[April 2013 organizational change]
Reorganized to explore new research possibilities > Center for Sustainable Resource Science



Discovery of the only remaining unelucidated biosynthetic enzyme gene for Gibberellin A1
- The key to creating gibberellin with decreased bioactivity -

January 15, 2013

PSC researchers have identified two genes encoding GA 13-oxidase in rice. The genes, which encode biosynthesis of GA-13 oxidase, remained the only ones unelucidated for gibberellin GA1, a growth hormone common to many flowering plants.

The PSC researches found two cytochrome P450 genes whose products have GA 13-hydroxylation activity from rice. Moreover, GA measurements of a rice double mutant of these genes indicated that the levels of 13-hydroxy GAs including GA1 were decreased, whereas those of non 13-hydroxy GAs including GA4 (which is more active than GA1) were increased in the double mutant. The double mutant plants showed tall phenotype compared with wild-type controls at heading stage, and this is mainly attributed to elongated uppermost internodes. These results indicate that these two genes play a predominant role in GA 13-hydroxylation in rice, and suggest that GA 13-oxidases play a role in fine-tuning plant growth by decreasing GA bioactivity in rice.

Since moderate suppression of plant height offers the possibility of improved crop yields, these findings show promise for the development of new plant growth control technologies in which GA 13-oxidase can be used to fine-tune GA quality.

Original article:
Proceedings of the National Academy of Science of the United States of America, 2013, doi: 10.1073/pnas.1215788110
Hiroshi Magome, Takahito Nomura, Atsushi Hanada, Noriko Takeda-Kamiya, Toshiyuki Ohnishi, Yuko Shinma, Takumi Katsumata, Hiroshi Kawaide, Yuji Kamiya, Shinjiro Yamaguchi
"CYP714B1 and CYP714B2 encode gibberellin 13-oxidases that reduce gibberellin activity in rice" 


Dr.Hiroshi Magome (Research Scientist)
RIKEN Plant Science Center