Overexpression of a type-A response regulator alters rice [Oryza sativa] morphology and cytokinin metabolism

• Published in: Plant and cell physiology Vol. 48; no. 3; pp. 523 - 539
• Main Authors: Hirose, N.(Institute of Physical and Chemical Research, Yokohama (Japan). Plant Science Center), Makita, N, Kojima, M, Kamada Nobusada, T, Sakakibara, H
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01.03.2007; Oxford Publishing Limited (England)
• Subjects: ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; anatomy & histology; Base Sequence; CITOQUININAS; CYTOKININE; CYTOKININS; Cytokinins - metabolism; DNA, Plant; DNA, Plant - genetics; DWARFISM; ENANISMO; ESTRES; EXPRESION GENICA; EXPRESSION DES GENES; GENE EXPRESSION; gene expression regulation; gene overexpression; genes; Genes, Plant; genetics; hormone metabolism; inflorescences; metabolism; Molecular Sequence Data; NANISME; Oligonucleotide Array Sequence Analysis; Oryza; Oryza - anatomy & histology; Oryza - genetics; Oryza - metabolism; ORYZA SATIVA; Phenotype; PLANT ANATOMY; Plant Leaves; Plant Leaves - metabolism; Plant Roots; Plant Roots - metabolism; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants, Genetically Modified; PROTEIN SYNTHESIS; rice; root systems; shoots; Signal Transduction; SINTESIS DE PROTEINAS; STRESS; stress response; SYNTHESE PROTEIQUE; TRANSCRIPCION; TRANSCRIPTION; TRANSGENIC PLANTS; zeatin; Response regulator; Microarray; Cytokinin; Gene chip
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcm022

Genome-wide analyses of rice (Oryza sativa L.) cytokinin (CK)-responsive genes using the Affymetrix GeneChip® rice genome array were conducted to define the spectrum of genes subject to regulation by CK in monocotyledonous plants. Application of trans-zeatin modulated the expression of a wide variety of genes including those involved in hormone signaling and metabolism, transcriptional regulation, macronutrient transport and protein synthesis. To understand further the function of CK in rice plants, we examined the effects of in planta manipulation of a putative CK signaling factor on morphology, CK metabolism and expression of CK-responsive genes. Overexpression of the CK-inducible type-A response regulator OsRR6 abolished shoot regeneration, suggesting that OsRR6 acts as a negative regulator of CK signaling. Transgenic lines overexpressing OsRR6 (OsRR6-ox) had dwarf phenotypes with poorly developed root systems and panicles. Increased content of trans-zeatin-type CKs in OsRR6-ox lines indicates that homeostatic control of CK levels is regulated by OsRR6 signaling. Expression of genes encoding CK oxidase/dehydrogenase decreased in OsRR6-ox plants, possibly accounting for elevated CK levels in transgenic lines. Expression of a number of stress response genes was also altered in OsRR6-ox plants.