Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 43pg1
RFLP ANALYSIS OF DELETIONS PRODUCED BY MAIZE PLANTS THAT
CONTAIN THE r-X1 DEFICIENCY.
David Weber, Tim Helentjaris, and Zuo-Yu Zhao, Dept. of
Biological Sciences, Illinois State University, Normal, IL 61761
and Dept. of Plant Sciences, University of Arizona, Tucson, AZ
85721.
Maize monosomics and trisomics are recoverable from female
gametes that contain the r-XI deficiency because nondisjunction
frequently takes place in these gametes during the second embryo
sac division. Deficiencies for chromosomal segments are also
recoverable from these gametes. Eighty progeny of
r-X1-containing female gametes that had characteristics
indicating that they might contain a deficiency were analyzed
with RFLP markers on each of the 20 chromosome arms of maize.
One deficiency was detected in each of 38 of these plants and two
deficiencies were detected in five. These 48 deficiencies
involved 13 chromosome arms (lS, 1L, 2S, 2L, 5L, 6S, 6L, 7L, 8S,
8L, 9S, 9L, and 10L); thus, the r-X1 system breaks most, probably
all maize chromosome arms. Maternal chromosomal segments were
lost in 38, paternal segments were lost in eight, and maternal
and paternal segments of the same chromosome were lost in two of
the deficiencies. Breaks were detected at five different points
in chromosome 1 and four in chromosome 6; therefore, the r-X1
system causes breaks at several different points in a chromosome.
We estimate that at least 2.6% of the progeny of r-XI-containing
gametes contain a deficiency.
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