New male-sterile mutant alleles

--Trimnell, MR, Fox, TW, Albertsen, MC

As part of our ongoing effort to map new male-sterile loci in maize, we have identified 16 new alleles of known male-sterile genes. Eight of the mutants (ms*-6026, ms*-6048, ms*-6052, ms*-6054, ms*-6057, ms*-6060, ms*-6061, ms*-6065) were identified by the late Dr. Earl Patterson (MNL 69:126–128) and given to us in the early 1990’s. Two of the mutants (ms*-MG04, ms*-MG07) were identified by Major Goodman in the course of his studies on cytoplasmic diversity among exotic maize lines and given to MCA in the early 1980’s. Mutant ms*-SB370 was identified by MRT and MCA in a Mutator population originally constructed by Dr. Steve Briggs when he was with Pioneer. The mutant designated ms*-DR87B was found segregating in the Ac-tester line, r-sc:m3. Mutants ms*-PR92 and ms*-NP92 were identified by Evan Elsing and MCA among segregating breeding material in our 1992 Hawaii nurseries. Included also are two mutants from chemical mutagenesis. Mutant ms*-HC8-4-4-1 originated from an inbred treated with sodium azide by Ken Hibberd, a fellow graduate student with MCA at the University of Minnesota in the late 1970’s. Mutant ms*-G39-4 originated from an inbred treated with EMS by MCA in 1983. Segregations of these male-sterile mutations as F2 families are shown below.

Genotype Year Identified Year Grown # Fertile Plants # Sterile Plants χ2(3:1)+
ms*-6026/A632)1 -- 1997 10 5 0.56
ms*-6026/B73)1 -- 1997 15 1 3.00
 
ms*-6048/A632)1 -- 1997 13 5 0.07
ms*-6048/B73)1 -- 1995 13 1 2.38
 
ms*-6052/A632)1 -- 1997 12 4 0.00
ms*-6052/B73)1 -- 1997 9 7 3.00
 
ms*-6054/A632)1 -- 1998 9 2 0.27
ms*-6054/B73)1 -- 1998 11 3 0.10
 
ms*-6057/A632)1 -- 1997 16 1 3.31
ms*-6057/B73)1 -- 1997 9 5 0.86
 
ms*-6060/A632)1 -- 1997 12 5 0.18
ms*-6060/B73)1 -- 1997 11 4 0.02
 
ms*-6061/A632)1 -- 1997 13 1 2.38
ms*-6061/B73)1 -- 1997 10 4 0.10
 
ms*-6065/A632)1 -- 1997 9 7 3.00
ms*-6065/B73)1 -- 1997 10 6 1.33
 
ms*-MG04/A632)1 -- 1998 9 6 1.80
ms*-MG04/B73)1 -- 1998 15 4 0.16
 
ms*-MG07/A632)1 -- 1998 12 3 0.20
ms*-MG07/B73)1 -- 1997 12 3 0.20
 
ms*-SB370 F2 1991 1992 26 8 0.04
 
ms*-DR87B/A632)1 1989 1995 16 1 3.31
ms*-DR87B/B73)2 1989 1993 14 4 0.07
 
ms*-NP92/A632)1 1992 1995 6 5 2.45
ms*-NP92/B73)1 1992 1995 9 6 1.80
 
ms*-PR92/A632)1 1992 1995 15 1 3.00
ms*-PR92/B73)1 1992 1995 16 3 0.86
 
ms*-HC8-4-4-1/A632)1 1978 1997 9 4 0.23
ms*-HC8-4-4-1/B73)1 1978 1997 12 3 0.20
 
ms*-G39-4/A632)1 1984 1999 18 2 2.40
ms*-G39-4/B73)1 1984 1997 18 6 0.00

+(3:1, P>0.050=3.84)

 

Between 1997 and 2003, we planted F2 families in Hawaii and Johnston, IA, to determine the map location of these mutants. As part of our standard procedure in working with previously unknown male-sterile mutants, we first determine the chromosome arm location for a given mutant, and then we conduct the appropriate allele testcrosses. Leaf punches were taken from 24 male-sterile plants and from 24 male-fertile plants in the mapping families for DNA isolation. Ninety-six SSR markers, dispersed throughout the genome, were used to genotype these samples. SSR mapping results are as follows:

Family Linked Markers % Recombination++ Mutant Map Position
ms*-6026 phi364545 10  
ms*-6026 phi452693 35 6L
 
ms*-6048 bnlg653 0 5L
 
ms*-6052 umc1736 0 2L
 
ms*-6054 umc1736 4.2  
ms*-6054 umc2205 26.1 2L
 
ms*-6057 bnlg1129 6.5 9L
 
ms*-6060 phi331888 16.7 5
ms*-6061 phi331888 0  
ms*-6061 bnlg653 2.2 5L
 
ms*-6065 bnlg1065 25  
ms*-6065 bnlg1129 16.7 9L
 
ms*-MG04 phi96100 25  
ms*-MG04 bnlg1064 18.8  
ms*-MG04 bnlg1396 31.1 2S
 
ms*-MG07 cyp6 22.5 7
 
ms*-SB370 bnlg653 4.5 5L
 
ms*-DR87B umc1075 6.8  
ms*-DR87B bnlg1194 0 8S
 
ms*-NP92 bnlg1189 8.3  
ms*-NP92 bnlg2244 0 4L
 
ms*-PR92 bnlg1056 21.7  
ms*-PR92 bnlg1065 4.3 8L
 
ms*-HC8-4-4-1 phi059 2.1  
ms*-HC8-4-4-1 bnlg1079 4.2  
ms*-HC8-4-4-1 mgs1 8.3 10
 
ms*-G39-4 bnlg619 10.4  
ms*-G39-4 phi236654 20 9L

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

 

After receiving the mapping data, we made testcrosses with all of the known recessive male-sterile genes that mapped to the same respective chromosome as these mutants, as well as crossing with the unmapped recessive male-sterile genes (ms27, ms31). The resultant progeny were grown in our 2001, 2002, or 2003 Johnston nursery. The male fertility phenotype of at least 40 plants was observed for most of the testcrosses. The results of reciprocal testcrosses of those mutants that showed allelism with known male steriles are shown below, along with their respective allele designations.

Female Male Progeny χ2(1:1) Allele Designation
ms*-6026 ms50 34 Fertiles:
27 Steriles		 0.80  
ms50 ms*-6026 23 Fertiles:
35 Steriles		 2.48 ms50-6026
 
ms*-6048 ms5 33 Fertiles:
32 Steriles		 0.02  
ms5 ms*-6048 44 Fertiles:
31 Steriles		 2.25 ms5-6048
 
ms*-6052 ms33 34 Fertiles:
35 Steriles		 0.01  
ms33 ms*-6052 46 Fertiles:
17 Steriles		 13.35  
ms*-6052 ms33-EA89A 20 Fertiles:
20 Steriles		 0.00  
ms33-EA89A ms*-6052 22 Fertiles:
21 Steriles		 0.02 ms33-6052
 
ms*-6054 ms38 18 Fertiles:
23 Steriles		 0.61  
ms38 ms*-6054 21 Fertiles:
21 Steriles		 0.00 ms38-6054
 
ms*-6057 ms25-YA85A 33 Fertiles:
39 Steriles		 0.50 ms25-6057
 
ms13 ms*-6060 23 Fertiles:
30 Steriles		 0.92 ms13-6060
 
ms*-6061 ms5 35 Fertiles:
28 Steriles		 0.78  
ms5 ms*-6061 23 Fertiles:
33 Steriles		 1.79 ms5-6061
 
ms*-6065 ms25-YA85A 33 Fertiles:
37 Steriles		 0.23  
ms25-YA85A ms*-6065 23 Fertiles:
25 Steriles		 0.08 ms25-6065
 
ms*-MG04 ms40 23 Fertiles:
24 Steriles		 0.02  
ms40 ms*-MG04 20 Fertiles:
22 Steriles		 0.10 ms40-MG04
 
ms*-MG07 ms7 30 Fertiles:
15 Steriles		 5.00  
ms7 ms*-MG07 18 Fertiles:
23 Steriles		 0.61 ms7-MG07
 
ms*-SB370 ms5 36 Fertiles:
39 Steriles		 0.12  
ms5 ms*-SB370 18 Fertiles:
27 Steriles		 1.80 ms5-SB370
 
ms*-DR87B ms23 67 Fertiles:
15 Steriles		 1.97+++  
ms23 ms*-DR87B 48 Fertiles:
44 Steriles		 0.17 ms23-DR87B
 
ms*-NP92 ms30 20 Fertiles:
25 Steriles		 0.56 ms30-NP92
 
ms*-PR92 ms8 32 Fertiles:
34 Steriles		 0.06  
ms8 ms8-PR92 32 Fertiles:
28 Steriles		 0.27 ms8-PR92
 
ms*-HC8-4-4-1 ms11 25 Fertiles:
20 Steriles		 0.56  
ms11 ms*-HC8-4-4-1 25 Fertiles:
19 Steriles		 0.82 ms11-HC8-4
 
ms*-G39-4 ms25-YA85A 5 Fertiles:
10 Steriles		 1.67  
ms25-YA85A ms*-G39-4 22 Fertiles:
20 Steriles		 0.10 ms25-G39-4

(All females homozygous for mutation unless noted otherwise; all males heterozygous for mutation)

+++Chi square value calculated for a 3:1 expected segregation ratio as female was heterozygous for the mutation in this testcross only.