How plants can produce species without sex

Plants can transfer their entire genetic material to a partner in an asexual manner, research reveals.

German scientists at the Max Planck Institute of Molecular Plant Physiology have shown for the first time that new species can be generated in an asexual manner as well.

It was generally believed that a combination of desired traits can be obtained by grafting, but there is no exchange or recombination of genetic material - so-called horizontal gene transfer - between the grafted plants.

"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," said lead researcher Ralph Bock.

Now we wanted to investigate if there is a transfer of genetic information between the nuclei as well, Bock added.

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, 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.

The scientists succeeded in growing up numerous doubly resistant plantlets.

"We managed to produce allopolyploid plants (having two or more complete sets of chromosomes derived from different species) without sexual reproduction", said Sandra Stegemann, joint first author of the study.

When the scientists grew their new plants in the greenhouse, it became obvious that they combined characteristics of both progenitor species.

Also, the new plants grew remarkably faster than their parents.

"Grafting two species and selecting for horizontal genome transfer could become an interesting method for breeders who could use this approach to create new crop plants with higher yields and improved properties," researchers concluded.