IN THIS ISSUE:

Tissue-Specific siRNAs That Silence CHS Genes in Soybean

Nancy A. Eckardt

Plant Cell 2009 21: 2983-2984. First Published on October 30, 2009; doi:10.1105/tpc.109.072421

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IN BRIEF:

OWL1 Is a Phytochrome A Signaling Component Dedicated to the Very Low Fluence Response

Nancy R. Hofmann

Plant Cell 2009 21: 2985. First Published on October 6, 2009; doi:10.1105/tpc.109.211010

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Loss of an Exosome Complex Component Potentiates R Gene–Independent Cell Death in Barley

Jennifer Mach

Plant Cell 2009 21: 2986. First Published on October 27, 2009; doi:10.1105/tpc.109.211011

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RESEARCH ARTICLES:

A Population Genomics Study of the Arabidopsis Core Cell Cycle Genes Shows the Signature of Natural Selection

Roel Sterken, Raphaël Kiekens, Emmy Coppens, Ilse Vercauteren, Marc Zabeau, Dirk Inzé, Jonathan Flowers, and Marnik Vuylsteke

Plant Cell 2009 21: 2987-2998. First Published on October 30, 2009; doi:10.1105/tpc.109.067017

This work is a systematic study for signatures of natural selection on the core cell cycle genes of Arabidopsis. The results reveal that only certain gene families of the cell cycle system are highly constrained, while other genes appear less constrained or, in some cases, even subject to positive selection.

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

Evolution of Allometry in Antirrhinum

Xianzhong Feng, Yvette Wilson, Jennifer Bowers, Richard Kennaway, Andrew Bangham, Andrew Hannah, Enrico Coen, and Andrew Hudson

Plant Cell 2009 21: 2999-3007. First Published on October 30, 2009; doi:10.1105/tpc.109.069054

A computation method for characterizing variation in the size and shape of Antirrhinum leaves and petals is presented. This work shows that much of the variation between Antirrhinum species involves correlated changes in the size of leaves and petals that can be explained by developmental constraints without selection.

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

MOSAIC FLORAL ORGANS1, an AGL6-Like MADS Box Gene, Regulates Floral Organ Identity and Meristem Fate in Rice

Shinnosuke Ohmori, Mayumi Kimizu, Maiko Sugita, Akio Miyao, Hirohiko Hirochika, Eiji Uchida, Yasuo Nagato, and Hitoshi Yoshida

Plant Cell 2009 21: 3008-3025. First Published on October 9, 2009; doi:10.1105/tpc.109.068742

The mosaic floral organs1 (mfo1) mutant in rice has defects in the identities of several floral organ and in floral meristem determinacy. MFO1 encodes an AGAMOUS-LIKE6-like MADS box gene and has redundant roles with the SEPALLATA-like gene LHS1 in floral organ specification and in regulation of the establishment and determinacy of floral meristem.

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

Exocytosis Precedes and Predicts the Increase in Growth in Oscillating Pollen Tubes

Sylvester T. McKenna, Joseph G. Kunkel, Maurice Bosch, Caleb M. Rounds, Luis Vidali, Lawrence J. Winship, and Peter K. Hepler

Plant Cell 2009 21: 3026-3040. First Published on October 27, 2009; doi:10.1105/tpc.109.069260

Exocytosis has been examined in oscillating pollen tubes of lily and tobacco. The results indicate that increases in wall material or the enzyme pectin methyl esterase precede the increase in growth rate by about one-third of a growth cycle. Statistical analysis further reveals that the amount of new wall material highly predicts the rate and extent of subsequent growth.

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

Fleshy Fruit Expansion and Ripening Are Regulated by the Tomato SHATTERPROOF Gene TAGL1 Julia Vrebalov, Irvin L. Pan, Antonio Javier Matas Arroyo, Ryan McQuinn, MiYoung Chung, Mervin Poole, Jocelyn Rose, Graham Seymour, Silvana Grandillo, James Giovannoni, and Vivian F. Irish Plant Cell 2009 21: 3041-3062. First Published on October 30, 2009; doi:10.1105/tpc.109.066936 This work shows that TAGL1 links the networks regulating fleshy fruit expansion and ripening to promote seed dispersal. This supports the notion that the TAGL1 lineage of MADS box genes is a key player in evolutionary transitions between dry and fleshy fruit development. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Endogenous, Tissue-Specific Short Interfering RNAs Silence the Chalcone Synthase Gene Family in Glycine max Seed Coats Jigyasa H. Tuteja, Gracia Zabala, Kranthi Varala, Matthew Hudson, and Lila O. Vodkin Plant Cell 2009 21: 3063-3077. First Published on October 9, 2009; doi:10.1105/tpc.109.069856 This work describes naturally occurring tissue-specific silencing by short interfering RNAs targeting members of a gene family, including those with diverged sequences located on other chromosomes. The phenomenon results in inhibition of a metabolic pathway in one tissue, while the pathway is expressed in other organs. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Stage-Specific Regulation of Solanum lycopersicum Leaf Maturation by Class 1 KNOTTED1-LIKE HOMEOBOX Proteins

Eilon Shani, Yogev Burko, Lilach Ben-Yaakov, Yael Berger, Ziva Amsellem, Alexander Goldshmidt, Eran Sharon, and Naomi Ori

Plant Cell 2009 21: 3078-3092. First Published on October 9, 2009; doi:10.1105/tpc.109.068148

KNOXI proteins have been shown to influence compound leaf morphology. This study finds that KNOXI proteins enable the development of compound leaves in tomato by hindering the progress of leaf differentiation and that KNOXI activity is interpreted in a species and developmental context–dependent manner.

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

LYRATE Is a Key Regulator of Leaflet Initiation and Lamina Outgrowth in Tomato Rakefet David-Schwartz, Daniel Koenig, and Neelima R. Sinha Plant Cell 2009 21: 3093-3104. First Published on October 9, 2009; doi:10.1105/tpc.109.069948 This study shows that LYRATE, which promotes lateral outgrowth in aerial organs, interacts with KNOX and auxin transcriptional networks to regulate compound leaf formation in tomato. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

YABBYs and the Transcriptional Corepressors LEUNIG and LEUNIG_HOMOLOG Maintain Leaf Polarity and Meristem Activity in Arabidopsis

Melissa I. Stahle, Janine Kuehlich, Lindsay Staron, Albrecht G. von Arnim, and John F. Golz

Plant Cell 2009 21: 3105-3118. First Published on October 16, 2009; doi:10.1105/tpc.109.070458

Here it is shown that YABBYs physically interact with components of a transcriptional repressor complex to promote adaxial cell identity in leaves, embryonic shoot apical meristem initiation, and postembryonic SAM maintenance.

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

Phenotypic Plasticity of Adventitious Rooting in Arabidopsis Is Controlled by Complex Regulation of AUXIN RESPONSE FACTOR Transcripts and MicroRNA Abundance

Laurent Gutierrez, John D. Bussell, Daniel I. Pacurar, Josèli Schwambach, Monica Pacurar, and Catherine Bellini

Plant Cell 2009 21: 3119-3132. First Published on October 9, 2009; doi:10.1105/tpc.108.064758

This work examines the balance of three AUXIN RESPONSE FACTOR genes, one negative and two positive regulators of adventitious root initiation, and finds that the three genes show overlapping expression and complex interdependent gene regulation, including feedback regulation of microRNA levels.

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

NO VEIN Mediates Auxin-Dependent Specification and Patterning in the Arabidopsis Embryo, Shoot, and Root

Ryuji Tsugeki, Franck Anicet Ditengou, Yoshinori Sumi, William Teale, Klaus Palme, and Kiyotaka Okada

Plant Cell 2009 21: 3133-3151. First Published on October 30, 2009; doi:10.1105/tpc.109.068841

Local efflux-dependent auxin gradients and maxima mediate organ and tissue development in plants. Auxin efflux is regulated by expression and subcellular localization of the PIN auxin-efflux proteins. The Arabidopsis nuclear factor NO VEIN influences cell fate decisions associated with auxin gradients and maxima, thereby establishing PIN expression and polarity and auxin-mediated development.

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

Functional Analyses of LONELY GUY Cytokinin-Activating Enzymes Reveal the Importance of the Direct Activation Pathway in Arabidopsis Takeshi Kuroha, Hiroki Tokunaga, Mikiko Kojima, Nanae Ueda, Takashi Ishida, Shingo Nagawa, Hiroo Fukuda, Keiko Sugimoto, and Hitoshi Sakakibara Plant Cell 2009 21: 3152-3169. First Published on October 16, 2009; doi:10.1105/tpc.109.068676 This work analyzes recombinant proteins, loss- and gain-of-function phenotypes, expression patterns, and subcellular localizations of members of the Arabidopsis LOG family of cytokinin-activating enzymes to show that they play a pivotal role in regulating cytokinin activity during growth and development. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

Protein Phosphatases 2C Regulate the Activation of the Snf1-Related Kinase OST1 by Abscisic Acid in Arabidopsis

Florina Vlad, Silvia Rubio, Americo Rodrigues, Caroline Sirichandra, Christophe Belin, Nadia Robert, Jeffrey Leung, Pedro L. Rodriguez, Christiane Laurière, and Sylvain Merlot

Plant Cell 2009 21: 3170-3184. First Published on October 23, 2009; doi:10.1105/tpc.109.069179

Profiling of the protein phosphatase 2C (PP2C) HAB1 substrate preference identifies the activation loop of the abscisic acid (ABA)-activated SnRK2 kinase OST1 as a putative target. HAB1 as well as ABI1 and ABI2, two other PP2Cs implicated in ABA signaling, dephosphorylate and deactivate OST1 in vivo. These results suggest that the inhibition of PP2C by ABA is responsible for the activation of SnRK2s.

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

Crosstalk between Cold Response and Flowering in Arabidopsis Is Mediated through the Flowering-Time Gene SOC1 and Its Upstream Negative Regulator FLC

Eunjoo Seo, Horim Lee, Jin Jeon, Hanna Park, Jungmook Kim, Yoo-Sun Noh, and Ilha Lee

Plant Cell 2009 21: 3185-3197. First Published on October 13, 2009; doi:10.1105/tpc.108.063883

This work describes a feedback loop between cold response and flowering-time regulation. During a cold spell in early spring, this feedback loop would delay flowering through the increase of FLC, a strong floral repressor, but when floral induction occurs, the loop suppresses the cold response by the repression of cold inducible genes by SOC1.

[Abstract] [Full Text] [PDF]

DIE NEUTRALIS and LATE BLOOMER 1 Contribute to Regulation of the Pea Circadian Clock

Lim Chee Liew, Valérie Hecht, Rebecca E. Laurie, Claire L. Knowles, Jacqueline K. Vander Schoor, Richard C. Macknight, and James L. Weller

Plant Cell 2009 21: 3198-3211. First Published on October 20, 2009; doi:10.1105/tpc.109.067223

The pea photoperiod response gene DIE NEUTRALIS (DNE) is needed for delay of flowering, shoot branching, and extended flowering phase under short-day conditions. This study shows that DNE is an ortholog of Arabidopsis EARLY FLOWERING4 and establishes roles for DNE in diurnal and circadian regulation of clock gene expression and in light-dependent stem elongation.

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

OWL1: An Arabidopsis J-Domain Protein Involved in Perception of Very Low Light Fluences

Julia Kneissl, Volker Wachtler, Nam-Hai Chua, and Cordelia Bolle

Plant Cell 2009 21: 3212-3225. First Published on October 6, 2009; doi:10.1105/tpc.109.066472

This work identifies OWL1 as a signaling intermediate specific for phytochrome A–mediated very low fluence responses. OWL1 interacts with the helix-loop-helix transcription factor HFR1 and is essential for germination, cotyledon opening, hypocotyl elongation, and directional hypocotyl growth under very low light conditions.

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

Domain Swapping to Assess the Mechanistic Basis of Arabidopsis Phototropin 1 Receptor Kinase Activation and Endocytosis by Blue Light Eirini Kaiserli, Stuart Sullivan, Matthew A. Jones, Kevin A. Feeney, and John M. Christie Plant Cell 2009 21: 3226-3244. First Published on October 30, 2009; doi:10.1105/tpc.109.067876 Phototropins (phots) are plasma membrane–associated receptor kinases that elicit effects of blue light on plant growth. Using a domain-swapping approach, this study uncovers a function for the LOV1 chromophore binding domain of phot1 in controlling light-driven chloroplast movements and a mechanism for mediating phosphorylation-dependent receptor endocytosis from the plasma membrane. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

The Photosystem II Light-Harvesting Protein Lhcb3 Affects the Macrostructure of Photosystem II and the Rate of State Transitions in Arabidopsis Jakob T. Damkjær, Sami Kereïche, Matthew P. Johnson, Laszlo Kovacs, Anett Z. Kiss, Egbert J. Boekema, Alexander V. Ruban, Peter Horton, and Stefan Jansson Plant Cell 2009 21: 3245-3256. First Published on October 30, 2009; doi:10.1105/tpc.108.064006 Plants lacking the photosystem II chlorophyll a/b binding protein Lhcb3 compensate by increasing the amounts of Lhcb1 and Lhcb2. The replacement causes a minor alteration of the PSII complex: a small rotation of the M trimer of LHCII. However, plants lacking Lhcb3 perform state transitions quicker than the wild type. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

ARABIDOPSIS TRITHORAX-RELATED7 Is Required for Methylation of Lysine 4 of Histone H3 and for Transcriptional Activation of FLOWERING LOCUS C

Yosuke Tamada, Jae-Young Yun, Seung chul Woo, and Richard M. Amasino

Plant Cell 2009 21: 3257-3269. First Published on October 23, 2009; doi:10.1105/tpc.109.070060

The authors show that two classes of H3K4 methylases, a Set1-class ARABIDOPSIS TRITHORAX-RELATED7 (ATXR7) and a Trx-class ARABIDOPSIS TRITHORAX1 (ATX1), are required for methylation of lysine 4 of histone H3 (H3K4) at FLOWERING LOCUS C (FLC). H3K4 methylation by ATXR7 and ATX1 is indispensable for transcriptional activation of FLC by an active allele of FRIGIDA and thus for a winter-annual habit.

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

Arabidopsis Decapping 5 Is Required for mRNA Decapping, P-Body Formation, and Translational Repression during Postembryonic Development

Jun Xu and Nam-Hai Chua

Plant Cell 2009 21: 3270-3279. First Published on October 23, 2009; doi:10.1105/tpc.109.070078

This work addresses the function of DCP5 in plant cells. DCP5 interacts with the decapping machinery in Arabidopsis and regulates the translation and degradation of seed storage protein mRNAs during postembryonic development. The results shed light on the structure and function of plant processing bodies.

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

Transcript-Based Cloning of RRP46, a Regulator of rRNA Processing and R Gene–Independent Cell Death in Barley–Powdery Mildew Interactions Liu Xi, Matthew J. Moscou, Yan Meng, Weihui Xu, Rico A. Caldo, Miranda Shaver, Dan Nettleton, and Roger P. Wise Plant Cell 2009 21: 3280-3295. First Published on October 27, 2009; doi:10.1105/tpc.109.066167 Transcriptome analysis identified the gene encoding rRNA-processing protein 46 (RRP46) as responsible for non-R gene–associated cell death induced in a barley mutant by inoculation with the powdery mildew fungus. The authors then examined transcriptome changes induced in the mutant, both associated with and independent of the R-AVR gene interaction, finding key effects on RNA processing. [Abstract] [Full Text] [PDF] [Supplemental Data][Author Profile] OPEN ACCESS ARTICLE

Cotranslational Proteolysis Dominates Glutathione Homeostasis to Support Proper Growth and Development

Frédéric Frottin, Christelle Espagne, José A. Traverso, Caroline Mauve, Benoît Valot, Caroline Lelarge-Trouverie, Michel Zivy, Graham Noctor, Thierry Meinnel, and Carmela Giglione

Plant Cell 2009 21: 3296-3314. First Published on October 23, 2009; doi:10.1105/tpc.109.069757

The study of N-terminal Met excision (NME) under nonlethal conditions provides molecular mechanistic insight into events associated with early inhibition of the NME process in Arabidopsis thaliana and other organisms. The coupling of two fundamental signaling pathways, the thiol status and proteolysis pathways, by the NME process is reported.

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

CYP76M7 Is an ent-Cassadiene C11-Hydroxylase Defining a Second Multifunctional Diterpenoid Biosynthetic Gene Cluster in Rice Sivakumar Swaminathan, Dana Morrone, Qiang Wang, D. Bruce Fulton, and Reuben J. Peters Plant Cell 2009 21: 3315-3325. First Published on October 13, 2009; doi:10.1105/tpc.108.063677 Functional characterization of a cytochrome P450 operating on the diterpene produced by neighboring diterpene synthases defines a second biosynthetic gene cluster in rice. The unique multifunctionality of the gene cluster and the lack of coregulation highlight the role played by coinheritance in driving the assembly of such biosynthetic gene clusters in plants. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

The Ferroportin Metal Efflux Proteins Function in Iron and Cobalt Homeostasis in Arabidopsis Joe Morrissey, Ivan R. Baxter, Joohyun Lee, Liangtao Li, Brett Lahner, Natasha Grotz, Jerry Kaplan, David E. Salt, and Mary Lou Guerinot Plant Cell 2009 21: 3326-3338. First Published on October 27, 2009; doi:10.1105/tpc.109.069401 Metal efflux is required to load the xylem with metals for transport to the shoot and to sequester metals in the vacuole. Genetic analysis shows that FPN1 and FPN2, the Arabidopsis orthologs of the sole iron efflux protein in mammals, efflux both iron and cobalt into the xylem and the vacuole, respectively, and thus influence both the iron deficiency response and sensitivity to cobalt. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

A Zinc Finger Transcription Factor ART1 Regulates Multiple Genes Implicated in Aluminum Tolerance in Rice

Naoki Yamaji, Chao Feng Huang, Sakiko Nagao, Masahiro Yano, Yutaka Sato, Yoshiaki Nagamura, and Jian Feng Ma

Plant Cell 2009 21: 3339-3349. First Published on October 30, 2009; doi:10.1105/tpc.109.070771

Aluminum is a toxic element for plant growth. This work identifies a transcription factor specifically regulating at least 31 genes, which might be implicated in both the external and internal detoxification of aluminum in rice.

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

Overexpression of Several Arabidopsis Histone Genes Increases Agrobacterium-Mediated Transformation and Transgene Expression in Plants

Gabriela N. Tenea, Joerg Spantzel, Lan-Ying Lee, Yanmin Zhu, Kui Lin, Susan J. Johnson, and Stanton B. Gelvin

Plant Cell 2009 21: 3350-3367. First Published on October 9, 2009; doi:10.1105/tpc.109.070607

This work examines the effect of overexpressing various histone genes on susceptibility to Agrobacterium- mediated plant transformation, accumulation of transfected DNA, and gene expression from introduced DNA. The authors find that overexpression of histones H2A, H3-11, and H4 increased all three parameters, but overexpression of histones H2B and other H3 variants had no effect.

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

Rin4 Causes Hybrid Necrosis and Race-Specific Resistance in an Interspecific Lettuce Hybrid

Marieke J.W. Jeuken, Ningwen W. Zhang, Leah K. McHale, Koen Pelgrom, Erik den Boer, Pim Lindhout, Richard W. Michelmore, Richard G.F. Visser, and Rients E. Niks

Plant Cell 2009 21: 3368-3378. First Published on October 23, 2009; doi:10.1105/tpc.109.070334

This work examines the mechanism of hybrid necrosis in a hybrid between two species of lettuce, domestic (Lactuca sativa) and a wild relative (Lactuca saligna). The digenic allelic interaction producing necrosis also conditions disease resistance, and one of the interacting partners has highest sequence similarity to Arabidopsis RPM1 INTERACTING PROTEIN4.

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

Sfp-Type 4'-Phosphopantetheinyl Transferase Is Indispensable for Fungal Pathogenicity

Ralf Horbach, Alexander Graf, Fabian Weihmann, Luis Antelo, Sebastian Mathea, Johannes C. Liermann, Till Opatz, Eckhard Thines, Jesús Aguirre, and Holger B. Deising

Plant Cell 2009 21: 3379-3396. First Published on October 30, 2009; doi:10.1105/tpc.108.064188

Sfp-type 4'-phosphopantetheinyl transferases (PPTases) are key enzymes in the primary and secondary metabolism of filamentous fungi. This study reports the cloning and functional characterization of the PPTase gene of the maize anthracnose fungus Colletotrichum graminicola and shows that the encoded enzyme is critical for pathogenicity and pathogenesis-related morphogenesis.

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

The O-Mannosyltransferase PMT4 Is Essential for Normal Appressorium Formation and Penetration in Ustilago maydis Alfonso Fernández-Álvarez, Alberto Elías-Villalobos, and José I. Ibeas Plant Cell 2009 21: 3397-3412. First Published on October 30, 2009; doi:10.1105/tpc.109.065839 The O-mannosylation pathway plays a key role in the posttranslational modification of proteins. This work identifies members of all three protein families that catalyze the steps of this pathway in the corn smut fungus Ustilago maydis and analyzes their role in pathogenesis. [Abstract] [Full Text] [PDF] [Supplemental Data] OPEN ACCESS ARTICLE

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