Resistance to aflatoxin accumulation in kernels of maize inbreds selected for ear rot resistance in West and Central Africa

Thirty-six inbred hues selected in West and Central Africa for moderate to high resistance to maize ear rot under conditions of severe natural infecti on were screened for resistance to aflatoxin contamination using the previo usly established kernel screening assay. Results showed that more than half the inbreds accumulated aflatoxins at levels as low as or lower than the r esistant U.S. Lines GT-MAS:gk or M182. In 10 selected aflatoxin-resistant o r aflatoxin-susceptible inbreds, Aspergillus flavus growth, which was quant ified using an A. flavus transformant containing a GUS-B-tubulin reporter g ene construct, was, in general, positively related to aflatoxin accumulatio n. However, one aflatoxin-resistant inbred supported a relatively high leve l of fungal infection, whereas two susceptibles supported relatively low fu ngal infection. When kernels of the 10 tested lines were profiled for prote ins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, signif icant variations from protein profiles of U.S. lines were observed. Confirm ation of resistance in promising African lines in held trials may significa ntly broaden the resistant germplasm base available for managing aflatoxin contamination through breeding approaches. Biochemical resistance markers d ifferent from those being identified and characterized in U.S. genotypes, s uch as ones inhibitory to aflatoxin biosynthesis rather than to fungal infe ction, may also be identified in African lines. These discoveries could sig nificantly enhance the host resistance strategy of pyramiding different tra its into agronomically useful maize germplasm to control aflatoxin contamin ation.