Uq transposable elements in maize breeding populations

--Thomas Horejsi, Elizabeth E.O. Caldwell, and Peter A. Peterson

Active Uq transposable elements have been found in numerous maize breeding populations (Cormack, Crop Sci. 28:941-944). This observation could be explained in two ways. First, one could argue that the Uq elements are inadvertently grouped into the populations because they are linked to favorable alleles. If this is the case, one would expect the Uq elements to be limited to a few linkage groups. A second probable explanation is that they are specifically incorporated into the populations because they provide a useful function to the maize breeder. This would predict widely dispersed elements.

To address this problem, a diallel cross between 13 breeding populations was used to construct stocks that contained a Uq element from two different breeding populations. These stocks were crossed to a c-ruq tester as follows:

c-rcq/c-ruq Uq(pop. #1)/+ Uq(pop. #2)/+ X c-ruq/c-ruq

The results indicate that there is independent segregation in all but two cases. In these two cases there is only a weak linkage of about 40 centimorgans in one and about 30 centimorgans in the other.

The disperse nature of the Uq elements adds support to the argument that they are specifically selected and must be advantageous in maize breeding populations.

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