New male-sterile mutant alleles of known male-steriles --Trimnell, MR, Fox, TW, Albertsen, MC As part of our ongoing effort to identify new male-sterile loci in maize, we have identified numerous new alleles of known male-sterile genes. One of these new alleles, designated ms*-NEMS, was found in an EMS mutation population established by Stephen Smith, whereas the others (ms*-TG92A, ms*-EA89A, ms*FA92) arose spontaneously in various breeding materials. Todd Piper, who at the time was the corn breeder at our Eau Claire, WI, Research Station, identified the ms*-EA89 mutant and sent it to Marc Albertsen. Marc identified the other three mutations. The segregation of these male-sterile mutations in F2 familes is shown below except for ms*-NEMS, which also was grown as a sib-pollinated family, segregating 1:1 for the mutation.
 

Genotype

Year Identified
Year Grown
# Fertile Plants
# Sterile Plants
C2(1:1, P>0.050=3.84)
ms*-NEMS ms# Ear 10
1984
1997
10
6
1.00
ms*-NEMS ms# Ear 2
1984
1997
8
8
0.00
ms*-NEMS ms# Ear 7
1984
1997
5
2
1.29
         
(3:1, P>0.050=3.84)
ms*-NEMS/A632)1
1984
1999
12
8
2.40
ms*-NEMS/A632)2
1984
1999
12
6
0.67
           
ms*-TG92A/A632)1
1992
1995
10
4
0.10
           
ms*-EA89A/A632)1
1989
1995
14
2
1.33
ms*-EA89A/B73)1
1989
1995
13
5
0.07
           
ms*-FA92/A632)1
1992
1995
14
4
0.07
ms*-FA92/A632)2
1992
1995
12
4
0.00

In the 1999 Johnston, IA, nursery and the 1999 Hawaii winter nursery, we planted F2 families to determine the map location of these mutants. As part of our standard procedure in working with unmapped male-sterile mutants, we first determine the chromosome arm location for a given mutant, then we conduct the appropriate allele test-crosses. Leaf punches were taken from 24 male-sterile plants and from 24 male-fertile plants for DNA isolation. 96 SSR markers, dispersed throughout the genome, were used to genotype these samples. Results for the SSR mapping are as follows:
 
Family
Linked Markers
% Recombination*
Mutant Map Position
ms*-NEMS
phi96342
2.3
 
ms*-NEMS
bngl1079
4.8
 
ms*-NEMS
bngl1655
4.5
 
ms*-NEMS
bngl1071
23.8
 
ms*-NEMS
phi050
4.8
10C
       
ms*-TG92A
bngl1079
5.6
10L
       
ms*-EA89A
phi090
19
2L
       
ms*-FA92
bngl1065
2.1
 
ms*-FA92
bngl1056
23
 
ms*-FA92A
phi015
29
 
ms*-FA92
phi121
27.1
8L

* % Recombination was determined using only segregation scores from mutants.

After receiving the mapping data, we made test-crosses with all of the known recessive male-sterile alleles that mapped to the same respective chromosome as these mutants, as well as crossing with the unmapped recessive male-sterile alleles (ms27, ms31) and those with questionable mapping data (ms35). The resultant progeny were grown in our 2001 Johnston nursery. At least 40 plants were observed for most of the test-crosses. The reciprocal test-crosses of these mutants that showed allelism with known male-sterile mutants are shown below, along with their respective allele designations.
 
Female* Male*
Progeny
C2(1:1)
Allele Designation
ms*-NEMS ms11 22 Fertiles:20 Steriles
0.10
 
ms11 ms*-NEMS 18 Fertiles:22 Steriles
0.40
ms11-NEMS
         
ms*-TG92A ms29 21 Fertiles:20 Steriles
0.02
 
ms29 ms*-TG92A 7 Fertiles: 7 Steriles
0.00
ms29-TG92A
         
ms*-EA89A ms33-GC89A 17 Fertiles:12 Steriles
0.86
 
ms33-GC89A ms*-EA89A 14 Fertiles:23 Steriles
2.19
ms33-EA89A
         
ms*-FA92 ms8 14 Fertiles:15 Steriles
0.03
 
ms8 ms*-FA92 18 Fertiles:22 Steriles
0.40
ms8-FA92

* All females homozygous for mutation, all males heterozygous for mutation.
 
 


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