IN THIS ISSUE:

Role of Xyloglucan in Primary Cell Walls

Nancy A. Eckardt

Plant Cell 2008 20: 1421-1422. First Published on June 17, 2008; 10.1105/tpc.108.061382

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IN BRIEF:

High-Resolution Three-Dimensional Imaging of Plant Tissues

Nancy A. Eckardt

Plant Cell 2008 20: 1423. First Published on June 3, 2008; 10.1105/tpc.108.200610

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Ubiquitin Ligation RINGs Twice: Redundant Control of Plant Processes by E3 Ubiquitin Ligases

Jennifer Mach

Plant Cell 2008 20: 1424. First Published on June 13, 2008; 10.1105/tpc.108.200611

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Abscisic Acid–Mediated Suppression of Systemic Acquired Resistance Signaling

Nancy Hofmann

Plant Cell 2008 20: 1425. First Published on June 27, 2008; 10.1105/tpc.108.200612

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CURRENT PERSPECTIVE ESSAY: SPECIAL SERIES ON LARGE-SCALE BIOLOGY:

Arabidopsis Reactome: A Foundation Knowledgebase for Plant Systems Biology

Nicolas Tsesmetzis, Matthew Couchman, Janet Higgins, Alison Smith, John H. Doonan, Georg J. Seifert, Esther E. Schmidt, Imre Vastrik, Ewan Birney, Guanming Wu, Peter D'Eustachio, Lincoln D. Stein, Richard J. Morris, Michael W. Bevan, and Sean V. Walsh

Plant Cell 2008 20: 1426-1436. First Published on June 30, 2008; 10.1105/tpc.108.057976

[Full Text] [PDF] [Supplemental Data]

RESEARCH ARTICLES:

Arabidopsis DDB1-CUL4 ASSOCIATED FACTOR1 Forms a Nuclear E3 Ubiquitin Ligase with DDB1 and CUL4 That Is Involved in Multiple Plant Developmental Processes

Yu Zhang, Suhua Feng, Fangfang Chen, Haodong Chen, Jia Wang, Chad McCall, Yue Xiong, and Xing Wang Deng

Plant Cell 2008 20: 1437-1455. First Published on June 13, 2008; 10.1105/tpc.108.058891

Protein ubiquitination is a key posttranslational modification in eukaryotes. This study reveals a nuclear CULLIN4-based E3 ubiquitin ligase complex in Arabidopsis that plays a role in numerous plant developmental processes.

[Abstract] [Full Text] [PDF] [Supplemental Data]

SPIN1, a K Homology Domain Protein Negatively Regulated and Ubiquitinated by the E3 Ubiquitin Ligase SPL11, Is Involved in Flowering Time Control in Rice

Miguel E. Vega-Sánchez, Lirong Zeng, Songbiao Chen, Hei Leung, and Guo-Liang Wang

Plant Cell 2008 20: 1456-1469. First Published on June 27, 2008; 10.1105/tpc.108.058610

Both RNA processing and ubiquitination play important roles in the regulation of flowering. This work implicates the E3 ligase SPOTTED LEAF11 and its substrate SPIN1, a nuclear RNA/DNA binding protein of the STAR family, in rice flowering time control. This study links ubiquitination and RNA/DNA metabolism in flowering time regulation in plants.

[Abstract] [Full Text] [PDF] [Supplemental Data]

The Modified Flavonol Glycosylation Profile in the Arabidopsis rol1 Mutants Results in Alterations in Plant Growth and Cell Shape Formation

Christoph Ringli, Laurent Bigler, Benjamin M. Kuhn, Ruth-Maria Leiber, Anouck Diet, Diana Santelia, Beat Frey, Stephan Pollmann, and Markus Klein

Plant Cell 2008 20: 1470-1481. First Published on June 20, 2008; 10.1105/tpc.107.053249

Flavonoids have been shown to affect growth in a variety of plant species. This work demonstrates that changes in the Arabidopsis flavonol glycosylation profile can interfere with cell development, resulting in defects in cotyledon growth, pavement cell shape, stomatal development, and trichome formation.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Mutation of Arabidopsis BARD1 Causes Meristem Defects by Failing to Confine WUSCHEL Expression to the Organizing Center Pei Han, Qing Li, and Yu-Xian Zhu Plant Cell 2008 20: 1482-1493. First Published on June 30, 2008; 10.1105/tpc.108.058867 BARD1 represses the transcriptional activity of WUSCHEL, a gene essential for maintenance of stem cell fate in Arabidopsis. In a bard1-null mutant, severe shoot apical meristem defects are observed as a result of WUSCHEL expression outside of the meristem organizing center. BARD1 may inhibit a chromatin-remodeling process vital for WUS expression. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

High-Resolution Whole-Mount Imaging of Three-Dimensional Tissue Organization and Gene Expression Enables the Study of Phloem Development and Structure in Arabidopsis

Elisabeth Truernit, Hélène Bauby, Bertrand Dubreucq, Olivier Grandjean, John Runions, Julien Barthélémy, and Jean-Christophe Palauqui

Plant Cell 2008 20: 1494-1503. First Published on June 3, 2008; 10.1105/tpc.107.056069

This work images phloem development using a remarkable improvement in plant tissue staining that, in combination with confocal microscopy, reveals three-dimensional cellular organization of plant tissue with a precision that formerly required tissue sectioning. Furthermore, coupled with staining for β-glucuronidase activity, this method shows gene expression with single-cell resolution.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Peeking into Pit Fields: A Multiple Twinning Model of Secondary Plasmodesmata Formation in Tobacco

Christine Faulkner, Ozgur E. Akman, Karen Bell, Chris Jeffree, and Karl Oparka

Plant Cell 2008 20: 1504-1518. First Published on June 30, 2008; 10.1105/tpc.107.056903

Pores called plasmodesmata that connect plant cells arise at cytokinesis and secondarily during wall extension. This work uses a range of imaging and computational approaches to show that secondary plasmodesmata arise in direct contact with existing plasmodesmata during radial wall extension.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Disrupting Two Arabidopsis thaliana Xylosyltransferase Genes Results in Plants Deficient in Xyloglucan, a Major Primary Cell Wall Component David M. Cavalier, Olivier Lerouxel, Lutz Neumetzler, Kazuchika Yamauchi, Antje Reinecke, Glenn Freshour, Olga A. Zabotina, Michael G. Hahn, Ingo Burgert, Markus Pauly, Natasha V. Raikhel, and Kenneth Keegstra Plant Cell 2008 20: 1519-1537. First Published on June 10, 2008; 10.1105/tpc.108.059873 This study adopted a reverse genetics approach to provide evidence that two Arabidopsis xylosyltransferase genes are involved in xyloglucan biosynthesis in vivo. Disrupting both of these genes resulted in plants with a severe root hair phenotype that lacked detectable xyloglucan. These findings challenge conventional models of the plant primary cell wall. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Targeted Degradation of the Cyclin-Dependent Kinase Inhibitor ICK4/KRP6 by RING-Type E3 Ligases Is Essential for Mitotic Cell Cycle Progression during Arabidopsis Gametogenesis Jingjing Liu, Yiyue Zhang, Genji Qin, Tomohiko Tsuge, Norihiro Sakaguchi, Guo Luo, Kangtai Sun, Dongqiao Shi, Shiori Aki, Nuoyan Zheng, Takashi Aoyama, Atsuhiro Oka, Weicai Yang, Masaaki Umeda, Qi Xie, Hongya Gu, and Li-Jia Qu Plant Cell 2008 20: 1538-1554. First Published on June 13, 2008; 10.1105/tpc.108.059741 This work uses genetic and biochemical assays to examine two RING-type E3 ligases that interact with and target a specific inhibitor of cyclin-dependent kinases, ICK4/KRP6, for proteasome-mediated degradation. This cell cycle inhibitor is expressed during gametophyte meiosis and must be degraded prior to the subsequent mitotic divisions that form the male and female gametophytes. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Arabidopsis ELONGATED MITOCHONDRIA1 Is Required for Localization of DYNAMIN-RELATED PROTEIN3A to Mitochondrial Fission Sites

Shin-ichi Arimura, Masaru Fujimoto, Yoko Doniwa, Naoki Kadoya, Mikio Nakazono, Wataru Sakamoto, and Nobuhiro Tsutsumi

Plant Cell 2008 20: 1555-1566. First Published on June 17, 2008; 10.1105/tpc.108.058578

Mitochondrial fission is a fundamental but poorly understood process in plant cells. DYNAMIN-RELATED PROTEIN3A is a conserved eukaryotic mitochondrial fission factor found in Arabidopsis that forms a ring around and severs mitochondria. Here, we identify a novel plant-specific factor, ELONGATED MITOCHONDRIA1, that is required for the correct localization of DRP3A.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Arabidopsis PEROXIN11c-e, FISSION1b, and DYNAMIN-RELATED PROTEIN3A Cooperate in Cell Cycle–Associated Replication of Peroxisomes

Matthew J. Lingard, Satinder K. Gidda, Scott Bingham, Steven J. Rothstein, Robert T. Mullen, and Richard N. Trelease

Plant Cell 2008 20: 1567-1585. First Published on June 6, 2008; 10.1105/tpc.107.057679

This study examines the molecular interactions of PEROXIN11 isoforms with each other, with FISSION1 isoforms, and with DYNAMIN-RELATED PROTEIN3A (DRP3A) in peroxisome replication during cell division. Gene silencing and protein interaction experiments show that these proteins play distinct but overlapping roles in the elongation and fission of replicating peroxisomes.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Light-Induced Phosphorylation and Degradation of the Negative Regulator PHYTOCHROME-INTERACTING FACTOR1 from Arabidopsis Depend upon Its Direct Physical Interactions with Photoactivated Phytochromes

Hui Shen, Ling Zhu, Alicia Castillon, Manoj Majee, Bruce Downie, and Enamul Huq

Plant Cell 2008 20: 1586-1602. First Published on June 6, 2008; 10.1105/tpc.108.060020

PHYTOCHROME INTERACTING FACTOR1 is rapidly phosphorylated, ubiquitinated, and degraded under red and far-red light. Overexpression of a light-stable truncated PIF1 showed a constitutive photomorphogenic phenotype in the dark, suggesting that light-induced proteolytic degradation of negative regulators (e.g. PIFs) might be sufficient to promote photomorphogenesis.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Arabidopsis Nuclear-Encoded Plastid Transit Peptides Contain Multiple Sequence Subgroups with Distinctive Chloroplast-Targeting Sequence Motifs

Dong Wook Lee, Jong Kyoung Kim, Sumin Lee, Seungjin Choi, Sanguk Kim, and Inhwan Hwang

Plant Cell 2008 20: 1603-1622. First Published on June 13, 2008; 10.1105/tpc.108.060541

This work examines sequences critical for chloroplast protein import by alanine substitution mutagenesis of proteins with very different transit peptide sequences. This approach is complemented by bioinformatic grouping of peptides and motif identification within subgroups, producing a highly accurate algorithm to predict chloroplast localization.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Analysis of the Golgi Apparatus in Arabidopsis Seed Coat Cells during Polarized Secretion of Pectin-Rich Mucilage Robin E. Young, Heather E. McFarlane, Michael G. Hahn, Tamara L. Western, George W. Haughn, and A. Lacey Samuels Plant Cell 2008 20: 1623-1638. First Published on June 3, 2008; 10.1105/tpc.108.058842 Golgi stacks in Arabidopsis seed coat cells produce mucilage synchronously at a specific stage of differentiation. The morphology of stacks was dependent on the volume of mucilage produced, but the number was not, suggesting that proliferation of stacks is developmentally programmed. Mucilage-producing Golgi stacks were randomly distributed in the cell and not clustered at the site of secretion. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Two Distinct Interacting Classes of Nuclear Envelope–Associated Coiled-Coil Proteins Are Required for the Tissue-Specific Nuclear Envelope Targeting of Arabidopsis RanGAP

Qiao Zhao, Jelena Brkljacic, and Iris Meier

Plant Cell 2008 20: 1639-1651. First Published on June 30, 2008; 10.1105/tpc.108.059220

Tandem affinity purification and mass spectrometry were used to identify a family of novel coiled-coil proteins required for nuclear envelope association of RanGAP1 in Arabidopsis root tip cells. The findings suggest an unanticipated complexity of RanGAP nuclear envelope targeting in higher plant cells, involving at least two families of likely plant-specific nuclear pore–associated proteins.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Identification of the Gene Encoding the 1,3-Mannosyltransferase (ALG3) in Arabidopsis and Characterization of Downstream N-Glycan Processing

Maurice Henquet, Ludwig Lehle, Mariëlle Schreuder, Gerard Rouwendal, Jos Molthoff, Johannes Helsper, Sander van der Krol, and Dirk Bosch

Plant Cell 2008 20: 1652-1664. First Published on June 20, 2008; 10.1105/tpc.108.060731

This work describes the identification of a plant glycosyltransferase that is involved in the initial phase of N-glycan biosynthesis in the endoplasmic reticulum. A detailed analysis of a mutant of this glycosyltransferase provides insights into properties of downstream enzymes in the N-glycan biosynthesis pathway in plants.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Channelrhodopsin-1 Initiates Phototaxis and Photophobic Responses in Chlamydomonas by Immediate Light-Induced Depolarization

Peter Berthold, Satoshi P. Tsunoda, Oliver P. Ernst, Wolfgang Mages, Dietrich Gradmann, and Peter Hegemann

Plant Cell 2008 20: 1665-1677. First Published on June 13, 2008; 10.1105/tpc.108.057919

This study reanalyzed channelrhodopsin-1 (CHR1)–based photocurrents in Chlamydomonas and demonstrated that, in addition to H⁺, ChR1 also conducts other cations. This conductance enables the alga to orient in the light even at alkaline pH.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Antagonistic Interaction between Systemic Acquired Resistance and the Abscisic Acid–Mediated Abiotic Stress Response in Arabidopsis

Michiko Yasuda, Atsushi Ishikawa, Yusuke Jikumaru, Motoaki Seki, Taishi Umezawa, Tadao Asami, Akiko Maruyama-Nakashita, Toshiaki Kudo, Kazuo Shinozaki, Shigeo Yoshida, and Hideo Nakashita

Plant Cell 2008 20: 1678-1692. First Published on June 27, 2008; 10.1105/tpc.107.054296

Several types of self-protecting systems that involve hormone signaling allow plants to survive various types of external stresses. This work details antagonistic interactions between abscisic acid–mediated responses to environmental stresses and salicylic acid–mediated signaling in the induction of systemic acquired resistance to pathogens.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Arabidopsis DREB2A-Interacting Proteins Function as RING E3 Ligases and Negatively Regulate Plant Drought Stress–Responsive Gene Expression

Feng Qin, Yoh Sakuma, Lam-Son Phan Tran, Kyonoshin Maruyama, Satoshi Kidokoro, Yasunari Fujita, Miki Fujita, Taishi Umezawa, Yoriko Sawano, Ken-ichi Miyazono, Masaru Tanokura, Kazuo Shinozaki, and Kazuko Yamaguchi-Shinozaki

Plant Cell 2008 20: 1693-1707. First Published on June 13, 2008; 10.1105/tpc.107.057380

Drought-inducible gene expression is controlled by the key transcription factor DREB2A. We identified two C3HC4 RING domain–containing proteins that interact with DREB2A and function as E3 ubiquitin ligases to mediate DREB2A degradation to tightly control DREB2A protein abundance.

[Abstract] [Full Text] [PDF] [Supplemental Data]

Spermidine Exodus and Oxidation in the Apoplast Induced by Abiotic Stress Is Responsible for H₂O₂ Signatures That Direct Tolerance Responses in Tobacco

Panagiotis N. Moschou, Konstantinos A. Paschalidis, Ioannis D. Delis, Athina H. Andriopoulou, George D. Lagiotis, Dimitrios I. Yakoumakis, and Kalliopi A. Roubelakis-Angelakis

Plant Cell 2008 20: 1708-1724. First Published on June 24, 2008; 10.1105/tpc.108.059733

Polyamines play a protective role against stress challenges in plants. This work shows that abiotic stress induces spermidine secretion into the apoplast, where it is oxidized by polyamine oxidase. Depending on its levels and those of intracellular polyamines, the generated H₂O₂ induces either tolerance events or programmed cell death.

[Abstract] [Full Text] [PDF] [Supplemental Data]

CORRECTIONS:

Correction

Plant Cell 2008 20: 1725.

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