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J Agric Food Chem ; 2020 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-33305951


Fusarium oxysporum is a destructive root-infecting plant pathogen that causes significant yield losses in many economically important crop species. Hence, a deeper understanding of pathogen infection strategies is needed. With liquid chromatography-tandem mass spectrometry and gas chromatography-time of flight mass spectrometry platforms, we analyzed the metabolic changes in a time-course experiment with Arabidopsis accessions either resistant (Col-0) or susceptible (Ler-0) to isolates of Fusarium oxysporum forma specialis matthioli infection. We showed a concurrent effect of Fusarium-derived polyols and the mycotoxin beauvericin in the suppression of the immune response of susceptible hosts. A significant increase in oxidized glutathione in the resistant host was probably associated with effective reactive oxygen species-mediated resistance responses. Through a combination of targeted and untargeted metabolomics, we demonstrated the concurrent action of several Arabidopsis defense systems as well as the concurrent action of several virulence systems in the fungal attack of susceptible Arabidopsis.

New Phytol ; 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33006149


Entomopathogenic fungi (EPF) can display a plant-associated lifestyle as endophytes. Seed application of EPF can affect insect herbivory above ground, but the mechanisms behind this are not documented. Here we applied three EPF isolates, Beauveria bassiana, Metarhizium brunneum and M. robertsii, as seed inoculation of wheat and bean, and evaluated the effects on population growth of aphids, Rhopalosiphum padi and Aphis fabae, respectively. In wheat and bean leaves, we quantified benzoxazinoids and flavonoids, respectively, in response to EPF inoculation and aphid infestation to elucidate the role of specific plant secondary metabolites (PSMs) in plant-fungus-herbivore interactions. Inoculations of wheat and bean with M. robertsii and B. bassiana reduced aphid populations compared with control treatments, whereas M. brunneum unexpectedly increased the populations of both aphids. Concentrations of the majority of PSMs were differentially altered in EPF-treated plants infested with aphids. Changes in aphid numbers were associated with PSMs regulation rather than EPF endophytic colonisation capacity. This study links the effects of EPF seed inoculations against aphids with unique PSM accumulation patterns in planta. The understanding of PSM regulation in tri-trophic interactions is important for the future development of EPF for pest management.

Front Cell Dev Biol ; 8: 385, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32612989


One of the challenges in the area of diagnostics of human thyroid cancer is a preoperative diagnosis of thyroid nodules with indeterminate cytology. Herein, we report an untargeted metabolomics analysis to identify circulating thyroid nodule metabolic signatures, to find new novel metabolic biomarkers. Untargeted gas chromatography-quadrupole-mass spectrometry was used to ascertain the specific plasma metabolic changes of thyroid nodule patients, which consisted of papillary thyroid carcinoma (PTC; n = 19), and multinodular goiter (MNG; n = 16), as compared to healthy subjects (n = 20). Diagnostic models were constructed using multivariate analyses such as principal component analysis, orthogonal partial least squares-discriminant analysis, and univariate analysis including One-way ANOVA and volcano plot by MetaboAnalyst and SIMCA software. Because of the multiple-testing issue, false discovery rate p-values were also computed for these functions. A total of 60 structurally annotated metabolites were subjected to statistical analysis. A combination of univariate and multivariate statistical analyses revealed a panel of metabolites responsible for the discrimination between thyroid nodules and healthy subjects, with variable importance in the projection (VIP) value greater than 0.8 and p-value less than 0.05. Significantly altered metabolites between thyroid nodules versus healthy persons are those associated with amino acids metabolism, the tricarboxylic acid cycle, fatty acids, and purine and pyrimidine metabolism, including cysteine, cystine, glutamic acid, α-ketoglutarate, 3-hydroxybutyric acid, adenosine-5-monophosphate, and uracil, respectively. Further, sucrose metabolism differed profoundly between thyroid nodule patients and healthy subjects. Moreover, according to the receiver operating characteristic (ROC) curve analysis, sucrose could discriminate PTC from MNG (area under ROC curve value = 0.92). This study enhanced our understanding of the distinct metabolic pathways associated with thyroid nodules, which enabled us to distinguish between patients and healthy subjects. In addition, our study showed extensive sucrose metabolism in the plasma of thyroid nodule patients, which provides a new metabolic signature of the thyroid nodule's tumorigenesis. Accordingly, it suggests that sucrose can be considered as a circulating biomarker for differential diagnosis between malignancy and benignity in indeterminate thyroid nodules.

J Exp Bot ; 71(1): 234-246, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31494665


The biosynthesis of starch granules in plant plastids is coordinated by the orchestrated action of transferases, hydrolases, and dikinases. These enzymes either contain starch-binding domain(s) themselves, or are dependent on direct interactions with co-factors containing starch-binding domains. As a means to competitively interfere with existing starch-protein interactions, we expressed the protein module Carbohydrate-Binding Motif 20 (CBM20), which has a very high affinity for starch, ectopically in barley plastids. This interference resulted in an increase in the number of starch granules in chloroplasts and in formation of compound starch granules in grain amyloplasts, which is unusual for barley. More importantly, we observed a photosystem-independent inhibition of CO2 fixation, with a subsequent reduced growth rate and lower accumulation of carbohydrates with effects throughout the metabolome, including lower accumulation of transient leaf starch. Our results demonstrate the importance of endogenous starch-protein interactions for controlling starch granule morphology and number, and plant growth, as substantiated by a metabolic link between starch-protein interactions and control of CO2 fixation in chloroplasts.

Int J Mol Sci ; 18(10)2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-28973963


Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO), an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi© plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material.

Amilose/química , Plásticos Biodegradáveis/química , Ácido Cítrico/química , Reagentes para Ligações Cruzadas/química , Hordeum/química , Cristalização , Glicerol/química , Permeabilidade , Transição de Fase , Plantas Geneticamente Modificadas/química , Plastificantes/química , Amido/química