There are also synergistic effects between two important plant hormones

The team led by Professor Jan Roman, a cell biologist at the University of Heidelberg in Germany, found that the plant hormone auxin and cytokinin, which have been regarded as rivals, actually have a synergistic effect, and their interaction is much closer than previously thought The results of the study on the interaction of plant hormones were published in the June 24 issue of nature Two of the most important growth hormones in plants, hormone auxin and cytokinin, one provides growth potential and the other is used to grow leaves or flowers They have been regarded as rivals for a long time, and the latest research shows that they can also work together The interaction between the two is much closer than previously thought This is based on the experiment of Arabidopsis, a model organism, by scientists from Heidelberg, Tubingen and Yumo (Sweden) The aboveground parts of all plants, including leaves, flowers, stems and seeds, are actually derived from a small area of plant stem tip tissue, which contains the totipotent stem cells that maintain their vitality throughout the plant life cycle Unlike animals, plants can grow for many years, and at the same time produce new organs In this process, the cell auxin at the edge of growth zone is dedicated to differentiation of cells in stem cell pool, such as generation of leaves and flowers; on the other hand, the cytokinin stimulates stem cells to self divide and renew, and its task is to maintain the number of cells, thus maintaining the growth potential of plants Therefore, scientists have always believed that the two functions are relative and have no direct impact on each other It is now clear which genetic factors play a role in the growth of plants Professor Roman and his team focused on the tip growing region of Arabidopsis to conduct complex experiments to study the effect of auxin on this interrelated hormonal action Experiments have shown that auxin directly activates a "feedback loop": two genes activated by cytokinin - ARR7 and ARR15 - limit the effect of cytokinin, but auxin suppresses the two genes, thereby enhancing the effect of cytokinin The researchers explained that this effect of auxin can be seen as a positive feedback to the stem cell pool If it stimulates cells at the edge of the growth zone to form organs, it must at the same time ensure that there is sufficient stem cell supply This prevents the number of stem cells from falling below a threshold, which is essential for plant growth and survival Researchers say they are beginning to understand the rules of how hormones and genes interact to maintain activity in the growing regions It is now clear that hormones and genetic factors are not working alone, they are interrelated and interact with each other.