Psa causes leaf spots, dieback, and canker that sometimes lead to the death of the vine; while Pseudomonas syringae pv. actinidifoliorum (Psaf), which is also pathogenic on kiwifruit causes only leaf spots.
In order to conduct an epidemiological study to track the spread of the epidemics of these two pathogens in France, French scientists have developed a Multilocus Variable-Number of Tandem Repeats (VNTR) Analysis (MLVA).
MLVA was conducted on 340 strains of Psa biovar 3 isolated in Chile, China, France, Italy and New Zealand, and on 39 strains of Psaf (Pseudomonas syringae pv. actinidifoliorum) isolated in Australia, France and New Zealand.
Eleven polymorphic VNTR loci were identified in the genomes of Psa biovar 3 ICMP 18744 and of Psaf ICMP 18807. MLVA enable the structuring of Psa biovar 3 and Psaf strains in 55 and 16 haplotypes, respectively. MLVA and Discriminant Analysis of Principal Components revealed that strains isolated in Chile, China and New Zealand are genetically distinct from Psa strains isolated in France and in Italy, which appear to be closely related at the genetic level. In contrast, no structuring was observed for Psaf.
Scientists have developed a reliable set of tools, which combines MLSA (Multilocus Sequence Analysis) and MLVA schemes that are useful for exploring diversity among Psa strains isolated in France. This MLVA scheme is a good candidate for tracing the dispersal routes of Psa in other places in the world where kiwifruit canker spreads. Scientists conclude that it would be interesting to test this MLVA scheme by assessing the genetic structuring of Psa biovar 1 and Psa biovar 2 as well.
The full version is available online, since July 2015 at:
http://aem.asm.org/content/early/2015/07/20/AEM.01688-15.abstract
Source: A. Cunty, S. Cesbron, F. Poliakoff, M-A. Jacques, C. Manceau, 'The origin of the outbreak in France of Pseudomonas syringae pv. actinidiae biovar 3, the causal agent of bacterial canker of Kiwifruit, revealed by a Multilocus Variable-number of Tandem Repeat Analysis', 2015, Applied and Environmental Microbiology, doi:10.1128/AEM.01688-15
Contacts:
Charles Manceau
Laboratoire de la santé des végétaux, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail, Angers, France
Email: charles.manceau@anses.fr