"In our previous work we were able to prove that, contrary to the generally accepted dogma, there is horizontal gene transfer of chloroplast genes at the contact zone between grafted plants. Now we wanted to investigate if there is a transfer of genetic information between the nuclei as well" Ralph Bock says while explaining the recent study.
The researchers introduced resistance genes against two different antibiotics into nuclear genomes of the tobacco species Nicotiana tabacum and Nicotiana glauca, which usually cannot be crossed. Afterwards, Nicotiana glauca was grafted onto Nicotiana tabacum or the other way round. After fusion had occurred, the scientists excised tissue at the contact zone and cultivated it on a growth medium containing both antibiotics, so that only cells containing both resistance genes and thus, DNA from both species, should survive. Surprisingly, the scientists succeeded in growing up numerous doubly resistant plantlets.
To determine if the acquired double resistance is due to the transfer of single genes or the transfer of the entire genetic material, the researchers counted the chromosomes in the nuclei of the resistant plants. If complete genomes were transferred, the new plants would contain the sum of the chromosome numbers of the two species. "Indeed, we found 72 chromosomes in the resistant plants", Ralph Bock explains, "72 is the sum of the 24 N. glauca chromosomes and the 48 N. tabacum chromosomes." Thus, plantlets generated from the graft junction contained the genetic information of both species. "We managed to produce allopolyploid plants without sexual reproduction", Sandra Stegemann, joint first author of the study, is pleased to say.
When the scientists grew their new plants in the greenhouse, it became obvious that they combined characteristics of both progenitor species. But there was one striking
|Contact: Dr. Ralph Bock|