Effect of Different Postharvest Drying Temperatures on Aspergillus flavus Survival and Aflatoxin Content in Five Maize Hybrids

2005 ◽  
Vol 68 (7) ◽  
pp. 1521-1524 ◽  
Author(s):  
LEIGH K. HAWKINS ◽  
GARY L. WINDHAM ◽  
W. PAUL WILLIAMS
Keyword(s):  
Aspergillus Flavus ◽  
Fusarium Verticillioides ◽  
Seed Viability ◽  
Fungal Growth ◽  
Heat Stability ◽  
Corn Hybrids ◽  
Aflatoxin Content ◽  
Kernel Infection ◽  
Aflatoxin Concentration ◽  
Natural Infestation

After harvest, maize is dried artificially to halt fungal growth and mycotoxin production while in postharvest storage. The process often limits harvest capacity and has been a frequent cause of seed injury. Higher drying temperatures could lead to shorter drying periods and faster turnover; however, there is often a deterioration of the physical grain quality, including increased breakage susceptibility and loss of viability. The goals of this study were to determine the effect of different postharvest drying temperatures on Aspergillus flavus and Fusarium verticillioides survival and aflatoxin content in maize and to determine the viability of the seed. Five corn hybrids varying in resistance to A. flavus were side needle–inoculated with A. flavus, harvested at physiological maturity, and dried at temperatures ranging from 40 to 70°C. Kernels were evaluated for aflatoxin, stress cracks, germination, and kernel infection by A. flavus and a natural infestation of F. verticillioides. Drying temperature had no effects on aflatoxin concentration given the heat stability of the toxin. With increased temperatures from 40 to 70°C, germination decreased significantly, from 96 to 27%, and stress cracks increased significantly (1.4 up to 18.7). At temperatures above 60°C, F. verticillioides kernel infection was significantly reduced to less than 18%. At 70°C, there was a significant reduction in A. flavus kernel infection, from 11 to 3%. This information is useful in determining a range of temperatures that can be used for drying seed when fungal infection, stress cracks, and seed viability are of interest.

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.

Effects of Glufosinate-Ammonium and Urea on Aflatoxin and Fumonisin Levels in Corn

2006 ◽  
Vol 7 (1) ◽  
pp. 26 ◽  
Author(s):  
H. Arnold Bruns ◽  
H. K. Abbas
Keyword(s):  
Aqueous Solution ◽  
Zea Mays ◽  
Aspergillus Flavus ◽  
Ammonium Salt ◽  
Genetically Modified ◽  
Fusarium Verticillioides ◽  
Butanoic Acid ◽  
Glufosinate Ammonium ◽  
Aflatoxin Concentration ◽  
Plot Design

Glufosinate-ammonium [butanoic acid, 2-amino-4-(hydroxymethylphosphinyl)-ammonium salt] (G-A) and urea [CO(NH2)2] were evaluated as foliar treatments for suppression of pre-harvest aflatoxin and fumonisin contamination in corn (Zea mays). The experiment was conducted in Stoneville, MS as a randomized complete block split-plot design replicated four times. The whole plots were four commercial hybrids, two genetically modified to be resistant to G-A and two nonmodified. Twenty randomly-selected ears in each sub-plot were inoculated with a culture of F3W4 Aspergillus flavus using a pin bar. Infection by Fusarium verticillioides (= F. moniliforme) occurred naturally. The sub-plot treatments were applied as an aqueous solution (0.23 % v:v G-A, 1.13% v:v G-A, and 0.075 M urea) 60 days after silking. The experiment also included untreated controls with and without inoculation of A. flavus. Sub-plots were two rows 30 ft long, spaced 40 inches apart. The experiment was repeated four times starting in 2001 and ending in 2004. Among years, inoculated ears averaged 153.6 ppb to 257.3 ppb more aflatoxin than non-inoculated ears. Neither G-A nor urea reduced aflatoxin or fumonisin concentrations. Hybrids did not differ in yield or aflatoxin concentration. Fumonisin concentrations among hybrids ranged from 2.3 ppm to 7.5 ppm. Grain yields were less in 2004 (110 bu/acre) than 2001 (140 bu/acre) or 2002 (144 bu/acre). Accepted for publication 25 January 2006. Published 24 March 2006.

A Study of Aflatoxin Production by Aspergillus Flavus Growing on Wallboard

1997 ◽  
Vol 2 (4) ◽  
pp. 36-42 ◽  
Author(s):  
Carol Y. Rao ◽  
Richard C. Fink ◽  
Linda B. Wolfe ◽  
Daniel F. Liberman ◽  
Harriet A. Burge
Keyword(s):  
Aspergillus Flavus ◽  
High Performance ◽  
Building Materials ◽  
Culture Media ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Culture Collection ◽  
Indoor Environments ◽  
Toxigenic Fungi ◽  
Aflatoxin Concentration

The potential for exposure to mycotoxins in indoor environments is of increasing concern. In order to evaluate the potential for mycotoxin production by toxigenic fungi growing on water-damaged building materials, two aflatoxin producing strains of Aspergillus flavus (American Type Culture Collection 16875 and 15547) were inoculated onto culture media, plain wallboard, and vinyl wallpapered wallboard (cellulose-based and wheat-based wallpaper paste) and incubated at high relative humidity and room temperature for up to 16 weeks. Each sample was extracted with 60% methanol and aflatoxins in the crude extract were collected by immunoaffinity chromatography and quantified by fluorometry. Analysis by high performance liquid chromatography was performed for confirmation. Varying degrees of fungal growth were evident on all tested substrate types. Up to 4800 ppb of aflatoxin was detected when strain ATCC 16875 was grown on potato dextrose agar. However, when inoculation was standardized to minimize initial aflatoxin concentration in the inoculum, aflatoxin production was not detected on any wallboard sample under any of the incubation conditions provided. The presence of a toxigenic fungal strain on an indoor substrate does not necessarily indicate that the fungus is producing mycotoxins and our data provide evidence that wet wallboard is unlikely to provide appropriate conditions for aflatoxin production.

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 Mimosa tenuiflora Aqueous Extract: Role of Condensed Tannins in Anti-Aflatoxin B1 Activity in Aspergillus flavus

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 391
Author(s):  
Christopher Hernandez ◽  
Laura Cadenillas ◽  
Anwar El Maghubi ◽  
Isaura Caceres ◽  
Vanessa Durrieu ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aqueous Extract ◽  
Aflatoxin B1 ◽  
Condensed Tannins ◽  
Fungal Growth ◽  
Oxidation Reactions ◽  
Expression Of Genes ◽  
Dependent Inhibition ◽  
Interesting Candidate ◽  
Mimosa Tenuiflora

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin that contaminates numerous crops pre- and post-harvest. To protect foods and feeds from such toxins without resorting to pesticides, the use of plant extracts has been increasingly studied. The most interesting candidate plants are those with strong antioxidative activity because oxidation reactions may interfere with AFB1 production. The present study investigates how an aqueous extract of Mimosa tenuiflora bark affects both the growth of Aspergillus flavus and AFB1 production. The results reveal a dose-dependent inhibition of toxin synthesis with no impact on fungal growth. AFB1 inhibition is related to a down-modulation of the cluster genes of the biosynthetic pathway and especially to the two internal regulators aflR and aflS. Its strong anti-oxidative activity also allows the aqueous extract to modulate the expression of genes involved in fungal oxidative-stress response, such as msnA, mtfA, atfA, or sod1. Finally, a bio-guided fractionation of the aqueous extract demonstrates that condensed tannins play a major role in the anti-aflatoxin activity of Mimosa tenuiflora bark.

scholarly journals The Effect of Fusarium verticillioides Fumonisins on Fatty Acids, Sphingolipids, and Oxylipins in Maize Germlings

2021 ◽  
Vol 22 (5) ◽  
pp. 2435
Author(s):  
Marzia Beccaccioli ◽  
Manuel Salustri ◽  
Valeria Scala ◽  
Matteo Ludovici ◽  
Andrea Cacciotti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fusarium Verticillioides ◽  
Fungal Growth ◽  
Defense Responses ◽  
Ceramide Synthase ◽  
Ear Rot ◽  
In Planta ◽  
Disease Symptoms ◽  
The Impact

Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.

scholarly journals A Novel Niosome-Encapsulated Essential Oil Formulation to Prevent Aspergillus flavus Growth and Aflatoxin Contamination of Maize Grains During Storage

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 646 ◽  
Author(s):  
García-Díaz ◽  
Patiño ◽  
Vázquez ◽  
Gil-Serna
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Storage Conditions ◽  
Aflatoxin Contamination ◽  
Small Scale ◽  
Low Concentrations ◽  
Oil Formulation ◽  
Scale Test ◽  
Encapsulation Method

Aflatoxin (AF) contamination of maize is a major concern for food safety. The use of chemical fungicides is controversial, and it is necessary to develop new effective methods to control Aspergillus flavus growth and, therefore, to avoid the presence of AFs in grains. In this work, we tested in vitro the effect of six essential oils (EOs) extracted from aromatic plants. We selected those from Satureja montana and Origanum virens because they show high levels of antifungal and antitoxigenic activity at low concentrations against A. flavus. EOs are highly volatile compounds and we have developed a new niosome-based encapsulation method to extend their shelf life and activity. These new formulations have been successfully applied to reduce fungal growth and AF accumulation in maize grains in a small-scale test, as well as placing the maize into polypropylene woven bags to simulate common storage conditions. In this latter case, the antifungal properties lasted up to 75 days after the first application.

scholarly journals Systemic Infection by Fusarium verticillioides in Maize Plants Grown Under Three Temperature Regimes

Plant Disease ◽  
2008 ◽  
Vol 92 (12) ◽  
pp. 1695-1700 ◽  
Author(s):  
A. Murillo-Williams ◽  
G. P. Munkvold
Keyword(s):  
High Temperature ◽  
Environmental Factors ◽  
Fusarium Verticillioides ◽  
Systemic Infection ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Kernel Infection ◽  
Temperature Regimes ◽  
Maize Plants ◽  
Systemic Development

Fusarium verticillioides causes seedling decay, stalk rot, ear rot, and mycotoxin contamination (primarily fumonisins) in maize. Systemic infection of maize plants by F. verticillioides can lead to kernel infection, but the frequency of this phenomenon has varied widely among experiments. Variation in the incidence of systemic infection has been attributed to environmental factors. In order to better understand the influence of environment, we investigated the effect of temperature on systemic development of F. verticillioides during vegetative and reproductive stages of plant development. Maize seeds were inoculated with a green fluorescent protein-expressing strain of F. verticillioides, and grown in growth chambers under three different temperature regimes. In the vegetative-stage and reproductive-stage experiments, plants were evaluated at tasseling (VT stage), and at physiological maturity (R6 stage), respectively. Independently of the temperature treatment, F. verticillioides was reisolated from nearly 100% of belowground plant tissues. Frequency of reisolation of the inoculated strain declined acropetally in aboveground internodes at all temperature regimes. At VT, the high-temperature treatment had the highest systemic development of F. verticillioides in aboveground tissues. At R6, incidence of systemic infection was greater at both the high- and low-temperature regimes than at the average-temperature regime. F. verticillioides was isolated from higher internodes in plants at R6, compared to stage VT. The seed-inoculated strain was recovered from kernels of mature plants, although incidence of kernel infection did not differ significantly among treatments. During the vegetative growth stages, temperature had a significant effect on systemic development of F. verticillioides in stalks. At R6, the fungus reached higher internodes in the high-temperature treatment, but temperature did not have an effect on the incidence of kernels (either symptomatic or asymptomatic) or ear peduncles infected with the inoculated strain. These results support the role of high temperatures in promoting systemic infection of maize by F. verticillioides, but plant-to-seed transmission may be limited by other environmental factors that interact with temperature during the reproductive stages.

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