title: Ambient temperature enhanced freezing tolerance of Chrysanthemum dichrum CdICE1 Arabidopsis via miR398.
abstract: BACKGROUND
  ICE (Inducer of CBF Expression) family genes play an important role in the regulation of cold tolerance pathways. In an earlier study, we isolated the gene CdICE1 from Chrysanthemum dichrum and demonstrated that freezing tolerance was enhanced by CdICE1 overexpression. Therefore, we sought to determine the mechanism by which ICE1 family genes participate in freezing tolerance.
  
  
  RESULTS
  Using EMSA (Electrophoretic Mobility Shift Assay) and yeast one-hybrid assays, we confirmed that CdICE1 binds specifically to the MYC element in the CdDREBa promoter and activates transcription. In addition, overexpression of CdICE1 enhanced Arabidopsis freezing tolerance after transition from 23°C to 4°C or 16°C. We found that after acclimation to 4°C, CdICE1, like Arabidopsis AtICE1, promoted expression of CBFs (CRT/DRE Binding Factor) and their genes downstream involved in freezing tolerance, including COR15a (Cold-Regulated 15a), COR6.6, and RD29a (Responsive to Dessication 29a). Interestingly, we observed that CdICE1-overexpressing plants experienced significant reduction in miR398. In addition, its target genes CSD1 (Copper/zinc Superoxide Dismutase 1) and CSD2 showed inducible expression under acclimation at 16°C, indicating that the miR398-CSD pathway was involved in the induction of freezing tolerance.
  
  
  CONCLUSIONS
  Our data indicate that CdICE1-mediated freezing tolerance occurs via different pathways, involving either CBF or miR398, under acclimation at two different temperatures.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Jiafu
authors.initials: J
authors.lastname: Jiang
authors.forename: Aiping
authors.initials: A
authors.lastname: Song
authors.forename: Sumei
authors.initials: S
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Shan
authors.forename: Huolin
authors.initials: H
authors.lastname: Luo
authors.forename: Chunsun
authors.initials: C
authors.lastname: Gu
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.forename: Lu
authors.initials: L
authors.lastname: Zhu
authors.forename: Weimin
authors.initials: W
authors.lastname: Fang
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China. chenfd@njau.edu.cn.
authors.forename: Fadi
authors.initials: F
authors.lastname: Chen
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D031202:Chrysanthemum / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005615:Freezing; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C116166:COR15 protein, Arabidopsis; C510502:ICE1 protein, Arabidopsis; C543882:MIRN398 microRNA, Arabidopsis; D035683:MicroRNAs; C520629:RD29a protein, Arabidopsis; D014157:Transcription Factors; C072392:COR6.6 protein, Arabidopsis; D013482:Superoxide Dismutase; C586060:CSD1 protein, Arabidopsis; C586061:CSD2 protein, Arabidopsis