Table of Contents
IN BRIEF
CURRENT PERSPECTIVE ESSAYS
RESEARCH ARTICLES
- Maize Histone Deacetylase hda101 Is Involved in Plant Development, Gene Transcription, and Sequence-Specific Modulation of Histone Modification of Genes and Repeats
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.
- Characterization of the VIER F-BOX PROTEINE Genes from Arabidopsis Reveals Their Importance for Plant Growth and Development
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.
- Replication-Independent Long-Distance Trafficking by Viral RNAs in Nicotiana benthamiana
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.
- PIL5, a Phytochrome-Interacting bHLH Protein, Regulates Gibberellin Responsiveness by Binding Directly to the GAI and RGA Promoters in Arabidopsis Seeds
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.
- The DELLA Domain of GA INSENSITIVE Mediates the Interaction with the GA INSENSITIVE DWARF1A Gibberellin Receptor of Arabidopsis
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.
- An ERF Transcription Factor in Medicago truncatula That Is Essential for Nod Factor Signal Transduction
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.
- Heterotrimeric G Protein γ Subunits Provide Functional Selectivity in Gβγ Dimer Signaling in Arabidopsis
G proteins are important signaling molecules in plants and animal systems. This work provides evidence that plant heterotrimeric G proteins use both Gγ subunits to convey functional selectivity to the Gβγ dimers and reveals a mechanism underlying the complexity of G protein–mediated signaling in plants.
- Plant Mitochondrial Recombination Surveillance Requires Unusual RecA and MutS Homologs
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.
- The Arabidopsis D-Type Cyclin CYCD4 Controls Cell Division in the Stomatal Lineage of the Hypocotyl Epidermis
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.
- The Transcription Factor WIN1/SHN1 Regulates Cutin Biosynthesis in Arabidopsis thaliana
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.
- The Arabidopsis AAA ATPase SKD1 Is Involved in Multivesicular Endosome Function and Interacts with Its Positive Regulator LYST-INTERACTING PROTEIN5
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.
- The Balance between Protein Synthesis and Degradation in Chloroplasts Determines Leaf Variegation in Arabidopsis yellow variegated Mutants
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.
- The Nuclear-Encoded Factor HCF173 Is Involved in the Initiation of Translation of the psbA mRNA in Arabidopsis thaliana
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.
- Formation of DEG5 and DEG8 Complexes and Their Involvement in the Degradation of Photodamaged Photosystem II Reaction Center D1 Protein in Arabidopsis
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.
- Rice NON-YELLOW COLORING1 Is Involved in Light-Harvesting Complex II and Grana Degradation during Leaf Senescence
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.
- MONODEHYROASCORBATE REDUCTASE4 Is Required for Seed Storage Oil Hydrolysis and Postgerminative Growth in Arabidopsis
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 β-oxidation.
- Roles of Arabidopsis Cyclin-Dependent Kinase C Complexes in Cauliflower Mosaic Virus Infection, Plant Growth, and Development
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.
- SIZ1-Mediated Sumoylation of ICE1 Controls CBF3/DREB1A Expression and Freezing Tolerance in Arabidopsis
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.
- SCABP8/CBL10, a Putative Calcium Sensor, Interacts with the Protein Kinase SOS2 to Protect Arabidopsis Shoots from Salt Stress
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.
