Letter abstract


Nature Cell Biology 11, 845 - 851 (2009)
Published online: 21 June 2009 | doi:10.1038/ncb1892

OsHAL3 mediates a new pathway in the light-regulated growth of rice

Shi-Yong Sun1,4, Dai-Yin Chao1,4, Xin-Min Li1, Min Shi1, Ji-Ping Gao1, Mei-Zhen Zhu1, Hong-Quan Yang1, Sheng Luan2,3 & Hong-Xuan Lin1,2

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Plants show distinct morphologies in different light conditions through a process called photomorphogenesis. A predominant feature of photomorphogenesis is the reduced growth of seedlings under light conditions compared with darkness. For this adaptive event, the most well-known molecular mechanism involves photoreceptor-mediated inhibition of cell elongation1, 2, 3, 4. However, it is not known whether additional pathways exist. Here, we describe a newly discovered pathway of light-modulated plant growth mediated by the halotolerance protein HAL3, a flavin mononucleotide (FMN)-binding protein involved in cell division5, 6, 7, 8. We found that light, especially blue light, suppresses growth of rice seedlings by reducing the activity of Oryza sativa (Os) HAL3. Both in vitro and in vivo studies showed that OsHAL3 is structurally inactivated by light through photo-oxidation and by direct interaction with photons. In addition, the transcriptional expression of OsHAL3 is synergistically regulated by different light conditions. Further investigation suggested that OsHAL3 promotes cell division by recruiting a ubiquitin system, rather than by its 4'-phosphopantothenoylcysteine (PPC) decarboxylase activity. Our results uncover a new mechanism for light-regulated plant growth, namely, light not only inhibits cell elongation but also suppresses cell division through HAL3 and E3 ubiquitin ligase. This study thus brings new insights into our understanding of plant photomorphogenesis.

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  1. National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, 300 Fenglin Road, Shanghai 200032, China.
  2. SIBS-UC Berkeley Center for Molecular Life Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
  3. Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
  4. These authors contributed equally to this work.

Correspondence to: Hong-Xuan Lin1,2 e-mail: hxlin@sibs.ac.cn




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