Table of Contents
IN BRIEF
LARGE-SCALE BIOLOGY ARTICLE
GWAPP: A Web Application for Genome-Wide Association Mapping in ArabidopsisA user-friendly, interactive Web-based application is presented for conducting genome-wide association studies in Arabidopsis. Genome-wide scans for association between phenotype and ∼206,000 single nucleotide polymorphisms in 1386 public accessions can be completed in minutes. The application combines a state-of-the-art mixed model with interactive Manhattan and linkage disequilibrium plots, making it easy to carry out exploratory analyses without programming skills.
RESEARCH ARTICLES
Ln Is a Key Regulator of Leaflet Shape and Number of Seeds per Pod in SoybeanWhether the leaflet shape gene Ln has a pleiotropic effect on the number of seeds per pod (NSPP) trait or not has long been debated in soybean research. This study shows that both the leaflet shape and NSPP traits are regulated by a single gene, which is a homolog of Arabidopsis JAGGED that regulates leaf and flower development, and establishes a novel role for JAGGED in fruit development.
Evolution from the Prokaryotic to the Higher Plant Chloroplast Signal Recognition Particle: The Signal Recognition Particle RNA Is Conserved in Plastids of a Wide Range of Photosynthetic OrganismsThis article provides an analysis of chloroplast signal recognition particle (cpSRP) evolution within the green and red lineages. A focus lies on the distribution and characterization of the plastid-encoded SRP RNA component. Furthermore, the cpSRP system of Physcomitrella patens containing an SRP RNA and a cpSRP43 component was investigated, and the structure of the cpFtsY receptor was solved.
miR156 and miR390 Regulate tasiRNA Accumulation and Developmental Timing in Physcomitrella patensMany plant microRNAs are deeply conserved in all land plants, from mosses to flowering plants. We carry out functional studies of two such microRNAs, miR156 and miR390, in the moss Physcomitrella patens and identify them as components of a broadly conserved gene regulatory network that controls the timing of plant development.
Target of Rapamycin Signaling Regulates Metabolism, Growth, and Life Span in ArabidopsisThis work examines the postembryonic functions of Target of Rapamycin (TOR) in Arabidopsis by generating rapamycin-sensitive Arabidopsis plants via transgenic expression of a yeast protein. Examination of these lines indicates that in plants, as in animals, TOR acts in the integration of metabolism, nutrition, and life span.
A Dominant Point Mutation in a RINGv E3 Ubiquitin Ligase Homoeologous Gene Leads to Cleistogamy in Brassica napusThis work examines a Brassica napus mutant with a petal-closed phenotype, finding that it is caused by a dominant mutation in a RINGv E3 ubiquitin ligase homoeologous gene that is highly conserved across eukaryotes.
The SWI2/SNF2 Chromatin Remodeling ATPase BRAHMA Represses Abscisic Acid Responses in the Absence of the Stress Stimulus in ArabidopsisThis work shows that the chromatin remodeling ATPase BRAHMA ensures that postgermination growth arrest is triggered only upon sensing of the water stress hormone ABA. BRAHMA directly represses expression of ABA-responsive genes, including ABI5 by modulating nucleosome occupancy and position. Furthermore, brahma mutants display drought tolerance.
Soluble Carbohydrates Regulate Auxin Biosynthesis via PIF Proteins in ArabidopsisPlants adjust growth to suit opportunities and limitations in their environment. Sugars from photosynthesis, the hormone auxin, and members of the PHYTOCHROME INTERACTING FACTOR (PIF) family of proteins have all been shown individually to regulate growth. This work shows that sugars regulate auxin biosynthesis via PIF proteins, indicating that the three in fact act together in growth regulation.
A Triple Helix-Loop-Helix/Basic Helix-Loop-Helix Cascade Controls Cell Elongation Downstream of Multiple Hormonal and Environmental Signaling Pathways in ArabidopsisThis work reveals that two non-DNA binding HLH factors (PRE1 and IBH1) and a DNA binding bHLH factor (HBI1) form an interaction cascade that controls cell elongation. BR, GA, light, and temperature signals regulate the expression level of PRE1; PRE1 binds to and inhibits IBH1; IBH1 interacts with and inhibits HBI1 binding to promoter DNA of two EXPANSIN genes.
LSM Proteins Provide Accurate Splicing and Decay of Selected Transcripts to Ensure Normal Arabidopsis DevelopmentThis study describes the molecular and functional characterization of Arabidopsis LSM proteins. Results demonstrate that they are organized in two heptameric complexes, one nuclear and another cytoplasmic, that play a critical role in Arabidopsis development by ensuring appropriate development-related gene expression through the control of mRNA splicing and decay, respectively.
A MAPK Cascade Downstream of ERECTA Receptor-Like Protein Kinase Regulates Arabidopsis Inflorescence Architecture by Promoting Localized Cell ProliferationCoordinated spatiotemporal-specific cell proliferation is critical to plant growth and development. This study demonstrates the function of a mitogen-activated protein kinase cascade downstream of the ERECTA receptor-like kinase in regulating localized cell proliferation, which determines the inflorescence architecture and size in Arabidopsis thaliana.
BRK1, a Bub1-Related Kinase, Is Essential for Generating Proper Tension between Homologous Kinetochores at Metaphase I of Rice MeiosisThis work identifies a plant Bub1-related kinase 1 (BRK1) in rice and suggests that this protein corrects the merotelic attachment of paired sister kinetochores during metaphase I.
Germline-Specific MATH-BTB Substrate Adaptor MAB1 Regulates Spindle Length and Nuclei Identity in MaizeThe length and position of the spindle apparatus change significantly during the meiosis-to-mitosis transition. This study reports on the role of the germline-specific E3 ligase MATH-BTB adaptor protein MAB1 that is required for nuclei separation during meiosis II and asymmetric nuclei positioning during subsequent mega- and microspore division, respectively.
PSBP-DOMAIN PROTEIN1, a Nuclear-Encoded Thylakoid Lumenal Protein, Is Essential for Photosystem I Assembly in ArabidopsisPhotosystem I (PSI) is one of the largest and most complex macromolecular assemblies known in nature. However, the molecular mechanisms of the assembly process of PSI remain largely unknown. This study reports that PSBP-DOMAIN PROTEIN1, a nuclear-encoded chloroplast protein found in the thylakoid lumen, plays an important role in the assembly of the PSI reaction center heterodimer.
WRINKLED Transcription Factors Orchestrate Tissue-Specific Regulation of Fatty Acid Biosynthesis in ArabidopsisThe WRINKLED transcription factors are positive regulators of the fatty acid biosynthetic pathway in Arabidopsis. They trigger high rates of fatty acid production for the elaboration of different classes of complex lipids like storage lipids in seeds or cuticular lipids at the surface of epidermal cells.
Pectin Biosynthesis: GALS1 in Arabidopsis thaliana Is a β-1,4-Galactan β-1,4-GalactosyltransferaseGALS1, GALS2, and GALS3 are members of glycosyltransferase family GT92 in Arabidopsis thaliana. Loss-of-function mutants in the three corresponding genes are deficient in pectic β-1,4-galactan. GALS1 is shown to function as a β-1,4-galactan synthase in vitro, and GALS1 overexpressors have a 50% increased content of β-1,4-galactan in the cell walls.
Mitochondrial Targeting of the Arabidopsis F1-ATPase γ-Subunit via Multiple Compensatory and Synergistic Presequence MotifsThis work dissects the function of the N-terminal presequence of the Arabidopsis F1-ATPase γ-subunit, identifying multiple motifs that act at different steps of import to target this protein to the mitochondria. These motifs exhibit complex functional relationships, with some acting redundantly and others working synergistically.
Trafficking of Vacuolar Proteins: The Crucial Role of Arabidopsis Vacuolar Protein Sorting 29 in Recycling Vacuolar Sorting ReceptorThis work dissects the function of VPS29, a retromer complex component, in vacuolar trafficking of proteins in vegetative tissues of Arabidopsis plants, demonstrating that VPS29 is essential in recycling vacuolar sorting receptors from the prevacuolar compartment (PVC) to the trans-Golgi network (TGN), which is in turn crucial for trafficking of soluble vacuolar proteins from the TGN to the PVC.
Crystal Structure of Rice Importin-α and Structural Basis of Its Interaction with Plant-Specific Nuclear Localization SignalsA combination of crystallography, interaction analysis, and nuclear import assays demonstrates a distinct mode of autoinhibition in rice importin- α1a and the binding of plant-specific nuclear localization signals (NLSs) to its minor NLS binding site.
The R2R3-MYB–Like Regulatory Factor EOBI, Acting Downstream of EOBII, Regulates Scent Production by Activating ODO1 and Structural Scent-Related Genes in PetuniaUsing a protoplast-based promoter-activation system, this work identifies a MYB-like factor termed EOBI that is important in floral scent production. Direct interactions of EOBI with EOBII and of both proteins with ODO1 and structural phenylpropanoid scent-related genes allow tight regulation of scent throughout flower development.
UBIQUITIN-SPECIFIC PROTEASE16 Modulates Salt Tolerance in Arabidopsis by Regulating Na+/H+ Antiport Activity and Serine Hydroxymethyltransferase StabilityThis study indentifies Arabidopsis UBP16 as a functional ubiquitin-specific protease involved in salt tolerance and SERINE HYDROXYMETHYLTRANSFERASE1 as a putative target of UBP16.
Pipecolic Acid, an Endogenous Mediator of Defense Amplification and Priming, Is a Critical Regulator of Inducible Plant ImmunityThe Lys catabolite pipecolic acid (Pip) is identified as a critical signal for several forms of inducible plant immunity, acting as a central component of a feedback amplification mechanism that potentiates plant defense responses. Accumulation of Pip is necessary for the establishment of systemic acquired resistance (SAR) and sufficient to trigger SAR-related defense priming.
Relocalization of Late Blight Resistance Protein R3a to Endosomal Compartments Is Associated with Effector Recognition and Required for the Immune ResponseThis work examines effector recognition and signaling by NB-LRR resistance protein R3a, finding that recognition of AVR3A involves R3a relocalization to vesicular compartments in the endocytic pathway and attenuation of this relocalization suppressed the resultant hypersensitive cell death response.
In Planta Stage-Specific Fungal Gene Profiling Elucidates the Molecular Strategies of Fusarium graminearum Growing inside Wheat ColeoptilesThe fungal pathogen Fusarium graminearum was isolated from inside the host plant (wheat) during three stages of infection using laser microdissection and subjected to microarray analysis. Global expression profiles of in planta–grown and in vitro–grown F. graminearum were compared to elucidate overall infection strategies and the roles that several genes play in pathogenesis were validated.
Natural Variation in Small Molecule–Induced TIR-NB-LRR Signaling Induces Root Growth Arrest via EDS1- and PAD4-Complexed R Protein VICTR in ArabidopsisThis chemical genetics work reveals natural variation in a newly identified R protein homolog, named VICTR, that produces primary root growth arrest in response to the small molecule DFPM. DFPM perception and signal transduction require early components of the plant R gene resistance signaling network, and the R protein VICTR coresides in complexes not only with EDS1 but also PAD4.
