Isolation and functional characterization of the SpCBF1 gene from Solanum pinnatisectum.

Low temperature causes a negative impact on plant growth and development, but plants evolve a series of mechanisms to respond to chilling stress, and one of them is CBF [C-repeat (CRT)/dehydration-responsive element (DRE) binding factor] gene family which has been well studied in different crops. In this paper, a new CBF1 gene, named as SpCBF1, was isolated from frost-tolerant Solanum pinnatisectum by PCR and analyzed for its function in cold-tolerance by over-expression technique. The ORF of SpCBF1 was 666 bp long and encoded a protein of 221 amino acids with a predicted molecular mass 24.5821 kDa and theoretically isoelectric point 5.0. SpCBF1 protein contained a highly conserved specific AP2/ERF domain. SpCBF1 was expressed in all tested tissues with the highest level in tuber and the lowest in root, and induced by chilling stress (0 °C). Under natural low temperature condition (1-10 °C), plants over-expressing SpCBF1 (OE) exhibited slighter necrotic lesion and lower necrotic injury, compared with untransformed Solanum tuberosum cv. Désirée (WT) and antisense-StCBF1 control lines. Over-expression of CBF1 increased the level of COR (cold-regulated) gene transcripts in OE lines, and the physiological indexes related to cold tolerance like the contents of SOD, soluble protein, MDA, proline and soluble sugar were higher in OE lines than in WT except RWC which was lower. All these results indicated that SpCBF1 gene plays a promoting role in potato responding to cold stress.