Pioneer Hi-Bred Int., Inc.
University of Illinois
To reduce the number of subsequent allelism crosses required, we planted an F2 segregating family of ms*-6040 in our 1998 Johnston nursery to take leaf samples for chromosome arm mapping. Samples from 24 plants of each phenotypic class were taken for DNA isolation. Approximately 60 SSR markers were used to genotype this line. Linkage of the SSR marker bnlg619 (chromosome 9, Bin 7 or 8) was found with the male-sterility phenotype.
We then test-crossed ms*-6040
with the remaining male-sterile alleles on chromosome 9 (ms36, ms45`-9301)
as well as with the unmapped male-sterile alleles (ms24, ms27).
At least 40 progeny plants were observed of these test-crosses. The test-crosses
of ms36 and the unmapped mutants were all fertile, indicating ms*-6040
was not allelic to any of them. The reciprocal test-crosses of ms*-6040
with ms45`-9301 gave the following results, indicating allelism:
|Female (homogygous)||Male (heterozygous)||
|ms*-6040||ms45`-9301||17 Fertiles||15 Steriles||0.13|
|ms45`-9301||ms*-6040||13 Fertiles||21 Steriles||1.88|
Our new designation for this Ms45
allele is ms45-6040.
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