Transposon Ac/Ds -induced chromosomal rearrangements at the rice OsRLG5 locus

Abstract

<p>Previous studies have shown that pairs of closely-linked <em>Ac/Ds</em> transposable elements can induce various chromosomal rearrangements in plant genomes. To study chromosomal rearrangements in rice, we isolated a line ( <em>OsRLG5-161)</em> that contains two inversely-oriented <em>Ds</em> insertions in <em>OsRLG5</em> ( <em>Oryza sativa</em> Receptor like kinase Gene 5). Among approximately 300 plants regenerated from <em>OsRLG5-161</em> heterozygous seeds, 107 contained rearrangements including deletions, duplications and inversions of various sizes. Most rearrangements were induced by previously identified alternative transposition mechanism. Furthermore, we also detected a new class of rearrangements that contain juxtaposed inversions and deletions on the same chromosome. We propose that these novel alleles were generated by a previously unreported type of alternative transposition reactions involving the 5′ and 3′ termini of two inversely-oriented <em>Ds</em> elements located on the same chromatid. Finally, 11% of rearrangements contained inversions resulting from homologous recombination between the two inverted <em>Ds</em> elements in <em>OsRLG5-161</em> . The high frequency inheritance and great variety of rearrangements obtained suggests that the rice regeneration system results in a burst of transposition activity and a relaxation of the controls which normally limit the transposition competence of individual <em>Ds</em> termini. Together, these results demonstrate a greatly enlarged potential of the <em>Ac/Ds</em> system for plant chromosome engineering.</p>