title: OsWOX3A is involved in negative feedback regulation of the gibberellic acid biosynthetic pathway in rice (Oryza sativa).
abstract: The plant-specific WUSCHEL-related homeobox (WOX) nuclear proteins have important roles in the transcriptional regulation of many developmental processes. Among the rice (Oryza sativa) WOX proteins, a loss of OsWOX3A function in narrow leaf2 (nal2) nal3 double mutants (termed nal2/3) causes pleiotropic effects, such as narrow and curly leaves, opened spikelets, narrow grains, more tillers, and fewer lateral roots, but almost normal plant height. To examine OsWOX3A function in more detail, transgenic rice overexpressing OsWOX3A (OsWOX3A-OX) were generated; unexpectedly, all of them consistently exhibited severe dwarfism with very short and wide leaves, a phenotype that resembles that of gibberellic acid (GA)-deficient or GA-insensitive mutants. Exogenous GA3 treatment fully rescued the developmental defects of OsWOX3A-OX plants, suggesting that constitutive overexpression of OsWOX3A downregulates GA biosynthesis. Quantitative analysis of GA intermediates revealed significantly reduced levels of GA20 and bioactive GA1 in OsWOX3A-OX, possibly due to downregulation of the expression of KAO, which encodes ent-kaurenoic acid oxidase, a GA biosynthetic enzyme. Yeast one-hybrid and electrophoretic mobility shift assays revealed that OsWOX3A directly interacts with the KAO promoter. OsWOX3A expression is drastically and temporarily upregulated by GA3 and downregulated by paclobutrazol, a blocker of GA biosynthesis. These data indicate that OsWOX3A is a GA-responsive gene and functions in the negative feedback regulation of the GA biosynthetic pathway for GA homeostasis to maintain the threshold levels of endogenous GA intermediates throughout development.
authors.affiliation: Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea Present address: Division of Plant Science and Biochemistry, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Cho
authors.affiliation: Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
authors.forename: Kiyoon
authors.initials: K
authors.lastname: Kang
authors.affiliation: Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
authors.forename: Sang-Hwa
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Division of Plant Biosciences, Kyungpook National University, Daegu, 702-701, Republic of Korea.
authors.forename: In-Jung
authors.initials: IJ
authors.lastname: Lee
authors.affiliation: Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 151-921, Republic of Korea.
authors.forename: Nam-Chon
authors.initials: NC
authors.lastname: Paek
mesh_terms: D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D025461:Feedback, Physiological / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000096:biosynthesis* / Q000494:pharmacology; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D014230:Triazoles / Q000494:pharmacology
chemical_list: D005875:Gibberellins; D010940:Plant Proteins; D014230:Triazoles; C053370:paclobutrazol; C007842:gibberellic acid
keywords: Dwarfism; KAO; OsWOX3A; electrophoretic mobility shift assay; gibberellic acid; negative feedback regulation; rice.