from Nature Plants volume 4, pages1071–1081 (2018) (Kakimoto T., Chai J. & col.)
Researchers form Osaka University, in collaboration with laboratories from China, Germany and others form Japan, have found that a peptide hormone regulates two different cell division processes that generate centrally important structures for the flow of water through plants.
The study was carried out in Arabidopsis and it was shown that the genes encoding the peptide hormone CLE9/10 are active in cells that lead to the development of stomata in the leaf and also in cells that are precursors of water-conducting vessels (the xylem) in the root. The researchers identified two different receptors and also revealed that a co-receptor protein is involved in the leaf signaling system.
“In the primordial cells in leaves, binding of CLE9/10 to a protein receptor controls the number of stomatal pores,” said Pingping Qian. “But in the roots, it binds to a different protein receptor, and there it controls the production of xylem vessels.”
Tatsuo Kakimoto explained: “In animals, there are examples of signaling molecules that are perceived by multiple receptors. …This study shows that the same types of signaling systems operate in plants. It is interesting that the two developmental processes, involving distinct receptors in different parts of the plant, generate completely different structures that are both essential for water flow. These results have implications for understanding how multiple processes in plant development are coordinated.”
A model for the action of CLE9/10
CLE9/10 is perceived by two distinct receptor systems, one regulating stomatal development (left) and the other regulating xylem development (right). In the MMC, ER family receptor complexes are activated by EPF2 and the HSL1 complex is activated by CLE9/10. Signals from these receptor systems result in the phosphorylation and destabilization of SPCH. In the root meristem, CLE9/10 is perceived by BAM class receptors and represses the periclinal cell division of xylem precursor cells at the protoxylem file position.