ARS | Publication request: THE BIOLOGICAL BASIS OF EPISTASIS BETWEEN QUANTITATIVE TRAIT LOCI FOR FLAVONE AND 3-DEOXYANTHOCYANIN SYNTHESIS IN MAIZE (ZEA MAYS L.)

Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2001
Publication Date: August 1, 2001
Citation: MCMULLEN, M.D., SNOOK, M.E., LEE, E.A., BYRNE, P.F., KROSS, H., MUSKET, T.A., HOUCHINS, K.E., COE JR, E.H. THE BIOLOGICAL BASIS OF EPISTASIS BETWEEN QUANTITATIVE TRAIT LOCI FOR FLAVONE AND 3-DEOXYANTHOCYANIN SYNTHESIS IN MAIZE (ZEA MAYS L.). GENOME. 2001. V. 44(4). P. 667-676.

Interpretive Summary: The development of molecular markers for crop plants and farm animals has enabled research on the genetic basis of agronomic traits that are controlled by multiple genes with incremental effects. However, despite a decade of these studies called quantitative trait locus (QTL) analyses, the molecular basis for variation in agronomic traits is still largely unknown. .Our research group is addressing this deficiency by studying a model syste for QTL analysis, the genetic basis of resistance to the corn earworm in corn silk. In this study we demonstrated that the genes controlling QTL can consist of a particular class of genes called transcription factors, i.e., genes that control expression of other genes. We also demonstrate that the effects of specific combinations of genes can result from genes controlling different but interconnected biochemical pathways. This research will benefit geneticists and plant and animal breeders in identifying and understanding the genes controlling their traits of interest. The impact of this study is that it helps identification of specific gene targets that will need to be modified for crop improvement.

Technical Abstract: The accumulation of maysin, a C-glycosyl flavone, in maize silk is an important component of antibiosis to the corn earworm. We have previously demonstrated the importance of the p1 locus and the rem1 locus on maysin synthesis. We have proposed that the rem1 effect involves an interconnecting pathway with flavone synthesis. To directly test the importance of genes in interconnected pathways as quantitative trait loci (QTL) for maysin synthesis and to define the biological basis of epistatic interactions, we developed a (W23a1 x GT119)F2 population. The a1 locus is not required for the synthesis of flavones, but is required for the synthesus of 3-deoxyanthocyanins in maize silks. Results of analysis of maysin and 3-deoxyanthocyanins levels confirmed the importance of the p1 locus (P<0.0001) as a QTL for both flavones and 3-deoxyanthocyanins. The a1 locus was also highly significant (P<0.0001) as was the p1 x a1 epistatic interaction (P<0.0001) for both traits. Our results demonstrate that shunting of biochemical intermediates between pathways can be the biological basis of major QTL effects and epistatic interactions for QTL for agronomic traits.