Peanuts fruit underground and are in direct contact with soil populations of Aspergillus flavusand Aspergillus parasiticus, the two fungi responsible for producing aflatoxin in peanuts.
A laboratory procedure has been developed in which viable peanut seeds are wounded and inoculated with soil directly from the field. This research has shown that despite low spore densities in soil, aflatoxin-producing fungi preferentially invade peanuts over other soil-inhabiting fungi. Invasion is greatly influenced by seed moisture and soil temperature.
Seeds colonized by Aspergillusspecies
Effect of soil population density on peanut infection
This procedure is currently being used to assay different nontoxigenic A. flavusstrains for their ability to reduce aflatoxin in biological control.
Ability of eight nontoxigenic Aspergillus flavusstrains to inhibit aflatoxin production by specific aflatoxin-producing strains using the peanut seed assay
|Aflatoxin production by strain F35|
|Significant reduction of aflatoxin:||Strain A > B > C > D > E > F|
|No significant reduction in aflatoxin:||Strain G, H|
|Aflatoxin production by strain F14|
|Significant reduction of aflatoxin:||Strain G > C > E > A > D > F> H > B|
|Aflatoxin production by strain F86|
|Significant reduction of aflatoxin:||Strain H > A > C|
|No significant reduction in aflatoxin:||Strain B, E, D, G, F|
|Aflatoxin production by strain F44|
|Significant reduction of aflatoxin:||Strain C > A > D > G > E > F|
|No significant reduction in aflatoxin:||Strain B, H|
|F= Biological control strain in current use|
For more information contact Bruce Horn.