The results of a three-point linkage test for lg2, gl2, and et2 on chromosome 2 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, the resulting plants self-pollinated, and kernel samples from each self-pollinated ear planted in the sand bench. Seedlings grown from these kernels were scored for lg1, gl2, and the albino seedling phenotype conditioned by et2, which is more reliable to score than kernel etching. The following linkage relationship was established: lg1 - 15.4 - gl2 - 19.8 - et2. The lg1 gl2 distance of 15.4 cm is shorter than the value of 22 cM from the current genetic map (possibly due to undetected double crossovers in this interval), but the order of the three genes is clear, and gl2 - et2 distance of 19.8 cm places et2 in the vicinity of b1 on chromosome 2.

Table 1. Three-point linkage data for lg1 - gl2 - et2.
Testcross: Lg1 Gl2 Et2 X (lg1 gl2 Et2 / Lg1 Gl2 et2).
 

Reg.	Phenotype	No.	Totals
0	lg1 gl2 +	105
	+ + et2	86	191
1	lg1 + et2	24
	+ gl2 +	20	44
2	lg1 gl2 et2	27
	+ + +	30	57
1+2	lg1 + +	1
	+ gl2 et2	0	1

% recombination lg1--gl2 = 15.4 ± 2.1 % recombination gl2--et2 = 19.8 ± 2.3
% recombination lg1--et2 = 35.2 ± 2.8

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