Aflatoxin Accumulation in a Maize Diallel Cross

W Williams,Gary Windham

doi:10.3390/agriculture5020344

W Williams, Gary Windham

Open Access

https://doi.org/10.3390/agriculture5020344

Copy DOI

Abstract

Aflatoxins, produced by the fungus Aspergillus flavus, occur naturally in maize. Contamination of maize grain with aflatoxin is a major food and feed safety problem and greatly reduces the value of the grain. Plant resistance is generally considered a highly desirable approach to reduction or elimination of aflatoxin in maize grain. In this investigation, a diallel cross was produced by crossing 10 inbred lines with varying degrees of resistance to aflatoxin accumulation in all possible combinations. Three lines that previously developed and released as sources of resistance to aflatoxin accumulation were included as parents. The 10 parental inbred lines and the 45 single crosses making up the diallel cross were evaluated for aflatoxin accumulation in field tests conducted in 2013 and 2014. Plants were inoculated with an A. flavus spore suspension seven days after silk emergence. Ears were harvested approximately 60 days later and concentration of aflatoxin in the grain determined. Parental inbred lines Mp717, Mp313E, and Mp719 exhibited low levels (3–12 ng/g) of aflatoxin accumulation. In the diallel analysis, both general and specific combining ability were significant sources of variation in the inheritance of resistance to aflatoxin accumulation. General combining ability effects for reduced aflatoxin accumulation were greatest for Mp494, Mp719, and Mp717. These lines should be especially useful in breeding for resistance to aflatoxin accumulation. Breeding strategies, such as reciprocal recurrent selection, would be appropriate.

Highlights

Aflatoxins, produced by the fungus Aspergillus flavus, occur naturally in maize
Among the 10 parental inbred lines, mean aflatoxin accumulation over years ranged from 742 ng/g for PHW79 to a low of 3 ng/g for Mp717 (Table 1)
Aflatoxin concentration was lowest in Mp717, Mp313E, and Mp719, three lines that were developed and released as sources of resistance to A. flavus infection and aflatoxin accumulation by USDA-ARS [13,16,17]

Summary

Introduction

Aflatoxins, produced by the fungus Aspergillus flavus, occur naturally in maize. The most potent carcinogens found in nature, aflatoxins are toxic to humans, and to livestock, pets, and wildlife [1,2,3,4]. Dietary exposure to aflatoxins is one of the major causes of hepatocellular carcinoma, the fifth most common cancer in humans worldwide [5]. Their acute and chronic toxicity poses a major threat to humans in developing countries where maize is a dietary staple. Administration restricts the sale of grain with aflatoxin levels exceeding 20 ng/g [6].

Methods

Results

Discussion

Conclusion