title: The role of the miR399-PHO2 module in the regulation of flowering time in response to different ambient temperatures in Arabidopsis thaliana.
abstract: A moderate change in ambient temperature significantly affects plant physiology including flowering time. MiR399 and its target gene PHOSPHATE 2 (PHO2) are known to play a role in the maintenance of phosphate homeostasis. However, the regulation of flowering time by the miR399-PHO2 module has not been investigated. As we have previously identified miR399 as an ambient temperature-responsive miRNA, we further investigated whether a change in expression of the miR399-PHO2 module affects flowering time in response to ambient temperature changes. Here, we showed that miR399b-overexpressing plants and a loss-of-function allele of PHO2 (pho2) exhibited an early flowering phenotype only at normal temperature (23°C). Interestingly, their flowering time at lower temperature (16°C) was similar to that of wild-type plants, suggesting that alteration in flowering time by miR399 and its target PHO2 was seen only at normal temperature (23°C). Flowering time ratio (16°C/23°C) revealed that miR399b-overexpressing plants and pho2 mutants showed increased sensitivity to ambient temperature changes. Expression analysis indicated that expression of TWIN SISTER OF FT (TSF) was increased in miR399b-overexpressing plants and pho2 mutants at 23°C, suggesting that their early flowering phenotype is associated with TSF upregulation. Taken together, our results suggest that miR399, an ambient temperature-responsive miRNA, plays a role in ambient temperature-responsive flowering in Arabidopsis.
authors.affiliation: Creative Research Initiatives, School of Life Sciences and Biotechnology, Korea University, Seoul, 136-701, Korea.
authors.forename: Wanhui
authors.initials: W
authors.lastname: Kim
authors.forename: Hae Ji
authors.initials: HJ
authors.lastname: Ahn
authors.forename: Tzyy-Jen
authors.initials: TJ
authors.lastname: Chiou
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Ahn
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism*; D049488:Phosphatidylethanolamine Binding Protein / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; D003470:Culture Media; D035683:MicroRNAs; D010710:Phosphates; D049488:Phosphatidylethanolamine Binding Protein; C500577:TSF protein, Arabidopsis; C514696:UBC24 protein, Arabidopsis; D044763:Ubiquitin-Conjugating Enzymes