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1.
Plant J ; 100(1): 114-127, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31169939

RESUMO

Phytol is one of the key precursors for tocopherol synthesis in plants, however, the underlying mechanisms concerning the accumulation of tocopherol remain poorly understood. In this study, qVE5, a major QTL affecting tocopherol accumulation in maize kernels was identified via a positional cloning approach. qVE5 encodes a protochlorophyllide oxidoreductase (ZmPORB2), which localizes to the chloroplast. Overexpression of ZmPORB2 increased tocopherol content in both leaves and kernels. Candidate gene association analysis identified a 5/8-bp insertion/deletion (InDel058) in the 5' untranslated region (UTR) as the causal polymorphism in affecting ZmPORB2 expression and being highly associated with tocopherol content. We showed that higher expression of ZmPORB2 correlated with more chlorophyll metabolites in the leaf following pollination. RNA-sequencing and metabolic analysis in near isogenic lines (NILs) support that ZmPORB2 participates in chlorophyll metabolism enabling the production of phytol, an important precursor of tocopherol. We also found that the tocopherol content in the kernel is mainly determined by the maternal genotype, a fact that was further confirmed by in vitro culture experiments. Finally, a PCR-based marker based on Indel058 was developed in order to facilitate the high tocopherol (vitamin E) maize breeding.

2.
Food Chem ; 297: 125016, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253287

RESUMO

To gain a better understanding concerning factors underlying carotenoid metabolism in banana pulp we investigated the carotenoid profile, metabolome, proteome and relative expression levels of carotegenesis-associated genes of fruit pulp in the two banana varieties ON and GN, with ON being characterized of high carotenoid accumulation. Results showed that high carotenoid content in banana pulp was well correlated with the relative expression of carotenogenesis-associated genes and the abundance of the corresponding proteins. An elevated accumulation of sugar metabolism-related compounds and a decreased amino acid accumulation were also observed in ON. Additionally proteins involved in the glycolytic pathway were more highly abundant in ON suggesting that this supports the higher accumulation of carotenoid in this genotype. We suggest that up-regulated expression of carotenogenesis-associated genes alongside elevated carbohydrate accumulation contribute to high carotenoid content in banana pulp, implying that a multi-target approach is necessary in order to improve carotenoid content in banana.


Assuntos
Carotenoides/análise , Metaboloma , Metabolômica/métodos , Musa/metabolismo , Proteômica/métodos , Aminoácidos/análise , Aminoácidos/metabolismo , Metabolismo dos Carboidratos , Carotenoides/metabolismo , Cromatografia Líquida de Alta Pressão , Análise Discriminante , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Glicólise , Proteínas de Plantas/genética , Proteoma/análise , Espectrometria de Massas em Tandem
3.
Plant Cell ; 31(6): 1328-1343, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30996077

RESUMO

It has long been recognized that stomatal movement modulates CO2 availability and as a consequence the photosynthetic rate of plants, and that this process is feedback-regulated by photoassimilates. However, the genetic components and mechanisms underlying this regulatory loop remain poorly understood, especially in monocot crop species. Here, we report the cloning and functional characterization of a maize (Zea mays) mutant named closed stomata1 (cst1). Map-based cloning of cst1 followed by confirmation with the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR associated protein 9 system identified the causal mutation in a Clade I Sugars Will Eventually be Exported Transporters (SWEET) family gene, which leads to the E81K mutation in the CST1 protein. CST1 encodes a functional glucose transporter expressed in subsidiary cells, and the E81K mutation strongly impairs the oligomerization and glucose transporter activity of CST1. Mutation of CST1 results in reduced stomatal opening, carbon starvation, and early senescence in leaves, suggesting that CST1 functions as a positive regulator of stomatal opening. Moreover, CST1 expression is induced by carbon starvation and suppressed by photoassimilate accumulation. Our study thus defines CST1 as a missing link in the feedback-regulation of stomatal movement and photosynthesis by photoassimilates in maize.

5.
Food Res Int ; 120: 330-338, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31000247

RESUMO

The chemical composition of black tea during tea processing is in a state of flux. However, the dynamic changes of this sophisticated metabolic process are far from clear. GC-MS-based metabolomic analyses were performed to examine changes in volatile and non-volatile compounds throughout the five stages of tea processing. The results showed that the most striking differences were observed at the withering and rolling stages, during which 62 non-volatile and 47 volatile compounds were significantly changed. The levels of most monosaccharides decreased at the withering stage and increased in subsequent stages while di-saccharides decreased as the process progressed. Free amino acids increased sharply at the withering stage, and most kept increasing or remained stable afterwards. However, levels of catechin, epicatechin, epigallocatechin, and epigallocatechin gallate decreased after withering and remained at low levels afterwards. Among the 47 volatile compounds with altered levels, phenylpropanoids/benzenoids and carotenoid-derived volatiles, which contribute to the honey-like and rose-like fragrances and quality of Danxia2 tea, kept increasing during the processing, among them eight were newly produced. Furthermore, 19 volatiles with a grassy odor decreased during processing. This study provides a comprehensive profile of metabolic changes during black tea processing, which is potentially important for both quality control and improvement of the flavor of black teas.

6.
Food Chem ; 286: 669-677, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827662

RESUMO

Walnut (Juglans regia L.) is an abundant source of polyphenols. Although phenolic species in the walnut kernel have been studied comprehensively, their compositional profile in the internal fruit septum, a traditional nutraceutical material in China, has been rarely explored. In the current study, the methanolic extract of the walnut septum was analysed by Ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry. Totally seventy-five phenolics belonging to flavonoids, tannins and phenolic acids were identified based on mass spectra, references and literatures. Among them, quercetin-3-O-galactoside, quercetin-rhamnose-pentoside, quercetin-3-O-glucoside, quercetin-rhamnose-hexoside, kaempferol-rhamnoside, and two isomers of quercetin-rhamnoside were reported for the first time in walnut. The total polyphenol content was found to be 122.78 ±â€¯2.55 mg GAE/g dry weight in septum. This study is the first to comprehensively investigate and identify phenolic compounds in the fruit septum of walnut and indicates that the septum to be a rich resource of polyphenols.


Assuntos
Cromatografia Líquida/métodos , Juglans/química , Espectrometria de Massas/métodos , Fenóis/análise , China , Suplementos Nutricionais/análise , Flavonoides/análise , Frutas/química , Glucosídeos/análise , Nozes/química , Polifenóis/análise , Quercetina/análogos & derivados , Quercetina/análise
7.
Artigo em Inglês | MEDLINE | ID: mdl-30597417

RESUMO

A determination method to identify and quantify 18 multi-class antibiotics in urine was developed using liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS). Targeted antibiotics were extracted using preliminary dilution followed by d-SPE extraction. Specificity and selectivity, linearity, LOD and LOQ, accuracy, and precision were validated. LOQ of the majority of targeted compounds ranged from 0.3-7.5 µg/L. Excellent recovery in the range of 73-136% was achieved for most antibiotics, except macrolides whose recovery were of 52-78%. High precision was obtained with coefficients of variation (CV) less than 20%. All compounds were clearly separated and detected after a total run time of 15 min. Following development and validation, the method was applied to real urine samples where five out of 18 antibiotics were detected and high precision with CV less than 15% was obtained. The method was validated to be capable of quantifying antibiotics in urine for applications in supervision of antibiotics consumption or in pharmacokinetic studies.


Assuntos
Antibacterianos/urina , Cromatografia Líquida/métodos , Monitoramento de Medicamentos/métodos , Espectrometria de Massas em Tandem/métodos , Antibacterianos/isolamento & purificação , Criança , Humanos , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Extração em Fase Sólida
8.
Plant Mol Biol ; 98(4-5): 289-302, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30387038

RESUMO

KEY MESSAGE: This is the first time to dissect the mechanism of NACs-mediated disease resistance in plants using metabolomic approach and discover the involvement of ABA signaling pathway in NACs-mediated disease resistance. NAC transcription factors have been validated as important regulators in stress responses, but their molecular mechanisms in plant disease resistance are still largely unknown. Here we report that the NAC gene ONAC066 (LOC_Os01g09550) is significantly activated by rice blast infection. ONAC066 is ubiquitously expressed and this protein is localized in the nucleus. Overexpression of ONAC066 quantitatively enhances resistance to blast disease and bacterial blight in rice. The transcript levels of PR genes are also dramatically induced in ONAC066 overexpressing plants. Exogenous abscisic acid (ABA) strongly activates the transcription of ONAC066 in rice. Further analysis shows that overexpression of ONAC066 remarkably suppresses the expression of ABA-related genes, whereas there are no obvious differences for salicylic acid (SA) and jasmonic acid (JA)-related genes between wild-type and ONAC066 overexpressing plants. Consistently, lower endogenous ABA levels are identified in ONAC066 overexpressing plants compared with wild-type plants before and after blast inoculation, while no significant differences are observed for the SA and JA levels. Yeast one-hybrid assays demonstrate that ONAC066 directly binds to the promoters of LIP9 and NCED4 to modulate their expression. Moreover, the metabolomic study reveals that the ONAC066 overexpressing plants accumulated higher contents of soluble sugars and amino acids both before and after pathogen attack, when compared to wild-type plants. Taken together, our results suggest that ONAC066 positively regulates rice resistance to blast and bacterial blight, and ONAC066 exerts its functions on disease resistance by modulating of ABA signaling pathway, sugars and amino acids accumulation in rice.


Assuntos
Ácido Abscísico/fisiologia , Resistência à Doença/genética , Oryza/genética , Reguladores de Crescimento de Planta/fisiologia , Proteínas de Plantas/fisiologia , Transdução de Sinais , Fatores de Transcrição/fisiologia , Ciclopentanos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Regulação da Expressão Gênica de Plantas , Metabolômica , Oryza/metabolismo , Oryza/microbiologia , Oxilipinas/metabolismo , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Ácido Salicílico/metabolismo , Técnicas do Sistema de Duplo-Híbrido
9.
BMC Plant Biol ; 18(1): 257, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30367631

RESUMO

BACKGROUND: WRKY proteins are one of the largest gene families and are well-known for their regulatory roles in many aspects of plant development, including plant response to both biotic and abiotic stresses. Although the roles of WRKY proteins in leaf blast resistance have been well-documented in rice, their functions in panicle blast, the most destructive type of blast disease, are still largely unknown. RESULTS: Here, we identified that the transcription of OsWRKY67 was strongly activated by leaf and panicle blast infection. OsWRKY67 is ubiquitously expressed and sub-localized in the nucleus. Rice plants overexpressing OsWRKY67 showed quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. In contrast, silencing of OsWRKY67 increased the susceptibility to blast and bacterial blight diseases. RNA-seq analysis indicated that OsWRKY67 induces the transcription of a set of defense-related genes including the ones involved in the salicylic acid (SA)-dependent pathway. Consistent with this, the OsWRKY67-overexpressing plants accumulated higher amounts of endogenous SA, whereas lower endogenous SA levels were observed in OsWRKY67-silenced plants relative to wild-type Nipponbare plants before and after pathogen attack. Moreover, we also observed that OsWRKY67 directly binds to the promoters of PR1a and PR10 to activate their expression. CONCLUSIONS: These results together suggest the positive role of OsWRKY67 in regulating rice responses to leaf blast, panicle blast and bacterial blight disease. Furthermore, conferring resistance to two major diseases makes it a good target of molecular breeding for crop improvement in rice.


Assuntos
Oryza/genética , Oryza/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Núcleo Celular/genética , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Magnaporthe/patogenicidade , Oryza/metabolismo , Doenças das Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Ácido Salicílico/metabolismo , Xanthomonas/patogenicidade
10.
Plant Physiol Biochem ; 127: 590-598, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29729608

RESUMO

Seed storability is an important trait for crop breeding, however, the mechanism underlying seed storability remains largely unknown. Here, a mass spectrometry-based comparative metabolomic study was performed for rice seeds before and after 24-month natural storage between two hybrid rice cultivars, IIYou 998 (IIY) with low storability and BoYou 998 (BY) with relative high storability. A total of 48 metabolites among 90 metabolite peaks detected were conclusively identified, and most of them are involved in the primary metabolism. During the 24-month storage, 19 metabolites with significant changes in abundance were found in the storage-sensitive IIY seeds, but only 8 in the BY seeds, most of which are free amino acids and soluble sugars. The observed changes of the metabolites in IIY seeds that are consistent with our protoemics results are likely to be involved in its sensitivity to storage. Levels of all identified 18 amino acid-related metabolites and most sugar-related metabolites were significantly higher in IIY seeds both before and after storage. However the level of raffinose was lower in IIY seeds before and after storage, and did not change significantly throughout the storage period in both two cultivars, suggesting its potential role in seed storability. Taken together, these results may help to improve our understanding of seed storability.


Assuntos
Armazenamento de Alimentos , Metaboloma , Metabolômica , Oryza/metabolismo , Sementes/metabolismo , Fatores de Tempo
11.
Front Microbiol ; 8: 1812, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28983290

RESUMO

This study was conducted to compare the microbiome and metabolome differences in the colon lumen from two pig breeds with different genetic backgrounds. Fourteen weaned piglets at 30 days of age, including seven Landrace piglets (a lean-type pig breed with a fast growth rate) and seven Meihua piglets (a fatty-type Chinese local pig breed with a slow growth rate), were fed the same diets for 35 days. Untargeted metabolomics analyses showed that a total of 401 metabolites differed between Landrace and Meihua. Seventy of these 401 metabolites were conclusively identified. Landrace accumulated more short-chain fatty acids (SCFAs) and secondary bile acids in the colon lumen. Moreover, expression of the SCFAs transporter (solute carrier family 5 member 8, SLC5A8) and receptor (G protein-coupled receptor 41, GPR41) in the colon mucosa was higher, while the bile acids receptor (farnesoid X receptor, FXR) had lower expression in Landrace compared to Meihua. The relative abundances of 8 genera and 16 species of bacteria differed significantly between Landrace and Meihua, and were closely related to the colonic concentrations of bile acids or SCFAs based on Pearson's correlation analysis. Collectively, our results demonstrate for the first time that there were differences in the colonic microbiome and metabolome between Meihua and Landrace piglets, with the most profound disparity in production of SCFAs and secondary bile acids.

12.
J Integr Plant Biol ; 59(11): 774-791, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28731217

RESUMO

Due to global climate change, temperature stress has become one of the primary causes of crop losses worldwide. Much progress has been made in unraveling the complex stress response mechanisms in plants, particularly in the identification of temperature stress responsive protein-coding genes. Recently discovered microRNAs (miRNAs) and endogenous small-interfering RNAs (siRN As) have also been demonstrated as important players in plant temperature stress response. Using high-throughput sequencing, many small RNAs, especially miRNAs, have been identified to be triggered by cold or heat. Subsequently, several studies have shown an important functional role for these small RNAs in cold or heat tolerance. These findings greatly broaden our understanding of endogenous small RNAs in plant stress response control. Here, we highlight new findings regarding the roles of miRNAs and siRNAs in plant temperature stress response and acclimation. We also review the current understanding of the regulatory mechanisms of small RNAs in temperature stress response, and explore the outlook for the use of these small RNAs in molecular breeding for improvement of temperature stress tolerance in plants.


Assuntos
RNA de Plantas/genética , RNA Interferente Pequeno/genética , Regulação da Expressão Gênica de Plantas/genética , MicroRNAs/genética , Temperatura Ambiente
13.
Food Funct ; 8(2): 808-815, 2017 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-28121324

RESUMO

Dietary phenolics exhibit hypolipidemic activity by changing lipid metabolism-related microRNA (miRNA) expression. Quercetin 3-O-rutinoside-7-O-α-l-rhamnosidase (quercetin 3-rut-7-rha), rutin and (-)-epicatechin are the main phenolics in lychee (Litchi chinensis Sonn.) pulp. A previous study reported that quercetin 3-rut-7-rha and rutin had hypolipidemic effects. To elucidate these effects and the underlying molecular mechanisms of lychee pulp phenolics (LPPs), the hepatic mRNA and protein expression of lipid metabolism-related genes and their associated miRNAs were measured after ten weeks of treatment with a high-fat diet (HFD) alone or in combination with LPPs. The administration of LPPs significantly reduced the HFD-induced increase in serum total cholesterol and triglyceride levels but increased the HDL-c content. The mRNA and protein expression levels of hepatic adenosine triphosphate-binding cassette transporter A1 (ABCA1) and carnitine palmitoyltransferase 1a (CPT1a) were upregulated, while fatty acid synthase (FAS) mRNA and the corresponding protein expression levels were downregulated by LPPs. Furthermore, the expression levels of miR-33, which directly modulates ABCA1 and CPT1a, and miR-122, which indirectly regulates FAS, were downregulated in mouse hepatocytes. The repression of miR-33 and miR-122 is a possible molecular mechanism of the hypolipidemic effects of LPPs in the liver. Our results suggest a novel hypolipidemic mechanism of LPPs.


Assuntos
Hiperlipidemias/tratamento farmacológico , Metabolismo dos Lipídeos/efeitos dos fármacos , Litchi/química , Fígado/metabolismo , MicroRNAs/genética , Fenóis/administração & dosagem , Extratos Vegetais/administração & dosagem , Transportador 1 de Cassete de Ligação de ATP/genética , Transportador 1 de Cassete de Ligação de ATP/metabolismo , Animais , Carnitina O-Palmitoiltransferase/genética , Carnitina O-Palmitoiltransferase/metabolismo , Dieta Hiperlipídica/efeitos adversos , Regulação para Baixo/efeitos dos fármacos , Ácido Graxo Sintases/genética , Ácido Graxo Sintases/metabolismo , Frutas/química , Humanos , Hiperlipidemias/etiologia , Hiperlipidemias/genética , Hiperlipidemias/metabolismo , Fígado/efeitos dos fármacos , Fígado/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo
14.
Sci Rep ; 7: 41403, 2017 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-28134261

RESUMO

Moringa oleifera (M. oleifera) is a remarkable species with high nutritional value and good biomass production, which can be used as livestock fodder. In this study, we examined changes in the faecal microbiota of thirty dairy cows in response to alternative M. oleifera diets and their effects on nutrient digestion, milk traits and the faecal concentrations of short-chain fatty acids. No differences in milk yield and constituents were found between the control and the M. oleifera alternative groups. Cows fed M. oleifera silage had lower dry matter digestibility, as well as the propionate and isovalerate concentrations in M. oleifera treated group. Using 16S rDNA gene sequencing, 1,299,556 paired-end reads were obtained. Clustering analysis revealed 13 phyla and 93 genera across all samples. Firmicutes and Bacteroidetes were the co-dominant phyla. Ten taxa displayed a significant difference in response to the high M. oleifera diet. In addition, strong correlations between Akkermansia and Prevotella with milk yield and protein indicated that some bacterial groups could be used to improve milk traits. Our results provided an insight into the microbiome-associated responses to M. oleifera in livestock diets, and could aid the development of novel applications of M. oleifera.


Assuntos
Ração Animal/análise , Indústria de Laticínios , Dieta , Fezes/microbiologia , Comportamento Alimentar , Microbiota , Moringa oleifera/química , Silagem , Animais , Bovinos , Ácidos Graxos Voláteis/metabolismo , Leite , Anotação de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
15.
Wei Sheng Wu Xue Bao ; 57(1): 24-32, 2017 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-29746057

RESUMO

Seeds with high oil contents are more susceptible to aflatoxin contamination after infected by Aspergillus species. However, in vitro studies showed that different types of fatty acids have striking difference on fungal growth, sporulation and aflatoxin biosynthesis in Aspergillus. Recent studies revealed that, although all fatty acids examined promote aflatoxin production, oxidized polyunsaturated fatty acids inhibit aflatoxin biosynthesis. The inhibiting effect is derived from oxylipins produced during autoxidation. In this article, we provide an overview for recent progress in fatty acids and oxylipins on fungal growth, sporulation and aflatoxin production in Aspergillus species.


Assuntos
Aflatoxinas/biossíntese , Aspergillus flavus/metabolismo , Ácidos Graxos/metabolismo , Oxilipinas/metabolismo , Esporos Fúngicos/crescimento & desenvolvimento , Aspergillus flavus/genética , Aspergillus flavus/crescimento & desenvolvimento , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo
16.
Plant Mol Biol ; 92(4-5): 411-423, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27631432

RESUMO

KEY MESSAGE: This is the first report that GLP gene (OsGLP2-1) is involved in panicle blast and bacterial blight resistance in rice. In addition to its resistance to blast and bacterial blight, OsGLP2-1 has also been reported to co-localize with a QTLs for sheath blight resistance in rice. These suggest that the disease resistance provided by OsGLP2-1 is quantitative and broad spectrum. Its good resistance to these major diseases in rice makes it to be a promising target in rice breeding. Rice (Oryza sativa) blast caused by Magnaporthe oryzae and bacterial blight caused by Xanthomonas oryzae pv. oryzae are the two most destructive rice diseases worldwide. Germin-like protein (GLP) gene family is one of the important defense gene families which have been reported to be involved in disease resistance in plants. Although GLP proteins have been demonstrated to positively regulate leaf blast resistance in rice, their involvement in resistance to panicle blast and bacterial blight, has not been reported. In this study, we reported that one of the rice GLP genes, OsGLP2-1, was significantly induced by blast fungus. Overexpression of OsGLP2-1 quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. The temporal and spatial expression analysis revealed that OsGLP2-1is highly expressed in leaves and panicles and sub-localized in the cell wall. Compared with empty vector transformed (control) plants, the OsGLP2-1 overexpressing plants exhibited higher levels of H2O2 both before and after pathogen inoculation. Moreover, OsGLP2-1 was significantly induced by jasmonic acid (JA). Overexpression of OsGLP2-1 induced three well-characterized defense-related genes which are associated in JA-dependent pathway after pathogen infection. Higher endogenous level of JA was also identified in OsGLP2-1 overexpressing plants than in control plants both before and after pathogen inoculation. Together, these results suggest that OsGLP2-1 functions as a positive regulator to modulate disease resistance. Its good quantitative resistance to the two major diseases in rice makes it to be a promising target in rice breeding.


Assuntos
Resistência à Doença/genética , Glicoproteínas/genética , Glicoproteínas/metabolismo , Oryza/genética , Oryza/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ciclopentanos/farmacologia , Resistência à Doença/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/genética , Peróxido de Hidrogênio/metabolismo , Magnaporthe/fisiologia , Oryza/efeitos dos fármacos , Oryza/metabolismo , Oxilipinas/farmacologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Planta/farmacologia , Proteínas de Plantas/efeitos dos fármacos , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Xanthomonas/fisiologia
17.
Fungal Genet Biol ; 81: 229-37, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25498164

RESUMO

Aflatoxins produced by Aspergillus species are among the most toxic and carcinogenic compounds in nature. Although it has been known for a long time that seeds with high oil content are more susceptible to aflatoxin contamination, the role of fatty acids in aflatoxin biosynthesis remains controversial. Here we demonstrate in A. flavus that both the saturated stearic acid (C18:0) and the polyunsaturated linolenic acid (C18:3) promoted aflatoxin production, while C18:3, but not C18:0, inhibited aflatoxin biosynthesis after exposure to air for several hours. Further experiments showed that autoxidated C18:3 promoted mycelial growth, sporulation, and kojic acid production, but inhibited the expression of genes in the AF biosynthetic gene cluster. Mass spectrometry analyses of autoxidated C18:3 fractions that were able to inhibit aflatoxin biosynthesis led to the identification of multiple oxylipin species. These results may help to clarify the role of fatty acids in aflatoxin biosynthesis, and may explain why controversial results have been obtained for fatty acids in the past.


Assuntos
Aflatoxinas/antagonistas & inibidores , Aflatoxinas/biossíntese , Aspergillus flavus/efeitos dos fármacos , Aspergillus flavus/metabolismo , Vias Biossintéticas/efeitos dos fármacos , Oxilipinas/metabolismo , Ácido alfa-Linoleico/metabolismo , Aspergillus flavus/crescimento & desenvolvimento , Espectrometria de Massas , Oxirredução , Pironas/metabolismo , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , Ácidos Esteáricos/metabolismo
18.
BMC Microbiol ; 14: 95, 2014 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-24742119

RESUMO

BACKGROUND: Aflatoxins (AFs) are potent carcinogenic compounds produced by several Aspergillus species, which pose serious threats to human health. As sugar is a preferred carbohydrate source for AF production, we examined the possibility of using sugar analogs to inhibit AF biosynthesis. RESULTS: We showed that although D-glucal cannot be utilized by A. flavus as the sole carbohydrate source, it inhibited AF biosynthesis and promoted kojic acid production without affecting mycelial growth when applied to a glucose-containing medium. The inhibition occurred before the production of the first stable intermediate, norsolorinic acid, suggesting a complete inhibition of the AF biosynthetic pathway. Further studies showed that exogenous D-glucal in culture led to reduced accumulation of tricarboxylic acid (TCA) cycle intermediates and reduced glucose consumption, indicating that glycolysis is inhibited. Expression analyses revealed that D-glucal suppressed the expression of AF biosynthetic genes but promoted the expression of kojic acid biosynthetic genes. CONCLUSIONS: D-glucal as a non-metabolizable glucose analog inhibits the AF biosynthesis pathway by suppressing the expression of AF biosynthetic genes. The inhibition may occur either directly through interfering with glycolysis, or indirectly through reduced oxidative stresses from kojic acid biosynthesis.


Assuntos
Aflatoxinas/antagonistas & inibidores , Aflatoxinas/biossíntese , Aspergillus flavus/efeitos dos fármacos , Aspergillus flavus/metabolismo , Desoxiglucose/análogos & derivados , Pironas/metabolismo , Aspergillus flavus/crescimento & desenvolvimento , Meios de Cultura/química , Desoxiglucose/metabolismo , Perfilação da Expressão Gênica , Hifas/efeitos dos fármacos , Hifas/crescimento & desenvolvimento
19.
BMC Microbiol ; 12: 106, 2012 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-22694821

RESUMO

BACKGROUND: Aflatoxins (AFs) are highly carcinogenic compounds produced by Aspergillus species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productions, although reasons for this remain unknown. RESULTS: In this study, we showed that when Aspergillus flavus was grown in peptone-containing media, higher initial spore densities inhibited AF biosynthesis, but promoted mycelial growth; while in glucose-containing media, more AFs were produced when initial spore densities were increased. This phenomenon was also observed in other AF-producing strains including A. parasiticus and A. nomius. Higher peptone concentrations led to inhibited AF production, even in culture with a low spore density. High peptone concentrations did however promote mycelial growth. Spent medium experiments showed that the inhibited AF production in peptone media was regulated in a cell-autonomous manner. mRNA expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with high initial spore densities. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia grown in peptone media with a high initial spore density showed suppressed fatty acid biosynthesis, reduced tricarboxylic acid (TCA) cycle intermediates, and increased pentose phosphate pathway products. Additions of TCA cycle intermediates had no effect on AF biosynthesis, suggesting the inhibited AF biosynthesis was not caused by depleted TCA cycle intermediates. CONCLUSIONS: We here demonstrate that Aspergillus species grown in media with peptone as the sole carbon source are able to sense their own population densities and peptone concentrations to switch between rapid growth and AF production. This switching ability may offer Aspergillus species a competition advantage in natural ecosystems, producing AFs only when self-population is low and food is scarce.


Assuntos
Aflatoxinas/biossíntese , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus flavus/metabolismo , Carbono/metabolismo , Peptonas/metabolismo , Esporos Fúngicos/crescimento & desenvolvimento , Meios de Cultura/química , Perfilação da Expressão Gênica , Glucose/metabolismo , Metaboloma , Micélio/crescimento & desenvolvimento , RNA Mensageiro/biossíntese , RNA Mensageiro/genética
20.
J Proteome Res ; 11(5): 2739-53, 2012 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-22424419

RESUMO

An immune response is triggered in host cells when host receptors recognize conserved molecular motifs, pathogen-associated molecular patterns (PAMPs), such as ß-glucans, and chitin at the cell surface of a pathogen. Effector-triggered immunity occurs when pathogens deliver effectors into the host cell to suppress the first immune signaling. Using a differential proteomic approach, we identified an array of proteins responding to aflatoxins in cotyledons of peanut (Arachis hypogaea) infected with aflatoxin-producing (toxigenic) but not nonaflatoxin-producing (atoxigenic) strains of Aspergillus flavus. These proteins are involved in immune signaling and PAMP perception, DNA and RNA stabilization, induction of defense, innate immunity, hypersensitive response, biosynthesis of phytoalexins, cell wall responses, peptidoglycan assembly, penetration resistance, condensed tannin synthesis, detoxification, and metabolic regulation. Gene expression analysis confirmed the differential abundance of proteins in peanut cotyledons supplemented with aflatoxins, with or without infection with the atoxigenic strain. Similarly, peanut germination and A. flavus growth were altered in response to aflatoxin B1. These findings show an additional immunity initiated by aflatoxins. With the PAMP- and effector-triggered immune responses, this immunity constitutes the third immune response of the immune system in peanut cotyledon cells. The system is also a three-grade coevolution of plant-pathogen interaction.


Assuntos
Aflatoxina B1/imunologia , Arachis/imunologia , Aspergillus flavus/patogenicidade , Imunidade Vegetal , Proteoma/análise , Aflatoxina B1/genética , Arachis/genética , Arachis/microbiologia , Parede Celular , Clonagem Molecular , Cotilédone/genética , Cotilédone/imunologia , Cotilédone/microbiologia , Regulação da Expressão Gênica de Plantas , Germinação , Interações Hospedeiro-Patógeno , Micélio/crescimento & desenvolvimento , Micélio/imunologia , Células Vegetais/imunologia , Células Vegetais/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Proteínas de Armazenamento de Sementes/imunologia , Sementes/imunologia , Sementes/microbiologia , Transdução de Sinais , Especificidade da Espécie
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