CLoning And Function Analyses Of HDA903 Gene From Populus Trichocarpa

Histone deacetylases(HDACs)plays an important role in plant growth,development and stress responses.HDACs catalyze histone deacetylation,which can affect the structure of chromatin and regulate gene transcription.To date,the function of woody plant HDACs in salt stress responses was less known.In this study,the RPD3/HDA1 subfamily gene HDA903 was cloned from Populus trichocarpa and its protein sequence,gene expression and function were studied.(1)The ORF sequence length of the HDA903 gene is 1506bp,and its encoded protein contains 501 amino acids.The HDA903 is a stable and hydrophilic protein,and its isoelectric point is 5.26.There is an HD AC domain at the N terminal of the protein.According to the systematic evolution tree,the HDA903 protein is closely related to the HDA19 from poplar(Populus euphratica).(2)Real-time PCR analyses showed that HDA903 gene could be expressed in different organs of Populus trichocarpa,but its expression was not tissue specific.The expression of HDA903 gene under ABA,salt and low temperature stress was analyzed.The results showed that salt stress could inhibit the expression of HDA903,cold could induce the expression of HDA903,and ABA could also regulate the expression of HDA903.(3)The vector containing HDA903-GFP fusion gene was constructed,and the fusion gene was introduced into the onion epidermal cells using a gene gun to observe the fluorescence signal.The results showed that the protein encoded by the HDA903 gene was localized in the nucleus.(4)The plant overexpressing vector pROK2-HDA903 was constructed,and the HDA903 gene was transformed into 84K poplar by Agrobacterium-mediated method to study the function of HDA903 in the response of poplar to salt stress.Under the salt stress,the plant height,fresh weight,dry weight and chlorophyll content of transgenic plants were higher than those of non-transgenic plants.Compared with non-transgenic plants,the activity of SOD,POD and content of proline in transgenic plants increased significantly,while the content of malondialdehyde(MDA)decreased.The above physiological indexes show that the overexpression of the HDA903 gene in the poplar greatly improved the salt tolerance of the transgenic plants.In conclusion,the HDA903 gene plays an important role in the response of poplar to salt stress.