INHERITANCE OF RESISTANCE TO ASPERGILLUS EAR ROT AND AFLATOXIN IN CORN GENOTYPES

The inheritance of resistance to Aspergillus ear rot of corn (Zea mays) caused by Aspergillus flavus was studied in progeny derived from crosses between resistant (LB31, L317, CI2, N6, 75-R001, B37Ht2, OH513, Tex6, and H103) and susceptible (B73 and/or Mo17) inbreds following inoculation. In 1992 and 1993 the parental, F-1, F-2, F-3, and both backcross generations of 11 crosses were tested. The number of generations evaluated for each cross was dependent on the year. Parental and F-1 generations, as well as five F-2 and three F-3 populations, were evaluated for aflatoxin content in 1992 and 1993. Generation mean analysis indicated additive and dominance gene action were of primary importance in resistance to Aspergillus ear rot. Dominance genetic effects estimates ranged from 0.0 to 87.3% of the variation between generation means. Inbreds TexB, LB31, CI2, and OH513 consistently had the highest levels of resistance. Frequency distributions of aflatoxin content of ears on F-2 plants and ears on F-3 families (lines) of the Mo17 x Tex6 and B73 x LB31 populations were highly skewed toward the resistant parent, indicative of genic dominance. The F-2 and F-3 generations indicated various levels of transgressive segregation for resistance to Aspergillus ear rot and to aflatoxin production.