We report the results of a four-point linkage test for ae pr lw2 gl8 (Table 1). The linkage test was set up as a modified backcross as indicated in Table 1. Kernels from the backcross ear were planted in the field, the resulting plants selfed, and the selfed ears scored for ae, pr, and lw2. Approximately 50 kernels from each selfed ear were grown to seedling stage in a sandbench, and the seedlings were scored for lw2 and gl8. The following linkage relationships were established (distances presented in centimorgans): ae-7.4-pr-0.64-lw2-0.32-gl8. These data are consistent with the reported linkage relationships between ae, pr, and gl8 (ae-10-pr-1-gl8), and would place lw2 between pr and gl8. However, it should be noted that the standard errors for the map distances in the pr-lw2-gl8 interval are large compared to the distances themselves. Also, no double crossovers were observed. Therefore, the placement of lw2 between pr and gl8 must be viewed as tentative until more data are collected. For now, the suggested map revision is:

Table 1. Four-point linkage data for ae pr lw2 gl8.

Testcross: Ae Ae Pr Pr Lw2 Lw2 Gl8 Gl8 x (ae pr Lw2 gl8/Ae Pr lw2 Gl8)
 

Reg.	Phenotype	No.	Totals
0	ae pr + gl8	144
	+ + lw2 +	142	286
1	ae + lw2 +	11
	+ pr + gl8	12	23
2	ae pr lw2 +	2
	+ + + gl8	0	2
3	ae pr + +	1
	+ + lw2 gl8	0	1

no multiple crossovers observed
% recombination ae--pr=7.4±1.5
% recombination pr--lw2=0.64±0.45
% recombination lw2--gl8=0.32±0.32