An Affordable, Scalable, and Labor-less Experimental Setup for the Vacuum-assisted, Agrobacterium-mediated Transient Expression in Tomato (Solanum lycopersicum)

Several methods are available for use, to deliver the gene of interest into plants. Among these, Agrobacterium-mediated transformation utilizes binary vector systems to achieve the stable transformation of plants. Alas, this process is labor-intensive and time-consuming as several months are needed to obtain a true transgenic plant. Transient gene expression (e.g., vacuum-infiltration) systems were offered as an alternative over stable transformation, specifically to overcome time-related drawbacks. However, this method requires expensive equipment such as vacuum chambers. In this study, we report a vacuum-infiltration protocol for the transient expression of a reporter gene, modified green fluorescent protein (mGFP), in tomato seedling. With a basic experimental setup (including a custom-built growth chamber) with affordable equipment, we showed that the entire leaf can be infiltrated by applying a mere 200 millibar vacuum for 6 minutes, and thus the transient expression can be achieved in tomato plant, evidenced by PCR-based detection of the T-DNA, detection of mGFP both analytically with SDS-page analysis, and visually by the images acquired by fluorescence microscopy. Furthermore, different Agrobacterium tumefaciens strains were tested for their transformation efficiency, and we showed that LBA4404 was the most effective strain to use in the vacuum-assisted transient expression.