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Frontiers | Calcium-Mediated Abiotic Stress Signaling in Roots | Plant Physiology

Roots are subjected to a range of abiotic stresses as they forage for water and nutrients. Cytosolic free calcium is a common second messenger in the signalling of abiotic stress. In addition, roots take up calcium both as a nutrient and to stimulate exocytosis in growth. For calcium to fulfil its multiple roles must require strict spatio-temporal regulation of its uptake and efflux across the plasma membrane, its buffering in the cytosol and its sequestration or release from internal stores. This prompts the question of how specificity of signaling output can be achieved against the background of calcium’s other uses. Threats to agriculture such as salinity, water availability and hypoxia are signalled through calcium. Nutrient deficiency is also emerging as a stress that is signaled through cytosolic free calcium, with progress in potassium, nitrate and boron deficiency signaling now being made. Heavy metals have the capacity to trigger or modulate root calcium signaling depending on their dose and their capacity to catalyse production of hydroxyl radicals. Mechanical stress and cold stress can both trigger an increase in root cytosolic free calcium, with the possibility of membrane deformation playing a part in initiating the calcium signal. This review addresses progress in identifying the calcium transporting proteins (particularly channels such as annexins and cyclic nucleotide-gated channels) that effect stress-induced calcium increases in roots and explores links to reactive oxygen species, lipid signalling, and the unfolded protein response.

Wilkins KA, Matthus E, Swarbreck SM, Davies JM DOI: 10.3389/fpls.2016.01296

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Nature Scientific Reports: The LIKE SEX FOUR2 regulates root development by modulating reactive oxygen species homeostasis in Arabidopsis

Nature Scientific Reports: The LIKE SEX FOUR2 regulates root development by modulating reactive oxygen species homeostasis in Arabidopsis | Science Tools | Scoop.it
Maintaining reactive oxygen species (ROS) homeostasis plays a central role in plants, and is also critical for plant root development. Threshold levels of ROS act as signals for elongation and differentiation of root cells. The protein phosphatase LIKE SEX FOUR2 (LSF2) has been reported to regulate starch metabolism in Arabidopsis, but little is known about the mechanism how LSF2 affect ROS homeostasis. Here, we identified that LSF2 function as a component modulating ROS homeostasis in response to oxidative stress and, thus regulate root development. Compared with wild type Arabidopsis, lsf2-1 mutant exhibited reduced rates of superoxide generation and higher levels of hydrogen peroxide upon oxidative stress treatments. The activities of several antioxidant enzymes, including superoxide dismutase, catalase, and ascorbate peroxidase, were also affected in lsf2-1 mutant under these oxidative stress conditions. Consequently, lsf2-1 mutant exhibited the reduced root growth but less inhibition of root hair formation compared to wild type Arabidopsis plants. Importantly, protein phosphatase LSF2 interacted with mitogen-activated protein kinase 8 (MPK8), a known component of ROS homeostasis pathways in the cytoplasm. These findings indicated the novel function of LSF2 that controls ROS homeostasis to regulate root development. Zhao P, Sokolov LN, Ye J, Tang CY, Shi J, Zhen Y, Lan W, Hong Z, Qi J, Lu GH, Pandey GK, Yang YH DOI: 10.1038/srep28683
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Nature: Three technologies that changed genetics

Nature: Three technologies that changed genetics | Science Tools | Scoop.it

Genome editing uses enzymes that are targeted to sequences of DNA to make cuts. These cuts are then repaired by the cell's machinery. This technology allows scientists to disrupt or modify genes with unprecedented precision.

By Amy Maxmen (infographic by Denis Mallet)

DOI:10.1038/528S2a

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Long non-coding RNAs and their functions in plants

Long non-coding RNAs and their functions in plants | Science Tools | Scoop.it

Eukaryotic genomes encode thousands of long noncoding RNAs (lncRNAs), which play important roles in essential biological processes. Although lncRNAs function in the nuclear and cytoplasmic compartments, most of them occur in the nucleus, often in association with chromatin. Indeed, many lncRNAs have emerged as key regulators of gene expression and genome stability. Emerging evidence also suggests that lncRNAs may contribute to the organization of nuclear domains. This review briefly summarizes the major types of eukaryotic lncRNAs and provides examples of their mechanisms of action, with focus on plant lncRNAs, mainly in Arabidopsis thaliana, and describes current advances in our understanding of the mechanisms of lncRNA action and the roles of lncRNAs in RNA-dependent DNA methylation and in the regulation of flowering time.
JA Chekanova
DOI: 10.1016/j.pbi.2015.08.003

 

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Plant J: D-Root: a system to cultivate plants with the root in darkness or under different light conditions

In nature roots grow in darkness and in opposite direction from light (negative phototropism). However, most current research in root biology has been done growing the root system in the presence of light. Here, we have engineered a device, called Dark-Root (D-Root), to grow plants in vitro with the aerial part under in normal light/dark photoperiod while roots are in darkness or exposed to specific wavelengths or light intensity. The D-Root provides an efficient system to cultivate a large number of seedlings and to easily characterize root architecture in darkness. At the morphological level, root illumination shortens root length and promotes early emergence of lateral roots, therefore inducing root system expansion. Surprisingly, root illumination also affects shoot development, including flowering time. Our analyses also show that root illumination alters proper response to hormones or abiotic stress, such as salt or osmotic, and nutrient starvation, enhancing root growth inhibition. In conclusion, the D-Root provides a closer-to-natural growing system to assay Arabidopsis plants, and therefore its use will contribute to better understanding the mechanisms involved in root development, hormonal signaling and response to stress.
Silva-Navas J, Moreno-Risueno MA, Manzano C,  Pallero-Baena M, Navarro-Neila S, Téllez-Robledo B, Garcia-Mina JM, Baigorri R, Gallego FJ, del Pozo JC
DOI: 10.1111/tpj.12998

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Cancer Biology & Therapy: Strigolactone analogues act as new anti-cancer agents in inhibition of breast cancer in xenograft model

Strigolactones (SLs) are a novel class of plant hormones. Previously, we found that analogues of SLs induce growth arrest and apoptosis in breast cancer cell lines. These compounds also inhibited the growth of breast cancer stem cell enriched-mammospheres with increased potency. Furthermore, strigolactone analogues inhibited growth and survival of colon, lung, prostate, melanoma, osteosarcoma and leukemia cancer cell lines. To further examine the anti-cancer activity of SLs in vivo, we have examined their effects on growth and viability of MDA-MB-231 tumor xenografts model either alone or in combination with paclitaxel. We show that strigolactone act as new anti-cancer agents in inhibition of breast cancer in xenograft model. In addition we show that SLs affect the integrity of the microtubule network and therefore may inhibit the migratory phenotype of the highly invasive breast cancer cell lines that were examined.
Mayzlish-Gati E1, Laufer D, Shaknof J, Sananes A, Bier A, Ben-Harosh S, Belausov E, Grivas CF, Johnson MD, Yarden RI, Artuso E, Levi O, Genin O, Prandi C, Halaila I, Pines M, Kapulnik Y, Koltai H.
DOI: 10.1080/15384047.2015.1070982

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J Exp Bot: RootGraph: a graphic optimization tool for automated image analysis of plant roots

This paper outlines a numerical scheme for accurate, detailed, and high-throughput image analysis of plant roots. In contrast to existing root image analysis tools that focus on root system-average traits, a novel, fully automated and robust approach for the detailed characterization of root traits, based on a graph optimization process is presented. The scheme, firstly, distinguishes primary roots from lateral roots and, secondly, quantifies a broad spectrum of root traits for each identified primary and lateral root. Thirdly, it associates lateral roots and their properties with the specific primary root from which the laterals emerge. The performance of this approach was evaluated through comparisons with other automated and semi-automated software solutions as well as against results based on manual measurements. The comparisons and subsequent application of the algorithm to an array of experimental data demonstrate that this method outperforms existing methods in terms of accuracy, robustness, and the ability to process root images under high-throughput conditions.
Cai J, Zeng Z, Connor JN, Huang CY, Melino V, Kumar PJ, Miklavcic SJ
DOI: 10.1093/jxb/erv359

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J Exp Bot: Root phenotyping: from component trait in the lab to breeding

In the last decade cheaper and faster sequencing methods have resulted in an enormous increase in genomic data. High throughput genotyping, genotyping by sequencing and genomic breeding are becoming a standard in plant breeding. As a result, the collection of phenotypic data is increasingly becoming a limiting factor in plant breeding. Genetic studies on root traits are being hampered by the complexity of these traits and the inaccessibility of the rhizosphere. With an increasing interest in phenotyping, breeders and scientists try to overcome these limitations, resulting in impressive developments in automated phenotyping platforms. Recently, many such platforms have been thoroughly described, yet their efficiency to increase genetic gain often remains undiscussed. This efficiency depends on the heritability of the phenotyped traits as well as the correlation of these traits with agronomically relevant breeding targets. This review provides an overview of the latest developments in root phenotyping and describes the environmental and genetic factors influencing root phenotype and heritability. It also intends to give direction to future phenotyping and breeding strategies for optimizing root system functioning. A quantitative framework to determine the efficiency of phenotyping platforms for genetic gain is described. By increasing heritability, managing effects caused by interactions between genotype and environment and by quantifying the genetic relation between traits phenotyped in platforms and ultimate breeding targets, phenotyping platforms can be utilized to their maximum potential.
Kuijken RC, Van Eeuwijk FA, Marcelis LF, Bouwmeester HJ.
DOI: 10.1093/jxb/erv239

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Plant physiol: Interaction between Glucose and Brassinosteroid during the Regulation of Lateral Root Development in Arabidopsis

Glucose (Glc) plays a fundamental role in regulating lateral root (LR) development as well as LR emergence. In this study, we show that brassinosteroid (BR) signaling works downstream of Glc in controlling LR production/emergence in Arabidopsis (Arabidopsis thaliana) seedlings. Glc and BR can promote LR emergence at lower concentrations, while at higher concentrations, both have an inhibitory effect. The BR biosynthesis and perception mutants showed highly reduced numbers of emerged LRs at all the Glc concentrations tested. BR signaling works downstream of Glc signaling in regulating LR production, as in the glucose insensitive2-1brassinosteroid insensitive1 double mutant, Glc-induced LR production/emergence was severely reduced. Differential auxin distribution via the influx carriers AUXIN RESISTANT1/LIKE AUXIN RESISTANT1-3 and the efflux carrier PIN-FORMED2 plays a central role in controlling LR production in response to Glc and BR. Auxin signaling components AUXIN RESISTANT2,3 and SOLITARY ROOT act downstream of Glc and BR. AUXIN RESPONSE FACTOR7/19 work farther downstream and control LR production by regulating the expression of LATERAL ORGAN BOUNDARIES-DOMAIN29 and EXPANSIN17 genes. Increasing light flux could also mimic the Glc effect on LR production/emergence. However, increased light flux could not affect LR production in those BR and auxin signaling mutants that were defective for Glc-induced LR production. Altogether, our study suggests that, under natural environmental conditions, modulation of endogenous sugar levels can manipulate root architecture for optimized development by altering its nutrient/water uptake as well as its anchorage capacity.
Gupta A, Singh M, Laxmi A
DOI: 10.1104/pp.114.256313

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Nature Comm: Translational diffusion of hydration water correlates with functional motions in folded and intrinsically disordered proteins


Hydration water is the natural matrix of biological macromolecules and is essential for their activity in cells. The coupling between water and protein dynamics has been intensively studied, yet it remains controversial. Here we combine protein perdeuteration, neutron scattering and molecular dynamics simulations to explore the nature of hydration water motions at temperatures between 200 and 300 K, across the so-called protein dynamical transition, in the intrinsically disordered human protein tau and the globular maltose binding protein. Quasi-elastic broadening is fitted with a model of translating, rotating and immobile water molecules. In both experiment and simulation, the translational component markedly increases at the protein dynamical transition (around 240 K), regardless of whether the protein is intrinsically disordered or folded. Thus, we generalize the notion that the translational diffusion of water molecules on a protein surface promotes the large-amplitude motions of proteins that are required for their biological activity.
Schirò G, Fichou Y, Gallat FX, Wood K, Gabel F, Moulin M, Härtlein M, Heyden M, Colletier JP, Orecchini A, Paciaroni A, Wuttke J, Tobias DJ, Weik M.
DOI: 10.1038/ncomms7490.

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Biochimica et Biophysica Acta (BBA): Calcium is an organizer of cell polarity in plants

Highlights
• Calcium signals hallmark polarity.
• Calcium coordinates differential membrane trafficking.
• Calcium controls cytoskeleton dynamics.
• Calcium signaling is interconnected with ROP polarization.
• Calcium integrates mechanical polarity signals.
Abstract
Cell polarity is a fundamental property of pro- and eukaryotic cells. It is necessary for coordination of cell division, cell morphogenesis and signaling processes. How polarity is generated and maintained is a complex issue governed by interconnected feed-back regulations between small GTPase signaling and membrane tension-based signaling that controls membrane trafficking, and cytoskeleton organization and dynamics. Here, we will review the potential role for calcium as a crucial signal that connects and coordinates the respective processes during polarization processes in plants. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.
Himschoot E, Beeckman T, Frimlc J, Vanneste S
DOI: 10.1016/j.bbamcr.2015.02.017

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J Exp Bot: Strigolactones contribute to shoot elongation and to the formation of leaf margin serrations in Medicago truncatula R108

Strigolactones were recently identified as a new class of plant hormones involved in the control of shoot branching. The characterization of strigolactone mutants in several species has progressively revealed their contribution to several other aspects of development in roots and shoots. In this article, we characterize strigolactone-deficient and strigolactone-insensitive mutants of the model legume Medicago truncatula for aerial developmental traits. The most striking mutant phenotype observed was compact shoot architecture. In contrast with what was reported in other species, this could not be attributed to enhanced shoot branching, but was instead due to reduced shoot elongation. Another notable feature was the modified leaf shape in strigolactone mutants: serrations at the leaf margin were smaller in the mutants than in wild-type plants. This phenotype could be rescued in a dose-dependent manner by exogenous strigolactone treatments of strigolactone-deficient mutants, but not of strigolactone-insensitive mutants. Treatment with the auxin transport inhibitor N-1-naphthylphtalamic acid resulted in smooth leaf margins, opposite to the effect of strigolactone treatment. The contribution of strigolactones to the formation of leaf serrations in M. truncatula R108 line represents a novel function of these hormones, which has not been revealed by the analysis of strigolactone mutants in other species.
Lauressergues D, André O, Peng J, Wen J, Chen R, Ratet P, Tadege M, Mysore K S, Rochange S F.
DOI: 10.1093/jxb/eru471

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J Exp Bot: ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1) is required for cell production, patterning, and morphogenesis in root development

J Exp Bot: ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1) is required for cell production, patterning, and morphogenesis in root development | Science Tools | Scoop.it

 ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1/SDG27), a known regulator of flower development, encodes a H3K4histone methyltransferase that maintains a number of genes in an active state. In this study, the role of ATX1 in root development was evaluated. The loss-of-function mutant atx1-1 was impaired in primary root growth. The data suggest that ATX1 controls root growth by regulating cell cycle duration, cell production, and the transition from cell proliferation in the root apical meristem (RAM) to cell elongation. In atx1-1, the quiescent centre (QC) cells were irregular in shape and more expanded than those of the wild type. This feature, together with the atypical distribution of T-divisions, the presence of oblique divisions, and the abnormal cell patterning in the RAM, suggests a lack of coordination between cell division and cell growth in the mutant. The expression domain of QC-specific markers was expanded both in the primary RAM and in the developing lateral root primordia of atx1-1 plants. These abnormalities were independent of auxin-response gradients. ATX1 was also found to be required for lateral root initiation, morphogenesis, and emergence. The time from lateral root initiation to emergence was significantly extended in the atx1-1 mutant. Overall, these data suggest that ATX1 is involved in the timing of root development, stem cell niche maintenance, and cell patterning during primary and lateral root development. Thus, ATX1 emerges as an important player in root system architecture.
Napsucialy-Mendivil S, Alvarez-Venegas R, Shishkova1 S, Dubrovsky1 JG
doi: 10.1093/jxb/eru355

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Education: How to win at evolution : Nature : Nature Research

Education: How to win at evolution : Nature : Nature Research | Science Tools | Scoop.it

Stuart West and helpers compare the cut and thrust of three games that explore life's greatest competition.

DOI: 10.1038/528192a

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Curr Op Plant Biol: The biosensor toolbox for plant developmental biology

Curr Op Plant Biol: The biosensor toolbox for plant developmental biology | Science Tools | Scoop.it

The biosensor toolbox for plant developmental biology
Highlights
• Plant development is linked to metabolic state and environmental conditions.
• Biosensors and reporters can reveal dynamics of nutrients, metabolites and signaling molecules in vivo.
• Novel sensor designs allow combinatorial measurements to unravel metabolic networks during development.
Plant development is highly interconnected with the metabolic state of tissues and cells. Current research efforts focus on the identification of the links and mechanisms that govern the interplay between metabolic and gene-regulatory networks. Genetically encoded sensors that allow detection of small molecules in vivo and at high spatio-temporal resolution promise to be the tools of choice for quantifying and visualizing the dynamics of metabolite flux in plants. We provide an overview about current approaches to measure signaling molecules, such as hormones, calcium and sugars, as well as for monitoring the metabolic state via energy equivalents and pH. Biosensors show great potential to address questions of plant development but there are also limitations where alternative approaches are needed.
Uslu VV, Grossmann G
DOI: 10.1016/j.pbi.2015.12.001

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Current Biology: The Cyclic Nucleotide-Gated Channel CNGC14 Regulates Root Gravitropism in Arabidopsis thaliana: Current Biology

Highlights
•CNGC14 regulates auxin- and gravity-induced Ca2+ signaling in Arabidopsis roots
•cngc14 mutants exhibit delayed growth responses to auxin and gravitropic stimulation
•Rapid auxin-induced inhibition of Arabidopsis root growth requires Ca2+ signaling
Summary
In plant roots, auxin inhibits cell expansion, and an increase in cellular auxin levels on the lower flanks of gravistimulated roots suppresses growth and thereby causes downward bending. These fundamental features of root growth responses to auxin were first described over 80 years ago [ 1 ], but our understanding of the underlying molecular mechanisms has remained scant. Here, we report that CYCLIC NUCLEOTIDE-GATED CHANNEL 14 (CNGC14) is essential for the earliest phase of auxin-induced ion signaling and growth inhibition in Arabidopsis roots. Using a fluorescence-imaging-based genetic screen, we found that cngc14 mutants exhibit a complete loss of rapid Ca2+ and pH signaling in response to auxin treatment. Similarly impaired ion signaling was observed upon gravistimulation. We further developed a kinematic analysis approach to study dynamic root growth responses to auxin at high spatiotemporal resolution. These analyses revealed that auxin-induced growth inhibition and gravitropic bending are significantly delayed in cngc14 compared to wild-type roots, where auxin suppresses cell expansion within 1 min of treatment. Finally, we demonstrate that auxin-induced cytosolic Ca2+ changes are required for rapid growth inhibition. Our results support a direct role for CNGC14-dependent Ca2+ signaling in regulating the early posttranscriptional phase of auxin growth responses in Arabidopsis roots.
Shih HW, DePew C.L, Miller N.D, Monshausen G.B
DOI: 10.1016/j.cub.2015.10.025

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Curr Op Plant Biol: Suberization—the second life of an endodermal cell

Curr Op Plant Biol: Suberization—the second life of an endodermal cell | Science Tools | Scoop.it

• The root endodermis undergoes two states of differentiation, Casparian strip formation and suberization.
• Suberin is a hydrophobic secondary cell wall with a function distinct from Casparian strips.
• Passage cells remain unsuberized and are thought to be entry points in mature endodermis.
• Endodermal suberization regulates transport of water and nutrients and responds to (a)biotic stresses.
Andersen TG, Barberon M, Geldner N
DOI: 10.1016/j.pbi.2015.08.004

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Plant Phys: Strigolactone Hormones and Their Stereoisomers Signal through Two Related Receptor Proteins to Induce Different Physiological Responses in Arabidopsis

Two α/β-fold hydrolases, KARRIKIN INSENSITIVE2 (KAI2) and Arabidopsis thaliana DWARF14 (AtD14), are necessary for responses to karrikins (KARs) and strigolactones (SLs) in Arabidopsis (Arabidopsis thaliana). Although KAI2 mediates responses to KARs and some SL analogs, AtD14 mediates SL but not KAR responses. To further determine the specificity of these proteins, we assessed the ability of naturally occurring deoxystrigolactones to inhibit Arabidopsis hypocotyl elongation, regulate seedling gene expression, suppress outgrowth of secondary inflorescences, and promote seed germination. Neither 5-deoxystrigol nor 4-deoxyorobanchol was active in KAI2-dependent seed germination or hypocotyl elongation, but both were active in AtD14-dependent hypocotyl elongation and secondary shoot growth. However, the nonnatural enantiomer of 5-deoxystrigol was active through KAI2 in growth and gene expression assays. We found that the four stereoisomers of the SL analog GR24 had similar activities to their deoxystrigolactone counterparts. The results suggest that AtD14 and KAI2 exhibit selectivity to the butenolide D ring in the 2′R and 2′S configurations, respectively. However, we found, for nitrile-debranone (CN-debranone, a simple SL analog), that the 2′R configuration is inactive but that the 2′S configuration is active through both AtD14 and KAI2. Our results support the conclusion that KAI2-dependent signaling does not respond to canonical SLs. Furthermore, racemic mixtures of chemically synthesized SLs and their analogs, such as GR24, should be used with caution because they can activate responses that are not specific to naturally occurring SLs. In contrast, the use of specific stereoisomers might provide valuable information about the specific perception systems operating in different plant tissues, parasitic weed seeds, and arbuscular mycorrhizae.
Scaffidi A, Waters MT, Sun YK, Skelton BW, DixonKW, Ghisalberti EL, Flematti GR, Smith SM
DOI:  10.1104/pp.114.240036

 

 

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Science, Plant Evolution: Convergent evolution of strigolactone perception enabled host detection in parasitic plants

Obligate parasitic plants in the Orobanchaceae germinate after sensing plant hormones, strigolactones, exuded from host roots. In Arabidopsis thaliana, the α/β-hydrolase D14 acts as a strigolactone receptor that controls shoot branching, whereas its ancestral paralog, KAI2, mediates karrikin-specific germination responses. We observed that KAI2, but not D14, is present at higher copy numbers in parasitic species than in nonparasitic relatives. KAI2 paralogs in parasites are distributed into three phylogenetic clades. The fastest-evolving clade, KAI2d, contains the majority of KAI2 paralogs. Homology models predict that the ligand-binding pockets of KAI2d resemble D14. KAI2d transgenes confer strigolactone-specific germination responses to Arabidopsis thaliana. Thus, the KAI2 paralogs D14 and KAI2d underwent convergent evolution of strigolactone recognition, respectively enabling developmental responses to strigolactones in angiosperms and host detection in parasites.
Conn CE, Bythell-Douglas R, Neumann D, Yoshida S, Whittington B, Westwood JH, Shirasu K, Bond CS, Dyer KA, Nelson DC
DOI: 10.1126/science.aab1140.

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Scientific Reports : iMSRC: converting a standard automated microscope into an intelligent screening platform

Scientific Reports : iMSRC: converting a standard automated microscope into an intelligent screening platform | Science Tools | Scoop.it
Coline Balzergue's insight:

Microscopy in the context of biomedical research is demanding new tools to automatically detect and capture objects of interest. The few extant packages addressing this need, however, have enjoyed limited uptake due to complexity of use and installation. To overcome these drawbacks, we developed iMSRC, which combines ease of use and installation with high flexibility and enables applications such as rare event detection and high-resolution tissue sample screening, saving time and resources.
Carro A, Perez-Martinez M, Soriano J, Pisano D G & Megias D.
DOI:10.1038/srep10502

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Plant physiol: Identification of the Primary Lesion of Toxic Aluminum in Plant Roots

Plant physiol: Identification of the Primary Lesion of Toxic Aluminum in Plant Roots | Science Tools | Scoop.it

Despite the rhizotoxicity of aluminum (Al) being identified over 100 years ago, there is still no consensus regarding the mechanisms whereby root elongation rate is initially reduced in the approximately 40% of arable soils worldwide that are acidic. We used high-resolution kinematic analyses, molecular biology, rheology, and advanced imaging techniques to examine soybean (Glycine max) roots exposed to Al. Using this multidisciplinary approach, we have conclusively shown that the primary lesion of Al is apoplastic. In particular, it was found that 75 µm Al reduced root growth after only 5 min (or 30 min at 30 µm Al), with Al being toxic by binding to the walls of outer cells, which directly inhibited their loosening in the elongation zone. An alteration in the biosynthesis and distribution of ethylene and auxin was a second, slower effect, causing both a transient decrease in the rate of cell elongation after 1.5 h but also a longer term gradual reduction in the length of the elongation zone. These findings show the importance of focusing on traits related to cell wall composition as well as mechanisms involved in wall loosening to overcome the deleterious effects of soluble Al.
Kopittke PM, Moore KL, Lombi E, Gianoncelli A, Ferguson BJ, Blamey FP, Menzies NW, Nicholson TM, McKenna BA, Wang P, Gresshoff PM, Kourousias G, Webb RI, Green K, Tollenaere A.
DOI: 10.1104/pp.114.253229

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Nature: The future of the postdoc

Nature: The future of the postdoc | Science Tools | Scoop.it

There is a growing number of postdocs and few places in academia for them to go. But change could be on the way.
Powell K
doi:10.1038/520144a

 

 

Coline Balzergue's insight:

I wanna be a Superdoc

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Nature: Primary transcripts of microRNAs encode regulatory peptides

MicroRNAs (miRNAs) are small regulatory RNA molecules that inhibit the expression of specific target genes by binding to and cleaving their messenger RNAs or otherwise inhibiting their translation into proteins1. miRNAs are transcribed as much larger primary transcripts (pri-miRNAs), the function of which is not fully understood. Here we show that plant pri-miRNAs contain short open reading frame sequences that encode regulatory peptides. The pri-miR171b of Medicago truncatula and the pri-miR165a of Arabidopsis thaliana produce peptides, which we term miPEP171b and miPEP165a, respectively, that enhance the accumulation of their corresponding mature miRNAs, resulting in downregulation of target genes involved in root development. The mechanism of miRNA-encoded peptide (miPEP) action involves increasing transcription of the pri-miRNA. Five other pri-miRNAs of A. thaliana and M. truncatula encode active miPEPs, suggesting that miPEPs are widespread throughout the plant kingdom. Synthetic miPEP171b and miPEP165a peptides applied to plants specifically trigger the accumulation of miR171b and miR165a, leading to reduction of lateral root development and stimulation of main root growth, respectively, suggesting that miPEPs might have agronomical applications.
Lauressergues D, Couzigou JM, San Clemente H, Martinez Y, Dunand C, Bécard G, Combier JP
DOI: 10.1038/nature14346

 

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The Use of Mitochondria-Targeted Endonucleases to Manipulate mtDNA - Methods Enzymol.

The Use of Mitochondria-Targeted Endonucleases to Manipulate mtDNA - Methods Enzymol. | Science Tools | Scoop.it

Bacman et al, 2014

For more than a decade, mitochondria-targeted nucleases have been used to promote double-strand breaks in the mitochondrial genome. This was done in mitochondrial DNA (mtDNA) homoplasmic systems, where all mtDNA molecules can be affected, to create models of mitochondrial deficiencies. Alternatively, they were also used in a heteroplasmic model, where only a subset of the mtDNA molecules were substrates for cleavage. The latter approach showed that mitochondrial-targeted nucleases can reduce mtDNA haplotype loads in affected tissues, with clear implications for the treatment of patients with mitochondrial diseases. In the last few years, designer nucleases, such as ZFN and TALEN, have been adapted to cleave mtDNA, greatly expanding the potential therapeutic use. This chapter describes the techniques and approaches used to test these designer enzymes.


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