The fused gene STI-STII-LTB was cloned into plant expression vector pBI121-MARs to replace GUS gene, another plant expression vector was constructed without MAR sequence.

• 将融合基因STI-STII-LTB构建到带有核基质结合区序列(MARs)的植物表达载体pBI121-MARs中GUS基因的位置。