Abstract: Objective To explore the mechanisms by which HFBI fusions increase recombinant fusion protein accumulation in
plants. Methods The HFBI sequence from Trichoderma reesei was synthesized and two plant expression vectors for expression
of green fluorescence protein (GFP) and GFP-HFBI were constructed. The vectors were inoculated in Nicotiana benthamiana
plants through agroinfiltration, and the expression levels and mRNA accumulation levels of GFP in Nicotiana leaves were
examined by Western blotting, ELISA and RT-PCR. Results The HFBI fusion tag significantly enhanced the accumulation of
GFP in the leaves of N. benthamiana without causing toxic effects. Endoplasmic reticulum-targeted GFP-HFBI fusion induced
the formation of spherical protein particles in the plant cells. Conclusion HFBI fusions can increase the accumulation of its
fusion partner in plants by forming stable protein particles, which probably shields the target protein from endogenous
protease-induced degadation. HFBI fusion technology provides an alternative to improving recombinant protein expression in
plants from agroinfection-compatible expression vectors.