Abstract:

Cold repeat binding factor (CBF) proteins, specifically binding to the cold repeat (CRT)/dehydration-responsive element (DRE), have been identified as a group of important transcription activators of plants which regulate the expression of genes in response to the cold, drought and high-salt stresses. PtCBF5 from Populus tomentosa was cloned by RT-PCR methods, GenBank accession No. DQ354395. It contained an ORF of 696 bp encoding 231 amino acids domain that showed the typical characteristics of CBF gene family. The transcripts of PtCBF5 were the most abundant mRNA products in leaves, however relatively scarce in stem and roots using semi-quantitative RT-PCR. The shoots were treated with low-temperature, dehydration, NaCl, and ABA (abscisic acid). PtCBF5 gene could be greatly induced by low-temperature and dehydration stresses. Expression of PtCBF5 gene was increased in 30 min after freezing or drought treatments, and reached to a peak after 2 h in freezing or 6 h in dehydration. PtCBF5 may play very important roles in early signal transduction related to the cold and dehydration stresses.

Key words: poplar(Populus tomentosa), gene expression, cold repeat /dehydration responsive element (CRT/DRE), transcription analysis