JOHNSTON, IOWA

Pioneer Hi-Bred Int., Inc.

URBANA, ILLINOIS

University of Illinois

 New male-sterile allele of the male-fertility gene Ms45 --Trimnell, MR, Fox, TW, Patterson, E, Albertsen, MC A new male-sterile allele of Ms45 has been identified from a series of male-sterile mutants received several years ago from the late Dr. Earl Patterson of the University of Illinois. Earl had designated this mutant as ms*-6040 (see MNL 69:126-128). In the 1980�s, Earl and we started allelism studies by making some of the test-crosses of ms*-6040 to the known male-sterile alleles located on chromosome 9 (ms2), as well as to unmapped male-sterile alleles that were later found to be located on chromosome 9 (ms25-6022, previously ms*-6022; and ms35, previously ms*-6011). Progenies from these test-crosses were fertile, indicating the mutants were not allelic.

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)
Progeny
 X2(1:1)
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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