Horizontal Gene Transfer in Ferns May Have Allowed Them To Elude Extinction

This article discusses a genetic discovery in ferns that may be the reason they still exist. During the age of the dinosaurs, when trees and flowering plants began to evolve, the new plants were flourishing because of their ability to reproduce using micro and mega spores instead of having a true gametophyte generation. Angiosperms were able to reproduce very quickly and in a widespread manner, which can be a death sentence for plants that can't keep up and may become blocked from the sunlight. Scientists at Duke University have discovered a gene that appeared in ancient ferns called neochrome. Neochrome is unique because while most plants sense and move towards blue light, plants with this gene can sense both blue and red light. This was beneficial to the ferns because when trees form a canopy, the light that filters through the leaves to reach the lower plants is mostly red, not blue. This gene allowed the ferns to detect the light they needed to survive and move towards it.

The truly interesting thing about this gene, however, is where it came from. Instead of evolving it on their own, scientists have discovered that the ferns were able to "borrow" the gene from a group of bryophytes called hornworts. Because ferns and hornworts diverged in evolution 400 million years ago, there would be more plants with the neochrome gene if it had been passed on from a common ancestor. As this is not the case, it has been concluded that the gene was given to the ferns through horizontal gene transfer. The idea of horizontal gene transfer in macro organisms is relatively new-it mostly applies to bacteria, and is how many resistances to antibiotics are formed. This particular transfer most likely took place between the hornworts and the gametophyte generation of the ferns-the gametophyte generation is low the the ground, like bryophytes, and doesn't have any sort of protective cuticle on it. The gametophyte is where the sex organs of the fern are housed, so that is where genetic information was most likely exchanged. This discovery is very new, and there is still much research to be done on it. Hopefully there will be more information available in the near future.

Secondary article: http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/genetic-exchange/exchange/exchange.html