scholarly journals The PHD Transcription Factor Rum1 Regulates Morphogenesis and Aflatoxin Biosynthesis in Aspergillus flavus

Toxins ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 301 ◽  
Author(s):  
Yule Hu ◽  
Guang Yang ◽  
Danping Zhang ◽  
Yaju Liu ◽  
Yu Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Homologous Recombination ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Biological Function ◽  
Biological Synthesis ◽  
Deletion Mutants ◽  
Aflatoxin Biosynthesis

Aspergillus flavus produces mycotoxins especially aflatoxin B1 and infects crops worldwide. As a PHD transcription factor, there is no report on the role of Rum1 in the virulence of Aspergillus spp. yet. This study explored the biological function of Rum1 in A. flavus through the construction of rum1 deletion mutants and rum1 complementation strains with the method of homologous recombination. It was found, in the study, that Rum1 negatively regulates conidiation through abaA and brlA, positively regulates sclerotia formation through nsdC, nsdD, and sclR, triggers aflatoxin biological synthesis, and enhances the activity of amylase. Our findings suggested that Rum1 plays a major role in the growth of mycelia, conidia, and sclerotia production along with aflatoxin biosynthesis in A. flavus.

scholarly journals Impact of Silver Nanoparticles on Gene Expression in Aspergillus Flavus Producer Aflatoxin B1

2018 ◽  
Vol 6 (4) ◽  
pp. 600-605 ◽  
Author(s):  
Mohamed Mahmoud Deabes ◽  
Wagdy Khalil Bassaly Khalil ◽  
Ashraf Gamil Attallah ◽  
Tarek Ahmed El-Desouky ◽  
Khayria Mahmoud Naguib
Keyword(s):  
Silver Nanoparticles ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Inhibitory Effect ◽  
Aflatoxin Biosynthesis ◽  
Qrt Pcr ◽  
Methyltransferase Gene ◽  
Polymerase Chain ◽  
Yeast Extract Sucrose ◽  
Quantitative Pcr Assay

AIM: In this study, we evaluated the effect of silver nanoparticles (AgNPs) on the production of aflatoxin B1 (AFB1) through assessment the transcription activity of aflatoxin biosynthesis pathway genes in Aspergillus flavus ATCC28542.MATERIAL AND METHODS: The mRNAs were quantitative by Real Time-polymerase chain reaction (qRT-PCR) of A. flavus grown in yeast extract sucrose (YES) medium containing AgNPs. Specific primers that are involved in the AFB1 biosynthesis which highly specific to A. flavus, O-methyltransferase gene (omt-A), were designed and used to detect the fungus activity by quantitative PCR assay. The AFB1 production (from A. flavus growth) which effected by AgNPs were measured in YES medium by high-pressure liquid chromatography (HPLC).RESULTS: The AFB1 produced by A. flavus have the highest reduction with 1.5 mg -100 ml of AgNPs were added in media those records 88.2%, 67.7% and 83.5% reduction by using AgNP HA1N, AgNP HA2N and AgNP EH, respectively. While on mycelial growth give significantly inhibitory effect. These results have been confirmed by qRT-PCR which showed that culture of A. flavus with the presence of AgNPs reduced the expression levels of omt-A gene.CONCLUSION: Based on the results of the present study, AgNPs inhibit growth and AFB1 produced by Aspergillus flavus ATCC28542. This was confirmed through RT-PCR approach showing the effect of AgNPs on omt-A gene involved in aflatoxin biosynthesis.

scholarly journals Osmotic-Adaptation Response of sakA/hogA Gene to Aflatoxin Biosynthesis, Morphology Development and Pathogenicity in Aspergillus flavus

Toxins ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 41 ◽  
Author(s):  
Elisabeth Tumukunde ◽  
Ding Li ◽  
Ling Qin ◽  
Yu Li ◽  
Jiaojiao Shen ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Wall Stress ◽  
Mitogen Activated Protein Kinase ◽  
Human Beings ◽  
Aflatoxin Biosynthesis ◽  
Wild Type ◽  
Adaptation Response ◽  
Seed Crops

Aspergillus flavus is one of the fungi from the big family of Aspergillus genus and it is capable of colonizing a large number of seed/crops and living organisms such as animals and human beings. SakA (also called hogA/hog1) is an integral part of the mitogen activated protein kinase signal of the high osmolarity glycerol pathway. In this study, the AfsakA gene was deleted (∆AfsakA) then complemented (∆AfsakA::AfsakA) using homologous recombination and the osmotic stress was induced by 1.2 mol/L D-sorbital and 1.2 mol/L sodium chloride. The result showed that ∆AfsakA mutant caused a significant influence on conidial formation compared to wild-type and ∆AfsakA::AfsakA strains. It was also found that AfsakA responds to both the osmotic stress and the cell wall stress. In the absence of osmotic stress, ∆AfsakA mutant produced more sclerotia in contrast to other strains, whereas all strains failed to generate sclerotia under osmotic stress. Furthermore, the deletion of AfsakA resulted in the increase of Aflatoxin B1 production compared to other strains. The virulence assay on both maize kernel and peanut seeds showed that ∆AfsakA strain drastically produced more conidia and Aflatoxin B1 than wild-type and complementary strains. AfSakA-mCherry was located to the cytoplasm in the absence of osmotic stress, while it translocated to the nucleus upon exposure to the osmotic stimuli. This study provides new insights on the development and evaluation of aflatoxin biosynthesis and also provides better understanding on how to prevent Aspergillus infections which would be considered the first step towards the prevention of the seeds damages caused by A. flavus.

Resistance to Aflatoxin Contamination in Corn as Influenced by Relative Humidity and Kernel Germination

1996 ◽  
Vol 59 (3) ◽  
pp. 276-281 ◽  
Author(s):  
B. Z. GUO ◽  
J. S. RUSSIN ◽  
R. L. BROWN ◽  
T. E. CLEVELAND ◽  
N. W. WIDSTROM
Keyword(s):  
Relative Humidity ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Resistance Mechanisms ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Aflatoxin Accumulation ◽  
Moisture Conditions ◽  
Very High ◽  
Fungus Growth

Kernels of corn population GT-MAS:gk, resistant to aflatoxin B1 production by Aspergillus flavus, and susceptible Pioneer hybrid 3154 were tested for aflatoxin when incubated under different relative humidities (RH). High aflatoxin levels were not detected in either genotype at RH < 91%. Resistance in GT-MAS:gk was consistent across all RH levels (91 to 100%) at which significant aflatoxin accumulation was detected. Aflatoxin levels in GT-MAS:gk averaged about 98% less than those in susceptible Pioneer 3154, which suggests that storage of this or other genotypes with similar resistance mechanisms may be possible under moisture conditions less exacting than are required with susceptible hybrids. Results for fungus growth and sporulation ratings on kernel surfaces were similar to those for aflatoxin levels. When kernels of both genotypes were preincubated 3 days at 100% RH prior to inoculation with A. flavus, germination percentages increased to very high levels compared to those of kernels that were not preincubated. In preincubated kernels aflatoxin levels remained consistently low in GT-MAS:gk but decreased markedly (61%) in Pioneer 3154. When eight susceptible hybrids were evaluated for aflatoxin accumulation in preincubated kernels, seven of these supported significantly lower toxin levels than kernels not subjected to preincubation. Average reduction across hybrids was 83%, and reductions within hybrids ranged from 68 to 96%. Preincubated kernels of one susceptible hybrid (Deltapine G-4666) supported aflatoxin levels comparable to those in resistant GT-MAS:gk. Data suggest that an inhibitor of aflatoxin biosynthesis may be induced during kernel germination. Possible mechanisms for embryo effects on resistance to aflatoxin accumulation are discussed.

scholarly journals The bZIP Transcription Factor AflRsmA Regulates Aflatoxin B1 Biosynthesis, Oxidative Stress Response and Sclerotium Formation in Aspergillus flavus

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 271
Author(s):  
Xiuna Wang ◽  
Wenjie Zha ◽  
Linlin Liang ◽  
Opemipo Esther Fasoyin ◽  
Lihan Wu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Stress Response ◽  
Secondary Metabolites ◽  
Secondary Metabolism ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Opportunistic Pathogen ◽  
Oxidative Stress Response ◽  
Bzip Transcription Factor

Fungal secondary metabolites play important roles not only in fungal ecology but also in humans living as beneficial medicine or harmful toxins. In filamentous fungi, bZIP-type transcription factors (TFs) are associated with the proteins involved in oxidative stress response and secondary metabolism. In this study, a connection between a bZIP TF and oxidative stress induction of secondary metabolism is uncovered in an opportunistic pathogen Aspergillus flavus, which produces carcinogenic and mutagenic aflatoxins. The bZIP transcription factor AflRsmA was identified by a homology research of A. flavus genome with the bZIP protein RsmA, involved in secondary metabolites production in Aspergillus nidulans. The AflrsmA deletion strain (ΔAflrsmA) displayed less sensitivity to the oxidative reagents tert-Butyl hydroperoxide (tBOOH) in comparison with wild type (WT) and AflrsmA overexpression strain (AflrsmAOE), while AflrsmAOE strain increased sensitivity to the oxidative reagents menadione sodium bisulfite (MSB) compared to WT and ΔAflrsmA strains. Without oxidative treatment, aflatoxin B1 (AFB1) production of ΔAflrsmA strains was consistent with that of WT, but AflrsmAOE strain produced more AFB1 than WT; tBOOH and MSB treatment decreased AFB1 production of ΔAflrsmA compared to WT. Besides, relative to WT, ΔAflrsmA strain decreased sclerotia, while AflrsmAOE strain increased sclerotia. The decrease of AFB1 by ΔAflrsmA but increase of AFB1 by AflrsmAOE was on corn. Our results suggest that AFB1 biosynthesis is regulated by AflRsmA by oxidative stress pathways and provide insights into a possible function of AflRsmA in mediating AFB1 biosynthesis response host defense in pathogen A. flavus.

scholarly journals Effect of Carotenoids on Aflatoxin B1 Synthesis by Aspergillus flavus

1997 ◽  
Vol 87 (8) ◽  
pp. 814-821 ◽  
Author(s):  
Robert A. Norton
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Culture Method ◽  
Aflatoxin Biosynthesis ◽  
Ring Type ◽  
Yellow Corn ◽  
Norsolorinic Acid ◽  
Aflatoxin B ◽  
Hydroxy Groups ◽  
Β Carotene

Carotenes and xanthophylls occurring in yellow corn and related terpenoids were tested for their effect on growth and aflatoxin B1 production by Aspergillus flavus NRRL 3357, using the suspended disc culture method. Aflatoxin synthesis was inhibited at concentrations of β-carotene, lutein, and zeaxanthin comparable to those found in the horny endosperm of mature corn. Usually growth was not significantly affected. Inhibition of aflatoxin biosynthesis was greater for compounds with an α-ionone-type ring (α-carotene, lutein, or α-ionone) compared with compounds with a β-ionone ring. The presence of hydroxy groups on the rings tended to decrease inhibition, but did not override the effect of the ring type; lutein was similar to α-carotene and zeaxanthin was similar to β-carotene in inhibition. A mutant accumulating norsolorinic acid (NA), A. parasiticus SRRC 162, incubated with α-carotene produced reduced levels of both NA and aflatoxin, indicating that inhibition occurred before NA. Additional A. flavus strains tested against 50 μg/ml of β-carotene had 89 to 96% inhibition, which was significantly more sensitive than NRRL 3357. A. parasiticus strains were less sensitive and generally had similar or lower inhibition than NRRL 3357. The results indicate that the presence of carotenoids in endosperm may decrease the amount of aflatoxin produced by A. flavus.

scholarly journals The PHD Transcription Factor Cti6 is Involved in the Fungal Colonization and Aflatioxin B1 Biological Synthesis of Aspergillus Flavus

2020 ◽  
Author(s):  
Mengjuan Zhang ◽  
Guanglan Lin ◽  
Xiaohua Pan ◽  
Weitao Song ◽  
Can Tan ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Biological Function ◽  
Vital Role ◽  
Biological Synthesis ◽  
Pcr Analysis ◽  
Fungal Colonization ◽  
Mycelium Growth ◽  
Formation Pathway ◽  
Novel Target ◽  
Phd Domain

Abstract Aspergillus flavus and its main secondary metabolite AFB1 pose a serious threat to several important crops worldwide. Recently, it has been reported that some PHD family transcription factors are involved in the morphogenesis and AFB1 biological synthesis in A. flavus, but the role of Cti6, a PHD domain containing protein in A. flavus, is totally unknown. The study was designed to reveal the biological function of Cti6 in the fungus by deletion of cti6, and its two domains (PHD and Atrophin-1) through homologous recombination, respectively. The results showed that Cti6 might up-regulate the mycelium growth, conidiation, sclerotia formation and AFB1 biological synthesis of A. flavus by its PHD domain, while Atrophin-1 also improved the conidiation of the fungus. The qRT-PCR analysis showed that Cti6 increased the conidiation of the fungus through AbaA and BrlA mediated conidiation pathway, triggered the formation of sclerotia by orthodox sclerotia formation pathway, and improved the production of AFB1 by orthodox AFB1 synthesis pathway. Crops models analysis showed that A. flavus Cti6 plays vital role in colonization and the production of AFB1 on the host grains mainly via PHD domain. Bioinformatics analysis showed Cti6 is conservative in Aspergillus spp., and mCherry mediated subcellular localization showed that most Cti6 accumulated in the nuclei, which reflected that Cti6 performed its important biological function in the nuclei in Aspergillus spp.. The results of the current study elucidate the roles of PHD domain containing proteins in the mechanism of the infection of crops by A. flavus, and provided a novel target for effectively controlling the contamination of Aspergillus spp. to crops.

scholarly journals The PHD transcription factor Cti6 is involved in the fungal colonization and aflatoxin B1 biological synthesis of Aspergillus flavus

IMA Fungus ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhang Mengjuan ◽  
Lin Guanglan ◽  
Pan Xiaohua ◽  
Song Weitao ◽  
Tan Can ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Biological Function ◽  
Vital Role ◽  
Biological Synthesis ◽  
Pcr Analysis ◽  
Fungal Colonization ◽  
Mycelium Growth ◽  
Formation Pathway ◽  
Novel Target ◽  
Phd Domain

AbstractAspergillus flavus and its main secondary metabolite AFB1 pose a serious threat to several important crops worldwide. Recently, it has been reported that some PHD family transcription factors are involved in the morphogenesis and AFB1 biological synthesis in A. flavus, but the role of Cti6, a PHD domain containing protein in A. flavus, is totally unknown. The study was designed to reveal the biological function of Cti6 in the fungus by deletion of cti6, and its two domains (PHD and Atrophin-1) through homologous recombination, respectively. The results showed that Cti6 might up-regulate the mycelium growth, conidiation, sclerotia formation and AFB1 biological synthesis of A. flavus by its PHD domain, while Atrophin-1 also improved the conidiation of the fungus. The qRT-PCR analysis showed that Cti6 increased the conidiation of the fungus through AbaA and BrlA mediated conidiation pathway, triggered the formation of sclerotia by orthodox sclerotia formation pathway, and improved the production of AFB1 by orthodox AFB1 synthesis pathway. Crops models analysis showed that A. flavus Cti6 plays vital role in colonization and the production of AFB1 on the host grains mainly via PHD domain. Bioinformatics analysis showed Cti6 is conservative in Aspergillus spp., and mCherry mediated subcellular localization showed that most Cti6 accumulated in the nuclei, which reflected that Cti6 performed its important biological function in the nuclei in Aspergillus spp.. The results of the current study elucidate the roles of PHD domain containing proteins in the mechanism of the infection of crops by A. flavus, and provided a novel target for effectively controlling the contamination of Aspergillus spp. to crops.

scholarly journals Deletion of the Aspergillus flavus Orthologue ofA. nidulans fluGReduces Conidiation and Promotes Production of Sclerotia but Does Not Abolish Aflatoxin Biosynthesis

2012 ◽  
Vol 78 (21) ◽  
pp. 7557-7563 ◽  
Author(s):  
Perng-Kuang Chang ◽  
Leslie L. Scharfenstein ◽  
Brian Mack ◽  
Kenneth C. Ehrlich
Keyword(s):  
Aspergillus Flavus ◽  
Fold Increase ◽  
Developmental Changes ◽  
Asexual Development ◽  
Aflatoxin Biosynthesis ◽  
Content Type ◽  
Fold Reduction ◽  
Sclerotial Formation ◽  
Conidial Development

ABSTRACTThefluGgene is a member of a family of genes required for conidiation and sterigmatocystin production inAspergillus nidulans. We examined the role of theAspergillus flavus fluGorthologue in asexual development and aflatoxin biosynthesis. Deletion offluGinA. flavusyielded strains with an approximately 3-fold reduction in conidiation but a 30-fold increase in sclerotial formation when grown on potato dextrose agar in the dark. The concurrent developmental changes suggest thatA. flavusFluG exerts opposite effects on a mutual signaling pathway for both processes. The altered conidial development was in part attributable to delayed expression ofbrlA, a gene controlling conidiophore formation. Unlike the loss of sterigmatocystin production byA. nidulans fluGdeletion strains, aflatoxin biosynthesis was not affected by thefluGdeletion inA. flavus. InA. nidulans, FluG was recently found to be involved in the formation of dehydroaustinol, a component of a diffusible signal of conidiation. Coculturing experiments did not show a similar diffusible meroterpenoid secondary metabolite produced byA. flavus. These results suggest that the function offluGand the signaling pathways related to conidiation are different in the two related aspergilli.

Mycotoxins - Their Biosynthesis in Fungi: Aflatoxins and other Bisfuranoids

1979 ◽  
Vol 42 (10) ◽  
pp. 805-809 ◽  
Author(s):  
J. W. BENNETT ◽  
L. S. LEE
Keyword(s):  
Experimental Data ◽  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Fungal Metabolites ◽  
Aflatoxin Biosynthesis ◽  
Mechanism Of Formation ◽  
13C Labeling

Aflatoxins are a family of highly toxic and carcinogenic secondary metabolites produced by certain strains of Aspergillus flavus and Aspergillus parasiticus. Biosynthetically, the aflatoxins are produced by a polyketide pathway. Most of the experimental data on aflatoxin biosynthesis are derived from 14C- and 13C-labeling experiments and use of blocked mutants. These data indicate that the general steps in aflatoxin biosynthesis are acetate → anthraquinones → sterigmatocystin → aflatoxin B1. Many details of the pathway remain unresolved; it is hoped that further research, particularly with cell-free systems, will improve our understanding of the mechanism of formation of these important fungal metabolites.

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