Characterization of secreted proteins by symbiont technology

By adding Agrobacterium plant growth regulator genes to a binary plant transformation vector also encoding a gene of interest, we engineered plant tissues capable of autonomous cell division and vascularization while expressing biomolecules on the stems of host plants and in vitro plant cell tissue culture cured of Agrobacterium. We refer to these repurposed Agrobacterium galls as symbionts to reflect their intended beneficial interaction with the host plant.  When grown in vitro, symbionts efficiently export secreted proteins into the culture media and may serve as an advantageous platform for heterologous protein expression from plant cells.  In this experiment we monitored accumulation of a secreted marker portein (Flowering Locus T, tagged with mCherry) in the media of tomato cell symbionts grown in-vitro and characterized the native proteins that also accumulated in the culture medium.