The location of Wrk1

--Scott Poethig

Wrk1 is a dominant, EMS-induced mutation that causes the endosperm to become deeply furrowed. Given its severe effect on endosperm development, it is interesting that this mutation has little or no seedling phenotype. Wrk1 was mapped to the short arm of chromosome 3 by M.G. Neuffer. Three point testcrosses involving Wrk1, Lg3, and Cg1 or Tp1 (Tables 1 and 2) demonstrate that Wrk1 is located 2.8 ± 0.9cM distal to Lg3. A two-point testcross between Wrk

Table 1. Lg3 + Cg1/+ Wrk1 + x +++
 
a) Lg3 + Cg1 96
+ Wrk1 + 85
b) Lg3 + + 25
+ Wrk1 Cg1 23
c) Lg3 Wrk1 + 0
+ + Cg1 4
d) Lg3 Wrk1 Cg1 1
+ + + 0
Total Progeny: 234

% Recombination
Wrk1--Cg1: (b + d) = 20.9 ± 2.6 ~
Lg3--Wrk1: (c + d) = 2.1 ± 0.9 %
Lg3--Cg1: (b + c) = 22.2 ± 2.7 %

Table 2. Lg3 + Tp3/+ Wrk1 + x +++
 
a) Lg3 + Tp3 20
+ Wrk1 + 41
b) Lg3 + + 8
+ Wrk1 Tp3 14
c) Lg3 Wrk1 + 1
+ + Tp3 3
Total Progeny: 87

% Recombination
Wrk1--Tp3: (b) = 25.3 ± 4.7 %
Lg3--Wrk1: (c) = 4.6 ± 2.2 %
Lg3--Tp3: (b + c) = 29.9 ± 4.9%

and Cl1 indicated that these genes are 1.9 ± 0.5cM apart (12/632). Only the non-wrinkled seeds were used in calculating this latter recombination frequency because Cl could not be reliably scored in Wrk1 seeds. Since cl1 is 5cM distal to Lg3, these data suggest the following map order: Lg3--3--Wrk1--2--cl1.

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