Mapping of glutamic dehydrogenase (Gdh) on chromosome 1, 20.1 recombination units distal to Adh1

The waxy marked reciprocal translocation stocks were used to determine the location of Gdh in the distal region of the long arm of chromosome 1. Linkage with waxy was observed with wx T1-9(8389) (1L.74; 9L.13) but not with any other of the translocation stocks tested (Table 1), including wx T1-9(4995) (1L.19; 9S.20),

Table 1. Segregation of wx and Gdh in crosses with reciprocal translocations involving chromosome 9 (T wx Gdh-N/Wx Gdh-T x wx Gdh-N/wx Gdh-N).
 
Translocation Wx Gdh-T Wx Gdh-N wx Gdh-T wx Gdh-N  Total
1-9c 11 9 10 10 40
1-9(4995) 10 10 10 10 40
1-9(8389)* 16 4 4 16 40
2-9b 13 7 14 6 40
3-9c 7 13 10 10 40
4-9b 10 10 14 6 40

*Observed segregation deviates significantly from the expected 1:1:1:1.

Table 2. Segregation of waxy translocation 1-9(4995), Adh and Gdh (T wx Adh-S Gdh-N/Wx Adh-F Gdh-T x wx Adh-F Gdh-N/wx Adh-F Gdh-N)
 
  Adh-F Gdh-T Adh-F Gdh-N Adh-S Gdh-T Adh-S Gdh-N Total
Wx 53 10 8 31 102
wx 41 8 17 46 112
Total 94 18 25 77 214

c2 [1] L (Adh-Gdh) = 148.8; p <<0.001;
Recombination Wx Adh = 41 ± 3.3%, Adh Gdh = 20.1 ± 2.7%

which has the break point in the proximal region of 1L. This location was confirmed by the demonstration of 20.1% recombination between Gdh and the Adh1 locus (Table 2), which is known to be between 0.80 and 0.90 on 1L (Birchler MNL 52:27-31). This cross also involved the wx T1-9(4995) translocation which as mentioned previously showed no linkage with Gdh, but did show a low but significant linkage of waxy with Adh. This indicates that the Gdh locus is about 20.1 recombination units distal to the Adh1 locus on 1L.

A. J. Pryor


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

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