Walking through a forest on a breezy September day, the very air seems to crackle with colour and life. The irony is, of course, that as you walk through trees with golden, crimson leaves, the vast majority of the plant material surrounding you is, in fact, dead. Plants have a complex way of regulating the life and death of their cells that remains a mystery to this day. Researchers at VIB-UGent have however just uncovered a few key pieces in the puzzle of programmed plant cell death. Their research may enable the development of environmentally friendly weed killers by manipulating weeds into killing their own cells.
When looking at a tree, the majority of the material we are seeing is nothing but dead wood. Although there are live cells in the leaves, roots and shoots of a tree or plant, the majority of the biomass is made up of persisting cell corpses, serving a structural function. In order to generate these corpses, which form everything we consider ‘wood’ in a plant, plant cells undergo a carefully controlled process of cell death.
We strive to understand the complex network of proteins that is necessary to execute cell death in plants. This knowledge might generate new leads on how to control cell death in weeds and crop plants. - Moritz Nowack, VIB-UGent.
Plant growth and development, and the cell death process needed for it to function, is important to humans around the world. If we understand the underlying mechanisms dictating how plants kill off their own cells, we can use that process to improve global agricultural practices, by killing weeds in an environmentally-friendly manner or even making crops more robust. The lab of Prof. Moritz Nowack (VIB-UGent Center for Plant Systems Biology) is investigating the regulation of these plant cell death processes in the model plant Arabidopsis. Dr. Huysmans, first author of their recent study explains:
“To study plant cell death, we are using the plant’s root cap as a model system. The root cap is situated at the tip of the growing root, guiding and protecting the delicate root tip as it pushes through the soil. Individual root cap cells are constantly regenerated and have a short life span that ends in programmed cell death.”
To understand how plant cell death works, the researchers in Nowack’s lab decided to study the genes that govern the process. In this project, they focused on transcription factors that regulate gene expression, as carefully regulated protein production is vital in ensuring orderly execution of cell death. Huysmans elaborates:
“To identify regulators of cell death, we compared which transcription factors are produced both in wood cells and in root cap cells. As both cell types undergo programmed cell death, we hoped to identify important regulators of this process. We found a number of common transcription factors and analyzed two of them, ANAC087 and ANAC046, in detail.”
Inducing naturally occurring cell death in weeds would be an environment-friendly way for weed control. - Moritz Nowack, VIB-UGent.
The researchers found that mutant plants where the transcription factors were produced outside of the root cap suffered from serious issues. In these abnormal plants, many cells died within 24 hours, and the plants suffered growth arrest and even seedling death. Conversely, other mutants that weren’t able to produce ANAC087 or ANAC046 at all presented with root cap cells that survived even longer than the cells of standard Arabidopsis specimens. Nowack commented on the findings:
“These results show that both transcription factors are important regulators of programmed cell death in Arabidopsis. Surprisingly, our results also revealed that root cap cells that are detached from the roots have a genetically determined life span.”
Read this previous BioVox article for more information on trends in agri-biotech.
War on weeds
Now that they have identified the transcription factors controlling the cell death program in plants, Nowack and his team can get into the nitty-gritty details of the process. The next step for the team is identifying the proteins that do the actual killing job. To do this, the genes targeted by ANAC087 and ANAC046 need to be analyzed. Only once this is done will the full potential of manipulating the process become clear. Nowack concludes:
“Ultimately, we strive to understand the complex network of proteins that is necessary to execute cell death in plants. This knowledge might generate new leads on how to control cell death in weeds and crop plants. Inducing naturally occurring cell death in weeds would be an environment-friendly way for weed control, while optimizing cell death processes in crop plants could contribute to stabilization of plant yield under adverse environmental conditions."
Eco-friendly weed control? Crops resistant to climate change? Foundational research, such as the work being done by Nowack’s team, is key when it comes to solving global agricultural challenges. As these scientists continue to improve our understanding of biology, we hope that their findings will translate into effective solutions to weeds woldwide.
Image credit: Mike (Flickr)