Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 67pg1
MOLECULAR MARKER MAPPING FOR CHROMOSOMAL REGIONS INFLUENCING
MAIZE KERNEL COMPOSITION TRAITS.
I. Goldman, T. Rocheford, J. Dudley, Y. Tadmor, J. Juvik, and
B. Marcotte, Department of Agronomy and Horticulture, University
of Illinois, Urbana, Illinois 61801.
We are currently RFLP mapping quantitative trait loci (QTLs)
influencing kernel composition of dent and sweet corn. RFLP
analyses were performed on a mapping population developed from a
cross of the high and low protein strains of the Illinois long
term selection experiment for maize kernel composition. We have
identified several chromosome regions associated with starch,
protein and oil concentration and kernel weight. Major QTLs for
starch and protein concentration have been identified on
chromosome arms: IS, 2S, 3L, 5L, 6L, 7L, 9L and 10L, and major
QTLs for oil concentration have been identified on chromosome
arms: 3L, 4L, 5S, 6S, 7L, and 9L. Multiple regression models
indicate that six loci explain 64% of the variation for starch
concentration and seven marker loci explain 76% of the variation
for oil concentration. This suggests molecular marker
facilitated selection for kernel composition may be feasible. A
notable finding is the detection of a QTL for starch
concentration by probing with the shrunken-2 (sh2) clone and
detection of a QTL for kernel weight by probing with the
brittle-2 (bt2) clone. The sh2 and bt2 alleles are starch
biosynthetic mutants and our results suggest that different wild
type alleles at these starch biosynthetic loci may influence
starch concentration and kernel weight, respectively. We are
currently DNA sequencing the sh2 locus Of the parents of our
mapping population. In sweet corn we mapped the sugary enhancer
(se) gene using RFLP markers on a mapping population developed
from a cross between sugary (su) and se strains. The se gene
maps to the long arm of chromosome 4.
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