scholarly journals Gene Expression Profile and Response to Maize Kernels by Aspergillus flavus

2011 ◽  
Vol 101 (7) ◽  
pp. 797-804 ◽  
Author(s):  
Brittiney N. Reese ◽  
Gary A. Payne ◽  
Dahlia M. Nielsen ◽  
Charles P. Woloshuk
Keyword(s):  
Aspergillus Flavus ◽  
Expression Profile ◽  
Developmental Stages ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Sole Source ◽  
Ear Rot ◽  
Phytase Gene ◽  
Kernel Infection ◽  
Maize Kernels

Aspergillus flavus causes an ear rot of maize, often resulting in the production of aflatoxin, a potent liver toxin and carcinogen that impacts the health of humans and animals. Many aspects of kernel infection and aflatoxin biosynthesis have been studied but the precise effects of the kernel environment on A. flavus are poorly understood. The goal of this research was to study the fungal response to the kernel environment during colonization. Gene transcription in A. flavus was analyzed by microarrays after growth on kernels of the four developmental stages: blister (R2), milk (R3), dough (R4), and dent (R5). Five days after inoculation, total RNA was isolated from kernels and hybridized to Affymetrix Gene Chip arrays containing probes representing 12,834 A. flavus genes. Statistical comparisons of the expression profile data revealed significant differences that included unique sets of upregulated genes in each kernel stage and six patterns of expression over the four stages. Among the genes expressed in colonized dent kernels were a phytase gene and six putative genes involved in zinc acquisition. Disruption of the phytase gene phy1 resulted in reduced growth on medium containing phytate as the sole source of phosphate. Furthermore, growth of the mutant (Δphy1) was 20% of the wild-type strain when wound inoculated into maize ears. In contrast, no difference was detected in the amount of aflatoxin produced relative to fungal growth, indicating that phy1 does not affect aflatoxin production. The study revealed the genome-wide effects of immature maize kernels on A. flavus and suggest that phytase has a role in pathogenesis.

RNA interference-based silencing of the alpha-amylase (amy1) gene in Aspergillus flavus decreases fungal growth and aflatoxin production in maize kernels

Planta ◽  
2018 ◽  
Vol 247 (6) ◽  
pp. 1465-1473 ◽  
Author(s):  
Matthew K. Gilbert ◽  
Rajtilak Majumdar ◽  
Kanniah Rajasekaran ◽  
Zhi-Yuan Chen ◽  
Qijian Wei ◽  
...  
Keyword(s):  
Rna Interference ◽  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Alpha Amylase ◽  
Maize Kernels

Growth of an Aspergillus flavus Transformant Expressing Escherichia coli β-Glucuronidase in Maize Kernels Resistant to Aflatoxin Production

1997 ◽  
Vol 60 (1) ◽  
pp. 84-87 ◽  
Author(s):  
ROBERT L. BROWN ◽  
THOMAS E. CLEVELAND ◽  
GARY A. PAYNE ◽  
CHARLES P. WOLOSHUK ◽  
DONALD G. WHITE
Keyword(s):  
Escherichia Coli ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Gene Promoter ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Glucuronidase Activity ◽  
Glucuronidase Reporter ◽  
Aflatoxin Accumulation ◽  
Maize Kernels

Kernels of a maize inbred that demonstrated resistance to aflatoxin production in previous studies were inoculated with an Aspergillus flavus strain containing the Escherichia coli β-d-glucuronidase reporter gene linked to a β-tubulin gene promoter and assessed for both fungal growth and aflatoxin accumulation. Prior to inoculation, kernels were pin-wounded through the pericarp to the endosperm, pin-wounded in the embryo region, or left unwounded. After 7 days incubation with the fungus, β-glucuronidase activity (fungal growth) in the kernels was quantified using a fluorogenic assay and aflatoxin B1 content of the same kernels was analyzed. Kernels of a susceptible inbred, similarly treated, served as controls. Results indicate a positive relationship between aflatoxin levels and the amount of fungal growth. However, resistant kernels wounded through the pericarp to the endosperm before inoculation supported an increase in aflatoxin B1 over levels observed in nonwounded kernels, without an increase in fungal growth. Wounding kernels of the resistant inbred through the embryo resulted in both the greatest fungal growth and the highest levels of aflatoxin B1 for this genotype. Maintenance of resistance to aflatoxin B1 in endosperm-wounded kernels may be due to the action of a mechanism which limits fungal access to the kernel embryo.

Control of Aspergillus flavus and aflatoxin production with spices in culture medium and rice

2013 ◽  
Vol 6 (1) ◽  
pp. 43-50 ◽  
Author(s):  
V. Aiko ◽  
A. Mehta
Keyword(s):  
Aspergillus Flavus ◽  
High Performance ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Culture Broth ◽  
Minimum Inhibitory Concentrations ◽  
Food Grains ◽  
Star Anise ◽  
Aflatoxin B ◽  
Layer Chromatography

Cinnamon, cardamom, star anise and clove were studied for their effect on growth of Aspergillus flavus and aflatoxin B1 (AFB1) synthesis. The experiments were carried out in yeast extract sucrose culture broth as well as in rice supplemented with spices. AFB1 produced was analysed qualitatively and quantitatively using thin layer chromatography and high performance liquid chromatography, respectively. At a concentration of 10 mg/ml, cardamom and star anise did not exhibit any antifungal or anti-aflatoxigenic activity in culture broth, whereas cinnamon and clove inhibited A. flavus growth completely. The minimum inhibitory concentrations of cinnamon and clove were 4 and 2 mg/ml, respectively. Concentrations of cinnamon and clove below their minimum inhibitory concentrations showed enhanced fungal growth, while AFB1 synthesis was reduced. Clove inhibited the synthesis of AFB1 significantly up to 99% at concentrations ≥1.0 mg/ml. The spices also inhibited AFB1 synthesis in rice at 5 mg/g, although fungal growth was not inhibited. Clove and cinnamon inhibited AFB1 synthesis significantly up to 99 and 92%, respectively, and star anise and cardamom by 41 and 23%, respectively. The results of this study suggest the use of whole spices rather than their essential oils for controlling fungal and mycotoxin contamination in food grains.

No Effect of Soybean Lipoxygenase on Aflatoxin Production in Aspergillus flavus–Inoculated Seeds

2002 ◽  
Vol 65 (12) ◽  
pp. 1984-1987 ◽  
Author(s):  
J. E. MELLON ◽  
P. J. COTTY
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Pathogens ◽  
Seed Viability ◽  
Soybean Seed ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Soybean Seeds ◽  
Heat Treated ◽  
Significant Difference

Soybean lines lacking lipoxygenase (LOX) activity were compared with soybean lines having LOX activity for the ability to support growth and aflatoxin B1 production by the fungal seed pathogen Aspergillus flavus. Whole seeds, broken seeds, and heat-treated (autoclaved) whole seeds were compared. Broken seeds, irrespective of LOX presence, supported excellent fungal growth and the highest aflatoxin levels. Autoclaved whole seeds, with or without LOX, produced good fungal growth and aflatoxin levels approaching those of broken seeds. Whole soybean seeds supported sparse fungal growth and relatively low aflatoxin levels. There was no significant difference in aflatoxin production between whole soybean seeds either with or without LOX, although there did seem to be differences among the cultivars tested. The heat treatment eliminated LOX activity (in LOX+ lines), yet aflatoxin levels did not change substantially from the broken seed treatment. Broken soybean seeds possessed LOX activity (in LOX+ lines) and yet yielded the highest aflatoxin levels. The presence of active LOX did not seem to play the determinant role in the susceptibility of soybean seeds to fungal pathogens. Seed coat integrity and seed viability seem to be more important characteristics in soybean seed resistance to aflatoxin contamination. Soybean seeds lacking LOX seem safe from the threat of increased seed pathogen susceptibility.

scholarly journals Inhibition of Growth of Aspergillus flavus and Fungal α-Amylases by a Lectin-Like Protein from Lablab purpureus

2001 ◽  
Vol 14 (8) ◽  
pp. 955-961 ◽  
Author(s):  
A. M. Fakhoury ◽  
C. P. Woloshuk
Keyword(s):  
Aspergillus Flavus ◽  
Insect Pests ◽  
Hyphal Growth ◽  
Aflatoxin Production ◽  
Lablab Purpureus ◽  
Ear Rot ◽  
Amylase Inhibitor ◽  
Isolation And Characterization ◽  
Novel Variant ◽  
Rot Disease

Aspergillus flavus is a fungal pathogen of maize causing an important ear rot disease when plants are exposed to drought and heat stress. Associated with the disease is the production of aflatoxins, which are a series of structurally related mycotoxins known to be carcinogenic. Previous research has suggested that the α-amylase of A. flavus promotes aflatoxin production in the endosperm of infected maize kernels. We report here the isolation and characterization of a 36-kDa α-amylase inhibitor from Lablab purpureus (AILP). AILP inhibited the α-amylases from several fungi but had little effect on those from animal and plant sources. The protein inhibited conidial germination and hyphal growth of A. flavus. The amino acid sequence indicated that AILP is similar to lectin members of a lectin-arcelin-α-amylase inhibitor family described in common bean and shown to be a component of plant resistance to insect pests. AILP also agglutinated papain-treated red blood cells from human and rabbit. These data indicate that AILP represents a novel variant in the lectin-arcelin-α-amylase inhibitor family of proteins having lectin-like and α-amylase inhibitory activity.

scholarly journals Evaluation of antifungal activity of Pittosporum undulatum L. essential oil against Aspergillus flavus and aflatoxin production

2011 ◽  
Vol 35 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Rosane Tamara da Silva Medeiros ◽  
Edlayne Gonçalez ◽  
Roberto Carlos Felicio ◽  
Joana D'arc Felicio
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Plant Oils ◽  
Food Commodities ◽  
And Storage ◽  
Main Producer ◽  
Mycelial Development

The presence of mycotoxins as a result of fungal attack can occur before, after and during the harvest and storage operations on agricultural crops and food commodities. Considering the inhibitory property of essential plant oils on the mycelial development of fungi and the importance of Aspergillus flavus, the main producer of aflatoxins, this research was designed to evaluate the toxicity of essential oil from Pittosporum undulatum against A. flavus. The essential oils were obtained from P. undulatum leaves, collected in different months and analyzed by GC/MS. The oils were rich in hydrocarbon, monoterpenes and sesquiterpenes and it was observed a significant variation on the chemical composition of the essential oil of leaves at different months. Besides, the essential oils were tested against fungal growth and the results showed different spectrum of inhibition on A. flavus. However, the essential oils inhibited the aflatoxin B1 production.

scholarly journals Post-harvest control of aflatoxin production in in-shell moist peanuts with sodium ortho-phenylphenate: III. Storage tests

1994 ◽  
Vol 51 (2) ◽  
pp. 369-373 ◽  
Author(s):  
H. Fonseca ◽  
C.R. Gallo ◽  
M.A. Calori-Domingues ◽  
E.M. Gloria ◽  
P.J. Approbatto ◽  
...  
Keyword(s):  
Uniform Distribution ◽  
Aspergillus Flavus ◽  
Rainy Season ◽  
Present Experiment ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Dry Season ◽  
Naked Eye ◽  
Spray System ◽  
Cleaning Machine

The present experiment aimed to evaluate the effect of sodium ortho-phenylphenate (SOP) application to in-shell moist peanuts for the control of aflatoxin production. Previous studies showed the need to improve the SOP solution distribution on peanut pods to evaluate the product. Thus, in this experiment the place of the spray system was the bag filler pipe of the pre-cleaning machine in the warehouse. In the 1989 rainy season two lots of 120 bags of in-shell moist peanuts were sprayed with 0.5 and 1% SOP solutions and aflatoxin production was not controlled. In the dry season of 1989 and in the rainy season of 1990, in-shell moist peanuts were sprayed with 5% SOP solution. The coverage of pods with the solution was efficient, allowing a uniform distribution of SOP solution on the pods. The results showed that only the 5.0% concentration of SOP solution utilized controlled the external fungal growth when a naked eye observation was made, however did not control aflatoxin production when applied to in-shell moist peanuts, probably due to the internal presence of Aspergillus flavus and because the fungicide could not penetrate inside to reach the kernels.

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