title: Clock-controlled and FLOWERING LOCUS T (FT)-dependent photoperiodic pathway in Lotus japonicus II: characterization of a microRNA implicated in the control of flowering time.
abstract: Plant circadian clock generates rhythms with a period close to 24 h, and it controls a wide variety of physiological and developmental events, including the transition to reproductive growth (or flowering). During the last decade, significant research progress in Arabidopsis thaliana has been made in defining the molecular mechanism by which the circadian clock regulates flowering time in response to changes in photoperiod. In Lotus japonicus, we have found that LjFTa, which encodes a ortholog of the Arabidopsis FLOWERING LOCUS T (FT), plays an important role in the promotion of flowering, but it is not clear how the expression of LjFTa is regulated in L. japonicus. Based on current knowledge of photoperiodic control of flowering time in A. thaliana, here we examined whether a microRNA is involved in the activation of LjFTa in L. japonicus. Two putative L. japonicus genes that are responsible for the production of miR172 (designated LjmiR172a and LjmiR172b) were cloned. Overexpression of LjmiR172a/b in A. thaliana resulted in markedly accelerated flowering through enhancement of the expression of FT, concomitantly reducing the expression level of TARGET OF EARLY ACTIVATION TAGGED 1 (TOE1) transcripts, the protein product of which functions as a transcriptional repressor of FT. These results suggest that LjmiR172 genes play a positive role in the LjFTa-mediated promotion of flowering in L. japonicus.
authors.affiliation: Laboratory of Molecular and Functional Genomics, School of Agriculture, Nagoya University, Nagoya, Japan. yamasino@agr.nagoya-u.ac.jp
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamashino
authors.forename: Saori
authors.initials: S
authors.lastname: Yamawaki
authors.forename: Emi
authors.initials: E
authors.lastname: Hagui
authors.forename: Kai
authors.initials: K
authors.lastname: Ishida
authors.forename: Hanayo
authors.initials: H
authors.lastname: Ueoka-Nakanishi
authors.forename: Norihito
authors.initials: N
authors.lastname: Nakamichi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizuno
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D057906:Circadian Clocks / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000254:growth & development*; D018506:Gene Expression Regulation, Plant; D000070116:Lotus / Q000235:genetics / Q000254:growth & development*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D017440:Photoperiod; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C418905:FT protein, Arabidopsis; D035683:MicroRNAs