ELONGATED UPPERMOST INTERNODE encodes a cytochrome P450 monooxygenase that epoxidizes gibberellins in a novel deactivation reaction in rice.
The recessive tall rice (Oryza sativa) mutant elongated uppermost internode (eui) is morphologically normal until its final internode elongates drastically at the heading stage. The stage-specific developmental effect of the eui mutation has been used in the breeding of hybrid rice to improve the performance of heading in male sterile cultivars. We found that the eui mutant accumulated exceptionally large amounts of biologically active gibberellins (GAs) in the uppermost internode. Map-based cloning revealed that the Eui gene encodes a previously uncharacterized cytochrome P450 monooxygenase, CYP714D1. Using heterologous expression in yeast, we found that EUI catalyzed 16alpha,17-epoxidation of non-13-hydroxylated GAs. Consistent with the tall and dwarfed phenotypes of the eui mutant and Eui-overexpressing transgenic plants, respectively, 16alpha,17-epoxidation reduced the biological activity of GA(4) in rice, demonstrating that EUI functions as a GA-deactivating enzyme. Expression of Eui appeared tightly regulated during plant development, in agreement with the stage-specific eui phenotypes. These results indicate the existence of an unrecognized pathway for GA deactivation by EUI during the growth of wild-type internodes. The identification of Eui as a GA catabolism gene provides additional evidence that the GA metabolism pathway is a useful target for increasing the agronomic value of crops.
Zhu
Yongyou
Y
National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Nomura
Takahito
T
Xu
Yonghan
Y
Zhang
Yingying
Y
Peng
Yu
Y
Mao
Bizeng
B
Hanada
Atsushi
A
Zhou
Haicheng
H
Wang
Renxiao
R
Li
Peijin
P
Zhu
Xudong
X
Mander
Lewis N
LN
Kamiya
Yuji
Y
Yamaguchi
Shinjiro
S
He
Zuhua
Z
D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D005875:Gibberellins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D006899:Mixed Function Oxygenases; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000033:anatomy & histology; D021381:Protein Transport
D005875:Gibberellins; D010940:Plant Proteins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases