816 research outputs found
The life and death of a plant cell
No full textLike all eukaryotic organisms, plants possess an innate program for controlled cellular demise termed programmed cell death (PCD). Despite the functional conservation of PCD across broad evolutionary distances, an understanding of the molecular machinery underpinning this fundamental program in plants remains largely elusive. As in mammalian PCD, the regulation of plant PCD is critical to development, homeostasis, and proper responses to stress. Evidence is emerging that autophagy is key to the regulation of PCD in plants and that it can dictate the outcomes of PCD execution under various scenarios. Here, we provide a broad and comparative overview of PCD processes in plants, with an emphasis on stress-induced PCD. We also discuss the implications of the paradox that is functional conservation of apoptotic hallmarks in plants in the absence of core mammalian apoptosis regulators, what that means, and whether an equivalent form of death occurs in plants
Cell death control: the interplay of apoptosis and autophagy in the pathogenicity of Sclerotinia sclerotiorum.
No full textProgrammed cell death is characterized by a cascade of tightly controlled events that culminate in the orchestrated death of the cell. In multicellular organisms autophagy and apoptosis are recognized as two principal means by which these genetically determined cell deaths occur. During plant-microbe interactions cell death programs can mediate both resistant and susceptible events. Via oxalic acid (OA), the necrotrophic phytopathogen Sclerotinia sclerotiorum hijacks host pathways and induces cell death in host plant tissue resulting in hallmark apoptotic features in a time and dose dependent manner. OA-deficient mutants are non-pathogenic and trigger a restricted cell death phenotype in the host that unexpectedly exhibits markers associated with the plant hypersensitive response including callose deposition and a pronounced oxidative burst, suggesting the plant can recognize and in this case respond, defensively. The details of this plant directed restrictive cell death associated with OA deficient mutants is the focus of this work. Using a combination of electron and fluorescence microscopy, chemical effectors and reverse genetics, we show that this restricted cell death is autophagic. Inhibition of autophagy rescued the non-pathogenic mutant phenotype. These findings indicate that autophagy is a defense response in this necrotrophic fungus/plant interaction and suggest a novel function associated with OA; namely, the suppression of autophagy. These data suggest that not all cell deaths are equivalent, and though programmed cell death occurs in both situations, the outcome is predicated on who is in control of the cell death machinery. Based on our data, we suggest that it is not cell death per se that dictates the outcome of certain plant-microbe interactions, but the manner by which cell death occurs that is crucial
Development of Glycine max Germplasm Highly Resistant to Sclerotinia sclerotiorum
No full textSclerotinia stem rot (SSR) of soybean caused by Sclerotinia sclerotiorum is a devastating disease of soybean, especially in the Upper Midwest region of the United States. To mitigate yield losses due to this disease, many control methods are available for producers, including cultural control practices, chemical control, and cultivars with quantitative resistance. However, due to there being few commercial cultivars with high levels of resistance, producers are often limited in their seed selection. The aim of this study was to develop novel conventional soybean cultivars with high levels of resistance to SSR, favorable agronomic traits, and resistance to additional economically important diseases. Initial crosses were conducted in 2016 with two different sources of SSR resistance. Across multiple generations of screening for resistance to SSR, three highly resistant soybean lines were identified as the elite lines. These elite lines were demonstrated to be highly resistant across multiple years in both greenhouse and field trials, including high levels of resistance to multiple diverse S. sclerotiorum isolates. The three selected elite lines also resulted in moderately high yields and favorable agronomic traits, such as low lodging and moderate branching, indicating their viability to be released for production. In addition to SSR resistance, these three elite lines demonstrated resistance to other economically important soybean diseases, such as frogeye leaf spot, anthracnose, Cercospora leaf blight, and brown stem rot. Overall, this work has led to three SSR-resistant soybean lines that could be useful for future breeding efforts or commercial soybean production.This article is published as Webster, Richard Wade, Megan McCaghey, Brian Mueller, Carol Groves, Febina Merlin Mathew, Asheesh Singh, Mehdi Kabbage, and Damon L. Smith. "Development of Glycine max Germplasm Highly Resistant to Sclerotinia sclerotiorum." PhytoFrontiers (2023). doi:10.1094/PHYTOFR-01-23-0009-R. Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license
Main and epistatic loci studies in soybean for Sclerotinia sclerotiorum resistance reveal multiple modes of resistance in multi-environments
No full textGenome-wide association (GWAS) and epistatic (GWES) studies along with expression studies in soybean [Glycine max (L.) Merr.] were leveraged to dissect the genetics of Sclerotinia stem rot (SSR) [caused by Sclerotinia sclerotiorum (Lib.) de Bary], a significant fungal disease causing yield and quality losses. A large association panel of 466 diverse plant introduction accessions were phenotyped in multiple field and controlled environments to: (1) discover sources of resistance, (2) identify SNPs associated with resistance, and (3) determine putative candidate genes to elucidate the mode of resistance. We report 58 significant main effect loci and 24 significant epistatic interactions associated with SSR resistance, with candidate genes involved in a wide range of processes including cell wall structure, hormone signaling, and sugar allocation related to plant immunity, revealing the complex nature of SSR resistance. Putative candidate genes [for example, PHYTOALEXIN DEFFICIENT 4 (PAD4), ETHYLENE-INSENSITIVE 3-LIKE 1 (EIL3), and ETHYLENE RESPONSE FACTOR 1 (ERF1)] clustered into salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways suggest the involvement of a complex hormonal network typically activated by both necrotrophic (ET/JA) and biotrophic (SA) pathogens supporting that S. sclerotiorum is a hemibiotrophic plant pathogen.This article is published as Moellers, Tara C., Arti Singh, Jiaoping Zhang, Jae Brungardt, Mehdi Kabbage, Daren S. Mueller, Craig R. Grau et al. "Main and epistatic loci studies in soybean for Sclerotinia sclerotiorum resistance reveal multiple modes of resistance in multi-environments." Scientific Reports 7, no. 1 (2017): 3554. doi: 10.1038/s41598-017-03695-9. Posted with permission.</p
Application of Analog Adaptive Filters for Dynamic Sensor Compensation
No full textThis paper investigates the application of analog adaptive techniques to the area of dynamic sensor compensation, of which there is little reported work in the literature. The case is illustrated by showing how the response of a load cell can be improved to speed up the process of measurement. The load cell is a sensor with an oscillatory output in which the measurand contributes to the response parameters. Thus, a compensation filter needs to track variation in measurand whereas a simple, fixed filter is only valid at one specific load value. To facilitate this investigation, computer models for the load cell and the adaptive compensation filter have been developed. To allow a practical implementation of the adaptive techniques, a novel piecewise linearization technique is proposed in order to vary a floating voltage-controlled resistor in a linear manner over a wide range. Simulation and practical results are presented, thus demonstrating the effectiveness of the proposed techniques
Amplified fragment length polymorphism in Mycosphaerella graminicola
No full textDoctor of PhilosophyDepartment of Plant PathologyWilliam W. BockusSeptoria tritici blotch caused by Mycosphaerella graminicola (anamorph Septoria tritici), is an important disease of wheat worldwide capable of reducing yields by as much as 30 to 40%. In Kansas, the disease is widespread and losses in individual fields can exceed 25%. This study examined the genetic structure of Kansas populations of M. graminicola at different spatial scales (micro-plot, macro-plot, and statewide) using amplified fragment length polymorphism (AFLP) markers. Three primer pairs were used to resolve 174 polymorphic loci from 476 isolates. The results indicated high levels of genotypic variability, which is consistent with a genetically diverse initial inoculum. Genetic identities among populations representing the three spatial scales were >98%. Tests for differentiation among populations due to population subdivision revealed that on average 97.5% of the genetic variability occurred within populations with a correspondingly high migration rate of 16 to 23 individuals per generation. We observed little evidence of linkage disequilibrium, on average, only 4.6% of locus pairs were in disequilibrium. Our results indicate that Kansas populations of M. graminicola are characterized by regular recombination, are genetically diverse, and appear to be homogenous across different spatial scales. These populations are probably components of a larger pathogen pool that is distributed at least across much of Kansas and probably the central Great Plains. Because of the frequent recombination, the risk of adaptation of Kansas populations of M. graminicola to fungicide treatments or resistance genes is high and could be dispersed very quickly, whether these new pathogenic traits occur locally through mutation or by migration from other areas
Branding the 'Beur' Author Minority Writing and the Media in France
No full textThis book reconsiders authorship by the descendants of North African immigrants to France by consulting how these authors' novels have been discussed and promoted in the national audio-visual media.Cover -- Contents -- Acknowledgements -- List of Illustrations -- 1. Authorship at a Crossroads -- 2. Mehdi Charef and the Invention of Beur Writing -- 3. Competing Visions of Minority Authorship -- 4. Eyewitness Narratives and the Creation of the Beurette -- 5. Rachid Djaïdani and the Shift from Beur to Banlieue Writing -- 6. Revising the Beurette Label -- 7. Sabri Louatah and the Collectif Qui Fait la France? -- Works Cited -- IndexThis book reconsiders authorship by the descendants of North African immigrants to France by consulting how these authors' novels have been discussed and promoted in the national audio-visual media.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
A new, 3D overlapping-sphere model of cell adhesion:
No full textCell adhesion refers to the ability of cells to make enduring and dynamic attachments to extracellular surfaces and to each other; rightly so it is a focal point of current biological research. I have designed a computational framework to model cell adhesion using a modified overlapping-sphere model. A core feature of the model is the three-dimensional representation of a cell surface that can interact mechanically with its environment. The generalization of a cell as a sphere gives our model the compactness to enable the simulations of thousands of cells, comparable to the number of cells typically encountered through small scale studies of early development and disease. Specifically, we use this computational framework to model adhesion between cells in a monolayer and a fibrous environment, cell shape change, as well as cell replication. We also include elements of cell orientation, or cell polarity, and touch on some aspects of mechanical feedback. We explore some general aspects of developmental biology as well as cancer in mammary ducts. Although we emphasize epithelial cells, which are cells that form monolayers, we also briefly consider migratory cells. The major results are that (1) Cells in a monolayer, like sheets and tubes, need to be both mobile and well-connected to adapt to mechanically stresses, (2) Cells that are not polarized do not produce a stable monolayer of cells, (3) Extracellular support, like a basement membrane, can minimize the stresses experienced at cell-cell junctions, (4) Mitosis triggered by tension can help maintain a monolayer of cells, (5) Cell shape needs to be incorporated into models to minimize undesirable stresses, (6) Our computational framework is useful to predict behavior of cells subjected to mechanical forces. As this is a new model, results are chiefly qualitative, and suggest future work in collaboration with experimentalists to verify and quantitate our results.M.S.Includes bibliographical references (p. 79-81)by Mehdi Doum
Correction: Synthesis and characterization of a new ZIF-67@MgAl 2 O 4 nanocomposite and its adsorption behaviour
No full textPublisher Copyright: © 2021 The Royal Society of Chemistry.The authors regret that an incorrect affiliation was given for co-author Mehdi Bazarganipour in the original article. The correct affiliations are as shown here. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers
RETHINKING INDUSTRIAL POLICY
No full textDespite the hold of the neoliberal orthodoxy on policy making in developing countries, industrial policy remains important for the promotion of industrial development. However, the context for the design of industrial policy has profoundly changed as a result of new rules governing international trade, the rise of global value chains and marketing networks, and other aspects of globalization. Traditionally, the case for industrial policy has been framed in terms of “market failures” but the paper argues that that is not a sufficient basis. After addressing the traditional points of criticism, an attempt is made to outline the “domains” of industrial policy in the current circumstances, especially for industrially lagging countries. As country contexts differ widely there are no satisfactory blueprints for policy making that countries can readily adopt. As in production decisions, considerable ingenuity and innovation is needed in designing policies. This is all the more necessary as the WTO rules have become increasingly stringent and the rise of international trading networks has created new barriers for young firms to enter the world market. These developments have changed the context but not the importance of policy in industrial development. The paper identifies areas where government intervention is needed and can still make a positive difference.
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