[Construction of vectors for expression of cleavable tandem repeat Thanatin fusion protein in plants]

Thanatin, a 21-residue antimicrobial peptide, is an inducible insect peptide with a broad range of activity against bacteria and fungi. It can improve the expression level of the antimicrobial peptide in plants to express the peptide as tandem repeat fusion protein containing multiple Thanatin copies. However, the fusion protein has no antimicrobial activity. To make the fusion protein automatically break into single Thanatin unit with antimicrobial activity, the fused Thanatin was spaced by a linker peptide, which was cleavable in vivo. The soybean (Glysine max L.) chitinase signal peptide was fused to the N end of the fusion protein to induce the antimicrobial peptide accumulated in intercellular space. To construct the vectors for expression of the fusion protein, the overlapped primers were used to clone the antimicrobial peptide gene and the co-adhesive end restriction and ligation strategy was used to add the repeat unit one by one. Vectors containing 1 to 5 repeat units of Thanatin were constructed respectively. These vectors were being used to transform plants to improve plant disease resistance.