ena-STUDY-Reseach Institute of Horticulture-07-08-2018-11:06:10:024-111
Characterization and phylogeny of Pseudomonas spp., on Cornus
In 2013-2018 on the leaves of cornelian cherry (Cornus mas L.) small necrotic spots with regular shape of 3 mm in diameter merging also to large necrotic lesions and in 2016 the on leaves of red dogwood (Cornus sanguinea L.) shrubs extensive necrotic area running from leaf petiole, were observed. From samples with diseased tissue, fluorescent bacteria were isolated, showing a morphology similar to that of the genus Pseudomonas. Their identity was confirmed by DNA amplification with primers Ps-for and Ps-rev, specific for the genus Pseudomonas. The phenotypic characters using LOPAT tests [levan production from sucrose (L), presence of oxidase (O), pectolytic activity on potato (P), the presence of arginine dihydrolase (A), hypersensitivity reaction on tobacco (T)], allowed to classify the isolates to species of Pseudomonas syringae (LOPAT group Ia). The pathogenicity of isolates from both hosts?? was proved on young leaves of  Cornus mas, confirming the ability to infect the species. Detection of genes coding for the phytotoxins coronatine (cfl), syringomycin (syrB and syrD), and yersiniabactin (irp1) showed that none of strains from cornelian cherry nor red dogwood possessed cfl gene, but 5 out of 6 cornelian cherry strains contained the irpl gene.. Only the strain 1439, isolated from red dogwood possessed the syrD and syrB genes. Sequence analysis of the 16S rRNA, and housekeeping genes gyrB and rpoB showed that strains from cornelian cherry are most closely related to the hazelnut pathogen Pseudomonas avellane, and that the strain from red dogwood could be identified as Pseudomonas syringae pv. syringae. Further research will determine the exact taxonomic position of the cornelian cherry strains.
In 2013-2018 on the leaves of cornelian cherry (Cornus mas L.) small necrotic spots with regular shape of 3 mm in diameter merging also to large necrotic lesions and in 2016 the on leaves of red dogwood (Cornus sanguinea L.) shrubs extensive necrotic area running from leaf petiole, were observed. From samples with diseased tissue, fluorescent bacteria were isolated, showing a morphology similar to that of the genus Pseudomonas. Their identity was confirmed by DNA amplification with primers Ps-for and Ps-rev, specific for the genus Pseudomonas. The phenotypic characters using LOPAT tests [levan production from sucrose (L), presence of oxidase (O), pectolytic activity on potato (P), the presence of arginine dihydrolase (A), hypersensitivity reaction on tobacco (T)], allowed to classify the isolates to species of Pseudomonas syringae (LOPAT group Ia). The pathogenicity of isolates from both hosts?? was proved on young leaves of  Cornus mas, confirming the ability to infect the species. Detection of genes coding for the phytotoxins coronatine (cfl), syringomycin (syrB and syrD), and yersiniabactin (irp1) showed that none of strains from cornelian cherry nor red dogwood possessed cfl gene, but 5 out of 6 cornelian cherry strains contained the irpl gene.. Only the strain 1439, isolated from red dogwood possessed the syrD and syrB genes. Sequence analysis of the 16S rRNA, and housekeeping genes gyrB and rpoB showed that strains from cornelian cherry are most closely related to the hazelnut pathogen Pseudomonas avellane, and that the strain from red dogwood could be identified as Pseudomonas syringae pv. syringae. Further research will determine the exact taxonomic position of the cornelian cherry strains.