Sharing is Caring: Plant Cells Exchange Organelles
Written by Kacey Zimmerman
Edited by Emily Moran
May 2, 2021
Edited by Emily Moran
May 2, 2021
All organisms participate in the exchange of genetic information, which is fundamental to maintaining diversity within species. Generally, this exchange takes place in a vertical transfer, from parents to offspring. However, horizontal transfers-- from one organism to another through a process separate from reproduction-- are extremely important too. In some organisms, like bacteria, the genetic material transferred is small collections of DNA. In plants, however, it was shown that entire organelles can be passed from one organism to another.
Horizontal gene transfer has been a known phenomenon in plants, but it wasn’t until recently that researchers discovered the exact mechanism. In 2009, a study at the Max Planck Institute of Molecular Plant Physiology showed that entire genomes could be transferred between grafted tobacco plants. Grafting is an agricultural technique that joins the tissues of two separate plants so that they will grow together. This study hypothesized that organelles were shared between the grafted plants, but researchers could not prove that it wasn’t simply large amounts of naked DNA.
In this recent study at the same institute, researchers were able to conclude that organelles were actually transferred between plants. Two separate tobacco plants were grafted together for this experiment. The first plant had an antibiotic resistance gene and fluorescent tag in the nucleus, and the second plant had a different antibiotic resistance gene and fluorescent tag in the chloroplast. This resulted in grafted plants that contained both fluorescent tags and were able to grow on media with both antibiotics. This proved the exchange of genetic information, but researchers still had to prove that such information was shared through organelles. To do this, they extracted cells from the grafted area then fixed and imaged them. These cells contained organelles that seemed to aggregate where the wall of one cell extended into another and were hypothetically small enough to have traveled through pores in the cell wall. Finally, researchers imaged live cells from the grafted area where they witnessed organelles physically move from one cell to another. While naked DNA could be transferred through this process as well, this experiment proved that organelles definitely play a role.
Horizontal gene transfer is extremely important because it allows for the transfer of advantageous traits within genomes and promotes diversity through the blending of different organisms. Researchers mentioned that this mechanism could play a role between plant-plant parasitism, and finding evidence of this organelle transfer in nature could prove to be an insightful future direction of this study.
References
1. Olena, A. (2021). Plant Cells Swap Organelles. The Scientist. https://www.the-scientist.com/news-opinion/plant-cells-swap-organelles-68326
2. Stegemann, S. & Bock, R. (2009). Exchange of Genetic Material Between Cells in Plant Tissue Grafts. Science. https://science.sciencemag.org/content/324/5927/649
3. Bilderback, T., Bir, R. E., & Ranney, T. G. (2014). Grafting and Budding Nursery Crop Plants. NC State Extension. https://content.ces.ncsu.edu/grafting-and-budding-nursery-crop-plants
4. Hertle, A., Haberl, B., & Bock, R. (2021). Horizontal genome transfer by cell-to-cell travel of whole organelles. Science Advances. https://advances.sciencemag.org/content/7/1/eabd8215