IN THIS ISSUE:

Thylakoid Development from Biogenesis to Senescence, and Ruminations on Regulation

Nancy A. Eckardt

Plant Cell 2007 19: 1135-1138.

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IN BRIEF:

Mitochondrial Recombination Surveillance

Nancy A. Eckardt

Plant Cell 2007 19: 1139.

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G Protein Subunits Provide Functional Selectivity

Nancy A. Eckardt

Plant Cell 2007 19: 1139.

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CURRENT PERSPECTIVE ESSAYS:

Making Holes in Leaves: Promoting Cell State Transitions in Stomatal Development

M. Kathryn Barton

Plant Cell 2007 19: 1140-1143. First Published on April 27, 2007; 10.1105/tpc.107.051177

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RESEARCH ARTICLES:

Maize Histone Deacetylase hda101 Is Involved in Plant Development, Gene Transcription, and Sequence-Specific Modulation of Histone Modification of Genes and Repeats

Vincenzo Rossi, Sabrina Locatelli, Serena Varotto, Guenter Donn, Raul Pirona, David A. Henderson, Hans Hartings, and Mario Motto

Plant Cell 2007 19: 1145-1162. First Published on April 27, 2007; 10.1105/tpc.106.042549

The modulation of chromatin structure is mediated by enzymes such as histone acetyltransferases and deacetylases (HDACs). This functional characterization of a maize HDAC, HDA101, shows that it reversibly regulates histone acetylation, thus controlling gene and repeat activity, setting the histone code, and modulating developmental programs.

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

Characterization of the VIER F-BOX PROTEINE Genes from Arabidopsis Reveals Their Importance for Plant Growth and Development

Katja M. Schwager, Luz Irina A. Calderon-Villalobos, Esther M.N. Dohmann, Björn C. Willige, Stephan Knierer, Carola Nill, and Claus Schwechheimer

Plant Cell 2007 19: 1163-1178. First Published on April 13, 2007; 10.1105/tpc.105.040675

E3 ubiquitin ligases target proteins for ubiquitin proteasome–mediated degradation, with substrate specificity conferred by F-box protein subunits. Plants have apparently recruited F-box proteins of the C subfamily to regulate phytohormone responses, axillary branching, and senescence, and this study suggests that VIER F-BOX PROTEINE family members function in lateral root formation and plant growth.

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

Replication-Independent Long-Distance Trafficking by Viral RNAs in Nicotiana benthamiana

Kodetham Gopinath and C. Cheng Kao

Plant Cell 2007 19: 1179-1191. First Published on April 6, 2007; 10.1105/tpc.107.050088

Systemic infection by viruses requires proper processing and transport of viral RNA throughout the plant. This work demonstrates that Brome mosaic virus RNA can traffic long distances through the phloem independent of replication. Viral movement protein and coat proteins may increase the efficiency of trafficking but are not essential for the trafficking event.

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

PIL5, a Phytochrome-Interacting bHLH Protein, Regulates Gibberellin Responsiveness by Binding Directly to the GAI and RGA Promoters in Arabidopsis Seeds

Eunkyoo Oh, Shinjiro Yamaguchi, Jianhong Hu, Jikumaru Yusuke, Byunghyuck Jung, Inyup Paik, Hee-Seung Lee, Tai-ping Sun, Yuji Kamiya, and Giltsu Choi

Plant Cell 2007 19: 1192-1208. First Published on April 20, 2007; 10.1105/tpc.107.050153

In plants, the proper decision to germinate is critical for plant survival. Light promotes seed germination by removing PIL5, a phytochrome-interacting light-labile bHLH transcription factor. It is shown here that PIL5 regulates gibberellin (GA) signaling genes by directly binding to their promoters and that PIL5-mediated light signaling regulates not only GA but also abscisic acid metabolism.

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

The DELLA Domain of GA INSENSITIVE Mediates the Interaction with the GA INSENSITIVE DWARF1A Gibberellin Receptor of Arabidopsis

Björn C. Willige, Soumya Ghosh, Carola Nill, Melina Zourelidou, Esther M.N. Dohmann, Andreas Maier, and Claus Schwechheimer

Plant Cell 2007 19: 1209-1220. First Published on April 6, 2007; 10.1105/tpc.107.051441

Gibberellic acid (GA) responses are repressed by proteins with a DELLA domain, which is essential for GA-dependent proteasomal degradation of the DELLA repressors. This work reveals that DELLA domain mutations described for a range of dwarfing alleles impair GA receptor interactions and that the DELLA domain of the repressor GIBBERELLIC ACID INSENSITIVE is sufficient for this interaction.

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

An ERF Transcription Factor in Medicago truncatula That Is Essential for Nod Factor Signal Transduction

Patrick H. Middleton, Júlia Jakab, R. Varma Penmetsa, Colby G. Starker, Jake Doll, Péter Kaló, Radhika Prabhu, John F. Marsh, Raka M. Mitra, Attila Kereszt, Brigitta Dudas, Kathryn VandenBosch, Sharon R. Long, Doug R. Cook, Gyorgy B. Kiss, and Giles E.D. Oldroyd

Plant Cell 2007 19: 1221-1234. First Published on April 20, 2007; 10.1105/tpc.106.048264

Legume/rhizobial symbiosis is a key player in the global nitrogen cycle by fixing atmospheric nitrogen. Recognition of bacteria by legumes requires the bacterial signaling molecule Nod factor, which induces early plant root responses in nodulation. This work identifies the transcription factor ERF Required for Nodulation as an important component of the Nod factor signal transduction pathway.

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

Heterotrimeric G Protein Subunits Provide Functional Selectivity in Gß Dimer Signaling in Arabidopsis Yuri Trusov, James Edward Rookes, Kimberley Tilbrook, David Chakravorty, Michael Glenn Mason, David Anderson, Jin-Gui Chen, Alan M. Jones, and José Ramón Botella Plant Cell 2007 19: 1235-1250. First Published on April 27, 2007; 10.1105/tpc.107.050096 G proteins are important signaling molecules in plants and animal systems. This work provides evidence that plant heterotrimeric G proteins use both G subunits to convey functional selectivity to the Gß dimers and reveals a mechanism underlying the complexity of G protein–mediated signaling in plants. [Abstract] [Full Text] [PDF] OPEN ACCESS ARTICLE

Plant Mitochondrial Recombination Surveillance Requires Unusual RecA and MutS Homologs Vikas Shedge, Maria Arrieta-Montiel, Alan C. Christensen, and Sally A. Mackenzie Plant Cell 2007 19: 1251-1264. First Published on April 27, 2007; 10.1105/tpc.106.048355 Substoichiometric shifting (SSS) is the amplification or suppression of subgenomic molecules in plant mitochondrial genomes. This report describes two nuclear genes, MSH1 and RECA3, that regulate SSS in Arabidopsis by controlling illegitimate recombination and presents the cellular and developmental implications of msh1 and recA3 mutant-associated mitochondrial genome instability in plants. [Abstract] [Full Text] [PDF] OPEN ACCESS ARTICLE

The Arabidopsis D-Type Cyclin CYCD4 Controls Cell Division in the Stomatal Lineage of the Hypocotyl Epidermis

Atsushi Kono, Chikage Umeda-Hara, Sumiko Adachi, Noriko Nagata, Mami Konomi, Tsuyoshi Nakagawa, Hirofumi Uchimiya, and Masaaki Umeda

Plant Cell 2007 19: 1265-1277. First Published on April 20, 2007; 10.1105/tpc.106.046763

D-type cyclins play an essential role in cell cycle progression in response to external signals. This study demonstrates a specific requirement of cyclin D in cell divisions associated with stomatal precursor formation in the hypocotyl.

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

The Transcription Factor WIN1/SHN1 Regulates Cutin Biosynthesis in Arabidopsis thaliana

Rubini Kannangara, Caroline Branigan, Yan Liu, Teresa Penfield, Vijaya Rao, Grégory Mouille, Herman Höfte, Markus Pauly, José Luis Riechmann, and Pierre Broun

Plant Cell 2007 19: 1278-1294. First Published on April 20, 2007; 10.1105/tpc.106.047076

The protective role of a plant's cuticle in abiotic stress and biotic interactions depends on its permeability. These results suggest that the transcription factor WAX INDUCER1 controls cuticle formation by directly or collaboratively activating the transcription of cutin biosynthesis genes and modulates cuticle permeability through its influence on cutin composition.

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

The Arabidopsis AAA ATPase SKD1 Is Involved in Multivesicular Endosome Function and Interacts with Its Positive Regulator LYST-INTERACTING PROTEIN5

Thomas J. Haas, Marek K. Sliwinski, Dana E. Martínez, Mary Preuss, Kazuo Ebine, Takashi Ueda, Erik Nielsen, Greg Odorizzi, and Marisa S. Otegui

Plant Cell 2007 19: 1295-1312. First Published on April 27, 2007; 10.1105/tpc.106.049346

Class E vacuolar protein sorting (VPS) proteins function in endosomal sorting of secretory and endocytic cargo. This work identifies an Arabidopsis homolog of the yeast and mammalian VPS4 protein, SUPPRESSOR OF K⁺ TRANSPORT GROWTH DEFECT1 (SKD1), which localizes to the cytoplasm and endosomes. In addition, LYST-INTERACTING PROTEIN5 is identified as a strong positive regulator of SKD1 ATPase activity.

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

The Balance between Protein Synthesis and Degradation in Chloroplasts Determines Leaf Variegation in Arabidopsis yellow variegated Mutants

Eiko Miura, Yusuke Kato, Ryo Matsushima, Verónica Albrecht, Soumaya Laalami, and Wataru Sakamoto

Plant Cell 2007 19: 1313-1328. First Published on April 6, 2007; 10.1105/tpc.106.049270

Leaf variegation has long been recognized as a genetic trait, but the question remains as to why and how green and white sectors are formed in the same leaf in a uniform genetic background. In this work, identification of trans-acting mutations that suppress leaf variegation in an Arabidopsis mutant demonstrates a mechanism for variegation associated with chloroplast activities.

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

The Nuclear-Encoded Factor HCF173 Is Involved in the Initiation of Translation of the psbA mRNA in Arabidopsis thaliana

Kerstin Schult, Karin Meierhoff, Susanne Paradies, Thomas Töller, Petra Wolff, and Peter Westhoff

Plant Cell 2007 19: 1329-1346. First Published on April 13, 2007; 10.1105/tpc.106.042895

Photosystem II is a genetic mosaic consisting of plastid- and nuclear-encoded subunits requiring coordinated gene expression in both compartments. This work finds that the nuclear-encoded factor HIGH CHLOROPHYLL FLUORESCENCE 173 is essential for photosystem II biogenesis. Lack of the protein results in drastically reduced D1 synthesis due to decreased translation of the psbA mRNA.

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

Formation of DEG5 and DEG8 Complexes and Their Involvement in the Degradation of Photodamaged Photosystem II Reaction Center D1 Protein in Arabidopsis

Xuwu Sun, Lianwei Peng, Jinkui Guo, Wei Chi, Jinfang Ma, Congming Lu, and Lixin Zhang

Plant Cell 2007 19: 1347-1361. First Published on April 20, 2007; 10.1105/tpc.106.049510

The widely distributed DEGP proteases play important roles in the degradation of damaged and misfolded proteins. This report reveals that Arabidopsis DEG5 and DEG8 form a hexamer in the thylakoid lumen and are important for efficient turnover of the photosystem II D1 protein and for protection against photoinhibition in vivo.

[Abstract] [Full Text] [PDF]

Rice NON-YELLOW COLORING1 Is Involved in Light-Harvesting Complex II and Grana Degradation during Leaf Senescence

Makoto Kusaba, Hisashi Ito, Ryouhei Morita, Shuichi Iida, Yutaka Sato, Masaru Fujimoto, Shinji Kawasaki, Ryouichi Tanaka, Hirohiko Hirochika, Minoru Nishimura, and Ayumi Tanaka

Plant Cell 2007 19: 1362-1375. First Published on April 6, 2007; 10.1105/tpc.106.042911

Leaf senescence involves degradation of photosynthetic pigments, proteins, and chloroplasts. This work finds that defects in a possible chlorophyll b reductase, the first enzyme in chlorophyll b degradation, inhibit LHCII and grana degradation in leaf senescence and result in a stay-green phenotype, suggesting that chlorophyll b degradation might be an important regulatory point in leaf senescence.

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

MONODEHYROASCORBATE REDUCTASE4 Is Required for Seed Storage Oil Hydrolysis and Postgerminative Growth in Arabidopsis

Peter J. Eastmond

Plant Cell 2007 19: 1376-1387. First Published on April 20, 2007; 10.1105/tpc.106.043992

This study reveals that a component of the peroxisomal membrane antioxidant system called MDAR4 is required for triacylglycerol breakdown and therefore postgerminative growth in the oilseed Arabidopsis. Evidence is presented to suggest that this system protects the oil body lipase SDP1 against hydrogen peroxide that is generated within the peroxisome as a by-product of fatty acid ß-oxidation.

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

Roles of Arabidopsis Cyclin-Dependent Kinase C Complexes in Cauliflower Mosaic Virus Infection, Plant Growth, and Development

Xiaofeng Cui, Baofang Fan, James Scholz, and Zhixiang Chen

Plant Cell 2007 19: 1388-1402. First Published on April 27, 2007; 10.1105/tpc.107.051375

Arabidopsis cyclin-dependent kinase CDKC;2 and its cyclin T partner CYCT1;5 encode two interacting proteins that form a complex with an important role in cauliflower mosaic virus (CaMV) infection. This report establishes these CDKC kinase complexes as important host targets of CaMV for transcriptional activation of viral genes and critical regulators of plant growth and development.

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

SIZ1-Mediated Sumoylation of ICE1 Controls CBF3/DREB1A Expression and Freezing Tolerance in Arabidopsis Kenji Miura, Jing Bo Jin, Jiyoung Lee, Chan Yul Yoo, Vicki Stirm, Tomoko Miura, Edward N. Ashworth, Ray A. Bressan, Dae-Jin Yun, and Paul M. Hasegawa Plant Cell 2007 19: 1403-1414. First Published on April 6, 2007; 10.1105/tpc.106.048397 Low temperatures initiate signaling pathways that control gene expression necessary for cold acclimation and chilling and freezing tolerances. This work establishes that SIZ1 is a regulator of cold acclimation through sumoylation of ICE1, which induces expression of CBF/DREB1 and its regulon and facilitates freezing tolerance. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

SCABP8/CBL10, a Putative Calcium Sensor, Interacts with the Protein Kinase SOS2 to Protect Arabidopsis Shoots from Salt Stress Ruidang Quan, Huixin Lin, Imelda Mendoza, Yuguo Zhang, Wanhong Cao, Yongqing Yang, Mei Shang, Shouyi Chen, José M. Pardo, and Yan Guo Plant Cell 2007 19: 1415-1431. First Published on April 20, 2007; 10.1105/tpc.106.042291 Functionally equivalent genes often display spatial and temporal differences in transcriptional regulation but may also have unique functions. As shown here, the similar calcium binding proteins SCABP8 and SOS3 protect shoot and root tissues, respectively, from salt stress by activating and recruiting the SOS2 kinase, but they also differ in additional regulatory mechanisms specific to each protein. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

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