title: Identification of microRNA 395a in 24-epibrassinolide-regulated root growth of Arabidopsis thaliana using microRNA arrays.
abstract: Brassinosteroids (BRs) are endogenous plant hormones and are essential for normal plant growth and development. MicroRNAs (miRNAs) of Arabidopsis thaliana are involved in mediating cell proliferation in leaves, stress tolerance, and root development. The specifics of BR mechanisms involving miRNAs are unknown. Using customized miRNA array analysis, we identified miRNAs from A. thaliana ecotype Columbia (Col-0) regulated by 24-epibrassinolide (EBR, a highly active BR). We found that miR395a was significantly up-regulated by EBR treatment and validated its expression under these conditions. miR395a was over expressed in leaf veins and root tissues in EBR-treated miR395a promoter::GUS plants. We integrated bioinformatics methods and publicly available DNA microarray data to predict potential targets of miR395a. GUN5-a multifunctional protein involved in plant metabolic functions such as chlorophyll synthesis and the abscisic acid (ABA) pathway-was identified as a possible target. ABI4 and ABI5, both genes positively regulated by ABA, were down-regulated by EBR treatment. In summary, our results suggest that EBR regulates seedling development and root growth of A. thaliana through miR395a by suppressing GUN5 expression and its downstream signal transduction.
authors.affiliation: Department of Life Science, National Taiwan University, Taipei 106, Taiwan. hlhsieh@ntu.edu.tw.
authors.forename: Li-Ling
authors.initials: LL
authors.lastname: Lin
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Wu
authors.forename: Hsuan-Cheng
authors.initials: HC
authors.lastname: Huang
authors.forename: Huai-Ju
authors.initials: HJ
authors.lastname: Chen
authors.forename: Hsu-Liang
authors.initials: HL
authors.lastname: Hsieh
authors.forename: Hsueh-Fen
authors.initials: HF
authors.lastname: Juan
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D060406:Brassinosteroids / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology; D008190:Lyases / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C470421:ABI4 protein, Arabidopsis; C409743:ABI5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D060406:Brassinosteroids; C572930:MIRN396 microRNA, Arabidopsis; D035683:MicroRNAs; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; D014157:Transcription Factors; D008190:Lyases; C561080:GUN5 protein, Arabidopsis; C023623:brassinolide