Overexpression of Chrysanthemum lavandulifolium ClCBF1 in Chrysanthemum morifolium 'White Snow' improves the level of salinity and drought tolerance

This paper reports the first study on plant CBF transcription factors (TF) in salt and drought stress responses in Chrysanthemum lavandulifolium. A CBF homolog gene, named as ClCBF1, from C. lavandulifolium was isolated using rapid amplification of cDNA ends (RACE). The deduced peptide is comprised of 210 amino acids (AA) containing an AP2 structural domain characteristic of the AP2 gene family. Quantitative real-time PCR revealed that ClCBF1 gene exhibit differential expression patterns across root, leaf and stem tissues, and it was strongly induced under salt and drought treatments of C. lavandulifolium. Overexpression of ClCBF1 in C. morifolium 'White Snow' resulted in stronger tolerance to salt and drought stresses. The ClCBF1 expression level, enzymatic activities of superoxide dismutase and peroxidase, and contents of proline and soluble proteins were enhanced in these transgenic lines, they were repressed in the antisense transgenic lines under the same stress conditions. Results indicate that ClCBF1 represents a promising candidate gene in improving abiotic stress tolerance among ornamental plants.