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This article in CS

  1. Vol. 38 No. 2, p. 461-471
     
    Received: June 26, 1997


    * Corresponding author(s): mcmullen@teosinte.agron.missouri.edu
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doi:10.2135/cropsci1998.0011183X003800020032x

Maize Silk Maysin Concentration and Corn Earworm Antibiosis: QTLs and Genetic Mechanisms

  1. P. F. Byrne,
  2. M. D. McMullen ,
  3. B. R. Wiseman,
  4. M. E. Snook,
  5. T. A. Musket,
  6. J. M. Theuri,
  7. N. W. Widstrom and
  8. E. H. Coe
  1. Dep. of Soil and Crop Sciences, Colorado State Univ., Ft. Collins, CO 80523
    USDA-ARS Plant Genetics Research Unit and Plant Science Unit, Univ. of Missouri, Columbia, MO 65211
    USDA-ARS Insect Biology and Population Management Research Laboratory, Tifton, GA 31793
    P.O. Box 5677, Univ. of Georgia, Athens, GA 30613
    Plant Science Unit, Univ. of Missouri, Columbia, MO 65211

Abstract

Abstract

Growth of the corn earworm (Helicoverpa zea Boddie), a major pest of maize (Zea mays L.), is inhibited by high concentrations of maysin, a C-glycosyl flavone, in maize silks. To advance understanding of the genetic control of silk maysin concentration and antibiosis to corn earworm, we conducted a quantitative trait locus (QTL) study in a population derived from a cross of high-maysin (GE37) and Iowmaysin (FF8) lines. Both lines have phenotypically identical, functional alleles at the pl locus, a regulator of the biochemical pathway leading to maysin synthesis. We evaluated 250 (GE37 × FF8)F2:3 families for (i) restriction fragment length polymorphisms at 121 loci, (ii) silk maysin concentrations in two locations (in Georgia and Missouri), and (iii) weight of corn earworm larvae grown on artificial diet containing oven-dried silks. For maysin concentration in both locations, composite interval mapping revealed major QTLs in the asg20-whp1 interval of chromosome 2 and near the wx1 locus on chromosome 9; smaller effects were detected on chromosomes 1, 6, and 8. For larval weight, the largest QTL was detected in the asg20-whp1 interval, and major effects were also associated with chromosomes 1 and 6. However, we found no effect on larval weight at wx1 Significant (P < 0.001) epistasis was observed for all traits. Our results suggest that whp1 on chromosome 2, a gene that encodes chalcone synthase and sm1, a silk-specific gene on chromosome 6, are candidate genes affecting maysin concentration and corn earworm larval weight in this population.

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