Expression And Function Analyses Of HDA909 Gene From Populus Trichocarpa

In this study,the RPD3/HDA1-type histone deacetylase gene was cloned from Populus trichocarpa,and its protein sequence,gene expression and function in response to drought and fungal infection were studied.(1)The length of HDA909 ORF sequence was 1323 bp,encoding a protein composed of 440 amino acids.The protein is an acidic and hydrophilic protein with an isoelectric point of 5.28.There is an HD AC domain at the N-terminal of the HDA909 protein.The phylogenetic tree analysis showed that this protein is closely related to the HDA6 of Populus euphratica.(2)Gene expression analysis showed that HDA909 could expresse in various organs,but the expression levels were not significantly different.(3)GFP-HDA909 fusion gene expression vector was constructed,and the fusion gene was introduced into onion epidermal cells using a gene gun to observe the fluorescence signal.The result showed that HDA909 protein was localized in the nucleus.(4)The pROK ?-HDA909 over-expressing vector was constructed,and the HDA909 gene was transformed into Populus trichocarpa by Agrobacterium-mediated method to study its function in response to drought and fungal infection.Under the drought induced by mannitol,the plant height,root length,root number and fresh weight of cultured transgenic plants were not significantly different from that of non-transgenic plants.Under the drought without watering,no significant differences in plant height and ground diameter were observed between the young transgenic and non-transgenic plants.To analyze the function of HDA909 in fungal infection,the leaves of the transgenic and non-transgenic plants were inoculated with fungus Alternaria alfernate.The Rate of fungal infection and the lesion area in the leaves of transgenic plants were respectively lower and smaller than that of non-transgenic plants.DAB staining results showed that the leaves of the transgenic plants accumulated less hydrogen peroxide in contrast to non-trangenic plants.The above results indicate that HDA909 gene has no obvious regulatory role in the response to drought stress,but plays an important role in the response to fungal infection.