A transposable element in diverse corn lines, Ubiquitous (Uq): allelism test

Since the discovery of the Uq transposable element system in the early 1980s, studies of Uq distribution have shown that Uq is pervasive in genetic stocks and corn populations including BSSS, the Illinois oil and protein lines, 'Lancaster', 'Jarvis' and several others. The assumption made was that Uq might have provided the variation that has contributed to maize breeding progress. Of the several inbreds tested in previous studies, only IaI159, one of the contributors to BSSS, contained an active Uq. The main question posed in our experiments was that of chromosomal location(s), or allelic relationships, of active Uq elements in diverse corn populations. Results showed that these Uq elements are allelic, linked or independent, though most found from corn populations show quite distant or independent linkage relationships with each other. The lack of a linear linkage map among these Uq elements may be interpreted to have resulted from transposition events and this might have led to the differentiated instability of an individual Uq element that was found to be variable. Other questions also discussed relate to the origin of Uq elements in corn populations and their role(s) in plant breeding.