Table of Contents
IN BRIEF
LARGE-SCALE BIOLOGY ARTICLE
Model-Assisted Analysis of Sugar Metabolism throughout Tomato Fruit Development Reveals Enzyme and Carrier Properties in Relation to Vacuole ExpansionA kinetic model combining enzyme activities and subcellular compartmentation was built to analyze the storage and interconversion of sugars in developing tomato fruit. This work shows that tonoplast carriers, sucrose hydrolysis, and accumulation of organic acids are major contributors to the vacuole expansion and the metabolic reprogramming that occur during early development.
RESEARCH ARTICLES
Comparative Transcriptome Atlases Reveal Altered Gene Expression Modules between Two Cleomaceae C3 and C4 Plant SpeciesTranscriptome atlases of Tarenaya hassleriana, a C3 plant, and the C4-species Gynandropsis gynandra were developed. Integrated analysis of RNA-seq and leaf anatomical data indicates altered regulation of the cell cycle and endoreduplication during the establishment of C4 leaf anatomy. C4 genes have been recruited to photosynthetic gene expression regulation from ancestral nonphotosynthetic functions in C3.
eQTL Mapping of Transposon Silencing Reveals a Position-Dependent Stable Escape from Epigenetic Silencing and Transposition of AtMu1 in the Arabidopsis LineageThis article describes mapping and molecular analysis of the differential transcriptional activity of a MULE1 DNA transposon in two commonly used lab strains. The study is expanded to over 200 accessions to describe the overall polymorphism of this transposon in the Arabidopsis lineage. This study provides insight into natural variation of transposon silencing.
Analysis of Natural and Induced Variation in Tomato Glandular Trichome Flavonoids Identifies a Gene Not Present in the Reference GenomeAnalysis of genomic resources, genetics, and biochemistry identified Sl-MOMT4 as a flavonol 3′ O-methyltransferase involved in the production of methylated flavonoids in glandular trichomes of the M82 cultivated tomato. This gene is missing in the tomato Heinz 1706 reference genome and represents an example of fast evolution of specialized metabolism genes among cultivated tomato varieties.
Production of Bioactive Diterpenoids in the Euphorbiaceae Depends on Evolutionarily Conserved Gene ClustersThe Euphorbiaceae produce a wide range of biologically active diterpenoids. Using castor (Ricinus communis) as a model, this work provides evidence that some of the genes required for the biosynthesis of these diterpenoids are arranged in physical gene clusters and describes a conserved oxidation step required for biosynthesis of a majority of diterpenoids that has been reported in this family.
Pollen-Specific Activation of Arabidopsis Retrogenes Is Associated with Global Transcriptional ReprogrammingThis study shows that 1% of Arabidopsis protein-coding genes are retrogenes (i.e., cDNAs integrated into the genome) and that retrogenes frequently acquire novel promoters at their insertion sites and are transcribed preferentially in male gametes. Thus, RNA-based gene duplication is a common process in plant genome evolution and generates functional genes with specific transcription patterns.
Identification of a Sphingolipid α-Glucuronosyltransferase That Is Essential for Pollen Function in ArabidopsisThis study found that IPUT1 is an enzyme required for the biosynthesis of glycosyl inositol phosphorylceramide sphingolipids in plants. These glycolipids are highly abundant and have many important cellular roles. IPUT1 adds glucuronic acid residues to the lipids. When the glucuronic acid residues are not incorporated in the sphingolipids, the pollen is unable to mediate fertilization.
The Arabidopsis 14-3-3 Protein RARE COLD INDUCIBLE 1A Links Low-Temperature Response and Ethylene Biosynthesis to Regulate Freezing Tolerance and Cold AcclimationThe Arabidopsis 14-3-3 RCI1A protein plays a critical role in freezing tolerance, partially through an ethylene-dependent signaling pathway. RCI1A interacts with different ACS isoforms to regulate the levels of ethylene that are necessary to promote accurate cold-induced gene expression and freezing tolerance under both control and low-temperature conditions.
A Mitogen-Activated Protein Kinase Cascade Module, MKK3-MPK6 and MYC2, Is Involved in Blue Light-Mediated Seedling Development in ArabidopsisThe connection between the MAP kinase cascade and light signaling is unknown. This work shows that the MKK3-MPK6 is activated by blue light in a MYC2-dependent manner during Arabidopsis seedling development. MPK6 physically interacts and phosphorylates MYC2, which in turn binds to the promoter of MPK6 and regulates its expression in a feedback mechanism under blue light signaling.
Manipulation of Mitogen-Activated Protein Kinase Kinase Signaling in the Arabidopsis Stomatal Lineage Reveals Motifs That Contribute to Protein Localization and Signaling SpecificityExpression of Arabidopsis MKK domain deletion variants in three discrete epidermal cell types, coupled with in vitro kinase assays, revealed regions of MKKs that promote signal propagation and regulate protein subcellular localization. Subcellular localization associated with a subset of MKK7/9 functions sheds light onto how signaling specificity is achieved.
The Microtubule Plus-End Tracking Protein ARMADILLO-REPEAT KINESIN1 Promotes Microtubule Catastrophe in ArabidopsisThis work determines that the ARMADILLO-REPEAT KINESIN1 (ARK1) of Arabidopsis accumulates at the plus ends of growing microtubules and promotes microtubule catastrophe. By inducing such events, ARK1 enables the recycling of tubulin subunits, which is important for maintaining rapid microtubule polymerization, a process that is critical for maintaining unidirectional tip growth in root hairs.
The Os-AKT1 Channel Is Critical for K+ Uptake in Rice Roots and Is Modulated by the Rice CBL1-CIPK23 ComplexThis work shows that the transport activity of the Shaker K+ channel Os-AKT1, which mediates K+ uptake in rice roots and influences grain yield, is modulated by Os-CBL1 and Os-CIPK23 proteins. These findings provide insight promoting efforts to improve rice K+ uptake efficiency and enhance rice tolerance to K+-deficiency stress.
The ABC Transporter ABCG1 Is Required for Suberin Formation in Potato Tuber PeridermThe water barrier function of potato tuber skin depends on the polyester suberin and associated waxes. Here, a transporter was identified that is required for the formation of suberin in potato tuber periderm; potato plants lacking this transporter give rise to tubers that are more prone to water loss.
Dynamics of Vacuoles and H+-Pyrophosphatase Visualized by Monomeric Green Fluorescent Protein in Arabidopsis: Artifactual Bulbs and Native Intravacuolar Spherical StructuresIn this work, expressing monomeric green fluorescent protein (GFP)-linked vacuolar H+-pyrophosphatase (H+-PPase) under the control of its own promoter revealed dynamic morphological changes in vacuoles and tonoplasts and tissue-specific expression patterns of H+-PPase. However, weak homodimerization of highly expressed GFP-tagged protein triggered the generation of artifactual bulbs in plant cells.
Functional Characterization of the Small Regulatory Subunit PetP from the Cytochrome b6f Complex in Thermosynechococcus elongatusSuccessful isolation of a highly active b6f complex including the PetP subunit allowed detailed analysis of the function of this recently discovered subunit. PetP appears to promote the stability and activity of the b6f complex and to influence linear electron transport.
Loss of Ceramide Kinase in Arabidopsis Impairs Defenses and Promotes Ceramide Accumulation and Mitochondrial H2O2 BurstsLoss of ceramide kinase in Arabidopsis causes altered temporal and/or spatial accumulation of sphingolipids and hydrogen peroxide along with increased cell death and fungal pathogen growth (Botrytis cinerea) prior to cell death. Thus, the balance of ceramides and/or the loss of ceramide phosphate are implicated in cell death control and in interactions with Botrytis cinerea during early stages of infection.
