Editing of StSR4 by Cas9-RNPs confers resistance to Phytophthora infestans in potato
Ki-Beom Moon, Sujin Park, Ji-Sun Park, Hyo‐Jun Lee, Seung Young Shin, Soo Min Lee, Gyung Ja Choi, Sang‐Gyu Kim, Hye Sun Cho, Jae-Heung Jeon, Yong-Sam Kim, Youn‐Il Park, Hyun‐Soon Kim
Abstract
Potato ( Solanum tuberosum L.) cultivation is threatened by various environmental stresses, especially disease. Genome editing technologies are effective tools for generating pathogen-resistant potatoes. Here, we established an efficient RNP-mediated CRISPR/Cas9 genome editing protocol in potato to develop Phytophthora infestans resistant mutants by targeting the susceptibility gene, Signal Responsive 4 ( SR4 ), in protoplasts. Mutations in StSR4 were efficiently introduced into the regenerated potato plants, with a maximum efficiency of 34%. High co-expression of StEDS1 and StPAD4 in stsr4 mutants induced the accumulation of salicylic acid (SA), and enhanced the expression of the pathogen resistance marker StPR1 . In addition, increased SA content in the stsr4 mutant enhanced its resistance to P. infestans more than that in wild type. However, the growth of stsr4_3-19 and stsr4_3-698 mutants with significantly high SA was strongly inhibited, and a dwarf phenotype was induced. Therefore, it is important to adequate SA accumulation in order to overcome StSR4 editing-triggered growth inhibition and take full advantages of the improved pathogen resistance of stsr4 mutants. This RNP-mediated CRISPR/Cas9-based potato genome editing protocol will accelerate the development of pathogen-resistant Solanaceae crops via molecular breeding.