Gh KCS13/CER6, encoding the cotton 3-ketoacyl-CoA synthase, in the cut1 background produced similar results. Promotion of Arabidopsis stem Elongation was accompanied by increased ACO transcript levels. Thus, VLCFAs may be involved in maximizing the extensibility of cotton fibers and multiple Arabidopsis Cell types, possibly by activating ethylene biosynthesis.

Thomas G Bernhardt - One of the best experts on this subject based on the ideXlab platform.

  • Cell division is antagonized by the activity of peptidoglycan endopeptidases that promote Cell Elongation
    Molecular Microbiology, 2020
    Co-Authors: Thao T Truong, Andrea Vettiger, Thomas G Bernhardt
    Abstract:

    A peptidoglycan (PG) Cell wall composed of glycans crosslinked by short peptides surrounds most bacteria and protects them against osmotic rupture. In Escherichia coli, Cell Elongation requires crosslink cleavage by PG endopeptidases to make space for the incorporation of new PG material throughout the Cell cylinder. Cell division, on the contrary, requires the localized synthesis and remodeling of new PG at midCell by the divisome. Little is known about the factors that modulate transitions between these two modes of PG biogenesis. In a transposon-insertion sequencing screen to identify mutants synthetically lethal with a defect in the division protein FtsP, we discovered that mutants impaired for Cell division are sensitive to elevated activity of the endopeptidases. Increased endopeptidase activity in these Cells was shown to interfere with the assembly of mature divisomes, and conversely, inactivation of MepS was found to suppress the lethality of mutations in essential division genes. Overall, our results are consistent with a model in which the Cell Elongation and division systems are in competition with one another and that control of PG endopeptidase activity represents an important point of regulation influencing the transition from Elongation to the division mode of PG biogenesis.

  • pathway directed screen for inhibitors of the bacterial Cell Elongation machinery
    Antimicrobial Agents and Chemotherapy, 2019
    Co-Authors: Jackson Buss, Vadim Baidin, Michael Welsh, Josue Floreskim, Hongbaek Cho, Mc Kay B Wood, Tsuyoshi Uehara, Suzanne Walker, Daniel Kahne, Thomas G Bernhardt
    Abstract:

    New antibiotics are needed to combat the growing problem of resistant bacterial infections. An attractive avenue toward the discovery of such next-generation therapies is to identify novel inhibitors of clinically validated targets, like Cell wall biogenesis. We have therefore developed a pathway-directed whole-Cell screen for small molecules that block the activity of the Rod system of Escherichia coli This conserved multiprotein complex is required for Cell Elongation and the morphogenesis of rod-shaped bacteria. It is composed of Cell wall synthases and membrane proteins of unknown function that are organized by filaments of the actin-like MreB protein. Our screen takes advantage of the conditional essentiality of the Rod system and the ability of the beta-lactam mecillinam (also known as amdinocillin) to cause a toxic malfunctioning of the machinery. Rod system inhibitors can therefore be identified as molecules that promote growth in the presence of mecillinam under conditions permissive for the growth of Rod- Cells. A screen of ∼690,000 compounds identified 1,300 compounds that were active against E. coli Pathway-directed screening of a majority of this subset of compounds for Rod inhibitors successfully identified eight analogs of the MreB antagonist A22. Further characterization of the A22 analogs identified showed that their antibiotic activity under conditions where the Rod system is essential was strongly correlated with their ability to suppress mecillinam toxicity. This result combined with those from additional biological studies reinforce the notion that A22-like molecules are relatively specific for MreB and suggest that the lipoprotein transport factor LolA is unlikely to be a physiologically relevant target as previously proposed.

  • coze is a member of the mrecd complex that directs Cell Elongation in streptococcus pneumoniae
    Nature microbiology, 2017
    Co-Authors: Andy Fenton, Lamya El Mortaji, Derek T C Lau, David Z Rudner, Thomas G Bernhardt
    Abstract:

    Most bacterial Cells are surrounded by a peptidoglycan Cell wall that is essential for their integrity. The major synthases of this exoskeleton are called penicillin-binding proteins (PBPs)1,2. Surprisingly little is known about how Cells control these enzymes, given their importance as drug targets. In the model Gram-negative bacterium Escherichia coli, outer membrane lipoproteins are critical activators of the class A PBPs (aPBPs)3,4, bifunctional synthases capable of polymerizing and crosslinking peptidoglycan to build the exoskeletal matrix1. Regulators of PBP activity in Gram-positive bacteria have yet to be discovered but are likely to be distinct due to the absence of an outer membrane. To uncover Gram-positive PBP regulatory factors, we used transposon-sequencing (Tn-Seq)5 to screen for mutations affecting the growth of Streptococcus pneumoniae Cells when the aPBP synthase PBP1a was inactivated. Our analysis revealed a set of genes that were essential for growth in wild-type Cells yet dispensable when pbp1a was deleted. The proteins encoded by these genes include the conserved Cell wall Elongation factors MreC and MreD2,6,7, as well as a membrane protein of unknown function (SPD_0768) that we have named CozE (coordinator of zonal Elongation). Our results indicate that CozE is a member of the MreCD complex of S. pneumoniae that directs the activity of PBP1a to the midCell plane where it promotes zonal Cell Elongation and normal morphology. CozE homologues are broadly distributed among bacteria, suggesting that they represent a widespread family of morphogenic proteins controlling Cell wall biogenesis by the PBPs.