Abstract:To enhance the expression of the sMdCAX1 gene in apple and improve the ability of Ca2+,absorption and transportion, an overexpression vector containing sMdCAX1 gene were constructed and transfered to Nagafu No. 6 by Agrobacterium-mediated method. In this research, MdCAX1 gene was cloned from apple Nagafu No. 6 and the nucleotide sequence encoding the N-terminal was removed from MdCAX1 by PCR method. The N-terminal truncated MdCAX1 was named as sMdCAX1. For constructing of the binary vector harboring sMdCAX1 fragment, the Sac I sites in sMdCAX1 fragment were mutated by overlapping PCR method under the condition of its encoding amino acid sequence unchanged. BamH I and Sac I restriction sites were added at the 3‘and 5‘ends of the mutated fragment, respectively, and named sMd1+2Mu. The sMd1+2Mu fragment and pYH4215 vector were digested by BamH I + Sac I respectively. The objective bands were recovered, ligated, transformed and screened. The plant over-expression vector pYH4215-sMd1 was obtained and introduced to apple cultivar Nagafu No. 6 with Agrobacterium tumefaciens EHA105 mediated transformation. The putative transgenic plantlets were identified by GUS histochemical staining and PCR testing. Two transformants were testified that sMdCAX1 was integrated to the apple genome. Moreover, sMdCAX1 gene was proved expressed in the 2 transgenic plants in transcriptional level by RT-PCR analysis. The study would contribute to further analysis of the MdCAX1 functions and laid a foundation for improving calcium content in apple fruits by transgenic approach. .