*3.4. Rearrangement*

A considerable number of NUPTs/NUMTs are arranged in tandem arrays of sequences originating from various regions of the plastid or/and mitochondrion genome (s); this phenomenon suggests that the transfer of organellar sequences undergo rearrangement before and/or after their insertion into the nuclear genome. In rice, the fragmentation and reshuffling events could occur immediately after plastid DNAs are integrated into the nuclear genome [36]. A detailed analysis of the *A. thaliana* 620-kb large NUMT shows that at least four rearrangement events have occurred, among which, three were localized at the initial 76 kb of the insertion [36]. These rearrangements may have occurred after integration, but they can also occur before transfer in the organelle via homologous recombination between repetitive sequences [71] or in the nucleus either before or during integration [11,39,72,73].
