Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: TRACKING DOWN ANCIENT PLANT TRANSPOSONS: ELUCIDATION OF MOBILE
ELEMENT INVOLVEMENT IN GENOME EVOLUTION
TRACKING DOWN ANCIENT PLANT TRANSPOSONS: ELUCIDATION OF MOBILE
ELEMENT INVOLVEMENT IN GENOME EVOLUTION.
Thomas E. Bureau, Shawn E. White and Susan R. Wessler, Department
of Botany/Genetics, University of Georgia, Athens, GA 30602
(email: BLTREAUT@BSCR.UGA.EDU).
Transposable elements are believed to be primary players in
the evolution of genes and genomes. Despite the numerous reports
of mutations caused by transposable element insertions, almost
nothing is known of their direct involvement in the evolution of
normal wild-type genes. We have found that computer-based
sequence similarity searches offer a powerful tool by which new
transposable elements can be identified and in some cases provide
compelling evidence as to their role in normal gene evolution.
This is illustrated by the following summary of our findings. (i)
Over 100 mono- and dicotyledonous normal plant gene sequences
listed in the GenBank and EMBL databases harbor a member of
either the Tourist or Stowaway family of transposons. The
location of several elements correspond to previously identified
cis-acting regulatory domains. The most striking find, however,
is a Tourist element that supplies the promoter of the maize
auxin-binding protein gene (abp1). (ii) copia-like
retrotransposons flank twenty-three normal plant genes and in
some cases also correspond to putative cis-acting regulatory
domains. (iii) During a search for transposable elements in
previously-sequenced normal genes, we found that the first
reported plant retrotransposon, Bs1, contains a cellular gene
fragment. This is the first indication of transduction by a
retrotransposon and provides an important missing link in the
evolution of retroviruses.
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