title: TAWAWA1, a regulator of rice inflorescence architecture, functions through the suppression of meristem phase transition.
abstract: Inflorescence structures result from the activities of meristems, which coordinate both the renewal of stem cells in the center and organ formation at the periphery. The fate of a meristem is specified at its initiation and changes as the plant develops. During rice inflorescence development, newly formed meristems acquire a branch meristem (BM) identity, and can generate further meristems or terminate as spikelets. Thus, the form of rice inflorescence is determined by a reiterative pattern of decisions made at the meristems. In the dominant gain-of-function mutant tawawa1-D, the activity of the inflorescence meristem (IM) is extended and spikelet specification is delayed, resulting in prolonged branch formation and increased numbers of spikelets. In contrast, reductions in TAWAWA1 (TAW1) activity cause precocious IM abortion and spikelet formation, resulting in the generation of small inflorescences. TAW1 encodes a nuclear protein of unknown function and shows high levels of expression in the shoot apical meristem, the IM, and the BMs. TAW1 expression disappears from incipient spikelet meristems (SMs). We also demonstrate that members of the SHORT VEGETATIVE PHASE subfamily of MADS-box genes function downstream of TAW1. We thus propose that TAW1 is a unique regulator of meristem activity in rice and regulates inflorescence development through the promotion of IM activity and suppression of the phase change to SM identity.
authors.affiliation: Graduate School of Agriculture and Life Sciences,  The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657,  Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Yoshida
authors.forename: Masafumi
authors.initials: M
authors.lastname: Sasao
authors.forename: Naoko
authors.initials: N
authors.lastname: Yasuno
authors.forename: Kyoko
authors.initials: K
authors.lastname: Takagi
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Daimon
authors.forename: Ruihong
authors.initials: R
authors.lastname: Chen
authors.forename: Ryo
authors.initials: R
authors.lastname: Yamazaki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tokunaga
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kitaguchi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sato
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nagamura
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Ushijima
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kumamaru
authors.forename: Shigeru
authors.initials: S
authors.lastname: Iida
authors.forename: Masahiko
authors.initials: M
authors.lastname: Maekawa
authors.forename: Junko
authors.initials: J
authors.lastname: Kyozuka
mesh_terms: D004251:DNA Transposable Elements / Q000235:genetics; D005453:Fluorescence; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D017403:In Situ Hybridization; D056626:Inflorescence / Q000033:anatomy & histology* / Q000378:metabolism; D026161:MADS Domain Proteins / Q000378:metabolism; D018519:Meristem / Q000254:growth & development* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D012275:Oryza / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D004251:DNA Transposable Elements; D026161:MADS Domain Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins