Characterization Of Two Genes For Resistance To Aflatoxin Accumulation In Maize (Zea Mays L.)
Mylroie, J. Erik
AdvisorWilliams, W. Paul
Baldwin Brian, S.
Warburton, Marilyn L.
Maize (Zea mays L.) is one of the world’s largest food crops and thus any pathogens of maize are of great importance. Aspergillus flavus is one of these pathogens and it produces a carcinogenic metabolite called aflatoxin. Efforts to reduce infection by A. flavus and subsequent aflatoxin accumulation include the development of maize lines resistant to aflatoxin accumulation. However, resistant lines that have been developed contain agronomically unfavorable traits. Gene-based markers would allow for easier transfer of resistance from resistant inbred lines into maize lines with good agronomic traits. The focus of this research was the development of gene-based markers for resistance to aflatoxin accumulation. To this end, two genes were characterized for their association with reduced aflatoxin accumulation in maize. A gene coding for a photosytem II3 protein shown to be differentially regulated between maize lines Mp313E (resistant) and Va35 (susceptible) was used to develop the marker MpM1. This marker was shown to be associated with resistance to aflatoxin accumulation in three F2:3 mapping populations derived from Mp313E x B73, Mp313E x Va35, and Mp715 x T173 and identified a new quantitative trait locus (QTL) on chromosome 4. The second gene chosen was the chitinase A gene (chiA), which has been shown to inhibit fungal growth and is differentially regulated between resistant and susceptible lines of maize. ChiA also had an association with reduced aflatoxin accumulation in the three F2:3 mapping populations and identified a new QTL in the Mp313E x Va35 population. Together, MpM1 and chiA were associated with 27% of the phenotypic variation in one environment of the Mp313E x B73 population. These markers represent the first two gene-based markers developed for resistance to aflatoxin accumulation, and the methodology developed in this study can be used to screen other candidate genes for potential use as gene-based makers.