Discovery of a new pathway to activate a growth-promoting phytohormone

August 29, 2023

Anticipation for the application to increasing crop yields, including rice

Researchers at Nagoya University in cooperation with those at the RIKEN CSRS, the National Agriculture and Food Research Organization, and Okayama University discovered a new pathway that activates a cytokinin, a type of growth-promoting phytohormone.

Cytokinins are essential phytohormones that play pivotal roles in plant production, including plant growth promotion and rice panicle development in response to nitrogen nutrition. Cytokinin biosynthesis has been believed to occur within cells. However, the researchers revealed that the cytokinin/purine riboside nucleosidase 1 (CPN1) they identified is located in the cell wall (apoplastic) space in the leaves and that its precursors transported from the root are transformed into the active form via a metabolic pathway different from the intracellular one. They also showed that in the rice mutant that lost CPN1 function, normal cytokinin signaling was lost in the leaves, and the panicle size was reduced.

Since the use of the CPN1 gene allows the synthetic regulation of cytokinin actions, its application to increasing the yield of crops, including rice, is appreciated.

Original article
Proceedings of the National Academy of Sciences of the United States of America doi: 10.1073/pnas.2217708120
M. Kojima, N. Makita, K. Miyata, M. Yoshino, A. Iwase, M. Ohashi, A. Surjana, T. Kudo, N. Takeda-Kamiya, K. Toyooka, A. Miyao, H. Hirochika, T. Ando, A.o Shomura, M. Yano, T. Yamamoto, T. Hobo, H. Sakakibara,
"A cell wall-localized cytokinin/purine riboside nucleosidase is involved in apoplastic cytokinin metabolism in Oryza sativa".
Mikiko Kojima; Expert Technician
Mass Spectrometry and Microscopy Unit
Akira Iwase; Senior Scientist
Cell Function Research Team