Field aflatoxin production by Aspergillus flavus and A. parasiticus on maize kernels

Euphytica ◽  
1991 ◽  
Vol 61 (3) ◽  
pp. 187-191 ◽  
Author(s):  
D. P. Gorman ◽  
M. S. Kang ◽  
T. Cleveland ◽  
R. L. Hutchinson
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin Production ◽  
Maize Kernels

scholarly journals Amy1, the α-Amylase Gene of Aspergillus flavus: Involvement in Aflatoxin Biosynthesis in Maize Kernels

1999 ◽  
Vol 89 (10) ◽  
pp. 908-914 ◽  
Author(s):  
A. M. Fakhoury ◽  
C. P. Woloshuk
Keyword(s):  
Aspergillus Flavus ◽  
Type Strain ◽  
Wild Type Strain ◽  
Aflatoxin Production ◽  
Deficient Mutant ◽  
Wild Type ◽  
Amylase Gene ◽  
Endosperm Tissue ◽  
Bifunctional Inhibitor ◽  
Maize Kernels

Aspergillus flavus is the causal agent of an ear and kernel rot in maize. In this study, we characterized an α-amylase-deficient mutant and assessed its ability to infect and produce aflatoxin in wounded maize kernels. The α-amylase gene Amy1 was isolated from A. flavus, and its DNA sequence was determined to be nearly identical to Amy3 of A. oryzae. When Amy1 was disrupted in an aflatoxigenic strain of A. flavus, the mutant failed to produce extracellular α-amylase and grew 45% the rate of the wild-type strain on starch medium. The mutant produced aflatoxin in medium containing glucose but not in a medium containing starch. The α-amylase-deficient mutant produced aflatoxin in maize kernels with wounded embryos and occasionally produced aflatoxin only in embryos of kernels with wounded endosperm. The mutant strain failed to produce aflatoxin when inoculated onto degermed kernels. In contrast, the wild-type strain produced aflatoxin in both the endosperm and embryo. These results suggest that α-amylase facilitates aflatoxin production and growth of A. flavus from a wound in the endosperm to the embryo. A 14-kDa trypsin inhibitor associated with resistance to A. flavus and aflatoxin in maize also inhibited the α-amylase from A. flavus, indicating that it is a bifunctional inhibitor. The inhibitor may have a role in resistance, limiting the growth of the fungus in the endosperm tissue by inhibiting the degradation of starch.

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

Control of Aspergillus flavus growth and aflatoxin production in transgenic maize kernels expressing a tachyplesin-derived synthetic peptide, AGM182

Plant Science ◽  
2018 ◽  
Vol 270 ◽  
pp. 150-156 ◽  
Author(s):  
Kanniah Rajasekaran ◽  
Ronald J. Sayler ◽  
Christine M. Sickler ◽  
Rajtilak Majumdar ◽  
Jesse M. Jaynes ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Synthetic Peptide ◽  
Aflatoxin Production ◽  
Transgenic Maize ◽  
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.

Wax and Cutin Layers in Maize Kernels Associated with Resistance to Aflatoxin Production by Aspergillus flavus

1995 ◽  
Vol 58 (3) ◽  
pp. 296-300 ◽  
Author(s):  
BAO Z. GUO ◽  
JOHN S. RUSSIN ◽  
THOMAS E. CLEVELAND ◽  
ROBERT L. BROWN ◽  
NEIL W. WIDSTROM
Keyword(s):  
Aspergillus Flavus ◽  
Potassium Hydroxide ◽  
Aflatoxin Production ◽  
Maize Kernel ◽  
Maize Hybrids ◽  
Maize Population ◽  
Maize Genotypes ◽  
Aflatoxin Accumulation ◽  
Maize Kernels ◽  
Susceptible Group

Thirteen maize hybrids and one maize population, MAS:gk, were screened for susceptibility to aflatoxin production by Aspergillus flavus. Marked differences in aflatoxin B1 production were detected among the maize genotypes tested. Most commercial hybrids consistently supported high levels of aflatoxin accumulation. Aflatoxin levels did not differ between intact and wounded kernels of these genotypes. However, different results were obtained from 4 of the 13 hybrids and the maize population MAS:gk. Levels of aflatoxin accumulation in intact kernels of these genotypes were lower than in the previous susceptible group of genotypes. In addition, aflatoxin levels were higher in wounded than in intact kernels. MAS:gk not only supported the lowest levels of aflatoxin production in intact kernels, but aflatoxin levels in endosperm-wounded kernels also were significantly lower in MAS:gk than in wounded kernels of all tested hybrids. Treatment with KOH to remove cutin from intact kernels prior to inoculation with A. flavus effected substantial increases in aflatoxin accumulation in MAS:gk, but only marginal increases in the susceptible hybrid Pioneer 3154. Removing wax from the surface of MAS:gk kernels greatly increased the susceptibility of this genotype to aflatoxin accumulation. When wax removal was combined with treatment with potassium hydroxide (KOH) or purified cutinase, aflatoxin levels in kernels were equal to those in wounded control kernels in both genotypes. These results indicated that wax and cutin layers of maize kernel pericarps may play a role in resistance to aflatoxin accumulation in MAS:gk and some other genotypes. However, results suggest further that resistance in MAS:gk also may be due to other preformed compounds as well.

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.

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.

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