Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 68pg1
EVALUATION OF CHANGES IN MOLECULAR MARKER FREQUENCIES IN MAIZE
LONG TERM SELECTION EXPERIMENTS.
J. Sughroue, Y. Tadmor, T. Berke, V. Mikkilineni, 1. Goldman,
and T. Rocheford, Department of Agronomy, University of Illinois,
Urbana, Illinois 61801.
We are evaluating changes in molecular marker frequencies in
maize populations that have undergone long term selection. The
Illinois long term selection experiment for oil concentration has
been conducted for 92 generations producing the following
strains: Illinois High Oil (IHO), Illinois Low oil (ILO),
Illinois Reverse High Oil (RHO), Illinois Reverse Low Oil (RLO),
and Illinois Switchback High Oil (SHO). DNA from these strains
has been analyzed to determine RFLP allelic frequencies among
generation 90 of the strains. We observed a high degree of
polymorphism among the strains. We have detected RFLP allelic
frequency trends that suggest a response to selection for oil
concentration on chromosome arms: IL and S, 2S, 3L, 4L, 5L and S,
6L, 7S, and 9L. We are currently using RAPDS, which have
revealed similar types of trends when cycles 65 and 90 of the oil
strains are evaluated. These molecular markers are currently
being used for QT mapping in populations developed from the cross
of the high and low protein strains and the high and low oil
strains. We are also performing RFLP analyses on the Illinois
protein strains and will present data on RFLP allelic trends in
response to selection for protein concentration. We are
examining molecular variation in the ribosomal RNA genes of the
progenitor lines included in the Iowa Stiff Stalk Synthetic
(BSSS) selection experiments. Using the ribosomal spacer probe
pZmrs-1 we have detected considerable rDNA spacer-length
variation among the progenitor lines of BSSS. Selection for
adaptation to Iowa growing environments altered variants
frequencies, suggesting specific certain variants confer an
adaptive or selective advantage in maize. These results are
similar to observations in barley populations.
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