Introducing CRISPR/Cas9 into the kiwifruit pathogen Pseudomonas syringae pv. actinidiae (Psa)

Abstract

Pseudomonas syringae pv. actinidiae (Psa) is an emerging bacterial pathogen of kiwifruit, a major primary export of New Zealand. The emergence of Psa in New Zealand in 2010 caused immense financial grief with the disease affecting fruit yield and vine health. Psa is also found in other kiwifruit cultivating countries where it has also negatively impacted the kiwifruit industry, causing considerable financial strain for growers.

Genetic analysis has provided valuable insight into the origin and evolution of Psa in New Zealand, including the emergence of resistance to antimicrobials such as copper control compounds. This study provides a detailed comparison of New Zealand Psa with other Psa varieties, clarifying aspects such as restriction modification systems. Informed by this analysis, the study describes attempts to insert a CRISPR/ Cas9 genome editing tool into Psa. It is believed that to achieve this, alterations of the Streptococcus pyogenes derived CRISPR/Cas9 plasmid was required. The CRISPR/Cas9 system will provide a valuable tool for the analysis of Psa in terms of the pathogen virulence and resistance to control compounds.