Diallel Analysis of Aflatoxin Accumulation in Maize

Abstract

Aflatoxin, a toxin produced by the fungus Aspergillus flavus Link:Fries, occurs naturally in maize (Zea mays L.). It is a potent carcinogen, and its presence markedly reduces the value of grain. Host‐plant resistance to A. flavus infection and subsequent aflatoxin accumulation is generally considered a desirable means of reducing losses to aflatoxin. Maize germplasm lines with resistance to aflatoxin contamination have been developed in Mississippi. Four of the aflatoxin‐resistant lines and six other lines were used as parents to produce a diallel cross. The diallel cross was evaluated for resistance to aflatoxin contamination in field trials conducted in Mississippi in 2005 and 2006. General combining ability (GCA) and specific combining ability (SCA) were highly significant sources of variation each year. Reciprocal effects were not significant in 2005 or in the combined analysis over years. In the analysis over years, GCA effects for reduced aflatoxin were highly significant for the four lines developed as sources of resistance: Mp313E, Mp494, Mp715, and Mp717. The GCA effect for reduced aflatoxin was also highly significant for Mo18W and NC408. These lines should be useful in developing maize lines and hybrids with resistance to aflatoxin contamination. Breeding methods that maximize the use of GCA should be effective in enhancing resistance to aflatoxin accumulation when using these germplasm lines.