Abstract: Arabidopsis cold-tolerant gene AtCOR15a was controlled by cold-inducible promoter RD29A and was put into a binary expression vector. The gene was introduced into tomato variety Ailsa Craig mediated by Agrobacterium tumefaciens. The results showed that the cold tolerance of the three lines with high-level transgene expression was significantly enhanced compared with the wild type tomato. The expression levels of AtCOR15a in transgenic plants presented with a trend of first increasing and then decreasing，and reaching its maximum at 6 h after cold treatment at 4 ℃. Meanwhile，the expression of endogenous cold-inducible genes such as SlDehydrin-like（SlDEHL）and SlDehydrin Ci7（SlCi7）was promoted；the membrane permeability，malondialdehyde content，and the accumulations of reactive oxygen species H2O2 and were decreased；the activities of superoxide dismutase，peroxidase，and catalase，as well as free proline contents were increased in the transgenic lines compared with the wild type tomato under cold treatment. Therefore，ectopic expression of AtCOR15a could enhance the cold tolerance of transgenic tomato.

Key words: tomato, AtCOR15a, transgenic, cold tolerance