Over-expression of a C3H-type zinc finger gene contributes to salt stress tolerance in transgenic broccoli plants

C3H-type zinc finger proteins play important roles in plant growth, development, and stress responses. A C3H-type zinc finger gene, designated BoC3H, was isolated from broccoli (Brassica oleracea var. italica). The complete coding sequence of BoC3H was 1074 bp in length, encoding 357 amino acids with two CCCH motifs of C-X-7-C-X-5-C-X-3-H and C-X-5-C-X-4-C-X-3-H. The transcripts of BoC3H were profoundly induced by NaCl, and the highest expression level was observed at 18 h after treatment. Four broccoli lines over-expressing the BoC3H gene were obtained, and they exhibited higher germination rates, dry weight and chlorophyll content in response to salt stress as compared to those of wild type plants. Over-expression of BoC3H significantly decreased hydrogen peroxide (H2O2) level, relative electrical conductivity (REC) and malondialdehyde (MDA) contents, but dramatically increased free proline content, catalase, peroxidase and superoxide dismutase enzyme activities, resulting in less cell death in the leaves of transgenic plants. Taken together, our results suggest that BoC3H is likely to contribute to salt stress tolerance by regulating H2O2, REC, free proline, MDA and antioxidant enzyme levels in broccoli.