Abstract
Background: The third-generation genome editing system CRISPR/Cas had shown strong application prospects in crop genetic improvement. However, this technology largely depends on genetic transformation. Public concerns on GMO (genetically modified organisms) safety, as well as related regulations, have restricted the application. Therefore, establishing DNA-free transfection system is important to promote CRISPR/Cas genome editing in agriculture.Results：In this paper, cell penetrating peptides fusion protein (CPP-mCherry) was found to be effective on DNA-free transfection. DNA sequences of nine tandem arginine (R9), one cysteine (cys), reporter mCherry and histidine label were sequentially constructed into pET 45B+ expression vector and transformed into Escherichia coli BL21(DE3) strain. CPP-mCherry fusion protein can be induced by 1mM IPTG for at least 1 hour in 28 °C. CPP-mCherry fusion protein can be obtained by 200W ultrasonication, then purified by Ni column and MWCO dialysis. The Arabidopsis thaliana root tips and leaves, as well as Chinese cabbage microspores and 3-week-old microspore embryo can be used as transfected recipient. Concentration can be selected between 10-100μg/ml and incubated overnight at room temperature. R9-cys-mCherry protein can be translocated into the nucleus of microspore. The transfection efficiency of root tips reached 100% and of microspore and MDE was 8.13% and 94.79%, respectively. Conclusions: Here, a CPP mediated DNA-free transfection system was built in dicots. These results lay a technical foundation of DNA-free genome editing.
Reversible activation of pH-sensitive cell penetrating peptides attached to gold surfaces
