In 1991 in Johnston, IA, Steve Briggs grew out several hundred rows of Robertsonís 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:
|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
to the MNL 73 On-Line Index
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