224 research outputs found

    Apoplastic and vascular defences

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    The apoplast comprises the intercellular space between cell membranes, includes the xylem, and extends to the rhizoplane and the outer surfaces of the plant. The apoplast plays roles in different biological processes including plant immunity. This highly specialised space is often the first place where pathogen recognition occurs, and this then triggers the immune response. The immune response in the apoplast involves different mechanisms that restrict pathogen infection. Among these responses, secretion of different molecules like proteases, proteins related to immunity, small RNAs and secondary metabolites play important and often additive or synergistic roles. In addition, production of reactive oxygen species occurs to cause direct deleterious effects on the pathogen as well as reinforce the plant’s immune response by triggering modifications to cell wall composition and providing additional defence signalling capabilities. The pool of available sugar in the apoplast also plays a role in immunity. These sugars can be manipulated by both interactors, pathogens gaining access to nutrients whilst the plant’s responses restrict the pathogen’s access to nutrients. In this review, we describe the latest findings in the field to highlight the importance of the apoplast in plant – pathogen interactions and plant immunity. We also indicate where new discoveries are needed

    Sources for resistance to Soil-Borne Cereal Mosaic Virus (SBCMV) among cultivated accessions of common wheat and its wild relatives

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    Relatório de estágio do mestrado em Ensino da Educação Física nos Ensinos Básico e Secundário, apresentado à Faculdade de Ciências do Desporto e Educação Física da Universidade de CoimbraO Relatório Final de Estágio insere-se no plano curricular do 2º ano do Mestrado em Ensino da Educação Física nos Ensinos Básico e Secundário, da Faculdade de Ciências do Desporto e Educação Física da Universidade de Coimbra. Este pretende que o professor estagiário demonstre competências de análise crítica fundamentada e reflexão aprofundada a partir da sua experiência de Estágio Pedagógico. O Estágio Pedagógico caracteriza-se por um período de formação curricular onde é permitido ao professor estagiário, de uma forma orientada, exercer e cumprir com todas as funções inerentes ao cargo docente. Este constitui portanto, a componente prática da aplicação dos saberes teóricos adquiridos durante a formação inicial. A transição entre a teoria e a prática só é possível através de um olhar crítico sobre o contexto real de prática pedagógica, de modo a serem utilizados os meios mais eficazes para o desenvolvimento de aprendizagens significativas face à especificidade da realidade em que nos inserimos. No meu caso, o Estágio Pedagógico foi realizado na Escola Básica e Secundária da Quinta das Flores, no ano letivo de 2013/2014, sendo lecionada a disciplina de Educação Física à turma do 11ºA. Este estágio representa o culminar da formação académica e a aproximação à prática profissional, em que todas as experiências vivenciadas, aprendizagens realizadas e conhecimentos adquiridos devem representar as competências necessárias para o desenvolvimento de uma prática docente na área da Educação Física. O Relatório de Estágio pretende assim englobar toda a descrição e reflexão sobre as atividades desenvolvidas e aprendizagens realizadas durante o estágio pedagógico. Este relatório divide-se em três áreas fundamentais. A primeira trata-se de uma contextualização da prática desenvolvida. A segunda consiste numa análise reflexiva sobre a prática pedagógica. A terceira é o aprofundamento de um tema-problema, uma investigação realizada sobre: "A pertinência do uso do modelo de ensino "Teaching Games for Understanding" no ensino de jogos desportivos coletivos de invasão. Comparação da evolução de desempenhos entre duas turmas na modalidade de Andebol." The Final Training Report is part of the curriculum of the second year of the Master in Physical Education Teaching in Basic and Secondary Education at the School of Sport Science and Physical Education in Coimbra University. This report is intended to demonstrate the ability to make a reasoned critical analysis and deep reflection based on the experience as a Trainee Teacher. The Pedagogical Training is characterized by a period of training curriculum where the trainee teacher is allowed to exert and fulfill with all the functions inherent to the teaching in a supervised manner.Thus, this is the practical component of the theoretical knowledge acquired during the initial education. The transition between the theory and practice is only possible through a critical eye on the real context of pedagogical practice in order to use the most effective means for the development of significant learning experiences in contrast to the specificity of the reality in which we live. In my own case, the Pedagogical Training was carried out in the Basic and Secondary School of Quinta das Flores in the school year of 2013 - 2014, where Physical Education was taught to the 11th A class. This training represents the culmination of the academic education and the approach to the professional practice, in which all the experiences, learnings and knowledge acquired previously shall represent the required skills for the development of a teaching practice in the area of Physical Education. In this way, the Training Report intends to encompass the entire description and reflection on the developed activities and apprenticeships carried out during the pedagogic training. This report is divided in three basic areas. The first area refers to a contextualization of the practice developed. The second consists of a reflective analysis of the pedagogical practice. The third is the deepening of a theme-problem, a research on "The relevance of the use of the teaching model "Teaching Games for Understanding” in teaching collective sport invasion games. A comparative study on the evolution of performances between two Handball teams.

    Exploring the diversity of promoter and 5’UTR sequences in ancestral, historic and modern wheat

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    A dataset of promoter and 5’UTR sequences of homoeo-alleles of 495 wheat genes that contribute to agriculturally important traits in 95 ancestral and commercial wheat cultivars is presented here. The high stringency myBaits technology used made individual capture of homoeo-allele promoters possible, which is reported here for the first time. Promoters of most genes are remarkably conserved across the 82 hexaploid cultivars used with <7 haplotypes per promoter and 21% being identical to the reference Chinese Spring. InDels and many high-confidence SNPs are located within predicted plant transcription factor binding sites, potentially changing gene expression. Most haplotypes found in the Watkins landraces and a few haplotypes found in T. monococcum, germplasms hitherto not thought to have been used in modern wheat breeding, are already found in many commercial hexaploid wheats. The full dataset which is useful for genomic and gene function studies and wheat breeding is available at https://rrescloud.rothamsted.ac.uk/index.php/s/3vc9QopcqYEbIUs/authenticate

    Dissecting the molecular interactions between wheat and the fungal pathogen Zymoseptoria tritici

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    The Dothideomycete fungus Zymoseptoria tritici (previously known as Mycosphaerella graminicola and Septoria tritici) is the causative agent of Septoria tritici leaf blotch (STB) disease of wheat (Triticum aestivum L.). In Europe, STB is the most economically damaging disease of wheat, with an estimated ∼€1 billion per year in fungicide expenditure directed toward its control. Here, an overview of our current understanding of the molecular events that occur during Z. tritici infection of wheat leaves is presented. On the host side, this includes the contribution of (1) the pathogen-associated molecular pattern-triggered immunity (PTI) layer of plant defense, and (2) major Stb loci for resistance against Z. tritici. On the pathogen side of the interaction, we consolidate evidence from recent bioinformatic, transcriptomic and proteomic studies that begin to explain the contribution of Z. tritici effector proteins to the biphasic lifestyle of the fungus. This includes the discovery of chitin-binding proteins in the Z. tritici secretome, which contribute to evasion of immune surveillance by this pathogen, and the possible existence of ‘necrotrophic’ effectors from Z. tritici, which may actively stimulate host recognition in a manner similar to related necrotrophic fungal pathogens. We finish by speculating on how some of these recent fundamental discoveries might be harnessed to help improve resistance to STB in the world’s second largest food crop

    Characterisation of major genes mediating resistance to Septoria tritici blotch disease in wheat.

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    The fungus Zymoseptoria tritici is one of the most destructive wheat (Triticum aestivum) pathogens in Europe and worldwide, causing crop losses of up to 50% in high risk climates (Goodwin, 2007). Traditionally this disease has been controlled with widely used resistance genes and fungicides, but the high selection pressures placed on the fungi result in a serious risk of these protections being overcome, particularly when heavily relied upon. Some major resistances have already been widely broken – for example, the Stb6 resistance gene present in most European wheat cultivars is now ineffective against many Septoria strains in the field. It is therefore important that new, more diverse sources of resistance be identified and utilised in elite wheat lines. These will allow us to prepare for the breaking of currently common resistances but may also extend their lifetimes – Chartrain et al. (2004) found that many wheat lines with highly durable Septoria resistance contain multiple resistance (Stb) genes, suggesting that gene pyramiding may be a viable method for enhancing the longevity of resistances in this pathosystem. The research described here will screen currently known Stb genes against an array of recent Septoria field isolates to identify resistances still effective in the field and potentially interesting combinations of resistances that in combination could provide protection against most or all isolates tested. Such resistances will then be fine mapped using KASP markers to enable breeders to more easily integrate them into elite lines. In light of the recent identification of the Stb6 gene as a wall-associated receptor-like kinase (WAK) (Saintenac et al., 2018), WAK genes in the regions identified will be further investigated using Virus-induced gene silencing to identify individual resistance genes where possible, aiding in further investigations that may establish the methods through which these resistances function

    Virus-mediated transient expression techniques enable gene function studies in black-grass

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    Even though considerable progress has been made in weed ecology, weed molecular biology has been hindered by an inability to genetically manipulate weeds. Genetic manipulation is essential to demonstrate a causative relationship between genotype and phenotype. Herein we demonstrate that virus-mediated transient expression techniques developed for other monocots can be used in black-grass (Alopecurus myosuroides) for loss- and gain-of-function studies. We not only use virus induced gene silencing (VIGS) to create the black-grass exhibiting reduced PHYTOENE DESATURASE expression and virus-mediated overexpression (VOX) to drive GREEN FLUORESCENT PROTEIN, we demonstrate these techniques are applicable to testing hypotheses related to herbicide resistance in black-grass. We use VIGS to demonstrate that AmGSTF1 is necessary for the resistant biotype Peldon to survive fenoxaprop application and show the heterologous expression of the bialaphos resistance gene with VOX is sufficient to confer resistance to an otherwise lethal dose of glufosinate. Black-grass is the most problematic weed for winter-cereal farmers in the UK and Western Europe as it has rapidly evolved adaptions that allow it to effectively avoid current integrated weed management practices. Black-grass also reduces yields and therefore directly threatens food security and productivity. Novel disruptive technologies which mitigate resistance evolution and enable better control over this pernicious weed are therefore required. These virus-mediated protocols offer a step change in our ability to alter genes of interest under controlled laboratory conditions and therefore to gain a molecular-level understanding of how black-grass can survive in the agri-environment

    Cell surface immune receptors: the guardians of the plant’s extracellular spaces

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    Since the original ‘Zigzag model’, several iterations have been proposed to reconcile both the Pattern Triggered Immunity (PTI) and the Effector Triggered Immunity (ETI) branches of the plant immune system. The recent cloning of new disease resistance genes, functioning in gene-for-gene interactions, which structurally resemble cell surface broad spectrum Pattern Recognition Receptors, have further blurred the distinctions between PTI and ETI in plant immunity. In an attempt to simplify further the existing conceptual models, we, herein, propose a scheme based on the spatial localization of the key proteins (receptors) which function to induce plant immune responses. We believe this ‘Spatial Invasion model’ will prove useful for understanding how immune receptors interact with different pathogen types which peripherally or totally invade plant cells, colonize solely extracellularly or switch locations during a successful infection
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