ORIGINAL ARTICLE

Cell Research (2007): 402-410
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LAZY1 controls rice shoot gravitropism through regulating polar auxin transport

Peijin Li^1,*, Yonghong Wang^1,*, Qian Qian^2,*, Zhiming Fu¹, Mei Wang¹, Dali Zeng^1,2, Baohua Li¹, Xiujie Wang¹ and Jiayang Li¹

Correspondence: Jiayang Li Tel: +86-10-64852855; Fax: +86-10-64873428 E-mail: jyli@genetics.ac.cn *These three authors contributed equally to this work.

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Tiller angle of rice (Oryza sativa L.) is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yield. Although enormous efforts have been made over the past decades to study mutants with extremely spreading or compact tillers, the molecular mechanism underlying the control of tiller angle of cereal crops remains unknown. Here we report the cloning of the LAZY1 (LA1) gene that regulates shoot gravitropism by which the rice tiller angle is controlled. We show that LA1, a novel grass-specific gene, is temporally and spatially expressed, and plays a negative role in polar auxin transport (PAT). Loss-of-function of LA1 enhances PAT greatly and thus alters the endogenous IAA distribution in shoots, leading to the reduced gravitropism, and therefore the tiller-spreading phenotype of rice plants.

Cell Research (2007) 17:402–410. doi: 10.1038/cr.2007.38; published online 30 April 2007

Keywords: LAZY1, gravitropism, auxin transport, tiller angle, plant architecture, Oryza sativa L.