Crossingover frequencies between several translocations and four En-containing alleles

--Ruying Chang and Peter A. Peterson

In an effort to relocate highly transposing En-containing alleles to certain chromosome regions, crosses were made between several translocation stocks (shown in Table 1) and four En-containing alleles. These mutable alleles include the a1-m(papu), c2-m, a2-m and wx-m alleles. The F1 progenies from those crosses were testcrossed with the corresponding recessive alleles. Spotted kernels from semi-sterile ears of the testcross progenies were planted in order to obtain crossovers. This was tested by examining pollen fertility. Semi-sterility in pollen of those En-containing plants is an indication of a crossover between the specific allele and the breakpoint on the specific arm being labeled.

Specific mutable alleles are being linked to one of the seven translocation stocks. A description of the translocations, the mutable alleles, the crossover percentage, as well as the recorded map distance is given in Table 1.

Table 1. Translocation and crossingover data

The ratio of pollen-sterile plants vs. total plants gives the crossover percentage. As shown in Table 1, the cross between T6-9(5454) and wx-m allele is consistent with the map distance recorded (c2 = 1.56). Crosses T2-5(032-9) x a2-m and T4-5e x a2-m were also in agreement with the map distances if we consider the map distance for both as 15 (c2 = 2.24 and 0.49, respectively). The other four were highly discrepant from the published map distances. Three of the four had higher values than that expected [T1-3(5597) x a1-m(papu), c2 = 16.82; T1-4(8602) x c2-m, c2 = 132.07; T4-6(033-16) x c2-m, c2 = 30.75)]. The other one had a lower value than that expected [T2-3d x a1-m(papu), c2 = 14.04]


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