Multiple changes in tobacco mitochondrial DNA populations during tissue culture

Changes in the composition of mitochondrial DNA (mtDNA) in tobacco during the processes of long-term tissue culture and regeneration were detected by DNA gel blot analyses using several mtDNA fragments as probes. The changes in mtDNA were identified by differential accumulations of mtDNA fragments in cultured cells that were hybridized with probes atp6, cob, and nad3-rps12. The changes detected by each probe did not appear to be linked, since they were different with each probe and in different subcultures of calli. Based on the current results and previous detailed analyses of the changes detected by atp6, a possible model that explains the alterations in mtDNA during tissue culture is presented. In this model, the changes are attributed to multiple shifts in the equilibrium that was maintained between different subgenomic mtDNA molecules.