Dissection of mechanisms of resistance to Aspergillus flavus and aflatoxin using tropical maize germplasm

2018 ◽  
Vol 11 (2) ◽  
pp. 215-224 ◽  
Author(s):  
V. Garrido-Bazan ◽  
G. Mahuku ◽  
M. Bibbins-Martinez ◽  
A. Arroyo-Bacerra ◽  
M. Ángel Villalobos-López
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Biomass ◽  
Safety Issue ◽  
Inbred Lines ◽  
Aflatoxin Contamination ◽  
Tropical Maize ◽  
Mechanisms Of Resistance ◽  
Maize Germplasm ◽  
Maize Inbred Lines ◽  
Maize Varieties

Aspergillus flavus induced ear rots and subsequent contamination of maize (Zea mays L.) by aflatoxin is a serious food safety issue, especially in developing countries where the crop is mostly cultivated by smallholder famers for own consumption and income generation. A better understanding of the mechanisms of resistance could help breeders to develop resistant maize varieties. In this study, a set of six tropical maize inbred lines previously identified as resistant or susceptible under natural field conditions were evaluated for response to A. flavus colonisation and aflatoxin contamination. Fungal biomass was significantly higher (P<0.05) in susceptible than resistant maize inbred lines, and this was highly correlated (P=0.001) to aflatoxin levels. Maize inbred lines MRI, MR2 and MR3 had low fungal biomass and low aflatoxin levels, suggesting that resistance in these lines was mediated through restricted fungal colonisation and establishment. Among the three putatively resistant inbred lines mentioned above, MR2 had a relatively high colonisation compared to the other two lines, revealing that A. flavus could establish and colonise kernels that were injured during inoculation, but did not contain high levels of aflatoxin. This could signify the presence of host genes that interfere with the aflatoxin biosynthetic pathway.

Genotypic variation and relationships among traits for root morphology in a panel of tropical maize inbred lines under contrasting nitrogen levels

Euphytica ◽  
2019 ◽  
Vol 215 (3) ◽  
Author(s):  
Lívia Gomes Torres ◽  
Diego Gonçalves Caixeta ◽  
Wemerson Mendonça Rezende ◽  
Andreia Schuster ◽  
Camila Ferreira Azevedo ◽  
...  
Keyword(s):  
Root Morphology ◽  
Genotypic Variation ◽  
Inbred Lines ◽  
Tropical Maize ◽  
Nitrogen Levels ◽  
Maize Inbred Lines

Evaluation of resistance to aflatoxin contamination in kernels of maize genotypes using a GFP-expressing Aspergillus flavus strain

2013 ◽  
Vol 6 (2) ◽  
pp. 151-158 ◽  
Author(s):  
K. Rajasekaran ◽  
C.M. Sickler ◽  
R.L. Brown ◽  
J.W. Cary ◽  
D. Bhatnagar
Keyword(s):  
Fungal Infection ◽  
Aspergillus Flavus ◽  
Fluorescent Protein ◽  
Aflatoxin Contamination ◽  
Clear Correlation ◽  
Aleurone Layer ◽  
Screening Assay ◽  
Maize Germplasm ◽  
Antifungal Proteins ◽  
Green Fluorescent

Resistance or susceptibility of maize inbreds to infection by Aspergillus flavus was evaluated by the kernel screening assay. A green fluorescent protein-expressing strain of A. flavus was used to measure fungal spread and aflatoxin levels in real-time following fungal infection of kernels. Among the four inbreds tested, MI82 showed the most resistance and Ga209 the least. TZAR101 was also resistant to fungal infection, whereas Va35 was susceptible to fungal infection. However, Va35 produced lower aflatoxin levels compared to the susceptible line Ga209. Fluorescence microscopy indicated that the site of entry of the fungus into the kernel was consistently through the pedicel. Entry through the pericarp was never observed in undamaged kernels. In view of these results, incorporation or overexpression of antifungal proteins should be targeted to the pedicel and basal endosperm region in developing kernels. Once the fungus has entered through the pedicel, it spreads quickly through the open spaces between the pericarp and the aleurone layer, ultimately colonising the endosperm and scutellum and, finally, the embryo. A clear correlation was established between fungal fluorescence and aflatoxin levels. This method provides a quick, reliable means of evaluating resistance to A. flavus in undamaged kernels and provides breeders with a rapid method to evaluate maize germplasm.

scholarly journals Aspergillus Colonization and Aflatoxin Contamination in Peanut Genotypes with Resistance to Other Fungal Pathogens

Plant Disease ◽  
1997 ◽  
Vol 81 (12) ◽  
pp. 1429-1431 ◽  
Author(s):  
C. Corley Holbrook ◽  
David M. Wilson ◽  
Michael E. Matheron ◽  
William F. Anderson
Keyword(s):  
Drought Stress ◽  
Aspergillus Flavus ◽  
Fungal Pathogens ◽  
Sclerotium Rolfsii ◽  
Indirect Selection ◽  
Aflatoxin Contamination ◽  
White Mold ◽  
Mechanisms Of Resistance ◽  
Selection Tool ◽  
Aspergillus Flavus Group

Indirect selection tools would be valuable in the development of peanut (Arachis hypogaea) cultivars with resistance to aflatoxin contamination. The objective of this study was to determine whether resistance to other fungi could be used as an indirect selection tool for resistance to colonization of peanut by Aspergillus flavus group fungi or aflatoxin contamination. Nine peanut genotypes with resistance to late leaf spot (Cercosporidium personatum) or white mold (Sclerotium rolfsii) were evaluated for 2 years at Tifton, GA, and Yuma, AZ. Plots were subjected to late-season heat and drought stress. None of the genotypes exhibited less colonization of shells or kernels by A. flavus group fungi than cv. Florunner when tested in Georgia or Arizona. None of the genotypes showed a reduced level of aflatoxin contamination in comparison to Florunner at either location. These results indicate that the mechanisms of resistance to other fungi operating in these genotypes are not effective in providing resistance to colonization by A. flavus group fungi or reducing aflatoxin contamination. Therefore, resistance to these fungi cannot be used as an indirect selection tool for resistance to aflatoxin contamination.

scholarly journals Vibrio gazogenes inhibits aflatoxin production through downregulation of aflatoxin biosynthetic genes in Aspergillus flavus

2022 ◽  
Author(s):  
Shyam L. Kandel ◽  
Rubaiya Jesmin ◽  
Brian M. Mack ◽  
Rajtilak Majumdar ◽  
Matthew K. Gilbert ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolite ◽  
Aspergillus Flavus ◽  
Fungal Biomass ◽  
Expression Profiles ◽  
Health Hazard ◽  
Gene Clusters ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Control Samples

Aspergillus flavus is an opportunistic pathogen of oilseed crops such as maize, peanut, cottonseed, and tree nuts and produces carcinogenic secondary metabolites known as aflatoxins during seed colonization. Aflatoxin contamination not only reduces the value of the produce but also is a health hazard to humans and animals. Previously, we observed inhibition of A. flavus aflatoxin biosynthesis upon exposure to the marine bacterium, Vibrio gazogenes (Vg). In this study, we used RNA sequencing to examine the transcriptional profiles of A. flavus treated with both live and heat-inactivated dead Vg and control samples. Fungal biomass, total accumulated aflatoxins, and expression profiles of genes constituting secondary metabolite biosynthetic gene clusters were determined at 24, 30, and 40 h after treatment. Statistically significant reductions in total aflatoxins were detected in Vg-treated samples as compared to control samples at 40 h. But no statistical difference in fungal biomass was observed upon these treatments. The Vg treatments were most effective on aflatoxin biosynthesis as was reflected in significant downregulation of majority of the genes in the aflatoxin gene cluster including the aflatoxin pathway regulator gene, aflR. Along with aflatoxin genes, we also observed significant downregulation in some other secondary metabolite gene clusters including cyclopiazonic acid and aflavarin, suggesting that the treatment may inhibit other secondary metabolites as well. Finally, a weighted gene correlation network analysis identified an upregulation of ten genes that were most strongly associated with Vg-dependent aflatoxin inhibition and provide a novel start-point in understanding the mechanisms that result in this phenomenon.

scholarly journals Phenotypic and molecular characterization of a set of tropical maize inbred lines from a public breeding program in Brazil

BMC Genomics ◽  
2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Sirlene Viana de Faria ◽  
Leandro Tonello Zuffo ◽  
Wemerson Mendonça Rezende ◽  
Diego Gonçalves Caixeta ◽  
Hélcio Duarte Pereira ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Inbred Lines ◽  
Breeding Program ◽  
Tropical Maize ◽  
Maize Breeding ◽  
Breeding Programs ◽  
The Public ◽  
Maize Inbred Lines

Abstract Background The characterization of genetic diversity and population differentiation for maize inbred lines from breeding programs is of great value in assisting breeders in maintaining and potentially increasing the rate of genetic gain. In our study, we characterized a set of 187 tropical maize inbred lines from the public breeding program of the Universidade Federal de Viçosa (UFV) in Brazil based on 18 agronomic traits and 3,083 single nucleotide polymorphisms (SNP) markers to evaluate whether this set of inbred lines represents a panel of tropical maize inbred lines for association mapping analysis and investigate the population structure and patterns of relationships among the inbred lines from UFV for better exploitation in our maize breeding program. Results Our results showed that there was large phenotypic and genotypic variation in the set of tropical maize inbred lines from the UFV maize breeding program. We also found high genetic diversity (GD = 0.34) and low pairwise kinship coefficients among the maize inbred lines (only approximately 4.00 % of the pairwise relative kinship was above 0.50) in the set of inbred lines. The LD decay distance over all ten chromosomes in the entire set of maize lines with r2 = 0.1 was 276,237 kb. Concerning the population structure, our results from the model-based STRUCTURE and principal component analysis methods distinguished the inbred lines into three subpopulations, with high consistency maintained between both results. Additionally, the clustering analysis based on phenotypic and molecular data grouped the inbred lines into 14 and 22 genetic divergence clusters, respectively. Conclusions Our results indicate that the set of tropical maize inbred lines from UFV maize breeding programs can comprise a panel of tropical maize inbred lines suitable for a genome-wide association study to dissect the variation of complex quantitative traits in maize, mainly in tropical environments. In addition, our results will be very useful for assisting us in the assignment of heterotic groups and the selection of the best parental combinations for new breeding crosses, mapping populations, mapping synthetic populations, guiding crosses that target highly heterotic and yielding hybrids, and predicting untested hybrids in the public breeding program UFV.

scholarly journals Evaluation of maize inbred lines and topcross progeny for resistance to pre-harvest aflatoxin contamination

2019 ◽  
Vol 7 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Jake C. Fountain ◽  
Hamed K. Abbas ◽  
Brian T. Scully ◽  
Hong Li ◽  
Robert D. Lee ◽  
...  
Keyword(s):  
Inbred Lines ◽  
Aflatoxin Contamination ◽  
Maize Inbred Lines

scholarly journals Potential in a collection of adapted and exotic tropical maize inbred lines as resistance source for stem borers

2018 ◽  
Vol 10 (8) ◽  
pp. 183-190 ◽  
Author(s):  
Olaitan Oloyede-Kamiyo Qudrah ◽  
Oyewole Ajala Sam ◽  
Oluwatoyosi Job Anthony
Keyword(s):  
Inbred Lines ◽  
Tropical Maize ◽  
Stem Borers ◽  
Maize Inbred Lines ◽  
Resistance Source

Combining Ability, Genetic Distances, and Heterosis among Elite CIMMYT and IITA Tropical Maize Inbred Lines

Crop Science ◽  
2009 ◽  
Vol 49 (4) ◽  
pp. 1201-1210 ◽  
Author(s):  
Thanda Dhliwayo ◽  
Kevin Pixley ◽  
Abebe Menkir ◽  
Marilyn Warburton
Keyword(s):  
Combining Ability ◽  
Inbred Lines ◽  
Genetic Distances ◽  
Tropical Maize ◽  
Maize Inbred Lines
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