scholarly journals Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins

2021 ◽  
Vol 7 (8) ◽  
pp. 666
Author(s):  
Elisabeth Tumukunde ◽  
Rui Xie ◽  
Shihua Wang
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Posttranslational Modifications ◽  
Molecular Mechanisms ◽  
Aflatoxin Production ◽  
Economic Losses ◽  
Effective Strategies ◽  
Non Invasive ◽  
Cotton Seeds ◽  
Opportunistic Fungal Pathogen

Aspergillus flavus (A. flavus) is a ubiquitous and opportunistic fungal pathogen that causes invasive and non-invasive aspergillosis in humans and animals. This fungus is also capable of infecting a large number of agriculture crops (e.g., peanuts, maze, cotton seeds, rice, etc.), causing economic losses and posing serious food-safety concerns when these crops are contaminated with aflatoxins, the most potent naturally occurring carcinogens. In particular, A. flavus and aflatoxins are intensely studied, and they continue to receive considerable attention due to their detrimental effects on humans, animals, and crops. Although several studies have been published focusing on the biosynthesis of the aforementioned secondary metabolites, some of the molecular mechanisms (e.g., posttranslational modifications, transcription factors, transcriptome, proteomics, metabolomics and transcriptome, etc.) involved in the fungal development and aflatoxin biosynthesis in A. flavus are still not fully understood. In this study, a review of the recently published studies on the function of the genes and the molecular mechanisms involved in development of A. flavus and the production of its secondary metabolites is presented. It is hoped that the information provided in this review will help readers to develop effective strategies to reduce A. flavus infection and aflatoxin production.

scholarly journals Natural Occurence of Aflatoxins in Wheat from Central Transylvania

2011 ◽  
Vol 68 (2) ◽  
Author(s):  
Simona MAN ◽  
Maria TOFANA ◽  
Sevastiţa MUSTE ◽  
Adriana PAUCEAN ◽  
Anamaria BIROU (POP)
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Economic Losses ◽  
Important Food ◽  
And Storage ◽  
Harmful Effects

Aflatoxins (AFs), the secondary metabolites produced by species of Aspergillus, specifically Aspergillus flavus and Aspergillus parasiticus, have harmful effects on humans, animals, and crops that result in illnesses and economic losses. Wheat that is susceptible to these fungi infections through its growth, harvest, transport, and storage, is the most important food in Romania. Therefore, this study sought to present mycotoxins in wheat samples grown in different regions of Transyvania, the results being obtained in the climate of the year 2009-2010. Wheat samples were collected from Turda and Targu Mures. It was analyzed the presence of aflatoxins B1, B2, G1, G2, using HPTLC in twenty samples of wheat. Percentage of samples found positive for aflatoxin B1, B2, G1, G2 was 10%, 5%, 0%, 0%. Although the percentage of aflatoxin found in wheat is low, these percentages should be considered, in terms of exposure every day to mycotoxins through consumption of cereals and cereal-based products.

scholarly journals Transcriptional Regulation of Aflatoxin Biosynthesis and Conidiation in Aspergillus flavus by Wickerhamomyces anomalus WRL-076 for Reduction of Aflatoxin Contamination

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 81 ◽  
Author(s):  
Sui Hua ◽  
Siov Sarreal ◽  
Perng-Kuang Chang ◽  
Jiujiang Yu
Keyword(s):  
Aspergillus Flavus ◽  
Molecular Mechanisms ◽  
Field Experiments ◽  
Regulatory Gene ◽  
Aflatoxin Contamination ◽  
Economic Losses ◽  
Expression Levels ◽  
Wickerhamomyces Anomalus ◽  
Cultural Medium ◽  
Major Producer

Aspergillus flavus is a ubiquitous saprophytic fungus found in soils across the world. The fungus is the major producer of aflatoxin (AF) B1, which is toxic and a potent carcinogen to humans. Aflatoxin B1 (AFB1) is often detected in agricultural crops such as corn, peanut, almond, and pistachio. It is a serious and recurrent problem and causes substantial economic losses. Wickerhamomyces anomalus WRL-076 was identified as an effective biocontrol yeast against A. flavus. In this study, the associated molecular mechanisms of biocontrol were investigated. We found that the expression levels of eight genes, aflR, aflJ, norA, omtA, omtB, pksA, vbs, and ver-1 in the aflatoxin biosynthetic pathway cluster were suppressed. The decreases ranged from several to 10,000 fold in fungal samples co-cultured with W. anomalus. Expression levels of conidiation regulatory genes brlA, abaA, and wetA as well as sclerotial regulatory gene (sclR) were all down regulated. Consistent with the decreased gene expression levels, aflatoxin concentrations in cultural medium were reduced to barely detectable. Furthermore, fungal biomass and conidial number were significantly reduced by 60% and more than 95%, respectively. The results validate the biocontrol efficacy of W. anomalus WRL-076 observed in the field experiments.

scholarly journals Transcriptome Analysis Identified Coordinated Control of Key Pathways Regulating Cellular Physiology and Metabolism upon Aspergillus flavus Infection Resulting in Reduced Aflatoxin Production in Groundnut

2020 ◽  
Vol 6 (4) ◽  
pp. 370
Author(s):  
Pooja Soni ◽  
Spurthi N. Nayak ◽  
Rakesh Kumar ◽  
Manish K. Pandey ◽  
Namita Singh ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Molecular Mechanisms ◽  
Coordinated Control ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Rna Seq ◽  
Resistant Genotype ◽  
Cellular Physiology ◽  
Global Health Issue ◽  
Key Pathways

Aflatoxin-affected groundnut or peanut presents a major global health issue to both commercial and subsistence farming. Therefore, understanding the genetic and molecular mechanisms associated with resistance to aflatoxin production during host–pathogen interactions is crucial for breeding groundnut cultivars with minimal level of aflatoxin contamination. Here, we performed gene expression profiling to better understand the mechanisms involved in reduction and prevention of aflatoxin contamination resulting from Aspergillus flavus infection in groundnut seeds. RNA sequencing (RNA-Seq) of 16 samples from different time points during infection (24 h, 48 h, 72 h and the 7th day after inoculation) in U 4-7-5 (resistant) and JL 24 (susceptible) genotypes yielded 840.5 million raw reads with an average of 52.5 million reads per sample. A total of 1779 unique differentially expressed genes (DEGs) were identified. Furthermore, comprehensive analysis revealed several pathways, such as disease resistance, hormone biosynthetic signaling, flavonoid biosynthesis, reactive oxygen species (ROS) detoxifying, cell wall metabolism and catabolizing and seed germination. We also detected several highly upregulated transcription factors, such as ARF, DBB, MYB, NAC and C2H2 in the resistant genotype in comparison to the susceptible genotype after inoculation. Moreover, RNA-Seq analysis suggested the occurrence of coordinated control of key pathways controlling cellular physiology and metabolism upon A. flavus infection, resulting in reduced aflatoxin production.

scholarly journals Transcriptomic responses of Aspergillus flavus to temperature and oxidative stresses during aflatoxin production

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fei Tian ◽  
Sang Yoo Lee ◽  
So Young Woo ◽  
Hwa Young Choi ◽  
Seongeun Heo ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Antioxidant Properties ◽  
Culture Method ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Stress Conditions ◽  
Effective Control ◽  
Nadh:Ubiquinone Oxidoreductase ◽  
Transcriptomic Response

AbstractAflatoxin is a group of polyketide-derived carcinogenic and mutagenic secondary metabolites produced by Aspergillus flavus that negatively impact global food security and threaten the health of both humans and livestock. Aflatoxin biosynthesis is strongly affected by the fungal developmental stage, cultivation conditions, and environmental stress. In this study, a novel float culture method was used to examine the direct responses of the A. flavus transcriptome to temperature stress, oxidative stress, and their dual effects during the aflatoxin production stage. The transcriptomic response of A. flavus illustrated that the co-regulation of different secondary metabolic pathways likely contributes to maintaining cellular homeostasis and promoting cell survival under stress conditions. In particular, aflatoxin biosynthetic gene expression was downregulated, while genes encoding secondary metabolites with antioxidant properties, such as kojic acid and imizoquins, were upregulated under stress conditions. Multiple mitochondrial function-related genes, including those encoding NADH:ubiquinone oxidoreductase, ubiquinol-cytochrome C reductase, and alternative oxidase, were differentially expressed. These data can provide insights into the important mechanisms through which secondary metabolism in A. flavus is co-regulated and facilitate the deployment of various approaches for the effective control and prevention of aflatoxin contamination in food crops.

scholarly journals Distribution, Genetic Diversity and Biocontrol of Aflatoxigenic Aspergillus flavus in Serbian Maize Fields

Toxins ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 687
Author(s):  
Vanja Vlajkov ◽  
Mila Grahovac ◽  
Dragana Budakov ◽  
Marta Loc ◽  
Ivana Pajčin ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
High Performance ◽  
Critical Role ◽  
High Capacity ◽  
Aflatoxin Production ◽  
Elisa Test ◽  
Aflatoxin Contamination ◽  
Economic Losses ◽  
Enzyme Linked Immunosorbent Assay ◽  
The Republic

Maize is one of the leading export products in the Republic of Serbia. As a country where economic development depends on agriculture, maize production plays a critical role as a crop of strategic importance. Potential aflatoxin contamination of maize poses a risk to food and feed safety and tremendous economic losses. No aflatoxin contamination of maize samples harvested in 2019 and 2020 in different localities in the Republic of Serbia was detected by the Enzyme-Linked Immunosorbent Assay (ELISA) test and High-Performance Liquid Chromatography (HPLC) method. On the other hand, the Cluster Amplification Patterns (CAP) analyses of the isolated Aspergillus flavus strains from 2019 maize samples confirmed the presence of key biosynthesis genes responsible for aflatoxin production. Artificial inoculation and subsequent HPLC analysis of the inoculated maize samples confirmed the high capacity of the A. flavus strains for aflatoxin production, pointing to a high risk of contamination under favorable conditions. Prevention of aflatoxin contamination is primarily based on A. flavus control, where biocontrol agents play a significant role as sustainable disease management tools. In this study, antagonistic activity screening of the novel strains belonging to the Bacillus genus indicated superior suppression of A. flavus strains by two Bacillus strains isolated from the rhizosphere of Phaseolus vulgaris.

scholarly journals Draft Genome Sequences of 20 Aspergillus flavus Isolates from Corn Kernels and Cornfield Soils in Louisiana

2020 ◽  
Vol 9 (38) ◽  
Author(s):  
Solomon T. Gebru ◽  
Mark K. Mammel ◽  
Jayanthi Gangiredla ◽  
Carmen Tartera ◽  
Jeffrey W. Cary ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Fungal Pathogen ◽  
Draft Genome ◽  
Vegetative Compatibility ◽  
Genome Sequences ◽  
Content Type ◽  
Vegetative Compatibility Groups ◽  
Opportunistic Fungal Pathogen ◽  
Corn Kernels

ABSTRACT Aspergillus flavus is a common saprophyte and opportunistic fungal pathogen that infects plants, animals, and humans. It also produces numerous toxic and nontoxic secondary metabolites. Here, we report the draft genome sequences of 20 A. flavus isolates, belonging to 16 vegetative compatibility groups, from Louisiana corn kernels and cornfield soils.

scholarly journals Investigation of the Antifungal and Anti-Aflatoxigenic Potential of Plant-Based Essential Oils against Aspergillus flavus in Peanuts

2020 ◽  
Vol 6 (4) ◽  
pp. 383
Author(s):  
Premila Narayana Achar ◽  
Pham Quyen ◽  
Emmanuel C. Adukwu ◽  
Abhishek Sharma ◽  
Huggins Zephaniah Msimanga ◽  
...  
Keyword(s):  
Essential Oils ◽  
Aspergillus Flavus ◽  
High Performance ◽  
Opportunistic Infections ◽  
Aflatoxin Production ◽  
The United States ◽  
Microscopy Study ◽  
Aspergillus Species ◽  
Gas Chromatography Mass Spectrometry ◽  
Ammonia Vapor

Aspergillus species are known to cause damage to food crops and are associated with opportunistic infections in humans. In the United States, significant losses have been reported in peanut production due to contamination caused by the Aspergillus species. This study evaluated the antifungal effect and anti-aflatoxin activity of selected plant-based essential oils (EOs) against Aspergillus flavus in contaminated peanuts, Tifguard, runner type variety. All fifteen essential oils, tested by the poisoned food technique, inhibited the growth of A. flavus at concentrations ranging between 125 and 4000 ppm. The most effective oils with total clearance of the A. flavus on agar were clove (500 ppm), thyme (1000 ppm), lemongrass, and cinnamon (2000 ppm) EOs. The gas chromatography-mass spectrometry (GC-MS) analysis of clove EO revealed eugenol (83.25%) as a major bioactive constituent. An electron microscopy study revealed that clove EO at 500 ppm caused noticeable morphological and ultrastructural alterations of the somatic and reproductive structures. Using both the ammonia vapor (AV) and coconut milk agar (CMA) methods, we not only detected the presence of an aflatoxigenic form of A. flavus in our contaminated peanuts, but we also observed that aflatoxin production was inhibited by clove EO at concentrations between 500 and 2000 ppm. In addition, we established a correlation between the concentration of clove EO and AFB1 production by reverse-phase high-performance liquid chromatography (HPLC). We demonstrate in our study that clove oil could be a promising natural fungicide for an effective bio-control, non-toxic bio-preservative, and an eco-friendly alternative to synthetic additives against A. flavus in Georgia peanuts.

scholarly journals The Effect of Gut Bacteria on the Physiology of Red Palm Weevil, Rhynchophorus ferrugineus Olivier and Their Potential for the Control of This Pest

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 594
Author(s):  
Qian-Xia Liu ◽  
Zhi-Ping Su ◽  
Hui-Hui Liu ◽  
Sheng-Ping Lu ◽  
Bing Ma ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Management Strategies ◽  
Gut Bacteria ◽  
Economic Losses ◽  
Rhynchophorus Ferrugineus ◽  
Intestinal Immunity ◽  
Red Palm Weevil ◽  
Nutrient Metabolism ◽  
Palm Weevil

Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier, is a notorious pest, which infests palm trees and has caused great economic losses worldwide. At present, insecticide applications are still the main way to control this pest. However, pesticide resistance has been detected in the field populations of RPW. Thus, future management strategies based on the novel association biological control need be developed. Recent studies have shown that the intestinal tract of RPW is often colonized by multiple microbial species as mammals and model insects, and gut bacteria have been found to promote the growth, development and immune activity of RPW larvae by modulating nutrient metabolism. Furthermore, two peptidoglycan recognition proteins (PGRPs), PGRP-LB and PGRP-S1, can act as the negative regulators to modulate the intestinal immunity to maintain the homeostasis of gut bacteria in RPW larvae. Here, we summarized the current knowledge on the gut bacterial composition of RPW and their impact on the physiological traits of RPW larvae. In contrast with metazoans, it is much easier to make genetic engineered microbes to produce some active molecules against pests. From this perspective, because of the profound effects of gut bacteria on host phenotypes, it is promising to dissect the molecular mechanisms behind their effect on host physiology and facilitate the development of microbial resource-based management methods for pest control.

scholarly journals RNAseq Reveals Differential Gene Expression Contributing to Phytophthora nicotianae Adaptation to Partial Resistance in Tobacco

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 656
Author(s):  
Jing Jin ◽  
Rui Shi ◽  
Ramsey Steven Lewis ◽  
Howard David Shew
Keyword(s):  
Partial Resistance ◽  
Molecular Mechanisms ◽  
Biological Activities ◽  
Effective Means ◽  
Phytophthora Nicotianae ◽  
Economic Losses ◽  
Black Shank ◽  
Differential Gene ◽  
Go Terms

Phytophthora nicotianae is a devastating oomycete plant pathogen with a wide host range. On tobacco, it causes black shank, a disease that can result in severe economic losses. Deployment of host resistance is one of the most effective means of controlling tobacco black shank, but adaptation to complete and partial resistance by P. nicotianae can limit the long-term effectiveness of the resistance. The molecular basis of adaptation to partial resistance is largely unknown. RNAseq was performed on two isolates of P. nicotianae (adapted to either the susceptible tobacco genotype Hicks or the partially resistant genotype K 326 Wz/Wz) to identify differentially expressed genes (DEGs) during their pathogenic interactions with K 326 Wz/Wz and Hicks. Approximately 69% of the up-regulated DEGs were associated with pathogenicity in the K 326 Wz/Wz-adapted isolate when sampled following infection of its adapted host K 326 Wz/Wz. Thirty-one percent of the up-regulated DEGs were associated with pathogenicity in the Hicks-adapted isolate on K 326 Wz/Wz. A broad spectrum of over-represented gene ontology (GO) terms were assigned to down-regulated genes in the Hicks-adapted isolate. In the host, a series of GO terms involved in nuclear biosynthesis processes were assigned to the down-regulated genes in K 326 Wz/Wz inoculated with K 326 Wz/Wz-adapted isolate. This study enhances our understanding of the molecular mechanisms of P. nicotianae adaptation to partial resistance in tobacco by elucidating how the pathogen recruits pathogenicity-associated genes that impact host biological activities.

scholarly journals Circulating miRNAs Related to Epithelial–Mesenchymal Transitions (EMT) as the New Molecular Markers in Endometriosis

2021 ◽  
Vol 43 (2) ◽  
pp. 900-916
Author(s):  
Anna Zubrzycka ◽  
Monika Migdalska-Sęk ◽  
Sławomir Jędrzejczyk ◽  
Ewa Brzeziańska-Lasota
Keyword(s):  
Molecular Mechanisms ◽  
Immune Cell ◽  
Epithelial Mesenchymal Transition ◽  
Clinical Symptoms ◽  
Diagnostic Tools ◽  
Endometrial Stromal Cells ◽  
Disease Etiology ◽  
Diagnostic Biomarkers ◽  
Mesenchymal Transition ◽  
Non Invasive

Endometriosis is a chronic gynecological disease defined by the presence of endometrial-like tissue found outside the uterus, most commonly in the peritoneal cavity. Endometriosis lesions are heterogenous but usually contain endometrial stromal cells and epithelial glands, immune cell infiltrates and are vascularized and innervated by nerves. The complex etiopathogenesis and heterogenity of the clinical symptoms, as well as the lack of a specific non-invasive diagnostic biomarkers, underline the need for more advanced diagnostic tools. Unfortunately, the contribution of environmental, hormonal and immunological factors in the disease etiology is insufficient, and the contribution of genetic/epigenetic factors is still fragmentary. Therefore, there is a need for more focused study on the molecular mechanisms of endometriosis and non-invasive diagnostic monitoring systems. MicroRNAs (miRNAs) demonstrate high stability and tissue specificity and play a significant role in modulating a range of molecular pathways, and hence may be suitable diagnostic biomarkers for the origin and development of endometriosis. Of these, the most frequently studied are those related to endometriosis, including those involved in epithelial–mesenchymal transition (EMT), whose expression is altered in plasma or endometriotic lesion biopsies; however, the results are ambiguous. Specific miRNAs expressed in endometriosis may serve as diagnostics markers with prognostic value, and they have been proposed as molecular targets for treatment. The aim of this review is to present selected miRNAs associated with EMT known to have experimentally confirmed significance, and discuss their utility as biomarkers in endometriosis.

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