Molecular changes of organelle DNA sequences in rice through dedifferentiation, long-term culture, or the morphogenesis process.

Callus-specific rearranged DNA in rice (Oryza sativa L.) was isolated by in-gel reassociation procedure. Southern hybridization experiments revealed that some clones were amplified significantly in primary callus induced from scutellum tissue. Rapid amplification of these clones was observed within 2 days after plating seeds onto callus-induction medium containing 2,4-D. NAA gave no significant effect on DNA amplification event. Colony formation process from isolated protoplasts and plant regeneration process from callus showed clone-specific and process-specific fluctuation patterns of copy number. Sequence analysis of the clones suggested that most of the clones were originated from organelle DNA. Comparison of copy number fluctuation pattern of organelle functional genes with that of the clones suggested multiformity and/or construction-specific amplification of organelle DNA.