Plant Cell Advance Online Publication Papers

A Novel Form of Photoprotection in Cyanobacteria

Eckardt, N. A. — 2012-05-22T13:33:06-07:00

Wavelength Dependence of Quantum Yield for CO2 Fixation and Photochemical Efficiencies of Photosystems I and II

Eckardt, N. A. — 2012-05-22T13:33:05-07:00

Photosynthetic Quantum Yield Dynamics: From Photosystems to Leaves

2012-05-22T13:33:06-07:00

The quantum yield for CO₂ fixation is wavelength dependent due to (1) light absorption by nonphotosynthetic pigments, (2) inefficient energy transfer, and (3) the excitation balance between the two photosystems. The growth-light spectrum alters the excitation balance by altering the photosystem composition, as shown both in vivo and in vitro. Enhancement effects can increase the quantum yield.

Screening a cDNA Library for Protein-Protein Interactions Directly in Planta

2012-05-22T13:33:05-07:00

This article presents a method to screen a plant cDNA library for genes encoding proteins that interact with a bait protein directly in plants using bimolecular fluorescence complementation technology. Proof-of-concept experiments identified both known and novel Arabidopsis thaliana proteins important for Agrobacterium-mediated plant transformation.

Genome Comparison of Barley and Maize Smut Fungi Reveals Targeted Loss of RNA Silencing Components and Species-Specific Presence of Transposable Elements

2012-05-22T13:33:04-07:00

The genome sequence of Ustilago hordei revealed that transposable elements were involved in restructuring of the genome, which affected fungal reproductive biology and evolution of genes encoding effector proteins. Comparison to other smuts indicated loss of genome defense components in Ustilago maydis and control of repetitive sequences by repeat-induced point mutation in U. hordei.

Fatty Acid Phytyl Ester Synthesis in Chloroplasts of Arabidopsis

2012-05-22T13:33:05-07:00

This work identifies two phytyl ester synthases that act in fatty acid phytyl ester synthesis in chloroplasts during senescence and nitrogen deprivation to maintain the integrity of the photosynthetic membrane during abiotic stress and senescence.

The Sg-1 Glycosyltransferase Locus Regulates Structural Diversity of Triterpenoid Saponins of Soybean

2012-05-18T13:26:00-07:00

Group A saponins in soybean are diversified compounds belonging to a group of triterpene saponins and are causal components for bitterness and astringent aftertastes of soy products. This work describes the identification of Sg-1, a UDP-sugar–dependent glycosyltransferase gene that is responsible for the unpleasant tastes due to allelic variation regulating the terminal sugar species in group A saponins.

The Recombinases DMC1 and RAD51 Are Functionally and Spatially Separated during Meiosis in Arabidopsis

Kurzbauer, M.-T., Uanschou, C., Chen, D., Schlogelhofer, P. — 2012-05-15T12:35:22-07:00

This article presents evidence, obtained in Arabidopsis thaliana, that two central DNA repair proteins, the recombinases DMC1 and RAD51, are spatially and functionally separated, respectively, during meiotic DNA repair and shows that a well-known DNA damage response factor, the ATR kinase, is involved in regulating DMC1 deposition.

Nramp5 Is a Major Transporter Responsible for Manganese and Cadmium Uptake in Rice

Sasaki, A., Yamaji, N., Yokosho, K., Ma, J. F. — 2012-05-15T12:35:23-07:00

Rice accumulates high concentrations of Mn. The high uptake of Mn in rice is mediated by a member of Nramp proteins, which is polarly localized at the plasma membrane of both the exodermis and endodermis cells in the roots. This protein also functions as a major transporter of Cd.

Grass MicroRNA Gene Paleohistory Unveils New Insights into Gene Dosage Balance in Subgenome Partitioning after Whole-Genome Duplication

Abrouk, M., Zhang, R., Murat, F., Li, A., Pont, C., Mao, L., Salse, J. — 2012-05-15T12:35:22-07:00

Reconstruction of the grass genome paleohistory revealed subgenome partitioning of microRNA (miRNA) genes during post-whole-genome duplication diploidization. The evolutionary scenario of miRNAs from the ancestral founder pool to the modern complements displayed dosage balance constrictions on the deletion/retention of miRNAs and associated target genes wherein transposable elements may play a major role in miRNA gene synteny disruption.

A Membrane Microdomain-Associated Protein, Arabidopsis Flot1, Is Involved in a Clathrin-Independent Endocytic Pathway and Is Required for Seedling Development

2012-05-15T12:35:22-07:00

This work reveals that Flot1 functions in Arabidopsis thaliana seedling development and is involved in a membrane microdomain-dependent, but clathrin-independent, endocytic pathway. Moreover, the dynamic behavior of Flot1-positive puncta differs considerably from that of clathrin light chain–positive puncta.

Plant Vegetative and Animal Cytoplasmic Actins Share Functional Competence for Spatial Development with Protists

Kandasamy, M. K., McKinney, E. C., Roy, E., Meagher, R. B. — 2012-05-15T12:35:23-07:00

This study shows that the vegetative class of plant actins and the cytoplasmic class of animal actins share conserved functions that were inherited from an ancestral protist actin sequence. Thus, some single-celled protists contain actin that can perform the complex processes required for multicellular development.

Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenases Interact with Phospholipase D{delta} to Transduce Hydrogen Peroxide Signals in the Arabidopsis Response to Stress

Guo, L., Devaiah, S. P., Narasimhan, R., Pan, X., Zhang, Y., Zhang, W., Wang, X. — 2012-05-15T12:35:22-07:00

Plants produce hydrogen peroxide (H₂O₂) as a stress signal. This study shows that H₂O₂ promotes the binding of cytosolic, glycolytic enzymes, GAPCs, to the plasma membrane–associated phospholipase PLD. The GAPC–PLD interaction mediates the plant response to H₂O₂ and provides a molecular link between stress signaling and the alteration of cellular metabolism and growth in the plant response to drought.

Phosphorylation of FAR-RED ELONGATED HYPOCOTYL1 Is a Key Mechanism Defining Signaling Dynamics of Phytochrome A under Red and Far-Red Light in Arabidopsis

2012-05-11T13:03:35-07:00

When young plants emerge from the soil or canopy into direct sunlight, they must rapidly adapt to the new light environment containing a higher ratio of red/far-red light. This work reveals the molecular mechanism of how the photoreceptor phyA differentially transduces red and far-red light signals to light-responsive genes for better plant survival in natural environments.

A Vacuolar {beta}-Glucosidase Homolog That Possesses Glucose-Conjugated Abscisic Acid Hydrolyzing Activity Plays an Important Role in Osmotic Stress Responses in Arabidopsis

2012-05-11T13:03:35-07:00

This work presents evidence for a novel abscisic acid production pathway involving At-BG2, a β-glucosidase, in the vacuole. This result suggests that abscisic acid is produced in multiple places by multiple pathways in response to abiotic stress.

Assembly of Synthetic Locked Phycocyanobilin Derivatives with Phytochrome in Vitro and in Vivo in Ceratodon purpureus and Arabidopsis

Yang, R., Nishiyama, K., Kamiya, A., Ukaji, Y., Inomata, K., Lamparter, T. — 2012-05-11T13:03:35-07:00

This article shows that two synthetic "locked" chromophores, termed 15ZaPCB and 15EaPCB, are incorporated into recombinant phytochrome and that feeding of 15EaPCB to the moss Ceratodon purpureus and the seed plant Arabidopsis thaliana results in an onset of phytochrome effects in darkness. Thus, the 15EaPCB phytochrome adduct mimics Pfr, the physiologically active form of phytochrome.

Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

2012-05-08T14:08:03-07:00

This work examines the reproductive phase transition in rice using laser microdissection and microarrays in addition to biochemical and genetic approaches. The results support that PAP2, a MADS box gene belonging to a grass-specific subclade of the SEP subfamily, and three AP1/FUL-like genes coordinately act in the meristem to specify the identity of the inflorescence meristem downstream of the florigen signal.

A Chloroplast Light-Regulated Oxidative Sensor for Moderate Light Intensity in Arabidopsis

Dangoor, I., Peled-Zehavi, H., Wittenberg, G., Danon, A. — 2012-05-08T14:08:02-07:00

This study identifies a regulatory oxidative pathway, comprised of thioredoxin and peroxiredoxin, in Arabidopsis thaliana chloroplasts. It shows that the pathway is used to sense photosynthetic peroxide formation under low to moderate light intensity and proposes that the oxidative signal adjusts the photosynthetic linear electron flow to fluctuating environmental conditions.

The Golgi-Localized Arabidopsis Endomembrane Protein12 Contains Both Endoplasmic Reticulum Export and Golgi Retention Signals at Its C Terminus

Gao, C., Yu, C. K. Y., Qu, S., San, M. W. Y., Li, K. Y., Lo, S. W., Jiang, L. — 2012-05-08T14:08:02-07:00

A Golgi-localized polytopic integral membrane protein, EMP12, was shown to contain an endoplasmic reticulum export signal (FVY) and a Golgi retention signal (KXE/D) that interact with COPII and COPI subunits, respectively, in Arabidopsis cells. These sorting signals are highly conserved in all plant EMP isoforms and, thus, likely represent a general mechanism for EMP targeting in plant cells.

The ARP2/3 Complex Mediates Guard Cell Actin Reorganization and Stomatal Movement in Arabidopsis

2012-05-08T14:08:02-07:00

This study reports the isolation of hsr3, an allele of the Arabidopsis ARPC2 locus encoding a subunit of the ARP2/3 complex involved in the regulation of the actin cytoskeleton. In hsr3, reduced abscisic acid–induced stomatal closure is associated with failure of actin reassembly, indicating that modulation of the cytoskeleton through the ARP2/3 complex is crucial for stomatal regulation.

Mechanisms and Concepts Paving the Way towards a Complete Transport Cycle of Plant Vacuolar Sorting Receptors

Lousa, C. D. M., Gershlick, D. C., Denecke, J. — 2012-05-08T14:08:03-07:00

Delivery of proteins to the lytic vacuole in plants is a complex cascade of selective interactions that specifically excludes residents of the endoplasmic reticulum and secreted proteins. Vacuolar transport must be highly efficient to avoid mistargeting of hydrolytic enzymes to locations where they could be harmful. While plant vacuolar sorting signals have been well described for two decades, it is only during the last 5 years that a critical mass of data was gathered that begins to reveal how vacuolar sorting receptors (VSRs) may complete a full transport cycle. Yet, the field is far from reaching a consensus regarding the organelles that could be involved in vacuolar sorting, their potential biogenesis, and the ultimate recycling of membranes and protein machinery that maintain this pathway. This review will highlight the important landmarks in our understanding of VSR function and compare recent transport models that have been proposed so that an emerging picture of plant vacuolar sorting mechanisms can be drawn.

Operon flv4-flv2 Provides Cyanobacterial Photosystem II with Flexibility of Electron Transfer

2012-05-08T14:08:03-07:00

This work shows that the flv4-flv2 operon provides many β-cyanobacteria with a so far unknown photoprotection mechanism that evolved in parallel with oxygen-evolving photosystem II

The Gatsby Plant Science Summer School: Inspiring the Next Generation of Plant Science Researchers

Levesley, A., Jopson, J., Knight, C. — 2012-05-08T14:08:02-07:00

We provide evidence from a 5-year study to show that a single concerted effort at the start of undergraduate study can have a clear and lasting effect on the attitudes of students toward plant science. Attendance at a week-long residential plant science summer school in the first year of an undergraduate degree resulted in many students changing courses to include more plant science and increased numbers of graduates selecting plant-based PhDs. The evidence shows that the Gatsby Plant Science Summer School has increased the pool of high-quality plant science related PhD applicants in the UK and has had a positive impact on students’ career aspirations. The results are discussed within the context of enhancing the pipeline of future plant scientists and reversing the decline of this vulnerable and strategically important subject relevant to addressing food security and other major global challenges. We have shown that a single well-designed and timely intervention can influence future student behavior and as such offers a framework of potential use to other vulnerable disciplines.

Arabidopsis Microtubule-Associated Protein MAP65-3 Cross-Links Antiparallel Microtubules toward Their Plus Ends in the Phragmoplast via Its Distinct C-Terminal Microtubule Binding Domain

Ho, C.-M. K., Lee, Y.-R. J., Kiyama, L. D., Dinesh-Kumar, S. P., Liu, B. — 2012-05-08T14:08:02-07:00

MAP65-3 contains a distinct C-terminal microtubule binding site that is not shared by other Arabidopsis MAP-65 proteins. This study demonstrates that this C-terminal extension determines the protein’s specific function in cross-linking antiparallel microtubules in the phragmoplast midzone.

Identification of a Novel Maize Protein Important for Paramutation at the purple plant1 Locus

Mach, J. — 2012-05-04T11:53:25-07:00

Characterization of Arabidopsis NEET Reveals an Ancient Role for NEET Proteins in Iron Metabolism

2012-05-04T11:53:25-07:00

This work describes biochemical, biophysical, structural, and genetic analyses of an Arabidopsis homolog of mammalian NEET proteins, which are involved in a wide range of cellular processes. It finds that At-NEET plays a key role in plant development, senescence, reactive oxygen species homeostasis, and iron metabolism.

required to maintain repression2 Is a Novel Protein That Facilitates Locus-Specific Paramutation in Maize

2012-05-04T11:53:25-07:00

This research identifies a previously unknown clade of plant-specific proteins whose founding member is shown to facilitate meiotically heritable trans-homologue repression in maize. The findings highlight a diversification of epigenomic control mechanisms in higher plants.

Biochemical and Structural Characterization of the Arabidopsis Bifunctional Enzyme Dethiobiotin Synthetase-Diaminopelargonic Acid Aminotransferase: Evidence for Substrate Channeling in Biotin Synthesis

Cobessi, D., Dumas, R., Pautre, V., Meinguet, C., Ferrer, J.-L., Alban, C. — 2012-05-04T11:53:24-07:00

This article presents biochemical, kinetic, and structural characterizations of a bifunctional enzyme that catalyzes both the antepenultimate and the penultimate steps of biotin (vitamin B8) synthesis in Arabidopsis. This work shows that the intermediate substrate of the overall reaction is channeled between both distant active sites, probably through a polar trench at the surface of the enzyme.

The Fanconi Anemia Ortholog FANCM Ensures Ordered Homologous Recombination in Both Somatic and Meiotic Cells in Arabidopsis

2012-04-30T07:23:01-07:00

Arabidopsis FANCM, a homolog of human FANCM, is involved in the suppression of somatic homologous recombination. Here, it is shown that At-FANCM also plays a key role in meiosis, as it ensures the controlled formation of genetic exchange by suppressing erroneous interactions between parental genomes and by controlling meiotic crossover formation between homologs.

CDKF;1 and CDKD Protein Kinases Regulate Phosphorylation of Serine Residues in the C-Terminal Domain of Arabidopsis RNA Polymerase II

Hajheidari, M., Farrona, S., Huettel, B., Koncz, Z., Koncz, C. — 2012-04-30T07:23:00-07:00

This work identifies the roles of Arabidopsis CDKF;1 and CDKD protein kinases in the regulation of position-specific Ser phosphorylation of RNA polymerase II C-terminal domain (RNAPII CTD) and demonstrates that changes in the deposition of RNAPII CTD phosphoserine marks alter cotranscriptional processing and stability of a set of small RNAs and transcripts involved in their biogenesis.

NAP1 Family Histone Chaperones Are Required for Somatic Homologous Recombination in Arabidopsis

Gao, J., Zhu, Y., Zhou, W., Molinier, J., Dong, A., Shen, W.-H. — 2012-04-24T11:56:48-07:00

This work examines two types of histone chaperones and shows that depletion of NAP1 leads to decreased somatic homologous recombination (HR), but depletion of CAF-1 leads to increased HR and telomere shortening, which are NAP1 dependent and NAP1 independent, respectively. These results highlight distinct nucleosome assembly/disassembly pathways in regulation of genome stability and variability.

Alternative Oxidases (AOX1a and AOX2) Can Functionally Substitute for Plastid Terminal Oxidase in Arabidopsis Chloroplasts

Fu, A., Liu, H., Yu, F., Kambakam, S., Luan, S., Rodermel, S. — 2012-04-24T11:56:47-07:00

Plastid terminal oxidase (PTOX) is distantly similar to alternative oxidases (AOXs). Both reengineering of AOX1a into the plastid and overexpression of AOX2 are able to rescue the variegation phenotype of the Arabidopsis immutans mutant, which lacks PTOX. We propose that AOXs function in chloroplasts to supplement PTOX activity during early events in chloroplast biogenesis.

Lotus japonicus E3 Ligase SEVEN IN ABSENTIA4 Destabilizes the Symbiosis Receptor-Like Kinase SYMRK and Negatively Regulates Rhizobial Infection

Den Herder, G., Yoshida, S., Antolin-Llovera, M., Ried, M. K., Parniske, M. — 2012-04-24T11:56:48-07:00

This work shows that an E3 ubiquitin ligase interacts with, relocalizes, and negatively impacts the abundance of the symbiosis receptor kinase SYMRK. Our results implicate SINA E3 ligases in the turnover of SYMRK and suggest a clearance mechanism involving uptake from the plasma membrane.

Arabidopsis Annexin1 Mediates the Radical-Activated Plasma Membrane Ca2+- and K+-Permeable Conductance in Root Cells

2012-04-20T12:07:33-07:00

The Arabidopsis thaliana root cell plasma membrane contains a calcium channel that is activated by oxidizing conditions and operates in cell growth. It was identified here as the most abundant member of the Arabidopsis annexins. These are soluble proteins that can undergo conditional attachment to or insertion into membranes.

Secretory Pathway Research: The More Experimental Systems the Better

2012-04-20T12:07:33-07:00

Transient gene expression, in plant protoplasts or specific plant tissues, is a key technique in plant molecular cell biology, aimed at exploring gene products and their modifications to examine functional subdomains, their interactions with other biomolecules, and their subcellular localization. Here, we highlight some of the major advantages and potential pitfalls of the most commonly used transient gene expression models and illustrate how ectopic expression and the use of dominant mutants can provide insights into protein function.

Disruption of OPR7 and OPR8 Reveals the Versatile Functions of Jasmonic Acid in Maize Development and Defense

2012-04-20T12:07:33-07:00

Maize OPR7 and OPR8 are redundant paralogs responsible for JA biosynthesis. Double mutation in both genes revealed diverse roles of JA in developmental and defense processes, including regulation of sex determination and female organ outgrowth, anthocyanin pigmentation, leaf senescence, and immunity against insects and pathogens.

Emergent Decarboxylase Activity and Attenuation of {alpha}/{beta}-Hydrolase Activity during the Evolution of Methylketone Biosynthesis in Tomato

2012-04-20T12:07:33-07:00

Methylketones are insecticidal compounds that accumulate in certain plants as defense against herbivorous pests. Methylketone biosynthesis is a two-step process within the plant, with the second step, decarboxylation of 3-keto acids, catalyzed by Methylketone Synthase1 (MKS1). This study focuses on understanding the enzymatic mechanism of MKS1, which differs from proteins of the same structural class.

Oxylipins and Plant Palatability

Bertoni, G. — 2012-04-18T13:01:31-07:00

Mitogen-Activated Protein Kinase Signaling in Plant-Interacting Fungi: Distinct Messages from Conserved Messengers

Hamel, L.-P., Nicole, M.-C., Duplessis, S., Ellis, B. E. — 2012-04-18T13:01:31-07:00

Mitogen-activated protein kinases (MAPKs) are evolutionarily conserved proteins that function as key signal transduction components in fungi, plants, and mammals. During interaction between phytopathogenic fungi and plants, fungal MAPKs help to promote mechanical and/or enzymatic penetration of host tissues, while plant MAPKs are required for activation of plant immunity. However, new insights suggest that MAPK cascades in both organisms do not operate independently but that they mutually contribute to a highly interconnected molecular dialogue between the plant and the fungus. As a result, some pathogenesis-related processes controlled by fungal MAPKs lead to the activation of plant signaling, including the recruitment of plant MAPK cascades. Conversely, plant MAPKs promote defense mechanisms that threaten the survival of fungal cells, leading to a stress response mediated in part by fungal MAPK cascades. In this review, we make use of the genomic data available following completion of whole-genome sequencing projects to analyze the structure of MAPK protein families in 24 fungal taxa, including both plant pathogens and mycorrhizal symbionts. Based on conserved patterns of sequence diversification, we also propose the adoption of a unified fungal MAPK nomenclature derived from that established for the model species Saccharomyces cerevisiae. Finally, we summarize current knowledge of the functions of MAPK cascades in phytopathogenic fungi and highlight the central role played by MAPK signaling during the molecular dialogue between plants and invading fungal pathogens.

Fern and Lycophyte Guard Cells Do Not Respond to Endogenous Abscisic Acid

McAdam, S. A. M., Brodribb, T. J. — 2012-04-18T13:01:31-07:00

Abscisic acid (ABA) is widely known to regulate stomatal movement. This study shows that despite the augmentation of ABA in fern and lycophyte tissues during drought, their guard cells respond passively to plant water content and not ABA levels. Stomatal insensitivity in these basal plant lineages supports the concept that the link between ABA and stomatal control is derived in seed plants.

A Transit Peptide-Like Sorting Signal at the C Terminus Directs the Bienertia sinuspersici Preprotein Receptor Toc159 to the Chloroplast Outer Membrane

Lung, S.-C., Chuong, S. D. X. — 2012-04-18T13:01:31-07:00

This study shows that the C-terminal tail of the preprotein receptor Toc159 possesses the physicochemical and structural properties of chloroplast transit peptides. A number of fluorescent protein fusion constructs consistently demonstrated that this sorting signal is essential for the targeting of the Toc159 receptor to the chloroplast outer membrane.

Dynamic Antagonism between Phytochromes and PIF Family Basic Helix-Loop-Helix Factors Induces Selective Reciprocal Responses to Light and Shade in a Rapidly Responsive Transcriptional Network in Arabidopsis

2012-04-18T13:01:31-07:00

Genome-wide expression profiling identifies core elements of a transcriptional network that is regulated rapidly and reciprocally by light and vegetational shade signals, via a phytochrome transcription factor transduction interface. This signaling hub functions continuously to control early seedling and juvenile plant growth and development in response to the prevailing light environment.

Gene-Sharing Networks Reveal Organizing Principles of Transcriptomes in Arabidopsis and Other Multicellular Organisms

Li, S., Pandey, S., Gookin, T. E., Zhao, Z., Wilson, L., Assmann, S. M. — 2012-04-18T13:01:31-07:00

A novel computational pipeline was designed to study the distribution of gene expression levels across cell types, tissues, and organs in Arabidopsis, rice, human, and mouse. Thousands of cross-tissue gene-sharing events were identified and predicted gene functions were validated in Arabidopsis.

Augmin's Role in Microtubule Generation in Plants

Hofmann, N. R. — 2012-04-13T16:15:52-07:00

An Inducible RNA Interference System in Physcomitrella patens Reveals a Dominant Role of Augmin in Phragmoplast Microtubule Generation

2012-04-13T16:15:53-07:00

This study describes a conditional RNA interference system that enabled the knockdown of essential mitotic genes along with high-resolution live microscopy. Loss-of-function analyses of augmin and -TuRC constitute a proof of principle and provide insight into acentrosomal microtubule formation during plant mitosis.

Characterization of the Arabidopsis Augmin Complex Uncovers Its Critical Function in the Assembly of the Acentrosomal Spindle and Phragmoplast Microtubule Arrays

2012-04-13T16:15:53-07:00

This study reports the discovery of the Arabidopsis thaliana augmin complex composed of at least eight subunits, two of which are plant specific, that regulate the function of the -tubulin complex during mitosis and cytokinesis.

NADPH Thioredoxin Reductase C Is Localized in Plastids of Photosynthetic and Nonphotosynthetic Tissues and Is Involved in Lateral Root Formation in Arabidopsis

Kirchsteiger, K., Ferrandez, J., Pascual, M. B., Gonzalez, M., Cejudo, F. J. — 2012-04-13T16:15:53-07:00

NTRC functions in maintaining redox homeostasis of chloroplasts and heterotrophic plastids of Arabidopsis. Leaf-specific expression of NTRC was sufficient to restore leaf and root growth, but root-specific expression of NTRC was not. The results emphasize the function of chloroplasts not only as source of carbon and energy but also of signaling molecules for development of heterotrophic organs.

Oleic Acid-Dependent Modulation of NITRIC OXIDE ASSOCIATED1 Protein Levels Regulates Nitric Oxide-Mediated Defense Signaling in Arabidopsis

2012-04-06T12:57:36-07:00

This work shows that NITRIC OXIDE ASSOCIATED1 (NOA1) controlling nitric oxide (NO) biosynthesis is negatively regulated by oleic acid (18:1) via direct binding, leading to protease-dependent NOA1 degradation. Conversely, reductions in 18:1 lead to increased levels of NOA1, inducing NO synthesis and triggering upregulation of NO-responsive nuclear genes, thereby activating disease resistance.

Requirement of the Cytosolic Interaction between PATHOGENESIS-RELATED PROTEIN10 and LEUCINE-RICH REPEAT PROTEIN1 for Cell Death and Defense Signaling in Pepper

Choi, D. S., Hwang, I. S., Hwang, B. K. — 2012-04-06T14:44:05-07:00

This work identifies the pathogenesis-related protein10 (PR10) as an interacting partner of the leucine-rich repeat protein1 (LRR1). It shows that LRR1 expression enhances PR10-mediated cell death that is dependent on the cytoplasmic localization of the PR10-LRR1 complex.

Patterns and Evolution of Nucleotide Landscapes in Seed Plants

Serres-Giardi, L., Belkhir, K., David, J., Glemin, S. — 2012-04-06T14:44:05-07:00

Analysis of EST sequence data in more than 200 species reveals unexpected continuous variations in GC content in seed plant genomes, with several independent enrichment episodes from GC-poor and homogeneous genomes to more derived GC-rich and highly heterogeneous ones. It reveals the possible role of GC-biased gene conversion, a recombination-associated process favoring G and C bases.

Plastids Do Not Form Interconnected Networks

Farquharson, K. L. — 2012-04-03T11:59:55-07:00

De Novo Pyrimidine Nucleotide Synthesis Mainly Occurs outside of Plastids, but a Previously Undiscovered Nucleobase Importer Provides Substrates for the Essential Salvage Pathway in Arabidopsis

Witz, S., Jung, B., Furst, S., Mohlmann, T. — 2012-04-03T11:59:56-07:00

This work shows that the Nucleobase:Cation-Symporter1 family member PLUTO imports uracil, adenine, and guanine into plastids with high apparent affinity in a substrate-proton symport mode. It finds that PLUTO’s main function is to supply the essential plastidic pyrimidine salvage pathway with substrates for the formation of UMP.

CellSeT: Novel Software to Extract and Analyze Structured Networks of Plant Cells from Confocal Images

Pound, M. P., French, A. P., Wells, D. M., Bennett, M. J., Pridmore, T. P. — 2012-04-03T11:59:55-07:00

This article presents a tool to aid researchers in the analysis of confocal images. Tissue-scale structure is used to aid the segmentation of any number of cells. Additional techniques are described that can quantify the fluorescence of nuclear reporters, determine membrane protein polarity, and take many additional biologically relevant measurements.

Differential Coloring Reveals That Plastids Do Not Form Networks for Exchanging Macromolecules

2012-04-03T11:59:55-07:00

This work uses a photoconvertible protein for reappraising long-held views on interplastid connectivity via stroma-filled extensions. The findings contradict present thinking by demonstrating that each plastid is unique and does not fuse or exchange fluorescent proteins with other plastids. A strong basis for investigating plastid interactions with other cytoplasmic components is provided.

Root-Derived Oxylipins Promote Green Peach Aphid Performance on Arabidopsis Foliage

Nalam, V. J., Keeretaweep, J., Sarowar, S., Shah, J. — 2012-04-03T11:59:56-07:00

Genetic and biochemical evidence provided here indicates that roots of Arabidopsis thaliana are the source of one or more oxylipins synthesized by the LOX5-encoded lipoxygenase. This oxylipin(s) facilitates colonization of the foliage by the phloem-feeding green peach aphid (Myzus persicae Sülzer) and promotes both insect feeding from sieve elements and water consumption from the xylem.