Three-point linkage data for su1 bm3 gl7 on 4S
--Stinard, P

The results of a three-point linkage test for su1, bm3, and gl7 on chromosome 4 are presented in Table 1. The linkage test was set up as a modified backcross as indicated in Table 1. Kernels from the backcross ears were planted in the field and the resulting plants were scored for bm3. The plants were self-pollinated, and the self-pollinated ears were scored for the presence of su1. Kernel samples from each self-pollinated ear were planted in the sand bench, and seedlings grown from these kernels were scored for gl7 and v17. (Although v17 was included in this linkage test, the data for v17 linkage were not tabulated since no crossovers were observed between gl7 and v17. We conclude that v17 is tightly linked to gl7, and the population size used in this study was not large enough to detect crossovers.) The following linkage relationship was established: su1 - 4.7 - bm3 - 2.9 - gl7. Last year, we reported that gl7 and v17 are uncovered by TB-4Sa (MNL 71:83). Beckett reported in 1975 that bm3 is not uncovered by TB-4Sa (MNL 49:132). Coe recently reported in the Maize Database (ID#: 108126) that Beckett's data is ambiguous and that no determination can be made from the data whether bm3 is uncovered by TB-4Sa. Since our data place bm3 between su1 and gl7, we predict that bm3 will be uncovered by TB-4Sa. This test is in progress.

Table 1. Three-point linkage data for su1 - bm3 - gl7. Testcross: Su1 bm3 Gl7 X (su1 bm3 gl7 / Su1 Bm3 Gl7).
 

Reg.	Phenotype	No.	Totals
0	su1 bm3 gl7	198
	+ + +	218	416
1	su1 + +	12
	+ bm3 gl7	6	18
2	su1 bm3 +	5
	+ + gl7	5	10
1+2	su1 + gl7	1
	+ bm3 +	2	3

% recombination su1--bm3 = 4.7 +/- 1.0
% recombination bm3--gl7 = 2.9 +/- 0.8
% recombination su1--gl7 = 7.6 +/- 1.3

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