In 1991 in Johnston, IA, Steve Briggs grew out several hundred rows of Robertson�s Mutator families. We observed these families and found over 350 families segregating for male-sterile mutations. One of these families we designated as ms*-SB177.

In Johnston during the summer of 1992, we grew remnant seed of ms*-SB177. The family again segregated for male sterility, and crosses with inbreds A632 and B73 were made. These crosses were selfed in our Hawaii winter nursery that year, and the A632 segregating ears were grown in our Johnston nursery in 1993. The segregations for the original seed and resulting F2 ears are shown:
 

Genotype	Fertiles	Steriles	X2 (3:1)
Original	21 Fertiles	14 Steriles	4.20
A632 Ear #13	73 Fertiles	19 Steriles	0.93
A632 Ear #14	57 Fertiles	14 Steriles	1.06
A632 Ear #8	52 Fertiles	23 Steriles	1.28

In our 1995 Johnston nursery, segregating rows of ms*-SB177 were grown and leaf samples were taken for chromosome mapping. Bulk mapping was run as described in MNL 72:37 except that 19 male-fertile and 20 male-sterile plants were used for the DNA pools. Two RFLP markers on chromosome 3L, php20-080 and umc63, were polymorphic between the two bulks. DNA blots of male-sterile individuals were hybridized with the php10-080 marker. Four recombinant alleles out of 40 alleles total were detected, indicating that the ms*-SB177 gene is linked to php10-080 on chromosome 3L.

Testcrosses were made between ms*-SB177 and the known male-sterile mutants located on Chromosome 3 (ms3 and ms23) as well as with the unmapped male steriles ms24 and ms27. At least 40 plants were observed for each test-cross, and all test-cross progeny were found to be fertile, indicating ms*-SB177 was not allelic. We are designating ms*-SB177 as the reference allele for a new male-sterile mutant, ms37.
 

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