ObjectivePlants produce excessive reactive oxygen species(ROS)and have to suffer serious oxidative damage when exposed to long-term abiotic stress. Peroxisomes can remove ROS and regulate the re-dox balance of cells. The PEX gene is involved in the biogenesis and proliferation of peroxisomes. Overexpressing PEX11 lines improve the proliferation of peroxisomes, which is important for the promotion of antioxidant capacity in plants.Populus euphratica is an optimal material for studying stress resistance mechanism in woody plants.Here we are going to explore the function of PEX11 in P.euphratica response to abiotic stress.

MethodIn this study we isolated PEX11 gene from cDNA of P.euphratica leaves and named it as PePEX11, and bioinformatics tools were used to analyze PePEX11 protein, then qRT-PCR was used to analyze the expression pattern of PePEX11 in P.euphratica.Meanwhile, plant expression vector pCAMBIA1301-35S::PePEX11 was constructed, and Arabidopsis thaliana was transformed for detecting antioxidant capacity under salt stress.

ResultThe results showed that PePEX11 had 543 bp in length and encoding 180 amino acids. PePEX11 protein had multiple transmembrane domains and may function at the membrane.qRT-PCR analysis showed that PePEX11 gene highly expressed in mature leaves, following by young leaves, and had least expression in stems. The expression level of PePEX11 gene was also up-regulated by salt stress. Function analysis of PePEX11 overexpression lines in Arabidopsis thaliana showed that the root of oxPePEX11 was significantly longer than that of the wild type when treated with 150 mmol/L NaCl in the medium.After two weeks of salt treatment in soil, PePEX11 overexpression lines had better vegetative growth, showing better salt tolerance phenotype. Overexpression of PePEX11 significantly(P < 0.05)increased the activities of several antioxidant enzymes in A. thaliana. In addition, DAB staining assay displayed that the content of H₂O₂ in leaves of oxPePEX11 was lower than wild type.

ConclusionIn summary, we cloned PePEX11 from P. euphratica and proved that PePEX11 improved the antioxidant capacity under salt stress and confers salt tolerance in A. thaliana.