A protein that helps plant cell elongation

July 18, 2017

Will contribute to the development of technologies to control plant leaf size and height

Joint research by RIKEN CSRS, University of Tokyo and Ochanomizu University has elucidated the function of the homologous protein BIL4 (which is evolutionarily conserved across a wide variety of plants such as tomato, rice and wheat, but also in a variety of mammals such as humans and mice). Researchers used a chemical biology method with brassinosteroid biosynthesis inhibitor brassinazole (Brz) to activate brassinosteroid (BR) signaling, finding the regulatory protein BIL4. When investigating the movement of BIL4 (a 7-transmembrance-domain protein) in cells, the researchers discovered that the protein interacts with the brassinosteriod receptor BRI1 in the endosome. BRI1 is found in cell membranes and serves as a starting point for sensing extracellular BR and transmitting a signal into the cell; it is considered to be a very important factor for plant growth. In addition, it has become apparent in recent years that BIL4 is regulated by transport to vacuoles for degradation after being transported into the cell via endocytosis.

From the above, it became clear that BIL4 functions to prevent the degradation of BRI1, to activate signaling transduction of BR by suppressing the degradation of BR and to promote elongation of leaf cell hypocotyls (the stem portion of germinated seedlings).

These findings are expected to lead to the development of technologies for plant biomass and for controlling the leaf size and height of useful plants.

Original article
Scientific Reports doi:10.1038/s41598-017-06016-2
A. Yamagami, C. Saito, M. Nakazawa, S. Fujioka, T. Uemura, M. Matsui, M. Sakuta, K. Shinozaki, H. Osada, A. Nakano, T Asami, T. Nakano,
"Evolutionarily conserved BIL4 suppresses the degradation of brassinosteroid receptor BRI1 and regulates cell elongation".
Takeshi Nakano; Senior Research Scientist
Ayumi Yamagami; Research Scientist
Kazuo Shinozaki; Group Director
Gene Discovery Research Group