Ascorbate peroxidase(APX)is a key enzyme for active oxygen scavenging of higher plants,and it plays an important role in plants against abiotic stresses.In this study,a thylakoidal APX(TAPX)gene was cloned from sugarcane leaves by using RT-PCR technique,which was registered in GenBenk with the accession number JQ958327.Bioinformatics analysis showed that the new gene contained a 1,422 bp open reading frame and encoded 473 amino acids,and the predicted molecular weight was 51.1 kDa,containing the typical functional area and heme binding sites of peroxidase gene family.Real-time fluorescence quantitative PCR analysis showed the TAPX gene expressed in the roots,stems and leaves of sugarcane plant,and the highest expression level was found in the leaves.The TAPX gene was expressed in three exogenous stresses,i.e.polyethylene glycol(PEG),NaCl and H2O2.The expression pattern varied due to different regulatory mechanisms and the impact of low temperature stress on the expression is not significant.The TAPX gene was successfully expressed in E.coli.The TAPX gene excessive plant expression vector was built and transformed into tobacco with Agrobacterium-mediation,and transgenic tobacco plants were obtained.In conclusion,the TAPX gene was mainly expressed in the green tissue of sugarcane plant.It is presumed that TAPX gene is related with sugarcane resistance to osmotic stress.Further investigation on the biological functions of TAPX in sugarcane are warranted.