Occurrence and postharvest strategies to help mitigate aflatoxins and fumonisins in maize and their co-exposure to consumers in Mexico and Central America

Odjo, Sylvanus; Alakonya, Amos; Rosales-Nolasco, Aldo; Molina, Aide L.; Muñoz, Carlos; Palacios-Rojas, Natalia

doi:10.1016/j.foodcont.2022.108968

Cited by 23 publications

(8 citation statements)

References 114 publications

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“…Fumonisins are produced by toxigenic Fusarium members Gibberella fujikuroi complex which include F. verticillioides, F. proliferatum, F. subglutinans, and F. thapsinum which express the FUM1 gene ( Bluhm et al, 2004 ). Fusarium causes ear rot in maize characterized by white to pinkish scattered tufts of mold on the ears and are accompanied by starburst patterns on the kernels ( Odjo et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Efficacy of electron beam irradiation in reduction of mycotoxin-producing fungi, aflatoxin, and fumonisin, in naturally contaminated maize slurry

Mohamed

Chavez²,

Wagacha³

et al. 2022

Toxicon: X

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Section: Introductionmentioning

confidence: 99%

Efficacy of electron beam irradiation in reduction of mycotoxin-producing fungi, aflatoxin, and fumonisin, in naturally contaminated maize slurry

Mohamed

Chavez²,

Wagacha³

et al. 2022

Toxicon: X

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“…Another possibility is that indigenous farmers across the Americas were selecting silk-associated bacteria not only to combat F. graminearum but also other Fusarium species. Different Fusarium species and their associated mycotoxins have been reported to be prevalent in Mexico and Central America ( Odjo et al., 2022 ). GER caused by Fg pathogen is favored by high levels of moisture during silking, followed by moderate temperatures and high precipitation ( Sutton, 1982 ).…”

Section: Discussionmentioning

confidence: 99%

Bacteria existing in pre-pollinated styles (silks) can defend the exposed male gamete fertilization channel of maize against an environmental Fusarium pathogen

Shrestha,

Limay-Rios,

Brettingham

et al. 2023

Front. Plant Sci.

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In flowering plants, fertilization requires exposing maternal style channels to the external environment to capture pollen and transmit its resident sperm nuclei to eggs. This results in progeny seed. However, environmental fungal pathogens invade developing seeds through the style. We hypothesized that prior to environmental exposure, style tissue already possesses bacteria that can protect styles and seed from such pathogens. We further hypothesized that farmers have been inadvertently selecting immature styles over many generations to have such bacteria. We tested these hypotheses in maize, a wind-pollinated crop, which has unusually long styles (silks) that are invaded by the economically-important fungal pathogen Fusarium graminearum (Fg). Here, unpollinated silk-associated bacteria were cultured from a wild teosinte ancestor of maize and diverse maize landraces selected by indigenous farmers across the Americas, grown in a common Canadian field for one season. The bacteria were taxonomically classified using 16S rRNA sequencing. In total, 201 bacteria were cultured, spanning 29 genera, 63 species, and 62 unique OTUs, dominated by Pseudomonas, Pantoea and Microbacterium. These bacteria were tested for their ability to suppress Fg in vitro which identified 10 strains belonging to 6 species: Rouxiella badensis, Pantoea ananatis, Pantoea dispersa, Pseudomonas koreensis, Rahnella aquatilis, and Ewingella americana. Two anti-Fg strains were sprayed onto silks before/after Fg inoculation, resulting in ≤90% reductions in disease (Gibberella ear rot) and 70-100% reductions in associated mycotoxins (deoxynivalenol and zearalenone) in progeny seeds. These strains also protected progeny seeds post-harvest. Confocal fluorescent imaging showed that one silk bacterium (Rouxiella AS112) colonized susceptible entry points of Fg on living silks including stigmatic trichomes, wounds, and epidermal surfaces where they formed thick biofilms. Post-infection, AS112 was associated with masses of dead Fg hyphae. These results suggest that the maize style (silk) is endowed with potent bacteria from the mother plant to protect itself and progeny from Fusarium. The evidence suggests this trait may have been selected by specific indigenous peoples, though this interpretation requires further study.

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“…Quality shelling to avoid grain damage and proper drying are important prior to storage, especially to avoid the growth of fungi such as Aspergillus spp. that can produce mycotoxins harmful to humans and farm animals (Odjo et al, 2022a). Cobs damaged by insects and birds are more prone to Aspergillus and other fungal infections.…”

Section: Harvesting and Storagementioning

confidence: 99%

Review of agronomic research on the milpa, the traditional polyculture system of Mesoamerica

et al. 2023

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The milpa system is the basis of traditional agriculture in Mesoamerica. It is based on a polyculture of maize (Zea mays L.), bean (Phaseolus spp.) and squash (Cucurbita spp.) and is associated with a great diversity of crops and wild species. The milpa has great cultural and historical importance but can also be highly productive and provide sufficient and healthy diets for smallholder farmers. The milpa system is practiced less and less however, mainly due to socioeconomic changes, but also due to a lack of agronomic knowledge adapted to current conditions. To provide a starting point for new agronomic research, we reviewed the scientific literature to identify the current knowledge on milpa agronomy and determine research priorities to further improve the system. Given the wide diversity of conditions under which milpa is practiced, agronomic research is lacking, but indicates that improvements to the milpa can be made in all aspects of the milpa. 176 research articles on the milpa system were found in databases, of which 61 treated agronomic research. The main agronomic topics described in literature are crop variety, soil fertility management, weed management and productivity. Most research has focused only on maize and studies reporting on the associated crops are scarce. More research on all aspects of the milpa is needed to understand and improve the agronomy of the system under the changing conditions of modern agriculture. Reducing the workload associated with the milpa, as well as soil fertility and weed management can be identified as research priorities.

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Occurrence and postharvest strategies to help mitigate aflatoxins and fumonisins in maize and their co-exposure to consumers in Mexico and Central America

Cited by 23 publications

References 114 publications

Efficacy of electron beam irradiation in reduction of mycotoxin-producing fungi, aflatoxin, and fumonisin, in naturally contaminated maize slurry

Efficacy of electron beam irradiation in reduction of mycotoxin-producing fungi, aflatoxin, and fumonisin, in naturally contaminated maize slurry

Bacteria existing in pre-pollinated styles (silks) can defend the exposed male gamete fertilization channel of maize against an environmental Fusarium pathogen

Review of agronomic research on the milpa, the traditional polyculture system of Mesoamerica

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