Over the past few years, kiwi bacteriosis - caused by Pseudomonas syringae pv. actinidiae (Psa) - generated significant economic losses for what concerns both yields and fruit quality.

Disease indexes to assess the virulence of Pseudomonas syringae pv. actinidiae strains inoculated on plants and Actinidia chinensis var. Deliciosa 'Hayward' leaf disks.
The research team assessed both the genetic differences of six housekeeping and effector genes as well as the in vitro/in vivo virulence on the same strain. The analyses showed a higher disease index for the strains isolated in 2014 compared to 2010. Molecular fingerprinting revealed a high level of variability of the Pseudomonas syringae pv. actinidiae strain populations from Piedmont orchards.
Three populations were identified:
- Piedmont 2010 made up of 12 strains;
- Piedmont 2014 made up of 21 strains;
- Lazio made up of 5 strains.
Source: Simona Prencipe, Maria Lodovica Gullino, Davide Spadaro, 'Pseudomonas syringae pv. actinidiae isolated from Actinidia chinensis Var. deliciosa in Northern Italy: genetic diversity and virulence', Giugno 2017, European Journal of Plant Pathology.