Dr. Huysmans, first author of this study: “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.”
In this project, the researchers aimed at discovering new genes that control the cell death process in plants. To this end, they studied transcription factors, which regulate gene expression as the starting point of protein production. The regulated production of proteins is an important first step to ensure the orderly execution of cell death.
Huysmans: “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.”
In mutants that abnormally produced these factors outside the root cap, the team of Nowack found that many cells died within 24 hours, leading to growth arrest and seedling death. Conversely, when analyzing mutants that were unable to produce ANAC087 and ANAC046, they found that root cap cells lived much longer than in regular Arabidopsis plants.
Moritz Nowack (VIB-UGent Center for Plant Systems Biology): “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 and reside in the rhizosphere have a genetically determined life span.”
Identifying transcription factors controlling the cell death program is but a first step. To find the proteins that do the actual killing job, target genes controlled by ANAC087 and ANAC046 need to be analyzed.