Poster: Signaling, cell-to-cell

Abs # 451: Activation tagging of the OsBRI1 gene enhances responsiveness and reduces the levels of brassinosteroids in rice

Presenter:	Jeong, Dong-Hoon , dhjeong@postech.ac.kr
Authors	Jeong, Dong-Hoon  (A)   An, Suyoung  (A)   Lee, Sang-Choon  (B)   Seong-Ryong, Kim  (B)   Jong-Seong, Jeon  (C)   Suguru, Takatsuto  (D)   Shigeo, Yoshida  (E)   Shozo, Fujioka  (E)   An, Gynheung  (A)
Affiliations:	(A): Pohang University of Science and Technology (B): Sogang University (C): Kyung Hee University (D): Joetsu University of Education (E): RIKEN (The Institute of Physical and Chemical Research)

Brassinosteroids (BRs) are plant steroid hormones that are essential for plant growth and development. To gain further understanding of BR signaling in rice, we have investigated an activation tagging line, in which the brassinosteroid receptor gene, OsBRI1 was tagged. In the line, the 35S enhancer sequence was inserted 0.3 kb downstream of the OsBRI1 gene. We have observed that the OsBRI1 transcript level was significantly increased in the tagged lines. Compared to wild type, the OsBRI1-dominant (OsBRI1-D) activation tagging lines exhibited enhanced responses to exogenously treated Brassinolide (BL) and less accumulates the BR intermediates. In addition, the transcript level of BR biosynthetic enzyme gene was lower and those of BR inducible genes were higher in the OsBRI1-D than those in wild type plants. These results indicate OsBRI1 is a crucial component of BR signaling in rice.