JOHNSTON, IOWA
Pioneer Hi-Bred Int, Inc
URBANA, ILLINOIS
University of Illinois
FORT COLLINS, COLORADO
Colorado State University
New chromosome 2L male-sterile mutant ms33 and alleles
--Trimnell, MR, Patterson, E, Fox, TW, Bedinger, P, Albertsen, MC

Three new male-sterile mutants located on chromosome 2L have recently been identified. All three were found independently of one another.

Earl Patterson of the University of Illinois identified a male-sterile mutation he designated as ms*-6019. Earl discovered that other unknown male-steriles he had found were allelic to ms*-6019. They were ms*-6024, ms*-6029, ms*-6038 and ms*-6041. He found that these male-steriles mapped to the long arm of Chromosome 2 by using B-A translocations (see MNL 69:126-128).

Pat Bedinger of Colorado State University found a male sterile she identified as ms*-Stan1. In the winter of 1996, Pat provided us with segregating seed to map this unknown male-sterile mutant. The seed was grown in our Hawaii winter nursery and leaf samples were taken for mapping. Bulk mapping was performed as described in MNL 72:37 except that 17 male-sterile and 20 male-fertile plants were used in the creation of the bulks. The RFLP markers umc36 and php20-581b, on the long arm of chromosome 2, were both polymorphic between the two pools. Hybridization of these markers against DNA from the male-sterile individual plants revealed four recombinants for the php20-581b probe and one recombinant for umc36. This data indicates that ms*-Stan1 maps on chromosome 2L near the marker umc36.

In 1990, Don Morrow at our Garden City, KS Research Center identified a proprietary inbred line segregating for a male-sterile mutation that we named ms*-GC89A. He selfed the fertile plants in the row and sent us seed from 12 individual ears, as well as remnant seed from the original segregating ear. We grew one row of all 13 ears in 1992 in our Johnston summer nursery and found that 9 of the 13 rows segregated for male sterility.
 
Genotype Fertiles Steriles X2(3:1)
ms*-GC89A 12 3 0.20
ms*-GC89A (8 ears-1990 source) 108 30 0.78

In the 1995 Hawaii winter nursery, segregating rows of ms*-GC89A were grown, and leaf samples were taken for chromosome mapping. Bulk mapping was done using 19 male-sterile and 20 male-fertile plants for the DNA pools. Again, umc36 showed a polymorphism between the two phenotypic classes and also was found to be 100% linked to the trait when DNA blots from male-sterile individuals were run. Hybridization of the marker bnl17.14, also on chromosome 2L, gave 6 recombinants on the male-sterile individual plant DNA blot.

Because all three of these male-sterile mutants mapped to Chromosome 2, testcrosses were made among them to determine if they were allelic to one another. These testcrosses were grown in our Johnston, IA, nursery in 1998. The testcrosses and allelism results are listed below:
 
  Female Male Progeny
Ear #1 ms*-GC89A Hom ms*-6019 Het 12 Fertiles 10 Steriles
Ear #1 ms*-6019 Hom  ms*-GC89A Het 3 Fertiles 1Sterile
         
Ear #1 ms*-GC89A Hom ms*-Stan1 Het 14 Fertiles 10 Steriles
Ear #1 ms*-Stan1 Het ms*-GC89A Het 22 Fertiles 8 Steriles
         
Ear #1 ms*-Stan1 Het ms*-6019 Het 26 Fertiles 7 Steriles
Ear #1 ms*-6019 Hom  ms*-Stan1 Het 21 Fertiles 14 Steriles

These male steriles also were crossed with the known male steriles located on Chromosome 2 (ms30, ms31, ms32 (new from Pat Bedinger)), as well as ms24 and ms27 (both currently unmapped), and were found not to be allelic.

Since Earlís male-sterile lines were more than likely found before Patís or ours, we would like to designate ms*-6019 as the reference allele for a new male-sterile mutant, ms33. The other new alleles will be designated as follows: ms33-6024, ms33-6029, ms33-6038, ms33-6041, ms33-Stan1 and ms33-GC89A.
 


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