I am currently using a protoplast system to identify novel inhibitors of plant PTI (Pattern triggered immunity). I bulk-up the plasmid encoding for these inhibitors in E.coli and then isolate plasmid to transfect my protoplasts and express the inhibitor in them and then challange them with flg22. What i noticed is that my no flg22 controls seam to have higher PTI activation than untransformed controls. My suspicion is that some bacterial elicitors are present in the plasmid pre and therefore activate PTI. Has anyone come accross this problem before and if so how did they solve it? Any suggestions?
Many thanks in advance,