Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2004
Publication Date: February 1, 2005
Citation: Brooks, T.D., Krakowsky, M.D., Williams, W.P., Windham, G.L. 2005. Further investigation of resistance mechanisms responsible for reduced levels of aflatoxin accumulation in maize: QTL studies of two resistant inbreds [abstract]. Proceedings 2004 4th Annual Fungal Genomics, 5th Annual Multi-Crop Fumonisin Elimination and 17th Annual Multi-Crop Aflatoxin Elimination Workshops. p. 70. Technical Abstract: This study was designed to discover additional sources of genetic resistance to aflatoxin accumulation in maize. Previous studies have been performed that located quantitative trait loci(QTL)in the maize inbred Mp313E. Two separate mapping studies involving different susceptible parents and multiple environments resulted in the identification of two primary and many secondary loci which influence aflatoxin accumulation. Many of these QTL are shared between the two studies while some appear to be unique raising questions about the effect of genetic background on their performance. Currently these QTL are being backcrossed into susceptible inbreds and evaluated for their effect. Data from these tests are also being combined to examine genetic background effects on QTL performance. Further investigation into sources of resistance continue using different resistant and susceptible lines. Mp92:673 is a resistant inbred developed in the CHPRRU breeding program that is derived from a different genetic background than Mp313E. It is slightly less resistant than Mp313E while being less tropical in growth habit and earlier to flowering. NC300 was chosen as the susceptible inbred. It is a southern adapted inbred with relatively good combining ability. 280 F2 families derived from a cross of these parents were evaluated in an initial trial in 2003. Variation was observed to be sufficient for QTL analysis. In choosing these parents to develop a mapping population a new source of resistance will be studied, a susceptible inbred adapted to southern growing conditions will be used, and a larger population will be phenotyped. In addition, field data will be collected in Mississippi and Georgia locations so that genotype x environment interactions can be better studied. One year of field evaluation has been completed and aflatoxin levels of replicated plots are being determined. Genotyping of the population is under way. One more year of field data will be collected in Mississippi and Georgia. QTL analysis will be undertaken to determine relevant genetic regions affecting aflatoxin accumulation and their interactions with each other and the environment. Examination of these collective genetic studies should prove useful in characterizing the complex interactions of resistance loci with the environment, different genetic backgrounds, and other resistance genes.