Biologists have discovered a special mechanism by which the plant hormone cytokinin controls cell division. The new study, published in the journal Science, improves scientists’ understanding of how plants grow.
Cell division is fundamental to all life forms. All multicellular organisms, including plants and animals, develop from a single cell that divides billions of times to build a complex organism. Undifferentiated plant stem cells function as a reservoir of new cells from which a plant can grow and develop specialized tissues. New stems, leaves, roots and flowers come from small clusters of stem cells in specific growth areas – the apical meristems.
There, growth cells are constantly dividing in the process of mitosis, which is responsible for the architecture of the plant. Scientists have long known that cytokinin plays a central role in this process of cell division, but how exactly it stimulates cell proliferation remained unknown.
In a new study, scientists from the Sainsbury Laboratory at the University of Cambridge and the California Institute of Technology (Caltech) observed for the first time how cytokinin activates stem cell division in plants.
Using Arabidopsis thaliana, a member of the mustard family commonly used as a model plant in crop research, they showed that cytokinin directly promotes the transport of the MYB3R4 transcription factor from the cytoplasm to the nucleus. There, the hormone activates the expression of key genes in the cell cycle.
New research explains the mechanism by which cytokinin regulates stem cell division. The hormone moves proteins into the nucleus, where they activate genes involved in mitosis.
When mitotic cells divide (mitosis), chromosomes are replicated and then equally divided into two daughter cells. Using time-lapse confocal microscopy of living plants, scientists were able to capture the cellular dynamics of proteins that were found to be important in triggering mitosis.
Understanding how stem cell self-renewal is controlled is critical to understanding plant development. The study will help identify new ways to accelerate plant growth and lay the foundation for future work that will impact crop health and productivity.