Preliminary two-point linkage data for inr1 and du1 on 10L --Stinard, P Inr1 is a dominant R1 allele-specific aleurone color inhibitor that can be scored as pale or colorless aleurone in the presence of certain susceptible R1 (R1-S) alleles. The recessive inr1 allele provides full purple aleurone color in the presence of R1-S. Previous data (Stinard, P. 1999. MNL 73:89-90) had shown that inr1 is located on the long arm of chromosome 10, distal to the TB-10L19 breakpoint (10L.00), but proximal to g1. In order to further refine the map location of inr1, a three-point linkage test involving the 10L markers inr1, du1, and g1 was set up as indicated in Table 1. All stocks used in the crosses were homozygous for wx1 in order to enhance the expression of du1. Kernels from these crosses will be planted at a later date and the resulting plants scored for g1 in order to provide three-point linkage data. Preliminary two-point data involving only inr1 and du1 are presented in Table 1. These data indicate that inr1 and du1 are very tightly linked, with only an approximately 0.2 centimorgan distance between them. These data cannot be used to determine the global order of inr1 and du1 on chromosome 10. That determination will have to be made after the g1 data are collected.

Table 1. Two-point linkage data for inr1 and du1.
Testcross: (Du1 Inr1 G1 R1-S wx1 X du1 inr1 g1 R1-S wx1) X du1 inr1 g1 R1-S wx1.
Reg. Phenotype No. Totals
0 Inr1 Du1 4354  
  inr1 du1 4410 8764
1 Inr1 du1  7  
  inr1 Du1 8 15
% recombination inr1--du1 = 0.17 +/- 0.04

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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