Diverse chromosomal rearrangements induced by Ac/Ds at the OsRLG5 locus in regenerated rice plants

Abstract

Closely-located transposable elements (TEs) can induce chromosomal breakage and rearrangements via alternative transposition (AT) reactions. Our previous study showed that diverse chromosomal rearrangements were induced by two inversely-oriented Ds elements at the OsRLG5 (Oryza sativa receptor-like kinase gene 5) locus in regenerated rice plants. Here, several novel chromosomal rearrangements were identified in a population of tissue culture regenerants, and their proposed Ac/Ds-transposition mechanisms were discussed. In the first type of event, AT was induced by the same Ds element on each of two sister chromatids and resulted in the inversion of genomic DNA flanking the Ds element. In the second type of event, DNA segments of the inter-transposon segment (ITS) region were deleted or inverted. This novel local rearrangement likely resulted from an AT reaction of two directly-oriented Ds elements located on the same chromatid. The 5' and 3' termini of two Ds elements were re-inserted into two different sites inside the ITS, which generated the subsequent deletion and inversion. In the third type of event, two inversely-oriented Ds elements induced homologous recombination and chromosomal translocation. Together, these results showed the diversity of Ac/Ds-mediated chromosomal rearrangements and demonstrated the utility of the experimental system for examining the mechanisms underlying Ac/Ds AT reactions.