21 research outputs found

    REVIEW OF MODELING PREFERENCES FOR DECISION MODELS

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    A group decision problem is set in environments where there is a common issue to solve, a set of possible options to choose, and a set of individuals who are experts and express their opinions about the set of possible alternatives with the intention to reach a collective decision as the unique solution of the problem in question. The modeling of the preferences of the decision-maker is an essential stage in the construction of models used in the theory of decision, operations research, economics, etc. On decision problems experts use models of representation of preferences that are close to their disciplines or fields of work. The structures of information most commonly used for the representation of the preferences of experts are vectors of utility, orders of preference and preference relations. In decision problems, the expression of preferences domain is the domain of information used by the experts to express their preferences, the main are numerical, linguistic, and intervalar stressing the multi-granular linguistic. This paper is a review of these concepts. Its purpose is to provide a guide of bibliographic references for these concepts, which are briefly discussed in this document

    Biology and biotechnology of Trichoderma

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    Fungi of the genus Trichoderma are soilborne, green-spored ascomycetes that can be found all over the world. They have been studied with respect to various characteristics and applications and are known as successful colonizers of their habitats, efficiently fighting their competitors. Once established, they launch their potent degradative machinery for decomposition of the often heterogeneous substrate at hand. Therefore, distribution and phylogeny, defense mechanisms, beneficial as well as deleterious interaction with hosts, enzyme production and secretion, sexual development, and response to environmental conditions such as nutrients and light have been studied in great detail with many species of this genus, thus rendering Trichoderma one of the best studied fungi with the genome of three species currently available. Efficient biocontrol strains of the genus are being developed as promising biological fungicides, and their weaponry for this function also includes secondary metabolites with potential applications as novel antibiotics. The cellulases produced by Trichoderma reesei, the biotechnological workhorse of the genus, are important industrial products, especially with respect to production of second generation biofuels from cellulosic waste. Genetic engineering not only led to significant improvements in industrial processes but also to intriguing insights into the biology of these fungi and is now complemented by the availability of a sexual cycle in T. reesei/Hypocrea jecorina, which significantly facilitates both industrial and basic research. This review aims to give a broad overview on the qualities and versatility of the best studied Trichoderma species and to highlight intriguing findings as well as promising applications

    Fungal volatile organic compounds: emphasis on their plant growth-promoting

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    Fungal volatile organic compounds (VOCs) commonly formed bioactive interface between plants and countless of microorganisms on the above- and below-ground plant-fungus interactions. Fungal-plant interactions symbolize intriguingly biochemical complex and challenging scenarios that are discovered by metabolomic approaches. Remarkably secondary metabolites (SMs) played a significant role in the virulence and existence with plant-fungal pathogen interaction; only 25% of the fungal gene clusters have been functionally identified, even though these numbers are too low as compared with plant secondary metabolites. The current insights on fungal VOCs are conducted under lab environments and to apply small numbers of microbes; its molecules have significant effects on growth, development, and defense system of plants. Many fungal VOCs supported dynamic processes, leading to countless interactions between plants, antagonists, and mutualistic symbionts. The fundamental role of fungal VOCs at field level is required for better understanding, so more studies will offer further constructive scientific evidences that can show the cost-effectiveness of ecofriendly and ecologically produced fungal VOCs for crop welfare

    Light regulation of metabolic pathways in fungi

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    Light represents a major carrier of information in nature. The molecular machineries translating its electromagnetic energy (photons) into the chemical language of cells transmit vital signals for adjustment of virtually every living organism to its habitat. Fungi react to illumination in various ways, and we found that they initiate considerable adaptations in their metabolic pathways upon growth in light or after perception of a light pulse. Alterations in response to light have predominantly been observed in carotenoid metabolism, polysaccharide and carbohydrate metabolism, fatty acid metabolism, nucleotide and nucleoside metabolism, and in regulation of production of secondary metabolites. Transcription of genes is initiated within minutes, abundance and activity of metabolic enzymes are adjusted, and subsequently, levels of metabolites are altered to cope with the harmful effects of light or to prepare for reproduction, which is dependent on light in many cases. This review aims to give an overview on metabolic pathways impacted by light and to illustrate the physiological significance of light for fungi. We provide a basis for assessment whether a given metabolic pathway might be subject to regulation by light and how these properties can be exploited for improvement of biotechnological processes

    Inhibition de Phytophthora palmivora, agent de pourriture brune des cabosses de cacaoyer en Côte d’Ivoire, par Trichoderma sp.

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    La pourriture brune des cabosses du cacaoyer causée par Phytophthora palmivora entraîne en Côte d’Ivoire 30 % de pertes sur les productions. Actuellement, pour combattre cette maladie, la lutte intégrée est envisagée. Elle inclue les pratiques culturales, la sélection des variétés résistances et l’utilisation des antagonistes contre Phytophthora sp. notamment les espèces du genre Trichoderma. Cette dernière approche nécessite l’isolement, l’établissement d’une collection des Trichoderma issus de la cacaoyère et l’évaluation du potentiel antagoniste de celle-ci pour le choix des antagonistes efficaces à Phytophthora palmivora. A cet effet, des confrontations directes in vitro aussi bien que in vivo sur feuilles et sur cabosses ont été réalisées. Quarante trois isolats de Trichoderma montrent une activité antagoniste vis à vis de Phytophthora palmivora sur milieu de culture, avec des taux d’inhibition de l’ordre de 34 à 79 % mais, aussi réduisent significativement la sensibilité foliaire de 6 clones de cacaoyer et de cabosses. Ces tests in vitro et in vivo ont permis de retenir les isolats T.spirale T4, T.virens T7, T.asperellum T54 et T.harzianum T40 à forte action inhibitrice vis à vis de Phytophthora palmivora, offrant une forte aptitude à réduire la sensibilité et surtout à renforcer la résistance intrinsèque du clone sensible NA32 au parasite. Ces tests d’antagonistes ont permis la sélection des Trichoderma sp. candidats aux essais au champ. La réalisation des essais au champ évaluera l’efficacité en milieu réel des antagonistes naturels sur le développement de la maladie.Cocoa black pod disease in Côte d’ivoire, due to Phytophthora palmivora , can cause crop losses up to 30%. At present, for controlling cocoa black pod rot, an integrated pest management strategie was envisaged, and include cultural pratices, selection for resistant cocoa varieties and biological control microorganisms. The latter approach need isolation, establishment of collection microorganisms found in the cocoa ecology of Côte d’Ivoire and evaluations for their ability to control P. palmivora for screening biocontrol candidates. In vitro direct confrontation also although leaf disc and the cocoa pod biocontrol screening biotest have been carried out. Fortythree of isolates Trichoderma expressed in vitro inhibition against P. palmivora on high-nutrient media, with in the order of 34 à 79 % of inhibition rate but, also were significantly reduced the level of susceptibility of six clones and cocoa pods to P. Palmivora. The isolates T.spirale T4, T.virens T7, T.asperellum T54 et T.harzianum T40 were found to be very effective against P. palmivora by these in vitro and in vivo tests, exhibiting high potential to reduce the susceptibility and especially to reinforce intrinsic resistant susceptible clone (NA32) towards P. palmivora. These screening tests pemitted the selection of Trichoderma isolates candidates for field trials. This field trials will assess for efficacy biocontrol candidates from cacao agrosystems on the evolution of disease.Mots clés : Pourriture brune, Phytophthora palmivora, lutte biologique, Trichoderma sp, cacaoye

    Evaluation of the growth of Trichoderma pleurotum and Trichoderma pleuroticola isolates and their biotic interaction with Pleurotus sp.

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    Growth of Trichoderma pleurotum and T. pleuroticola isolates on the Potato Dextrose Agar (PDA) medium was investigated. T. pleuroticola isolates showed a significantly greater diameter of their mycelium colonies after 5 days of incubation than the T. pleurotum isolates. In addition, biotic interactions between T. pleurotum and T. pleuroticola isolates and species of Pleurotus sp. were determined. The following six species of oyster mushroom were used: P. florida, P. cornucopiae, P. pulmonarius, P. columbinus, P. ostreatus and P. eryngii. It was demonstrated that isolates of the T. pleuroticola species limited the growth of the examined species of oyster mushroom to a much greater extent than the isolates of the T. pleurotum species

    DNA barcoding survey of Trichoderma diversity in soil and litter of the Colombian lowland Amazonian rainforest reveals Trichoderma strigosellum sp. nov. and other species

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    The diversity of Trichoderma (Hypocreales, Ascomycota) colonizing leaf litter as well as the rhizosphere of Garcinia macrophylla (Clusiaceae) was investigated in primary and secondary rain forests in Colombian Amazonia. DNA barcoding of 107 strains based on the internal transcribed spacers 1 and 2 (ITS1 and 2) of the ribosomal RNA gene cluster and the partial sequence of the translation elongation factor 1 alpha (tef1) gene revealed that the diversity of Trichoderma was dominated (71 %) by three common cosmopolitan species, namely Trichoderma harzianum sensu lato (41 %), Trichoderma spirale (17 %) and Trichoderma koningiopsis (13 %). Four ITS 1 and 2 phylotypes (13 strains) could not be identified with certainty. Multigene phylogenetic analysis and phenotype profiling of four strains with an ITS1 and 2 phylotype similar to Trichoderma strigosum revealed a new sister species of the latter that is described here as Trichoderma strigosellum sp. nov. Sequence similarity searches revealed that this species also occurs in soils of Malaysia and Cameroon, suggesting a pantropical distribution

    Fungal genus Hypocrea/Trichoderma: from barcodes to biodiversity* §

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    Hypocrea/Trichoderma is a genus of soil-borne or wood-decaying fungi containing members important to mankind as producers of industrial enzymes and biocontrol agents against plant pathogens, but also as opportunistic pathogens of immunocompromised humans and animals, while others can cause damage to cultivated mushroom. With the recent advent of a reliable, BarCode-aided identification system for all known taxa of Trichoderma and Hypocrea, it became now possible to study some of the biological fundamentals of the diversity in this fungal genus in more detail. In this article, we will therefore review recent progress in (1) the understanding of the geographic distribution of individual taxa; (2) mechanisms of speciation leading to development of mushroom diseases and facultative human mycoses; and (3) the possible correlation of specific traits of secondary metabolism and molecular phylogeny
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