Three-point linkage data for su1, lw4, and gl4 on chromosome 4
--Philip S. Stinard

Table 1. Three-point linkage data for su1 - lw4 - gl4. Testcross: Su1 Lw4 Gl4 lw3 X (su1 Lw4 gl4 Lw3 / Su1 lw4 Gl4 Lw3).
 

Reg.	Phenotype	No.	Totals
0	su1 + gl4	68
	+ lw4 +	72	140
1	su1 lw4 +	9
	+ + gl4	10	19
2	su1 + +	4
	+ lw4 gl4	7	11
1+2	su1 lw4 gl4	0
	+ + +	1	1

% recombination su1--lw4 = 11.7 +/- 2.5
% recombination lw4--gl4 = 7.0 +/- 2.0
% recombination su1--gl4 = 18.7 +/- 2.5

The results of a three-point linkage test for su1, lw4, and gl4 on chromosome 4 are reported in Table 1. The linkage test was set up as a modified backcross as indicated in Table 1. Since lw3 and lw4 are a duplicate factor pair, the backcross to lw3 was necessary in order to score for lemon-white in the next generation. Kernels from the backcross ears were planted in the field, the resulting plants self-pollinated, and the ears scored for su1 and lw4. Kernel samples from each ear were planted in the sand bench, and the resulting seedlings were scored for lw4 (for confirmation of kernel phenotype) and gl4. The following linkage relationship was established: su1 - 11.7 - lw4 - 7.0 - gl4. The distance between su1 and gl4 (18.7 cM) is greater than that reported on the 1993 linkage map (15 cM), but is within the standard error of that reported in a previous linkage study of su1, lw4, and gl4 (MNL 65:17-18, 1991; 21.0 cM). When the data from this study are combined with the previous data (MNL 65:17-18, 1991), one obtains the following linkage relationship:

% recombination su1--lw4 = 11.3 +/- 2.0
% recombination lw4--gl4 = 8.2 +/- 1.7
% recombination su1--gl4 = 19.9 +/- 2.5

The data were scaled to fit the current linkage map; the suggested map revision is:

--su1--------------lw4---------gl4--
   47                       56               62 

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