THE PLANT CELL ONLINE -- Table of Contents (20 [1])

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EDITORIAL:

The Plant Cell: Into the Fifth Dimension: Cathie Martin; Plant Cell 2008 20: 1-2. First Published on January 31, 2008; 10.1105/tpc.108.200180; [Full Text] [PDF]

IN THIS ISSUE:

Grass Genome Evolution: Nancy A. Eckardt; Plant Cell 2008 20: 3-4.; [Full Text] [PDF]

IN BRIEFS:

A Repressor Complex That Functions in Organogenesis: Nancy A. Eckardt; Plant Cell 2008 20: 5. First Published on January 31, 2008; 10.1105/tpc.108.200110; [Full Text] [PDF]

Cell Cycle Control and Meristem Integrity: Nancy A. Eckardt; Plant Cell 2008 20: 6. First Published on January 31, 2008; 10.1105/tpc.108.200111; [Full Text] [PDF]

Defining a Functional Centromere: Nancy A. Eckardt; Plant Cell 2008 20: 7. First Published on January 31, 2008; 10.1105/tpc.108.200112; [Full Text] [PDF]

COMMENTARY:

Engineered Plant Minichromosomes: A Bottom-Up Success?: Andreas Houben, R. Kelly Dawe, Jiming Jiang, and Ingo Schubert; Plant Cell 2008 20: 8-10. First Published on January 25, 2008; 10.1105/tpc.107.056622; [Full Text] [PDF]

RESEARCH ARTICLES:

Identification and Characterization of Shared Duplications between Rice and Wheat Provide New Insight into Grass Genome Evolution: Jérôme Salse, Stéphanie Bolot, Michaël Throude, Vincent Jouffe, Benoît Piegu, Umar Masood Quraishi, Thomas Calcagno, Richard Cooke, Michel Delseny, and Catherine Feuillet; Plant Cell 2008 20: 11-24. First Published on January 4, 2008; 10.1105/tpc.107.056309; Inter- and intragenomic comparisons in wheat and rice reveal seven shared duplications between the two genomes. Using additional comparisons with maize and sorghum, the authors propose a model in which the grass genomes evolved from a common ancestor with a basic number of five chromosomes through a series of whole-genome and segmental duplications, chromosome fusions, and translocations.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Epigenetic Modification of Centromeric Chromatin: Hypomethylation of DNA Sequences in the CENH3-Associated Chromatin in Arabidopsis thaliana and Maize: Wenli Zhang, Hye-Ran Lee, Dal-Hoe Koo, and Jiming Jiang; Plant Cell 2008 20: 25-34. First Published on January 31, 2008; 10.1105/tpc.107.057083; The establishment and maintenance of plant centromeres are not determined by the underlying centromeric DNA sequences but by unknown epigenetic factors. This work demonstrates that the highly repetitive DNA sequences in Arabidopsis and maize centromeres are hypomethylated. The results suggest that DNA methylation plays an important role in epigenetic demarcation of the centromeric chromatin.; [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

A Genomic Map of Viroid RNA Motifs Critical for Replication and Systemic Trafficking: Xuehua Zhong, Anthony J. Archual, Amy A. Amin, and Biao Ding; Plant Cell 2008 20: 35-47. First Published on January 4, 2008; 10.1105/tpc.107.056606; RNA replication and systemic trafficking play key roles in developmental regulation and host–pathogen interactions, yet the underlying mechanisms remain poorly understood. This article describes systematic genetic identification of the structural motifs in a viroid RNA that mediate replication or trafficking, which forms a foundation for studying the mechanisms that regulate these processes.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Direct Repression of KNOX Loci by the ASYMMETRIC LEAVES1 Complex of Arabidopsis: Mengjuan Guo, Julie Thomas, Galen Collins, and Marja C.P. Timmermans; Plant Cell 2008 20: 48-58. First Published on January 18, 2008; 10.1105/tpc.107.056127; KNOX genes that promote stem cell activity must be switched off in cells, giving rise to determinate differentiating structures, such as leaves. This work shows how two proteins, AS1 and AS2, form a repressor complex that directly silences two such KNOX genes in Arabidopsis.; [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

CENL1 Expression in the Rib Meristem Affects Stem Elongation and the Transition to Dormancy in Populus: Raili Ruonala, Päivi L.H. Rinne, Jaakko Kangasjärvi, and Christiaan van der Schoot; Plant Cell 2008 20: 59-74. First Published on January 11, 2008; 10.1105/tpc.107.056721; Photoperiod-induced developmental transitions involve leaf-to-apex signaling. This study shows that the transition to dormancy in poplar requires participation of two apical morphogenetic units: the rib meristem (RM) and the shoot apical meristem. A key event in the transition appears to be the cessation of RM activity, involving downregulation of Arabidopsis TFL1 ortholog CENL1 in the RM domain.; [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

The Arabidopsis Small G Protein ROP2 Is Activated by Light in Guard Cells and Inhibits Light-Induced Stomatal Opening: Byeong Wook Jeon, Jae-Ung Hwang, Youngkyu Hwang, Won-Yong Song, Ying Fu, Ying Gu, Fang Bao, Daeshik Cho, June M. Kwak, Zhenbiao Yang, and Youngsook Lee; Plant Cell 2008 20: 75-87. First Published on January 4, 2008; 10.1105/tpc.107.054544; The results in this work show that light activates ROP2 to prevent excessive stomatal opening, suggesting an additional mechanism for the modulation of guard cell movement, which may play a role in water use efficiency.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Requirement of B2-Type Cyclin-Dependent Kinases for Meristem Integrity in Arabidopsis thaliana: Stig Uggerhøj Andersen, Sabine Buechel, Zhong Zhao, Karin Ljung, Ondrej Novák, Wolfgang Busch, Christoph Schuster, and Jan U. Lohmann; Plant Cell 2008 20: 88-100. First Published on January 25, 2008; 10.1105/tpc.107.054676; Plant stem cells are embedded in specialized tissues called meristems, and cell proliferation is differentially regulated in these tissues to maintain a functional stem cell niche. This study shows that a pair of plant-specific cell cycle regulators is required for shoot apical meristem integrity and suggests a link between cell cycle control, meristem function, and plant hormone signaling.; [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Rab-A2 and Rab-A3 GTPases Define a trans-Golgi Endosomal Membrane Domain in Arabidopsis That Contributes Substantially to the Cell Plate: Cheung-Ming Chow, Hélia Neto, Camille Foucart, and Ian Moore; Plant Cell 2008 20: 101-123. First Published on January 31, 2008; 10.1105/tpc.107.052001; Internal compartments in cells of animals, plants, and fungi are maintained by families of proteins. This work shows that specific members of one such family define a compartment that is involved both in internalization and in cell division. Although cell division in plants differs from that in other organisms, these data suggest that some of the proteins involved may be common.; [Abstract] [Full Text] [PDF] [Supplemental Data]

The Type B Phosphatidylinositol-4-Phosphate 5-Kinase 3 Is Essential for Root Hair Formation in Arabidopsis thaliana: Irene Stenzel, Till Ischebeck, Sabine König, Anna Holubowska, Marta Sporysz, Bettina Hause, and Ingo Heilmann; Plant Cell 2008 20: 124-141. First Published on January 4, 2008; 10.1105/tpc.107.052852; Plants maximize their root surface for nutrient uptake by forming root hairs as protrusions of epidermis cells. In root hairs of Arabidopsis, the phospholipid phosphatidylinositol-4,5-bisphosphate, formed by PI4P 5-kinase 3, is an important regulator of polar tip growth. Blocking the production of the lipid reduces root hair formation, whereas overproduction results in depolarized growth.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Membrane Association of the Arabidopsis ARF Exchange Factor GNOM Involves Interaction of Conserved Domains: Nadine Anders, Michael Nielsen, Jutta Keicher, York-Dieter Stierhof, Masahiko Furutani, Masao Tasaka, Karen Skriver, and Gerd Jürgens; Plant Cell 2008 20: 142-151. First Published on January 18, 2008; 10.1105/tpc.107.056515; Activation of ARF-GTPases by guanine nucleotide exchange factors (ARF-GEFs) is an essential regulatory step in the formation of clathrin- and COPI-coated vesicles in membrane trafficking. This work shows that the large ARF-GEF GNOM undergoes interdomain interactions that are essential for function and required for membrane association, providing a molecular mechanism of regulating activity.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Characterization of Arabidopsis and Rice DWD Proteins and Their Roles as Substrate Receptors for CUL4-RING E3 Ubiquitin Ligases: Jae-Hoon Lee, William Terzaghi, Giuliana Gusmaroli, Jean-Benoit F. Charron, Hye-Jin Yoon, Haodong Chen, Yizhou Joseph He, Yue Xiong, and Xing Wang Deng; Plant Cell 2008 20: 152-167. First Published on January 25, 2008; 10.1105/tpc.107.055418; Proteins with the variant WD40 domain called the DWD motif may act as specific substrate receptors for the cullin4-based E3 ubiquitin ligase complex and provide specificity for protein degradation. This work surveys DWD proteins of Arabidopsis and rice, examining their interaction with E3 complex components.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Analysis of the Arabidopsis O-Acetylserine(thiol)lyase Gene Family Demonstrates Compartment-Specific Differences in the Regulation of Cysteine Synthesis: Corinna Heeg, Cordula Kruse, Ricarda Jost, Michael Gutensohn, Thomas Ruppert, Markus Wirtz, and Rüdiger Hell; Plant Cell 2008 20: 168-185. First Published on January 25, 2008; 10.1105/tpc.107.056747; Cys is key to sulfur metabolism, protein synthesis, and protein structure. Analysis of Arabidopsis knockout mutants shows that Cys must be exchangeable between cytosol and organelles. Although most of the Cys biosynthetic activity resides in plastids and cytosol, mitochondria play the most important role for Cys synthesis.; [Abstract] [Full Text] [PDF] [Supplemental Data]

EST Analysis of Hop Glandular Trichomes Identifies an O-Methyltransferase That Catalyzes the Biosynthesis of Xanthohumol: Jana Nagel, Lana K. Culley, Yuping Lu, Enwu Liu, Paul D. Matthews, Jan F. Stevens, and Jonathan E. Page; Plant Cell 2008 20: 186-200. First Published on January 25, 2008; 10.1105/tpc.107.055178; Hop glandular trichomes synthesize and secrete the methylated prenylflavonoid xanthohumol, a compound with potential anticancer properties. Focusing on biosynthetic pathways active in trichomes, this study identifies the O-methyltransferase that forms xanthohumol. It also describes an EST resource that will accelerate gene discovery and molecular breeding efforts for hops.; [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Sad3 and Sad4 Are Required for Saponin Biosynthesis and Root Development in Oat: Panagiota Mylona, Amorn Owatworakit, Kalliopi Papadopoulou, Helen Jenner, Bo Qin, Kim Findlay, Lionel Hill, Xiaoquan Qi, Saleha Bakht, Rachel Melton, and Anne Osbourn; Plant Cell 2008 20: 201-212. First Published on January 18, 2008; 10.1105/tpc.107.056531; This study focuses on two genes, Sad3 and Sad4, which are required for synthesis of defence-related compounds (avenacins) and for normal root growth and development in oat. Sad3 is part of a gene cluster for avenacin A-1 synthesis and functions in glucosylation/sequestration, whereas Sad4 is unlinked and has a broader function.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Arabidopsis UEV1D Promotes Lysine-63–Linked Polyubiquitination and Is Involved in DNA Damage Response: Rui Wen, J. Antonio Torres-Acosta, Landon Pastushok, Xiaoqin Lai, Lindsay Pelzer, Hong Wang, and Wei Xiao; Plant Cell 2008 20: 213-227. First Published on January 4, 2008; 10.1105/tpc.107.051862; Lys-63–linked polyubiquitination plays important roles in regulating multiple cellular processes in eukaryotes; however, its roles in plants have not been explored. This article describes four genes required for Lys-63–linked polyubiquitination; inactivation of one of the genes in Arabidopsis results in compromised DNA damage tolerance.; [Abstract] [Full Text] [PDF] [Supplemental Data]

Activation of the Indole-3-Acetic Acid–Amido Synthetase GH3-8 Suppresses Expansin Expression and Promotes Salicylate- and Jasmonate-Independent Basal Immunity in Rice: Xinhua Ding, Yinglong Cao, Liling Huang, Jing Zhao, Caiguo Xu, Xianghua Li, and Shiping Wang; Plant Cell 2008 20: 228-240. First Published on January 11, 2008; 10.1105/tpc.107.055657; In rice, bacterial pathogens induce the accumulation of auxin, which induces the expression of cell wall–loosening expansins, thereby turning a normal cell growth process to the advantage of the pathogen. Rice GH3-8, an auxin-amino synthetase that functions in auxin-dependent development, can activate disease resistance by inhibiting expansin expression via suppressing auxin signaling.; [Abstract] [Full Text] [PDF] [Supplemental Data]