Abstract: Immature embryo-derived callus is more efficient for transgenic and plant regeneration than calli from other explant tissues. It’s reported that embryogenic callus can be initiated from mature embryos. The use of mature embryos from dry seed are easy to handle, available year round and in bulk quantities. In this study we established an efficient transgenic acceptor system and developed some new methods on maize (Zea mays L.) tissue culture, plant regeneration and genetic transformation with embryogenic callus initiated from mature embryos of three elite inbred lines CML295, CML304, and 18-599R. The calli were cultured in subculture medium of immature embryos. Tissue slice showed that the structure of callus formed from mature embryos was the same as those from immature embryos, being the typeⅡ embryogenic callus. The calli were transferred into regeneration medium of immature embryos supplemented with 2 mg L-1 6-BA. The regeneration frequencies of the calli from mature embryos of CML295, CML304, and 18-599R were 68.6%, 75.4%, and 84.8%, respectively. Vector pCAMBIA1301 was transformed into callus from mature embryos of CML295, CML304, and 18-599R by particle gun using GUS as a report gene; vector pCAMBIA1303 was transformed by particle gun using GFP as a report gene, with GUS staining frequency of 57.9%, 62.5%, and 73.1%; and GFP transient expression frequency of 23.3%, 40%, and 45.5%, respectively. The transgenic rates of embryogenic callus from mature embryos of the three inbred lines were similar to those from immature embryos. In conclusion, using embryogenic callus from mature embryos as transgenic acceptors is efficient and available.

Key words: Mature embryo, Maize, Embryogenic callus, Regenetion, Transformation