Effects of lighting conditions on Agrobacterium-mediated transient expression of recombinant hemagglutinin in detached Nicotiana benthamiana leaves inoculated with a deconstructed viral vector

Environmental control of plant incubation conditions before and after agroinfiltration is crucial during recombinant protein production using an Agrobacterium-mediated transient gene expression system to ensure high and consistent productivity. In an effort to design a low-cost and energy-saving upstream production process, we assessed the lighting effects during the post-agroinfiltration process on the leaf content of recombinant influenza hemagglutinin (HA) expressed by the magnICON® deconstructed viral vector system. Detached Nicotiana benthamiana leaves were incubated for 6 days post-agroinfiltration under five different lighting conditions: (1) 6-day dark (D–D), (2) 3-day dark followed by 3-day lighting at a photosynthetic photon flux density (PPFD) of 100 µmol m−2 s−1 (D–L100) and (3) its reversed lighting condition (L100–D), and (4) 6-day lighting at a PPFD of 100 µmol m−2 s−1 (L100–L100) and (5) 500 µmol m−2 s−1 (L500–L500). The HA content at 6 days post-agroinfiltration was 25 µg gFM−1 (D–D), 408 µg gFM−1 (D–L100), 566 µg gFM−1 (L100–L100), 693 µg gFM−1 (L500–L500) and 756 µg gFM−1 (L100–D), respectively. The HA content in L100–D was not less than that in the other lighting conditions, indicating that lighting during the latter half of the post-agroinfiltration process is not crucial for recombinant protein production. Based on these findings, we propose to implement a multiphase environment control in the upstream production process of transient expression system, wherein reduced number of light sources may provide a low-cost and energy-saving design for the post-agroinfiltration phase. Post-agroinfiltration 3-day lighting and subsequent 3-day dark enabled detached Nicotiana benthamiana leaves to produce and accumulate a high amount of recombinant influenza hemagglutinin using the magnICON® transient expression system.