Expression of a populus histone deacetylase gene 84KHDA903 in tobacco enhances drought tolerance.

Histone deacetylases (HDACs) play a key role in regulating plant growth, development and stress responses. However, functions of HDACs in woody plants are largely unknown. In this study, a novel gene encoding a RPD3/HDA1-type histone deacetylase was cloned from 84K poplar (Populus alba×Populus glandulosa) and designated as 84KHDA903. The 84KHDA903 encodes a protein composed of 500 amino acid residues, which contains a conserved HDAC domain. Transient expression of 84KHDA903 in onion epidermal cells suggested that it was exclusively localized in nucleus. The 84KHDA903 exhibited different expression patterns under drought, salt and ABA treatments. The expression of 84KHDA903 was responsive to drought and ABA but not to salt. To understand the function of 84KHDA903 in stress responses, the 84KHDA903 gene was transformed into tobacco. The expression of 84KHDA903 in tobacco increased the tolerance of transgenic seeds to mannitol but not to salt. In adult stage, the 84KHDA903-expressing tobacco exhibited drought tolerance and showed strong capacity to recover after drought. During the recovery period, the stress-responsive genes including NtDREB4, NtDREB3 and NtLEA5 were induced to be highly expressed in the 84KHDA903 transgenic plants in contrast to wild-type plants. Taken together, for the first time, we reported a RPD3/HDA1-type histone deacetylase from poplar, 84KHDA903, which acted as a positive regulator in drought stress responses.