High-Throughput Transfection and Analysis of Soybean (Glycine max ) Protoplasts

With the advent of plant synthetic biology, there is an urgent need to develop plant-based systems that are able to effectively enhance the speed of design-build-test cycles to screen large numbers of synthetic constructs. Thus far, protoplasts have served to fill this need, with cell suspension cultures serving as the primary source tissue to enable high-throughput protoplast experimentation. The possibility to use low-cost food-grade enzymes for cell wall digestion along with polyethylene glycol (PEG)-mediated transfection makes protoplasts particularly suited to automation and high-throughput screening. In other systems for which synthetic biology is well established (model bacteria and yeast), libraries of components, i.e., promoters, 5' untranslated regions, 3' untranslated regions, terminators, and transcription factors, serve as the basis for the design of complex genetic circuits. In order for synthetic biology to make similar strides in plant biology, well-characterized libraries of functional genetic parts for plants are required, necessitating the need for high-throughput protoplast assays.In this chapter, we describe an optimized method for the preparation of soybean (Glycine max ) dark-grown cell suspension cultures, followed by protoplast isolation, automated transfection , and subsequent screening.