Table of Contents
IN BRIEF
RESEARCH ARTICLES
- cis-Regulatory Elements and Chromatin State Coordinately Control Temporal and Spatial Expression of FLOWERING LOCUS T in Arabidopsis
Transcription of FLOWERING LOCUS T is tightly controlled by external and internal cues. This study reports that evolutionary conserved blocks of regulatory elements spaced at considerable distance within the promoter interact with factors regulating local chromatin structure to control transcription of the gene.
- ragged seedling2 Encodes an ARGONAUTE7-Like Protein Required for Mediolateral Expansion, but Not Dorsiventrality, of Maize Leaves
This work identifies ragged seedling2 as a maize homolog of Arabidopsis argonaute7 and focuses on the role of small RNA molecules in establishing leaf polarity.
- Distinct Regulation of Adaxial-Abaxial Polarity in Anther Patterning in Rice
This study demonstrates that an RNA-dependent RNA polymerase involved in trans-acting small interfering RNA production plays a role in establishing adaxial-abaxial polarity in rice floral organs. A model is presented for anther patterning in rice.
- Overexpression of Arabidopsis Acyl-CoA Binding Protein ACBP3 Promotes Starvation-Induced and Age-Dependent Leaf Senescence
Six genes encode acyl-CoA binding proteins (ACBPs) in Arabidopsis. This study suggests a role for Arabidopsis ACBP3 as a phospholipid binding protein in the regulation of leaf senescence by modulating membrane phospholipid metabolism and the stability of autophagy-related protein ATG8.
- Two Medicago truncatula Half-ABC Transporters Are Essential for Arbuscule Development in Arbuscular Mycorrhizal Symbiosis
In arbuscular mycorrhizal (AM) symbiosis, development of arbuscules, the structures responsible for mineral nutrient transfer to the plant, requires host plant functions. This work identifies two half-ABC transporters that are widely conserved in the vascular plants. Their interaction and function in the peri-arbuscular membrane is required for arbuscule development and a functional AM symbiosis.
- Plastidial Thioredoxin z Interacts with Two Fructokinase-Like Proteins in a Thiol-Dependent Manner: Evidence for an Essential Role in Chloroplast Development in Arabidopsis and Nicotiana benthamiana
This study describes a thioredoxin isoform (TRX z) that is crucial in plant development and functions in regulation of the plastid-encoded RNA polymerase. It shows that at least one TRX z target is regulated by light, indicative of a protein interaction module that might link plastid transcription to light signals.
- Stromal Hsp70 Is Important for Protein Translocation into Pea and Arabidopsis Chloroplasts
This work shows that chloroplast stromal Hsp70s play a critical role in the step of protein translocation across the chloroplast envelope. It provides evidence that stromal Hsp70 functions in parallel to the Hsp93 system during protein import, making the chloroplast unique among organelles by possessing two simultaneously functioning chaperone/motor systems for protein translocation.
- A Soluble Guanylate Cyclase Mediates Negative Signaling by Ammonium on Expression of Nitrate Reductase in Chlamydomonas
Nitrate assimilation genes in Chlamydomonas are negatively modulated by ammonium through a pathway that involves NO, cGMP, and calcium. This work shows that similar mechanisms might be operating in plants.
- Identification of the 2-Hydroxyglutarate and Isovaleryl-CoA Dehydrogenases as Alternative Electron Donors Linking Lysine Catabolism to the Electron Transport Chain of Arabidopsis Mitochondria
This study indicates that Lys catabolism can directly channel electrons to the mitochondrial electron transport chain in addition to sustaining the operation of the tricarboxylic acid cycle under carbon-limiting conditions.
- Conserved Alternative Splicing of Arabidopsis Transthyretin-Like Determines Protein Localization and S-Allantoin Synthesis in Peroxisomes
Conserved alternative splicing of an unusual internal targeting sequence turns the enzyme completing the peroxisomal pathway of ureide biosynthesis into a cytosolic protein with a different function.
- The RNA Binding Protein Tudor-SN Is Essential for Stress Tolerance and Stabilizes Levels of Stress-Responsive mRNAs Encoding Secreted Proteins in Arabidopsis
This study describes the role of Tudor-SN in optimal stress tolerance throughout the life cycle of Arabidopsis. It finds evidence suggestive of new mechanisms regulating the metabolism of mRNAs entering the secretory pathway.
- Alteration of Substrate Specificity: The Variable N-Terminal Domain of Tobacco Ca2+-Dependent Protein Kinase Is Important for Substrate Recognition
The variable N-terminal domain of CDPK1 is required for the recognition of the substrate RSG, which is a transcriptional activator involved in the gibberellin feedback regulation. This work opens the possibility of engineering the substrate specificity of CDPK by manipulation of the variable N-terminal domain, enabling a rational rewiring of cellular signaling pathways.
- Genetic Screening Identifies Cyanogenesis-Deficient Mutants of Lotus japonicus and Reveals Enzymatic Specificity in Hydroxynitrile Glucoside Metabolism
This work describes a high-throughput screen for mutants affected in their ability to release hydrogen cyanide using the model legume Lotus japonicus. Mutants revealed unexpected specificity in the enzymes of both synthesis and degradation of cyanogenic glucosides and closely related compounds. This may offer flexibility in the production of deterrents to herbivores by this species.
- The Growth Reduction Associated with Repressed Lignin Biosynthesis in Arabidopsis thaliana Is Independent of Flavonoids
This study reexamines the relationship between flavonoid accumulation and the growth reduction exhibited by Arabidopsis plants that are defective in lignin biosynthesis. It shows that flavonoids are not responsible for the observed growth inhibition, contrary to a previous report.
- The Arabidopsis Nitrate Transporter NRT1.8 Functions in Nitrate Removal from the Xylem Sap and Mediates Cadmium Tolerance
Environmental stresses affect the nitrate distribution between roots and shoots, and transporters that remove nitrate from the xylem sap are essential for long-distance nitrate transport. This study shows that the nitrate transporter NRT1.8 is induced by cadmium and removes nitrate from xylem vessels and furthermore establishes a correlation between nitrate allocation and cadmium tolerance.
