Finding an evolutionarily conserved polarized growth mechanism in a basal land plant – The secret behind rhizoid cells of Marchantia polymorpha
March 02(Fri), 2018
The research group of Hiroyasu Motose, Associate Professor, Kento Otani, a graduate student (at the time of the publication), Shogo Takatani, a graduate student, and Taku Takahashi, Professor at the Department of Biological Science, Graduate School of Natural Science and Technology, Okayama University, together with Kimitsune Ishizaki, Associate Professor at the Department of Biology, Graduate School of Science of Kobe University, and the group led by Takayuki Kohchi, Professor and Ryuichi Nishihama, Associate Professor at the Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, found a mechanism of a steady polarized growth toward a certain direction of a plant cell that was observed in a basal land plant, Marchantia polymorpha. The group also found that this mechanism had been maintained through the evolution of land plants, and it was necessary for the growth of a rhizoid tip that is considered to be an early rooting system.
These findings were published in the British science magazine “Development” at 12:30 a.m., March 2, 2018, British time (9:30 a.m. in Japan).
Currently, there exists a wide variety of land plants. These land plants are considered to have originated as freshwater algae that evolved through moss-like plants to their current stage. The early land plants are believed not to have had roots, rather they adhered to the ground using rhizoid cells to obtain water and nutrients in order to adapt to the land environment, just like the modern bryophyte. The (ventral) side of a rhizoid cell that is touching the ground shows a regional epidermis cell growth, and this part has a tip growth that becomes filamentary (the elongated string shape). However, the mechanism of how rhizoid cells grew remained unclear.
The research group of Professor Motose and others used Marchantia polymorpha, a kind of liverwort, which branched out during the early stage of the land plant evolution and still maintains its original form to reveal that the NIMA-related protein kinase 1 (MpNEK1) directs tip growth in rhizoids.
The research result will bring a new, universal understanding of how cells decide and stabilize growth directions. The NEK family of protein kinases exists universally in most of the eukaryotic species, such as humans and aspergillus. They control cell cleavages, nerve cell formations and flagellum and cilium formations, and a lack of the NEK family of protein kinases can be a cause of various diseases. This research result is expected to provide an important tip to understanding such diseases.
Authors: Kento Otani, Kimitsune Ishizaki, Ryuichi Nishihama, Shogo Takatani, Takayuki Kohchi, Taku Takahashi, Hiroyasu Motose
Title: An evolutionarily conserved NIMA-related kinase directs rhizoid tip growth in the basal land plant Marchantia polymorpha
Year of Publication:2018
Okayama University Silicon Valley Office (OUSVO)
Contact: Mototaka Senda, Ph.D.