aflatoxin accumulation
Recently Published Documents


TOTAL DOCUMENTS

137
(FIVE YEARS 24)

H-INDEX

28
(FIVE YEARS 3)

Crop Science ◽  
2021 ◽  
Author(s):  
J. Spencer Smith ◽  
William Paul Williams ◽  
Marilyn Warburton ◽  
Gary Windham ◽  
Wenwei Xu ◽  
...  

2021 ◽  
Author(s):  
Abu Mustapha Dadzie ◽  
Allen Oppong ◽  
Ebenezer Obeng-Bio ◽  
Marilyn L. Warburton

Aflatoxins are carcinogenic secondary metabolites produced predominantly by the fungi Aspergillus flavus and parasiticus. The toxin contaminate maize grains and threatens human food safety. Survey in Ghana revealed aflatoxin contamination of maize in excess of 941 ppb which is way beyond WHO and USA approved limits of 15 ppb and 20 ppb respectively. Host plant resistance is considered as the best strategy for reducing aflatoxins. This study was designed to (1) identify and select suitable maize lines that combine aflatoxin accumulation resistance and good agronomic traits under tropical conditions and (2) assess the genetic diversity among the exotic and locally adapted maize genotypes using significant morphological traits. Thirty-six maize genotypes, 19 from Mississippi State University, USA and 17 locally adapted genotypes in Ghana were evaluated for aflatoxin accumulation resistance and good agronomic characteristics across six contrasting environments using a 6x6 lattice design with three replicates. Five plants each per genotype were inoculated with a local strain of Aspergillus flavus inoculum at a concentration of 9 x 107/3.4 ml, two weeks after 50% mid silking. Total aflatoxin in the kernels were determined at harvest using HPLC method. Statistical analysis for agronomic traits and aflatoxin levels were performed using PROC GLM procedure implemented in SAS. The result indicated that genotype by environment interaction was significant (p < 0.05) for aflatoxin accumulation resistance and many other agronomic traits. Five genotypes (MP715, NC298, MP705, MP719, CML287 and TZEEI- 24) consistently displayed stable resistance across the environments and may serve as suitable candidates for developing aflatoxin resistant hybrids. Cluster analysis showed two distinct groups (locally adapted and exotic genotypes), an indication of re-cycled alleles per region. Broad sense heritability estimates for grain yield and aflatoxin accumulation resistance were moderately high, which could permit transfer of traits during hybrid development.


Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2285
Author(s):  
Jessee Spencer Smith ◽  
William Paul Williams

In-field infection of maize (Zea mays L.) ears by the fungus Aspergillus flavus Link:Fr causes pre-harvest aflatoxin contamination of maize grain. Germplasm lines with host-plant resistance to aflatoxin accumulation are available to breeders, but these lines often possess undesirable agronomic characteristics. Commercial lines with expired plant variety protection (ex-PVP lines) are a potential source of elite germplasm available to public maize breeders. A diallel cross containing three aflatoxin-accumulation-resistant germplasm lines and seven ex-PVP lines were evaluated in replicated trials for aflatoxin contamination after artificial inoculation and for yield. The resistant germplasm lines Mp313E, Mp715, and Mp717 were the only lines with significant general combining ability (GCA) for reduced aflatoxin accumulation. Of the ex-PVP lines evaluated, the Stiff-Stalk line F118 was the most promising line to use in breeding crosses. Based on its GCA, it was the only ex-PVP line that did not significantly increase aflatoxin and the only ex-PVP line that significantly increased yield. Second-cycle breeding lines derived from crosses between F118 and the resistant donor lines will be valuable if they combine the donor lines’ disease resistance with F118’s earlier maturity while introgressing the disease resistance into a genetic background that aligns with the industry’s well-defined heterotic groups.


Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 663
Author(s):  
Paula Tejero ◽  
Alberto Martín ◽  
Alicia Rodríguez ◽  
Ana Isabel Galván ◽  
Santiago Ruiz-Moyano ◽  
...  

Aspergillus flavus is a toxigenic fungal colonizer of fruits and cereals and may produce one of the most important mycotoxins from a food safety perspective, aflatoxins. Therefore, its growth and mycotoxin production should be effectively avoided to protect consumers’ health. Among the safe and green antifungal strategies that can be applied in the field, biocontrol is a recent and emerging strategy that needs to be explored. Yeasts are normally good biocontrol candidates to minimize mold-related hazards and their modes of action are numerous, one of them being the production of volatile organic compounds (VOCs). To this end, the influence of VOCs produced by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793 on growth, expression of the regulatory gene of the aflatoxin pathway (aflR) and mycotoxin production by A. flavus for 21 days was assessed. The results showed that both yeasts, despite producing different kinds of VOCs, had a similar effect on inhibiting growth, mycotoxin biosynthetic gene expression and phenotypic toxin production overall at the mid-incubation period when their synthesis was the greatest. Based on the results, both yeast strains, H. opuntiae L479 and H. uvarum L793, are potentially suitable as a biopreservative agents for inhibiting the growth of A. flavus and reducing aflatoxin accumulation.


2021 ◽  
Vol 13 (10) ◽  
pp. 15
Author(s):  
Allen Oppong ◽  
Abu M. Dadzie ◽  
Beatrice Ifie ◽  
Maxwell D. Asante ◽  
Ruth N. A. Prempeh ◽  
...  

Maize (Zea mays L.) is the most important cereal crop in sub-Saharan Africa providing food for many of its inhabitants. However, production is hampered by low yields and aflatoxin contamination, among others. The toxin contaminates maize before harvest and during storage. Ghana lacks regulatory infrastructure for monitoring and detecting aflatoxin in grains prior to market, and most of the local maize varieties have been found to be susceptible to aflatoxin accumulation. Host resistance is envisaged as a key approach in addressing the aflatoxin menace. Thus, this study was conducted to identify new hybrids that combine high yield with resistance to aflatoxin accumulation as well as study the mode of gene controlling tolerance to aflatoxin accumulation. Sixteen aflatoxin resistant inbreds from exotic sources were crossed as males to 10 local germplasm in a North Carolina II design to generate 160 new hybrids. These were planted together with 9 checks using a 13 &times; 13 alpha lattice with three replications. The new hybrids were evaluated across six environments in two seasons. Five plants each per hybrid were inoculated with a local strain of Aspergillus flavus at a concentration of 9 &times; 107conidia/ml. Ninety-six out of the 169 crosses were analyzed statistically. Significant effect of environment and genotypes for all traits especially, for aflatoxin accumulation resistance and yield were observed. The general combining ability effect of males for all traits were found significant (P &lt; 0.05) whereas that of the females were not significant for all traits. Inbreds with consistent significant negative GCA effect for aflatoxin reduction were identified (MP715, TZI8, MP719). Furthermore, the underlying genetic control for the aflatoxin accumulation resistance trait was found to be via both GCA and SCA effects. Heritability estimates were moderate, suggesting permissible transfer of traits during selection to create high yielding aflatoxin resistant hybrids for consumers.


Author(s):  
Sansern Rangsuwan ◽  
Chainarong Rattanakreetakul ◽  
Ratiya Pongpisutta

Aspergillus flavus is a frequent contaminant of maize grain. We isolated this fungus, determined the colony morphology and species (by internal transcribed spacer sequencing) and measured the aflatoxin content. The selected A. flavus fungi were placed into two groups, toxigenic and atoxigenic; both appeared similar morphologically, except that the atoxigenic group lacked sclerotia. An essential oil fumigation test with clove and cinnamon oils as antifungal products was performed on fungal conidial discs and fungal colonies in Petri plates. Cinnamon oil at 2.5 to 5.0 μL/plate markedly inhibited the mycelial growth from conidial discs of both strains, whereas clove oil showed less activity. The oils had different effects on fungal mycelia. The higher clove fumigation doses of 10.0 to 20.0 μL/plate controlled fungal growth, while cinnamon oil caused less inhibition. Compared with atoxigenic groups, toxigenic A. flavus responded stably. Within abnormal A. flavus hyphae, the essential oils degenerated the hyphal morphology, resulting in exfoliated flakes and shrinkage, which were related to fungal membrane injury and collapse of vacuoles and phialide. The treatments, especially those with cinnamon oil, increased the electroconductivity, which suggested a weak mycelium membrane structure. Moreover, the treatments with essential oils reduced the ergosterol content in mycelia and the aflatoxin accumulation in the culture broth. The fumigations with clove and cinnamon oils inhibited the development of both conidia and colonies of A. flavus in dose-dependent manners.


Agriculture ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 198
Author(s):  
Rahim Khan ◽  
Farinazleen Mohamad Ghazali ◽  
Nor Ainy Mahyudin ◽  
Nik Iskandar Putra Samsudin

The pre-harvest biocontrol approach currently used includes laboratory inoculations using non-aflatoxigenic strains of Aspergillus flavus. This strategy effectively suppresses the indigenous aflatoxigenic strains and reduces aflatoxin accumulation in sweetcorn. The current in vitro study’s main objective is to determine the diametric growth rates of both Aflatoxin (AF)+ and AF− strains and improve the understanding of competitive relationships among these strains in sweetcorn (Zea mays). Sweetcorn kernels inoculated with AF+ strains only, AF− strains only, and co-inoculated with AF+ + AF− strains were investigated for aflatoxin concentrations. The diametric growth results revealed that growth rates of AF− strains at 25 and 30 °C were much greater than AF+ strains, which was in line with previous studies. The in vitro findings showed that the AKR5− and AKL34− biocontrol strains effectively inhibited the colony propagation and subsequent AFB1 contamination (up to 79%) of AF+ strains. On the other hand, the AKR1− and AKL35− were least effective in reducing AFB1 contents only by 58% and 60%, respectively. There was a significant difference (p < 0.05) in the reduction of AFB1 contents achieved by AF− strains of A. flavus. The findings of the present study indicated the reduction in AFB1 with population expressions of AF+ strains by the AF− strains and supports the notion of competitive exclusion through vigorous development and propagation of the non-aflatoxigenic fungi.


age ◽  
2021 ◽  
Vol 4 (3) ◽  
Author(s):  
Oluwaseun Ogunola ◽  
J. Spencer Smith ◽  
Wenwei Xu ◽  
Dinakar Bhattramakki ◽  
Daniel Jeffers ◽  
...  

2020 ◽  
Author(s):  
Queen Nkem Obi ◽  
Abebe Menkir ◽  
Deborah F. Babalola ◽  
Melaku Gedil

Abstract BackgroundMolecular breeding has been recognized as one of the pillars to accelerate the rate of genetic gain in crop improvement towards meeting the need to feed an ever-growing world population. Establishing low-cost and flexible genotyping platforms in small and public laboratories and regionally can stimulate the application of molecular breeding in developing countries where many plant breeding projects require low to medium density markers for genomics-assisted selection and quality control (QC) activities. ResultsHere we present an optimization of the entire genotyping workflow (from sample collection to genotyping and data analysis) to accelerate the QC and genomic-assisted selection process, which can readily be adopted by National agricultural research system (NARS) partners in developing countries to fast-track molecular marker-based genotyping for crop improvement. An in-house KASP genotyping system combined with optimized sample collection and DNA preparation processes expedited the genotyping workflow from over five weeks (when outsourcing) to approximately three weeks (5 days per week) for a total of 637 samples. The QC experiment using a subset of 28 KASP SNPs validated for maize revealed the genetic identity of 4 maize varieties taken from 5 seed sources. Another subset of 10 KASP SNPs was sufficient in verifying the parentage of 388 F1 lines. The marker-based selection of high PVA maize lines identified nine lines harboring the favorable allele of the crtRB1 gene, which could serve as donor lines for the maize PVA breeding program. The ongoing marker-assisted backcrossing experiment to introgress resistance to aflatoxin accumulation in elite tropical maize lines has so far identified twenty-four maize lines harboring the favorable alleles associated with resistance to aflatoxin accumulation, and are currently undergoing field evaluation. The optimized genotyping workflow has so far generated over 1700 datapoints.ConclusionThe result of this work could serve as a prototype to fast-track maize improvement activities of IITA’s MIP group, and facilitate DNA fingerprinting for adoption tracking of improved crop varieties. It will also provide public and small laboratories in developing countries with the knowledge of efficient genotyping workflow to accelerate crop improvement activities.


Crop Science ◽  
2020 ◽  
Author(s):  
J. J. Williams ◽  
W. B. Henry ◽  
J. S. Smith ◽  
N. W. Buehring ◽  
D. L. Boykin

Sign in / Sign up

Export Citation Format

Share Document