Genetic analysis of trasgenic tobacco plants obtained by liposome-mediated transformation: absence of evidence for the mutagenic effect of inserted sequences in sixty characterized transformants
Résumé
Tobacco mesophyll protoplasts were transfected with a plasmid—pLGV23 neo—carrying a kanamycin resistance gene expressed in plant tissues. We performed transfections by fusing protoplasts with liposomes in which the plasmid had been encapsulated. One hundred independent clones selected for their resistance to kanamycin were regenerated and characterized. When tested for their level of resistance at the protoplast level, clones expressed a wide range of resistance to aminoglycosides. The level of resistance to paromomycin was not correlated with the number of copies of the inserted plasmid sequences. Resistance to kanamycin segregated in a Mendelian manner as a monogenic, dominant nuclear marker for 50% of the tested plants. We observed various new phenotypes among the regenerated plants or in their progeny but found no evidence for the mutagenic effect of inserted sequences. The new phenotypes we observed were therefore due to somacional variation. The kanamycin resistance marker was found to be linked to another genetic marker, Val′, in one of the transtormants, Ka110. Several transformants did not transmit the kanamycin resistance marker in a stable manner. Clone Ka120 transmitted kanamycin resistance normally when used as a female parent but transmitted the resistance at a very low frequency (2% instead of 50%) when used as a pollen donor.
