Chloroplasts on the move
How different plants can share their genetic material with each other.
The genetic material is well protected in the nucleus of cells and stores all the information that forms an organism. For example, information about the size or flower color is predefined here. In addition, cells contain small organelles that contain their own genetic material, including chloroplasts and mitochondria. But is the genetic material actually permanently stored within one cell? No! As known, the genetic material can migrate from cell to cell and thus even be exchanged between different organisms. Researchers at the Max Planck Institute of Molecular Plant Physiology have now been able to use new experimental approaches to show for the first time how the genetic material travels.
The transfer of genetic material occurs quite frequently in plants. This can either result in a new combination of the genetic material, or alternatively the recipient cell can establish both genetic variants in parallel. This union of two different genomes, called allopolyploidization, is very interesting in evolutionary terms, as it leads to the formation of new plant species and is widespread in many plant groups. Many important crops, such as bread and durum wheat, oats, cotton, canola, coffee, and tobacco have such combined genomes from at least two crossed species.
In order to understand the mechanisms of genome transfer from cell to cell, the researchers led by Ralph Bock at MPI-MP conducted experiments with tobacco plants using grafting, which is commonly used in agriculture. Here, two different tobacco plants were grafted onto each other and the cells of the junction were observed microscopically in real time. To differentiate between the genome of nucleus and plastids, fluorescent reporter proteins were integrated and expressed from both genomes and the researchers used a trick using a specialization of the chloroplasts.
In the plastids, a gene is integrated by transformation that encodes a chloroplast-specific fluorescence protein, which is produced exclusively in plastids and cannot leave them. This creates an absolutely specific and stable label for the plastids.
After a short time, the two partners grow together at the graft junction, resulting in a physiological connection between the two plants. “We were able to observe that genome transfer from cell to cell occurs in both directions with high frequency at this site”, explains Dr. Alexander Hertle, first author of the study.
Using a new experimental setup, the researchers were able to observe structural changes in the cell walls in the wound tissue of the graft site. “The cell walls formed protrusions, creating junctions between the two partners. The size of those created pores allows the migration of an entire plastid. Therefore, the genome does not migrate freely, but encapsulated from cell to cell,” Hertle continues. However, to actually make this possible, the plastids have to shrink and become mobile. These rod-shaped plastids are equal to an amoeba and grow back to normal size after transfer into the target tissue.
The researchers have thus uncovered a new pathway for intercellular exchange of very large cell structures, which may also be used by parasitic plants, such as mistletoe, to carry out gene exchange with their host. In addition, it now needs to be clarified whether mitochondria and the nuclear genome also use similar transfer mechanisms.
Dr. Alexander P. Hertle
Max Planck Institute of Molecular Plant Physiology
Tel. 0331/567 8618
Dr. Ulrike Glaubitz
Press and public relations
Max Planck Institute of Molecular Plant Physiology
Tel. 0331/567 8275
Alexander P. Hertle, Benedikt Haberl, Ralph Bock
Horizontal genome transfer by cell-to-cell travel of whole organelles
Science Advances, 01.01.2021, doi: 10.1126/sciadv.abd8215
All news from this category: Life Sciences and Chemistry
Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.
Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.
Scientists show how to attack the ‘fortress’ surrounding pancreatic cancer tumors
UNSW medical researchers have found a way to starve pancreatic cancer cells and ‘disable’ the cells that block treatment from working effectively. Their findings in mice and human lab models…
Novel nanotech improves cystic fibrosis antibiotic by 100,000-fold
World-first nanotechnology developed by the University of South Australia could change the lives of thousands of people living with cystic fibrosis (CF) as groundbreaking research shows it can improve the…
New evidence for electron’s dual nature found in a quantum spin liquid
Results from a Princeton-led experiment support a controversial theory that the electron is composed of two particles. A new discovery led by Princeton University could upend our understanding of how…