Maize LAZY1 Mediates Shoot Gravitropism and Inflorescence Development through Regulating Auxin Transport, Auxin Signaling, and Light Response

• Published in: Plant physiology (Bethesda) 2013-11, Vol.163 (3), p.1306-1322
• Main Authors: Dong, Zhaobin, Jiang, Chuan, Chen, Xiaoyang, Zhang, Tao, Ding, Lian, Song, Weibin, Luo, Hongbing, Lai, Jinsheng, Chen, Huabang, Liu, Renyi, Zhang, Xiaolan, Jin, Weiwei
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Auxins; Biological and medical sciences; Biological Transport - genetics; Biological Transport - radiation effects; Cell Membrane - metabolism; Cell Nucleus - metabolism; Coleoptiles; Corn; flowering; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; GENES, DEVELOPMENT, AND EVOLUTION; Gravitropism; Gravitropism - genetics; Gravitropism - physiology; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Indoleacetic Acids - metabolism; Inflorescence - genetics; Inflorescence - growth & development; Inflorescence - metabolism; Inflorescences; Light; Meristems; Microscopy, Electron, Scanning; molecular cloning; Molecular Sequence Data; Movements; mutants; Mutation; Phylogeny; Plant physiology and development; Plant Proteins - classification; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - metabolism; Plants; Reverse Transcriptase Polymerase Chain Reaction; Sequence Homology, Amino Acid; Signal Transduction - genetics; Signal Transduction - radiation effects; Tassels; Transcriptome; Zea mays - genetics; Zea mays - growth & development; Zea mays - metabolism
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.227314

Auxin is a plant hormone that plays key roles in both shoot gravitropism and inflorescence development. However, these two processes appear to be parallel and to be regulated by distinct players. Here, we report that the maize (Zea mays) prostrate stem1 mutant, which is allelic to the classic mutant lazy plant1 (la1), displays prostrate growth with reduced shoot gravitropism and defective inflorescence development. Map-based cloning identified maize ZmLA1 as the functional ortholog of LAZY1 in rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana). It has a unique role in inflorescence development and displays enriched expression in reproductive organs such as tassels and ears. Transcription of ZmLA1 responds to auxin and is repressed by light. Furthermore, ZmLA1 physically interacts with a putative auxin transport regulator in the plasma membrane and a putative auxin signaling protein in the nucleus. RNA-SEQ data showed that dozens of auxin transport, auxin response, and light signaling genes were differentially expressed in la1 mutant stems. Therefore, ZmLA1 might mediate the cross talk between shoot gravitropism and inflorescence development by regulating auxin transport, auxin signaling, and probably light response in maize.