IN THIS ISSUE:

Naughty Behavior of Maize Minichromosomes in Meiosis

Arnaud Ronceret, Christopher G. Bozza, and Wojciech P. Pawlowski

Plant Cell 2007 19: 3835-3837.

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IN BRIEF:

Chloroplast Intron Splicing Mechanisms

Nancy A. Eckardt

Plant Cell 2007 19: 3838.

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Systemic Acquired Acclimation to High Light

Nancy A. Eckardt

Plant Cell 2007 19: 3838.

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CURRENT PERSPECTIVE ESSAYS:

The JAZ Proteins Link Jasmonate Perception with Transcriptional Changes

Aaron Santner and Mark Estelle

Plant Cell 2007 19: 3839-3842. First Published on December 28, 2007; 10.1105/tpc.107.056960

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REVIEW ARTICLES:

Exploring the Molecular Etiology of Dominant-Negative Mutations

Reiner A. Veitia

Plant Cell 2007 19: 3843-3851. First Published on December 14, 2007; 10.1105/tpc.107.055053

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RESEARCH ARTICLES:

Minichromosome Analysis of Chromosome Pairing, Disjunction, and Sister Chromatid Cohesion in Maize

Fangpu Han, Zhi Gao, Weichang Yu, and James A. Birchler

Plant Cell 2007 19: 3853-3863. First Published on December 14, 2007; 10.1105/tpc.107.055905

This study investigated fundamental properties of minichromosomes. It was found that below a certain threshold, minichromosome pairing in meiosis does not depend upon size, but all small chromosomes exhibit a lack of sister chromatid cohesion at anaphase I whether pairing occurs or not.

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A CRM Domain Protein Functions Dually in Group I and Group II Intron Splicing in Land Plant Chloroplasts

Yukari Asakura and Alice Barkan

Plant Cell 2007 19: 3864-3875. First Published on December 7, 2007; 10.1105/tpc.107.055160

Group II introns are protein-dependent ribozymes prevalent in plant organelles. It is shown that the CRM RNA binding domain protein CFM2 acts with other CRM proteins to promote splicing of plastid group II introns and also aids group I intron splicing. This work expands the repertoire of RNA ligands known for CRM proteins and suggests an unanticipated complexity of chloroplast splicing mechanisms.

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Gibberellin Regulates Pollen Viability and Pollen Tube Growth in Rice

Tory Chhun, Koichiro Aya, Kenji Asano, Eiji Yamamoto, Yoichi Morinaka, Masao Watanabe, Hidemi Kitano, Motoyuki Ashikari, Makoto Matsuoka, and Miyako Ueguchi-Tanaka

Plant Cell 2007 19: 3876-3888. First Published on December 14, 2007; 10.1105/tpc.107.054759

This study shows that rice gibberellin (GA)–deficient mutations are transmitted in a non-Mendelian manner, whereas GA-insensitive mutations are transmitted normally. Analysis of pollen phenotypes and expression patterns of GA-related genes revealed that the transmission of GA-signaling genes occurs in a sporophytic manner and that of GA synthesis genes occurs in a gametophytic manner.

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Cytokinins Act Directly on Lateral Root Founder Cells to Inhibit Root Initiation

Laurent Laplaze, Eva Benkova, Ilda Casimiro, Lies Maes, Steffen Vanneste, Ranjan Swarup, Dolf Weijers, Vanessa Calvo, Boris Parizot, Maria Begoña Herrera-Rodriguez, Remko Offringa, Neil Graham, Patrick Doumas, Jiri Friml, Didier Bogusz, Tom Beeckman, and Malcolm Bennett

Plant Cell 2007 19: 3889-3900. First Published on December 7, 2007; 10.1105/tpc.107.055863

Whilst a great deal is known about how auxin promotes lateral root development, the mechanism of cytokinin repression is still unclear. This study shows that cytokinin inhibits lateral root initiation by downregulating the expression of auxin efflux carrier-encoding PIN genes in lateral root founder cells.

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Cytokinin Regulates Type-A Arabidopsis Response Regulator Activity and Protein Stability via Two-Component Phosphorelay

Jennifer P.C. To, Jean Deruère, Bridey B. Maxwell, Veronica F. Morris, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, and Joseph J. Kieber

Plant Cell 2007 19: 3901-3914. First Published on December 7, 2007; 10.1105/tpc.107.052662

This work shows that phosphorylation of the receiver domain is required for type-A ARR function, and negative regulation of cytokinin signaling by type-A ARRs most likely involves phosphorylation-dependent interactions. The results shed light on the mechanism by which type-A ARRs negatively regulate cytokinin signaling and reveal a novel mechanism by which cytokinin controls type-A ARR function.

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The Basic Helix-Loop-Helix Transcription Factor PIF5 Acts on Ethylene Biosynthesis and Phytochrome Signaling by Distinct Mechanisms

Rajnish Khanna, Yu Shen, Colleen M. Marion, Atsunari Tsuchisaka, Athanasios Theologis, Eberhard Schäfer, and Peter H. Quail

Plant Cell 2007 19: 3915-3929. First Published on December 7, 2007; 10.1105/tpc.107.051508

PIF5 is a phyB-interacting factor that inhibits growth in the dark, when expressed at abnormally high levels, by increasing ethylene production, and regulates growth in the light by modulating phyB levels via a negative feedback loop that induces phyB degradation.

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P-Glycoprotein4 Displays Auxin Efflux Transporter–Like Action in Arabidopsis Root Hair Cells and Tobacco Cells Misuk Cho, Sang Ho Lee, and Hyung-Taeg Cho Plant Cell 2007 19: 3930-3943. First Published on December 21, 2007; 10.1105/tpc.107.054288 The Arabidopsis ABC membrane transporter P-glycoprotein4 (PGP4) exhibits auxin influx transporter activity in vitro in yeast and animal cells. Taking advantage of the auxin-sensitive Arabidopsis root hair and tobacco cell suspension systems, this study indicates that PGP4 functions as an auxin efflux transporter in plant cells and that its membrane trafficking can be modulated by auxin. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Plastid Signals Remodel Light Signaling Networks and Are Essential for Efficient Chloroplast Biogenesis in Arabidopsis Michael E. Ruckle, Stephanie M. DeMarco, and Robert M. Larkin Plant Cell 2007 19: 3944-3960. First Published on December 7, 2007; 10.1105/tpc.107.054312 This report provides evidence for a plastid signal that allows plants to integrate signals describing the functional and developmental state of plastids with signals describing particular light environments to regulate the expression of nuclear genes encoding proteins active in photosynthesis and chloroplast biogenesis. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Two Distinct Forms of M-Locus Protein Kinase Localize to the Plasma Membrane and Interact Directly with S-Locus Receptor Kinase to Transduce Self-Incompatibility Signaling in Brassica rapa

Mitsuru Kakita, Kohji Murase, Megumi Iwano, Tomohito Matsumoto, Masao Watanabe, Hiroshi Shiba, Akira Isogai, and Seiji Takayama

Plant Cell 2007 19: 3961-3973. First Published on December 7, 2007; 10.1105/tpc.106.049999

The M-locus protein kinase (MLPK) is a cytoplasmic protein kinase essential for self-incompatibility (SI) signaling in Brassica. This work shows that MLPK has two isoforms that localize to the plasma membrane by different molecular mechanisms. Further analyses suggest that these MLPK isoforms interact directly with the S-locus receptor kinase on the plasma membrane to transduce SI signaling.

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3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase1 Interacts with NORK and Is Crucial for Nodulation in Medicago truncatula

Zoltán Kevei, Géraldine Lougnon, Peter Mergaert, Gábor V. Horváth, Attila Kereszt, Dhileepkumar Jayaraman, Najia Zaman, Fabian Marcel, Krzysztof Regulski, György B. Kiss, Adam Kondorosi, Gabriella Endre, Eva Kondorosi, and Jean-Michel Ané

Plant Cell 2007 19: 3974-3989. First Published on December 21, 2007; 10.1105/tpc.107.053975

The nodule-specific receptor-like kinase NORK is part of the Nod factor signaling pathway mediating root nodule development. This study shows that HMGR1, a key enzyme in the mevalonate biosynthetic pathway, interacts specifically with NORK and is crucial for nodulation. Recruitment of HMGR1 by NORK couples the isoprenoid pathway to symbiotic signaling and nodule development.

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A Naturally Occurring Mutation in an Arabidopsis Accession Affects a β-D-Galactosidase That Increases the Hydrophilic Potential of Rhamnogalacturonan I in Seed Mucilage

Audrey Macquet, Marie-Christine Ralet, Olivier Loudet, Jocelyne Kronenberger, Gregory Mouille, Annie Marion-Poll, and Helen M. North

Plant Cell 2007 19: 3990-4006. First Published on December 28, 2007; 10.1105/tpc.107.050179

This work demonstrates that the Shahdara accession is a naturally occurring mutant affected in the MUM2 gene. The β-D-galactosidase enzyme it encodes was shown to be required for the removal of galactose/galactan branches from the major polysaccharide constituting Arabidopsis mucilage, rhamnogalacturonan I, thus altering its physicochemical properties and increasing hydrated mucilage swelling.

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

The Arabidopsis MUM2 Gene Encodes a β-Galactosidase Required for the Production of Seed Coat Mucilage with Correct Hydration Properties

Gillian H. Dean, Huanquan Zheng, Jagdish Tewari, Jun Huang, Diana S. Young, Yeen Ting Hwang, Tamara L. Western, Nicholas C. Carpita, Maureen C. McCann, Shawn D. Mansfield, and George W. Haughn

Plant Cell 2007 19: 4007-4021. First Published on December 28, 2007; 10.1105/tpc.107.050609

This work demonstrates that the Arabidopsis seed coat can be used as a model system to identify enzymes that impact the properties of pectins in seed mucilage. The MUM2 gene encodes a β-galactosidase that is secreted to the apoplast and is required for the modification of pectin side chains, thus allowing mucilage expansion when mature seeds are hydrated.

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

Regulation of Rice NADPH Oxidase by Binding of Rac GTPase to Its N-Terminal Extension Hann Ling Wong, Reinhard Pinontoan, Kokoro Hayashi, Ryo Tabata, Takashi Yaeno, Kana Hasegawa, Chojiro Kojima, Hirofumi Yoshioka, Koh Iba, Tsutomu Kawasaki, and Ko Shimamoto Plant Cell 2007 19: 4022-4034. First Published on December 21, 2007; 10.1105/tpc.107.055624 Reactive oxygen species produced by NADPH oxidase (called the regulatory burst oxidase homolog or Rboh in plants) are important for the regulation of plant growth, development, and defense against pathogens. However, the regulatory mechanism of NADPH oxidase activity is unclear. This study shows that Rac GTPase binds to the N-terminal region and regulates the activity of Rboh in rice. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

RAR1 and HSP90 Form a Complex with Rac/Rop GTPase and Function in Innate-Immune Responses in Rice Nguyen Phuong Thao, Letian Chen, Ayako Nakashima, Shin-ichiro Hara, Kenji Umemura, Akira Takahashi, Ken Shirasu, Tsutomu Kawasaki, and Ko Shimamoto Plant Cell 2007 19: 4035-4045. First Published on December 21, 2007; 10.1105/tpc.107.055517 Rac/Rop GTPase plays an important role in innate immune responses in rice, but its molecular mechanism is not well understood. This study shows that it can form a complex with RAR1 and HSP90, which are conserved components of innate immunity responses in plants. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Natural Variation in RPS2-Mediated Resistance among Arabidopsis Accessions: Correlation between Gene Expression Profiles and Phenotypic Responses

Remco M.P. Van Poecke, Masanao Sato, Lisa Lenarz-Wyatt, Sanford Weisberg, and Fumiaki Katagiri

Plant Cell 2007 19: 4046-4060. First Published on December 14, 2007; 10.1105/tpc.107.053827

An analysis of Arabidopsis accessions differing in resistance to Pseudomonas syringae pv tomato containing the avrRpt2 effector gene shows that natural variation in induced gene expression profiles is correlated with natural variation in phenotypic responses, such as the hypersensitive response and resistance.

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

Interaction between SGT1 and Cytosolic/Nuclear HSC70 Chaperones Regulates Arabidopsis Immune Responses

Laurent D. Noël, Giuseppe Cagna, Johannes Stuttmann, Lennart Wirthmüller, Shigeyuki Betsuyaku, Claus-Peter Witte, Riyaz Bhat, Nathalie Pochon, Thomas Colby, and Jane E. Parker

Plant Cell 2007 19: 4061-4076. First Published on December 7, 2007; 10.1105/tpc.107.051896

The authors show that association in vivo between the plant cochaperone SGT1 and cytosolic/nuclear HSC70 chaperones is necessary for several biotic and abiotic stress responses. The SGT1-HSC70 interaction is mediated by the evolutionarily conserved SGT1 C-terminal SGS domain.

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

The Downy Mildew Effector Proteins ATR1 and ATR13 Promote Disease Susceptibility in Arabidopsis thaliana

Kee Hoon Sohn, Rita Lei, Adnane Nemri, and Jonathan D.G. Jones

Plant Cell 2007 19: 4077-4090. First Published on December 28, 2007; 10.1105/tpc.107.054262

Plant pathogens secrete into host cell effector proteins that suppress plant immunity. This work reports the development of a system to engineer and deliver Hyaloperonospora parasitica effectors to plant cells via a bacterial secretion system. Using this system, multiple alleles of two H. parasitica effectors are found to confer resistance or enhance susceptibility of Arabidopsis accessions to this pathogen.

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

Systemic and Intracellular Responses to Photooxidative Stress in Arabidopsis

Jan Bart Rossel, Pip B. Wilson, Dawar Hussain, Nick S. Woo, Matthew J. Gordon, Osman P. Mewett, Katharine A. Howell, Jim Whelan, Kemal Kazan, and Barry J. Pogson

Plant Cell 2007 19: 4091-4110. First Published on December 21, 2007; 10.1105/tpc.106.045898

As the sun tracks daily through the sky from east to west, different parts of the canopy are exposed to excess light. This study demonstrates that a novel, systemic signal is rapidly transmitted within 15 min from exposed to shaded leaves, resulting in similar global transcriptional and acclimatory responses in exposed and shaded leaves of wild-type and stress signaling mutants of Arabidopsis.

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

An Endoplasmic Reticulum Stress Response in Arabidopsis Is Mediated by Proteolytic Processing and Nuclear Relocation of a Membrane-Associated Transcription Factor, bZIP28 Jian-Xiang Liu, Renu Srivastava, Ping Che, and Stephen H. Howell Plant Cell 2007 19: 4111-4119. First Published on December 21, 2007; 10.1105/tpc.106.050021 This work identifies a membrane-associated bZIP transcription factor that serves as a sensor/transducer in the unfolded protein response in Arabidopsis. In response to endoplasmic reticulum (ER) stress, the transcriptional component of the sensor/transducer is activated and relocates from the ER to the nucleus, where it upregulates the expression of genes encoding ER folding proteins. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

S-Nitrosylation of Peroxiredoxin II E Promotes Peroxynitrite-Mediated Tyrosine Nitration Maria C. Romero-Puertas, Miriam Laxa, Alessandro Mattè, Federica Zaninotto, Iris Finkemeier, Alex M.E. Jones, Michele Perazzolli, Elodie Vandelle, Karl-Josef Dietz, and Massimo Delledonne Plant Cell 2007 19: 4120-4130. First Published on December 28, 2007; 10.1105/tpc.107.055061 S-nitrosylation is emerging as an important mechanism for the transduction of nitric oxide bioactivity. This study characterizes the molecular mechanism and functional significance for S-nitrosylation of peroxiredoxin II E, a protein that appears to play a crucial role in scavenging peroxynitrite, the product of the reaction of nitric oxide with superoxide, whose function in plants is still obscure [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

CORRECTIONS:

Correction

Plant Cell 2007 19: 4131-4132. First Published on December 28, 2007; 10.1105/tpc.107.191260

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