ARS | Publication request: FUNCTIONAL VARIANTS OF A MAYSIN QTL ... IS THERE A DIFFERENCE?

Submitted to: Maize Cooperation Newsletter
Publication Type: Other
Publication Acceptance Date: April 15, 1998
Publication Date: N/A

Technical Abstract: Genetic variation is essential to detect QTLs. The p1 locus is responsible for activating C-glycosyl flavone, 3-deoxyanthocyanin, and phlobaphene synthesis in pericarp, cob, and silk tissue. Because of its control over C-glycosyl flavone synthesis, p1 is a major QTL for maysin synthesis and corn earworm (Helicoverpa zea Boddie) antibiosis. There are five allelic variants of p1 that are distinguished by their tissue specificity: p1-rrb, p1-rww, p1-wrb, p1-wwb, and p1-www. Is the p1-wwb allele as effective as a p1-wrb allele in directing maysin synthesis? Are the antibiotic properties of p1-wwb silks equivalent to that of p1-wrb silks? We examined these questions in an F2 population developed from a cross between the inbred lines GT114 and NC7A. NC7A has a p1-wwb allele and GT114 has a p1-wrb allele. Both inbred lines accumulate appreciable amounts of maysin. Silk tissue was collected from the F2 plants and maysin levels were determined. Single-factor analysis of variance did not detect significant differences among the p1 genotypic class. Epistatic interactions between p1 and the other loci were also examined. Again, the p1 region was not involved in any significant epistatic interactions for maysin. So, even though the p1 alleles from the parents are different in terms of tissue specifications, in terms of maysin synthesis in silk tissues and corn earworm antibiosis they are equivalent to one another. Genetically distinct alleles at a QTL do not necessarily result in different phenotypic expression in all tissues and thus may not allow detection of the QTL. The genetic variation must be specific to the tissue in question.