Date: 3/29/99

Time: 2:10

Type: Symposium

Number: 36

Genetics of flavone synthesis and corn earworm antibiosis in maize silks

*M.D. McMullen, USDA-ARS Plant Genetics Research Unit and Plant Science Unit, University of Missouri, Columbia, MO 65211
Contact e-mail: mcmullen@teosinte.agron.missouri.edu

The interpretation of quantitative trait locus (QTL) studies of insect resistance is often limited by the lack of information on metabolic pathways leading to most economic traits. An exception is resistance to the corn earworm (CEW), Helicoverpa zea (Boddie), in maize (Zea mays L.) due to maysin, a C-glycosyl flavone, synthesized in silks via a branch of the well-characterized flavonoid pathway. Our results using flavone synthesis as a model QTL system indicate: 1) the importance of regulatory loci as QTLs, 2) the importance of interconnecting biochemical pathways on product levels, 3) evidence for "channeling" of intermediates, allowing independent synthesis of related compounds, 4) the utility of QTL analysis in clarifying the role of specific genes in a biochemical pathway, and 5) identification of a previously unknown locus on chromosome 9S affecting flavone level. A greater understanding of the genetic basis of maysin synthesis and associated CEW resistance should lead to improved breeding strategies.

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