Journal Article

<i>EUI1</i>, Encoding a Putative Cytochrome P450 Monooxygenase, Regulates Internode Elongation by Modulating Gibberellin Responses in Rice

Anding Luo, Qian Qian, Hengfu Yin, Xiaoqiang Liu, Changxi Yin, Ying Lan, Jiuyou Tang, Zuoshun Tang, Shouyun Cao, Xiujie Wang, Kai Xia, Xiangdong Fu, Da Luo and Chengcai Chu

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 47, issue 2, pages 181-191
Published in print February 2006 | ISSN: 0032-0781
Published online February 2006 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pci233
EUI1, Encoding a Putative Cytochrome P450 Monooxygenase, Regulates Internode Elongation by Modulating Gibberellin Responses in Rice

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  • Biochemistry
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Elongation of rice internodes is one of the most important agronomic traits, which determines the plant height and underlies the grain yield. It has been shown that the elongation of internodes is under genetic control, and various factors are implicated in the process. Here, we report a detailed characterization of an elongated uppermost internode1 (eui1) mutant, which has been used in hybrid rice breeding. In the eui1-2 mutant, the cell lengths in the uppermost internodes are significantly longer than that of wild type and thus give rise to the elongated uppermost internode. It was found that the level of active gibberellin was elevated in the mutant, whereas its growth in response to gibberellin is similar to that of the wild type, suggesting that the higher level accumulation of gibberellin in the eui1 mutant causes the abnormal elongation of the uppermost internode. Consistently, the expression levels of several genes which encode gibberellin biosynthesis enzymes were altered. We cloned the EUI1 gene, which encodes a putative cytochrome P450 monooxygenase, by map-based cloning and found that EUI1 was weakly expressed in most tissues, but preferentially in young panicles. To confirm its function, transgenic experiments with different constructs of EUI1 were conducted. Overexpression of EUI1 gave rise to the gibberellin-deficient-like phenotypes, which could be partially reversed by supplementation with gibberellin. Furthermore, apart from the alteration of expression levels of the gibberellin biosynthesis genes, accumulation of SLR1 protein was found in the overexpressing transgenic plants, indicating that the expression level of EUI1 is implicated in both gibberellin-mediated SLR1 destruction and a feedback regulation in gibberellin biosynthesis. Therefore, we proposed that EUI1 plays a negative role in gibberellin-mediated regulation of cell elongation in the uppermost internode of rice.

Keywords: Cytochrome P450 monooxygenase; Elongated uppermost internode 1; Gibberellin; Internode elongation; Rice; BAC, bacterial artificial chromosome; CaMV, cauliflower mosaic virus; CAPS, cleaved amplified polymorphic sequence; ELISA, enzyme-linked immunosorbent assay; EMS, ethylmethane sulfonate; EUI, elongated uppermost internode; ORF, open reading frame; RNAi, RNA interference; RT–PCR, reverse transcription–PCR

Journal Article.  6593 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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