2,106 research outputs found

    Metabolic and molecular changes of the phenylpropanoid pathway in tomato (Solanum lycopersicum) lines carrying different Solanum pennellii wild Chromosomal regions

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    Solanum lycopersicum represents an important dietary source of bioactive compounds including the antioxidants flavonoids and phenolic acids. We previously identified two genotypes (IL7-3 and IL12-4) carrying loci from the wild species Solanum pennellii, which increased antioxidants in the fruit. Successively, these lines were crossed and two genotypes carrying both introgressions at the homozygous condition (DHO88 and DHO88-SL) were selected. The amount of total antioxidant compounds was increased in DHOs compared to both ILs and the control genotype M82. In order to understand the genetic mechanisms underlying the positive interaction between the two wild regions pyramided in DHO genotypes, detailed analyses of the metabolites accumulated in the fruit were carried out by colorimetric methods and LC/MS/MS. These analyses evidenced a lower content of flavonoids in DHOs and in ILs, compared to M82. By contrast, in the DHOs the relative content of phenolic acids increased, particularly the fraction of hexoses, thus evidencing a redirection of the phenylpropanoid flux towards the biosynthesis of phenolic acid glycosides in these genotypes. In addition, the line DHO88 exhibited a lower content of free phenolic acids compared to M82. Interestingly, the two DHOs analyzed differ in the size of the wild region on chromosome 12. Genes mapping in the introgression regions were further investigated. Several genes of the phenylpropanoid biosynthetic pathway were identified, such as one 4-coumarate:CoA ligase and two UDP-glycosyltransferases in the region 12-4 and one chalcone isomerase and one UDP-glycosyltransferase in the region 7-3. Transcriptomic analyses demonstrated a different expression of the detected genes in the ILs and in the DHOs compared to M82.These analyses, combined with biochemical analyses, suggested a central role of the 4-coumarate:CoA ligase in redirecting the phenylpropanoid pathways towards the biosynthesis of phenolic acids in the pyramided lines. Moreover, analyses here carried out suggest the presence in the introgression regions of novel regulatory proteins, such as one Myb4 detected on chromosome 7 and one bHLH detected in chromosome 12. Overall our data indicates that structural and regulatory genes identified in this study might have a key role for the manipulation of the phenylpropanoid metabolic pathway in tomato fruit

    Factors affecting the production of Trichoderma harzianum secondary metabolites during the interaction with different plant pathogens

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    Strains of Trichoderma spp. produce numerous bioactive secondary metabolites. The in vitro production and antibiotic activities of the major compounds synthesized by Trichoderma harzianum strains T22 and T39 against Leptosphaeria maculans, Phytophthora cinnamomi and Botrytis cinerea were evaluated. Moreover, the eliciting effect of viable or nonviable biomasses of Rhizoctonia solani, Pythium ultimum or B. cinerea on the in vitro production of these metabolites was also investigated. T22azaphilone, 1-hydroxy-3-methyl-anthraquinone, 1,8-dihydroxy-3-methyl-anthraquinone, T39butenolide, harzianolide, harzianopyridone were purified, characterized and used as standards. In antifungal assays, T22azaphilone and harzianopyridone inhibited the growth of the pathogens tested even at low doses (1-10 mu g per plug), while high concentrations of T39butenolide and harzianolide were needed (> 100 mu g per plug) for inhibition. The in vitro accumulation of these metabolites was quantified by LC/MS. T22azaphilone production was not enhanced by the presence of the tested pathogens, despite its antibiotic activity. On the other hand, the anthraquinones, which showed no pathogen inhibition, were stimulated by the presence of P. ultimum. The production of T39butenolide was significantly enhanced by co-cultivation with R. solani or B. cinerea. Similarly, viable and nonviable biomasses of R. solani or B. cinerea increased the accumulation of harzianopyridone. Finally, harzianolide was not detected in any of the interactions examined. The secondary metabolites analysed in this study showed different levels of antibiotic activity. Their production in vitro varied in relation to: (i) the specific compound; (ii) the phytopathogen used for the elicitation; (iii) the viability of the elicitor; and (iv) the balance between elicited biosynthesis and biotransformation rates. The use of cultures of phytopathogens to enhance yields of Trichoderma metabolites could improve the production and application of novel biopesticides and biofertilizers based on the active compounds instead of the living microbe. This could have a significant beneficial impact on the management of diseases in crop plants

    Conversion of the Mycotoxin Patulin to the Less Toxic Desoxypatulinic Acid by the Biocontrol Yeast Rhodosporidium kratochvilovae Strain LS11

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    Se describe en este artículo el descubrimiento de la degradación de la micotoxina patulina por una levaduraThe infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After R. kratochvilovae LS11 had been incubated in the presence of 13C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process

    Effects of Cultivar and Process Variables on Dynamic-Mechanical and Sensorial Behavior of Value-Added Grape-Based Smoothies

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    The effects of either cooking temperature (45, 80, and 100 °C) or inclusion of seed particles on the dynamic-mechanical and sensorial properties of value-added Crimson seedless, Black Pearl, or Baresana grape-based smoothies were studied. The inclusion of seed particles resulted in significant increases of the phenolic content, both in Black Pearl and Baresana, but it did not affect in a negative way the sensorial characteristics of smoothies whereas it caused an increase of the viscoelastic behavior of Black Pearl and a slight decrease in Baresana grape-based smoothies. In particular, the investigated rheological parameters were the loss and storage modulus. Moreover, the loss tangent value (the ratio between loss and storage modulus) remained unchanged, indicating a pseudoplastic behavior of all samples, independent on the process conditions. The smoothies produced from Crimson grapes at the intermediate temperature (80 °C) showed sensorial and rheological characteristics similar to those manufactured at 45 °C and better than those manufactured at 100 °C

    Current Trends in Dental Composites

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    Clickbait Classification and Spoiling Using Natural Language Processing

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    Clickbait is the practice of engineering titles to incentivize readers to click through to articles. Such titles with sensationalized language reveal as little information as possible. Occasionally, clickbait will be intentionally misleading, so natural language processing (NLP) can scan the article and answer the question posed by the clickbait title, or spoil it. We tackle two tasks: classifying the clickbait into one of 3 types (Task 1), and spoiling the clickbait (Task 2). For Task 1, we propose two binary classifiers to determine the final spoiler type. For Task 2, we experiment with two approaches: using a question-answering model to identify the span of text of the spoiler, and using a large language model (LLM) to generate the spoiler. Because the spoiler is contained in the article, we frame the second task as a question-answering approach for identifying the starting and ending positions of the spoiler. We created models for Task 1 that were better than the baselines proposed by the dataset authors and engineered prompts for Task 2 that did not perform as well as the baselines proposed by the dataset authors due to the evaluation metric performing worse when the output text is from a generative model as opposed to an extractive model.Comment: 7 pages, 2 figures, 3 tables, 1 Appendix (3 Sections
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