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Plant Biotechnol J. 2017 Jul;15(7):850-864. doi: 10.1111/pbi.12681. Epub 2017 Mar 23.

Ectopic expression of specific GA2 oxidase mutants promotes yield and stress tolerance in rice.

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Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, ROC.
Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan, ROC.
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, ROC.
Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, ROC.
Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan, ROC.
Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan, ROC.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan.


A major challenge of modern agricultural biotechnology is the optimization of plant architecture for enhanced productivity, stress tolerance and water use efficiency (WUE). To optimize plant height and tillering that directly link to grain yield in cereals and are known to be tightly regulated by gibberellins (GAs), we attenuated the endogenous levels of GAs in rice via its degradation. GA 2-oxidase (GA2ox) is a key enzyme that inactivates endogenous GAs and their precursors. We identified three conserved domains in a unique class of C20 GA2ox, GA2ox6, which is known to regulate the architecture and function of rice plants. We mutated nine specific amino acids in these conserved domains and observed a gradient of effects on plant height. Ectopic expression of some of these GA2ox6 mutants moderately lowered GA levels and reprogrammed transcriptional networks, leading to reduced plant height, more productive tillers, expanded root system, higher WUE and photosynthesis rate, and elevated abiotic and biotic stress tolerance in transgenic rice. Combinations of these beneficial traits conferred not only drought and disease tolerance but also increased grain yield by 10-30% in field trials. Our studies hold the promise of manipulating GA levels to substantially improve plant architecture, stress tolerance and grain yield in rice and possibly in other major crops.


GA 2 oxidase 6; gibberellin; photosynthesis rate; plant architecture; rice; stress tolerance; yield

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