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Open Access Research article

Ambient temperature enhanced freezing tolerance of Chrysanthemum dichrum CdICE1 Arabidopsis via miR398

Yu Chen12, Jiafu Jiang1, Aiping Song1, Sumei Chen1, Hong Shan1, Huolin Luo1, Chunsun Gu1, Jing Sun1, Lu Zhu1, Weimin Fang1 and Fadi Chen1*

Author Affiliations

1 College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China

2 Grass Research Centre, Institute of Botany, Jiangsu Province & Chinese Academy of Sciences, Nanjing 210014, Jiangsu China

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BMC Biology 2013, 11:121  doi:10.1186/1741-7007-11-121

Published: 19 December 2013

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.

Keywords:
Chrysanthemum dichrum; CdICE1; Freezing tolerance; miR398; CSD