Does Alternative Transposition, a Potential Genome-restructuring Activity, Occur in Petunia?

Abstract

<p>Transposable Elements (TEs) are segments of DNA that can move throughout the genome. TEs are present in most species and can cause insertions and deletions in the genetic sequence. TEs encode a transposase enzyme which excises the TE and inserts it elsewhere. This is considered standard transposition. Alternative Transposition occurs when transposase acts on the termini of two different TEs. This action can result in major chromosomal rearrangements or chromosomal breakage. Alternative Transposition has been observed previously with maize Ac/Ds elements; here, we are asking whether it also occurs in Petunia hybrida. Petunias have dTph1 TEs which are small, non-autonomous transposons. The S857 allele contains two copies of dTph1 located approximately 30 bp apart and facing in opposite orientations. PCR (Polymerase Chain Reaction) will be used to identify petunias with both elements, and PCR experiments with primers facing in the same direction will be used to test for Alternative Transposition. A product should be generated only if Alternative Transposition has occurred and the primers are re-oriented to face one another. The results may provide evidence that Alternative Transposition can occur in multiple species, suggesting that it may have had a significant impact on the evolution of plant genomes.</p>