title: OsHAL3, a Blue Light-Responsive Protein, Interacts with the Floral Regulator Hd1 to Activate Flowering in Rice.
abstract: In flowering plants, photoperiodic flowering is controlled by a complicated network. Light is one of the most important environmental stimuli that control the timing of the transition from vegetative growth to reproductive development. Several photoreceptors, including PHYA, PHYB, CRY2, and FKF1 in Arabidopsis and their homologs (OsPHYA, OsPHYB, OsPHYC, and OsCRY2) in rice, have been identified to be related to flowering. Our previous study suggests that OsHAL3, a flavin mononucleotide-binding protein, may function as a blue-light sensor. Here, we report the identification of OsHAL3 as a positive regulator of flowering in rice. OsHAL3 overexpression lines exhibited an early flowering phenotype, whereas downregulation of OsHAL3 expression by RNA interference delayed flowering under an inductive photoperiod (short-day conditions). The change in flowering time was not accompanied by altered Hd1 expression but rather by reduced accumulation of Hd3a and MADS14 transcripts. OsHAL3 and Hd1 colocalized in the nucleus and physically interacted in vivo under the dark, whereas their interaction was inhibited by white or blue light. Moreover, OsHAL3 directly bound to the promoter of Hd3a, especially before dawn. We conclude that OsHAL3, a novel light-responsive protein, plays an essential role in photoperiodic control of flowering time in rice, which is probably mediated by forming a complex with Hd1. Our findings open up new perspectives on the photoperiodic flowering pathway.
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences and Collaborative Innovation Center of Genetics and Development, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Su
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences and Collaborative Innovation Center of Genetics and Development, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
authors.forename: Jun-Xiang
authors.initials: JX
authors.lastname: Shan
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences and Collaborative Innovation Center of Genetics and Development, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
authors.forename: Ji-Ping
authors.initials: JP
authors.lastname: Gao
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences and Collaborative Innovation Center of Genetics and Development, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China. Electronic address: hxlin@sibs.ac.cn.
authors.forename: Hong-Xuan
authors.initials: HX
authors.lastname: Lin
mesh_terms: D035264:Flowers / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D008027:Light; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000528:radiation effects; D011485:Protein Binding / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: Hd1; Oryza sativa; OsHAL3; blue-light-responsive protein; photoperiodic flowering