Three point linkage data for wx1 inr2 v30

--Stinard, PS

Dominant mutant alleles at the inr2 locus suppress aleurone color in crosses to specific r1 haplotypes (Stinard and Sachs, J Hered 93:421–428, 2002). Previous work (Stinard, MNL 77:76–66, 2003) places inr2 on the long arm of chromosome 9, approximately 23 cM from wx1. In order to refine this placement, we conducted a three point linkage test of wx1, inr2, and v30, the latter locus being on the long arm of chromosome 9 in the vicinity of where inr2 would be expected to map. The linkage testcross and results are indicated in Table 1. All lines are homozygous for the suppressible haplotype R1-Randolph to allow scoring for inr2. Kernels were scored for wx1 and inr2 on the test cross ears at maturity, and these kernels were subsequently planted in a cold sand bench and the resulting seedlings were scored for v30.

This linkage test establishes the global gene order as wx1 inr2 v30. The wx1-inr2 distance (22.3 ± 0.8 cM) agrees closely with those obtained previously (22.6 ± 0.9 cM and 22.9 ± 1.2 cM). The wx1-v30 distance (32.0 ± 0.9 cM) agrees with that indicated on the 1993 genetic map of chromosome 9 (31 cM; Neuffer et al., Mutants of Maize, Cold Spring Harbor Laboratory Press, 1997). inr2 maps about 9.7 cM proximally to v30, in the vicinity of bk2.

Testcross: [Wx1 Inr2-JD V30 R1-Randolph × wx1 inr2 v30 R1-Randolph] × wx1 inr2 v30 R1-Randolph.

Map distance wx1–inr2 = 22.3 ± 0.8 cM
Map distance inr2–v30 = 9.7 ± 0.6 cM
Map distance wx1–v30 = 32.0 ± 0.9 cM