Establishment of the straightforward electro-transformation system for Phytophthora infestans and its comparison with the improved PEG/CaCl2 transformation

• The straightforward electroporation was feasible for P. infestans.
• Efficiency of the electroporation was higher than that of the protoplast method.
• The electroporation is simpler than the protoplast method.
• The electroporation requires less starting materials than the protoplast method.
• The electroporation requires less operating time than the protoplast method.

Phytophthora infestans is the most devastating pathogen of potato. For the biology study of P. infestans at the molecular level, one of the difficulties is the technique for the genetic transformation. In this study, the straightforward electro-transformation system was established for P. infestans with a green fluorescent protein expression vector and compared with the improved PEG/CaCl2 mediated protoplast transformation system. The results showed that the straightforward electro-transformation could work in P. infestans and 32 positive transformants were obtained per about 1.10 × 106 zoospores. The transformants per μg of vector DNA were 1.08. The transformation efficiency of the straightforward electro-transformation was approximately 2 times higher than that of the improved PEG/CaCl2 mediated protoplast transformation (17 positive transformants per about 1.05 × 106 protoplasts, 0.58 transformants per μg of vector DNA) according to the reported procedures. Furthermore, compared with the improved PEG/CaCl2 transformation, the straightforward electroporation is simpler and requires less starting materials and operating time from collecting material to obtaining the resistant transformants. Our work will lay a foundation for the biology study of P. infestans in the future.