Genetics of 6-PGD isozymes in corn

We are using two starch gel buffer systems (L-histidine, citric acid at pH 5.7 and pH 6.5) for the separation of 6-PGD isozyme bands. Genetic studies of the variants indicate that two loci are involved in the expression of the 6-PGD banding patterns. We have identified nine alleles at the Pgd1 locus and three alleles at the Pgd2 locus. Heterodimers are formed between allelic isozymes at each locus and between nonallelic isozymes for the two loci.

Analyses of data from F2 populations suggest that the two loci segregate independently:

 

 

Pgd1

Pgd2

A2/A2

A2/A3.8

A3.8/A3.8

Total

B2.8/B2.8

(2.4)a

1

[2.6]b

(5.6)

6

[5.1]

(2.0)

3

[2.6]

10

[10.3]

B2.8/B5

(4.6)

4

[5.1]

(10.7)

13

[10.3]

(3.7)

2

[5.1]

19

[20.5]

B5/B5

(2.9)

5

[2.6]

(6.7)

4

[5.1]

(2.3)

3

[2.6]

12

[10.3]

Total

 

10

[10.3]

 

23

[20.5]

 

8

[10.3]

41

 

c24 (independence) = 5.589 0.10 < P < 0.25

c 28 (4:2:2:2:2:1:1:1:1) = 6.707 0.50 < P < 0.75

aExpected values, based upon independence, shown in parentheses.

bExpected values, based upon 4:2:2:2:2:1:1:1:1 segregation, shown in brackets.

Using linkage and trisomic analyses, Pgd1 has been located on chromosome 6 about five map units from the Ep locus. Pgd2 has not yet been assigned to a specific chromosome.

C. W. Stuber and M. M. Goodman

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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