Objective  In order to study the role of Populus tomentosa mitochondrial APX (PtomtAPX), the stress resistance of overexpression PtomtAPX transgenic tobacco was studied in this paper.

  Method  Overexpression PtomtAPX transgenic tobacco and wild type tobacco were treated with drought stress, salt stress and oxidative stress. Relative water content, chlorophyll content, malondialdehyde content, APX activity, AsA consumption, NADP/NADPH ratio, SOD activity were measured.

  Result  In this study, compared wild type plants with overexpression PtomtAPX, under oxidative stress, salt stress and drought stress, the APX activity, relative water content, chlorophyll content, AsA consumption, and NADP/NADPH ratio increase of the tobacco overexpression PtomtAPX gene were significantly higher than those of wild type, of which the APX activity of PtomtAPX transgenic tobacco was 1.77 times of wild type, the average relative water content was 1.15 times of wild type, the chlorophyll content was 1.6 times of wild type, AsA consumption was 1.11 times of wild type, and the ratio of NADP to NADPH was 1.18 times of the wild type. It suggested that the tobacco overexpressed PtomtAPX harbored stronger ROS scavenging ability.

  Conclusion  These indicate that mitochondrial APX acts a crucial role of abiotic stress tolerance in plants by eliminating H₂O₂ and preventing cell damage under abiotic stress.