P-207 - Immune Attenuation of Nicotiana benthamiana for Molecular Farming

Plant biofactories present an opportunity for sustainable, scalable production of recombinant proteins but currently face a bottleneck in production capacity. In Nicotiana benthamiana, yield may be limited by the plant immune response to Agrobacterium tumefaciens, used for transient expression systems. Changes to the N. benthamiana immune profile have previously been shown to improve recombinant protein accumulation in this host; knock-down of the immune receptor, CORE, resulted in 6- to 8-fold increase in GFP expression. A screen of further immunity gene knock-downs showed significantly increased recombinant protein yield for at least four further immunity targets. Here, we continue to explore immune attenuation for plant biofactory optimisation through virus-induced gene silencing (VIGS) of further immunity genes in older N. benthamiana plants, which offer far more biomass but are limited in use because of their developed immune responses. We then validate positive hits by generating virus-induced gene editing (VIGE) mutants and testing yield of industrially relevant proteins such as SARS-CoV-2 antibodies. We also explore the mechanistic role of ‘positive hit’ genes to improve our understanding of the interaction between A. tumefaciens and N. benthamiana. The ultimate aim of the work will be to generate novel N. benthamiana lines with attenuated immune responses to maximise recombinant protein output in molecular farming.