The codon optimised gene produces an active human basic fibroblastic growth factor in rice cell suspension culture

The coding sequence of human basic fibroblast growth factor (hbFGF) was optimised for expression in rice. An expression cassette was constructed by fusing the PCR-amplified RAmy3D promoter, along with its 5'UTR, 3'UTR, and terminator sequences, to the codon-optimised hbFGF sequence. This cassette was inserted into the pCAMBIA1304 shuttle vector, which also contained the RAmy3D signal peptide. Agrobacterium tumefaciens strain LBA 4404 was used to transform rice callus. Among the transformed lines, the callus expressing the highest level of bFGF (38.1 mg/kg fresh weight) was identified via ELISA and selected for establishing a cell suspension culture. Expression and secretion of the recombinant bFGF into the culture medium were observed three days after incubating the transgenic rice cells in sucrose-free medium. The presence of recombinant bFGF was confirmed through Western blot and SDS-PAGE analyses. Furthermore, the rice-derived bFGF effectively stimulated the proliferation of NIH/3T3 cells, demonstrating a comparable biological activity to that of commercial bFGF.