title: Mutation of rice BC12/GDD1, which encodes a kinesin-like protein that binds to a GA biosynthesis gene promoter, leads to dwarfism with impaired cell elongation.
abstract: The kinesins are a family of microtubule-based motor proteins that move directionally along microtubules and are involved in many crucial cellular processes, including cell elongation in plants. Less is known about kinesins directly regulating gene transcription to affect cellular physiological processes. Here, we describe a rice (Oryza sativa) mutant, gibberellin-deficient dwarf1 (gdd1), that has a phenotype of greatly reduced length of root, stems, spikes, and seeds. This reduced length is due to decreased cell elongation and can be rescued by exogenous gibberellic acid (GA₃) treatment. GDD1 was cloned by a map-based approach, was expressed constitutively, and was found to encode the kinesin-like protein BRITTLE CULM12 (BC12). Microtubule cosedimentation assays revealed that BC12/GDD1 bound to microtubules in an ATP-dependent manner. Whole-genome microarray analysis revealed the expression of ent-kaurene oxidase (KO2), which encodes an enzyme involved in GA biosynthesis, was downregulated in gdd1. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that GDD1 bound to the element ACCAACTTGAA in the KO2 promoter. In addition, GDD1 was shown to have transactivation activity. The level of endogenous GAs was reduced in gdd1, and the reorganization of cortical microtubules was altered. Therefore, BC12/GDD1, a kinesin-like protein with transcription regulation activity, mediates cell elongation by regulating the GA biosynthesis pathway in rice.
authors.affiliation: Research Center for Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Jiafu
authors.initials: J
authors.lastname: Jiang
authors.forename: Qian
authors.initials: Q
authors.lastname: Qian
authors.forename: Yunyuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Cui
authors.initials: C
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Xiao
authors.forename: Cheng
authors.initials: C
authors.lastname: Du
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Guoxing
authors.initials: G
authors.lastname: Zou
authors.forename: Mingluan
authors.initials: M
authors.lastname: Chen
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Huang
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Feng
authors.forename: Zhukuan
authors.initials: Z
authors.lastname: Cheng
authors.forename: Ming
authors.initials: M
authors.lastname: Yuan
authors.forename: Kang
authors.initials: K
authors.lastname: Chong
mesh_terms: D001483:Base Sequence; D049108:Cell Enlargement; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D005875:Gibberellins / Q000096:biosynthesis*; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D018749:RNA, Plant / Q000235:genetics; D017384:Sequence Deletion; D015533:Transcriptional Activation
chemical_list: D005875:Gibberellins; D010940:Plant Proteins; D018749:RNA, Plant; D016547:Kinesins