Phylogenetic status and host range of plant pathogen Pseudomonas syringae isolated from sugar beet fields in Serbia
Résumé
Background: Pseudomonas syringae is a very heterogeneous bacterial species, inhabiting various ecological niches, affecting numerous host plants and representing great phylogenetic diversity. In 2013, a leaf spot disease of sugar beet caused by P. syringae was detected for a first time in Serbia.
Objectives: We aimed to determine the phylogenetic diversity of isolates from sugar beet and the potential host range in order to define status of isolates within P. syringae species complex and estimate the pathogenic diversity.
Methods: Twenty representatives among 104 collected P. syringae isolates from commercial fields of sugar beet were tested. Sequencing of cts gene, sequence analysis by the Neighbor-joining method and comparison with 59 P. syringae strains from 13 phylogenetic groups was performed for all tested isolates. The host range was determined by leaf inoculation of 16 different plant species in controlled greenhouse conditions. The virulence and aggressiveness of tested isolates were measured.
Results: Phylogenetic analysis showed that all tested P. syringae isolates from sugar beet belong to the 02b phylogroup within the P. syringae species complex, representing one of the most abundant P. syringae phylogroups in the environment. Host range tests revealed extremely aggressive isolates causing symptoms on every tested plant (70% of tested isolates) as well as weakly aggressive isolates (30% of tested isolates). These findings provide the first insight to status of collected isolates from Serbian sugar beet fields within P. syringae metapopulation and provide information about potential risk to other crops.