JOHNSTON, IOWA
Pioneer Hi-Bred Int., Inc.
FORT COLLINS, COLORADO
Colorado State University
URBANA, ILLINOIS
University of Illinois
GRAND FORKS, NORTH DAKOTA
University of North Dakota

Two new alleles of the male-sterile mutant ms45
--Trimnell, MR, Bedinger, P, Patterson, E, Sheridan, W, Albertsen, MC

Two new male-sterile mutant alleles of ms45 have been identified. One of the alleles came from a Mutator family received from Bill Sheridan of the University of North Dakota. The other allele is a male-sterile mutant received from Earl Patterson of the University of Illinois.

Bill identified three male-sterile plants in a single Mutator-containing family. Not knowing for certain the allelic relationship of these mutants when we first received them, we designated the mutants as ms*-BS1, ms*-BS2, and ms*-BS3. Several crosses were made between these lines and known male-steriles to determine allelism. Because all of these were single male-sterile plants identified from the same ear row, and because of the results given below, we think that the three male-sterile plants represent the same mutation. In 1994, reciprocal test-crosses were made between ms45`-9301 heterozygotes and ms*-BS3 heterozygotes in our Hawaii winter nursery. The resultant progenies were grown in Johnston in 1995 and gave the following results, indicating allelism:
 
Female   Male Progeny  
ms45`-9301 Het  X ms*-BS3 Het 40 Fertiles 6 Steriles
ms*-BS3 Het X ms45`-9301 Het 29 Fertiles 11 Steriles

In 1995, test-crosses were made between ms45`-9301 homozygotes and ms*-BS1 heterozygotes in our Hawaii winter nursery. The resultant progenies were grown in Johnston in 1996 and gave the following results, again indicating allelism:
 
  Female   Male Progeny  
Ear #1  ms45`-9301 Homo X ms*-BS1 Het 13 Fertiles 17 Steriles
Ear #2  ms45`-9301 Homo X ms*-BS1 Het 23 Fertiles 20 Steriles

Pat Bedinger at Colorado State University crossed a ms*-BS1 homozygote with a ms*-BS2 heterozygote in 1996. Progeny from this ear were grown in our 1996 Hawaii winter nursery and segregated 11 fertiles and 7 steriles, indicating allelism between ms*-BS1 and ms*BS2. These results confirm that all three male-steriles are allelic to ms45, and, because of their ear-row origin, probably represent the same mutation. They will collectively be designated as ms45-BS1.

The other male-sterile mutant from Earl had been designated as ms*-6006. Earl had mapped this mutant to the long arm of Chromosome 9 using B-A translocations (see MNL 69:126-128). This mutant had been crossed to ms2 (located on 9L) and was not found to be allelic. It had not been crossed to ms45, however, which also is located on chromosome 9L. We made the test-crosses between ms45`-9301 heterozygotes and ms*-6006 heterozygotes in our 1996 Hawaii winter nursery. The resultant progenies were grown in Johnston in 1997 and gave the following results, indicating allelism:
 
  Female   Male Progeny  
Ear #1  ms*-6006 Het X ms45`-9301 Het 13 Fertiles 6 Steriles
Ear #2  ms*-6006 Het X ms45`-9301 Het 18 Fertiles 6 Steriles

Microsporocyte samples of this mutant were collected at different stages of microsporogenesis. Anthers were squashed and examined by Jennifer Williams in our lab. Her descriptions of the breakdown events of ms*-6006 matched observations we previously made using ms45 material. Our new designation for this ms45 allele is ms45-6006.


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