Poster Presentation Society for Molecular Biology and Evolution Conference 2016

The origin and evolution of the emergent plant pathogen Pseudomonas syringae pv. actinidiae (#610)

Honour McCann 1 , Li Li 2 , Yifei Liu 3 , Elena Colombi 1 , Matthew Templeton 4 , Paul Rainey 1 5 6 , Hongwen Huang 2 3
  1. Massey University, Auckland, NORTH ISLAND, New Zealand
  2. Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
  3. South China Botanical Institute, Chinese Academy of Sciences, Guangzhou, China
  4. Plant and Food Research, Auckland, New Zealand
  5. Max Planck Institute for Evolutionary Biology, Plon, Germany
  6. Ecole Superieure de Physique et de Chimie Industrielles, Paris, France

A new lineage of the bacterial plant pathogen Pseudomonas syringae pv. actinidiae (Psa) recently emerged to cause a pandemic of bleeding canker disease on kiwifruit (Actinidia chinenis). Evidence of recombination between the pandemic lineage and strains isolated during earlier outbreaks led us to predict the existence of a genetically diverse and recombining source population of Psa, from which stochastic sampling events followed by selection in agricultural environments for host specialization occurred. We hypothesized that China was the likeliest origin of the pathogen source population, as it is the origin of A. chinensis and the center of kiwifruit abundance and diversity. In order to identify the location of and extent of diversity within the source population of Psa, pinpoint the origin of the recent pandemic, and investigate the evolutionary processes leading to its emergence, a phylogenomics study was initiated to sample P. syringae from kiwifruit across six provinces in China as well as Japan and Korea. To date, we have found that all Chinese Psa are members of the same lineage as the pandemic isolates. Our work reveals there is far greater diversity within this lineage than was previously known, indicating Psa was circulating in China before the global outbreak began. While the sublineage responsible for the latest pandemic emerged in China, Japan and Korea harbour strains from multiple lineages of Psa, suggesting the center of origin of the pathogen is outside the center of host plant diversity.