Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro

Abstract

Citrus blast caused by bacterium <i>Pseudomonas syringae</i> is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 <i>P. syringae</i> isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (<i>Citrus reticulata</i>) in Montenegro, using multilocus sequence analysis of <i>gyrB</i>, <i>rpoD</i>, and <i>gap1</i> gene sequences. Gene sequences from a collection of 54 reference pathotype strains of <i>P. syringae</i> from the Plant Associated and Environmental Microbes Database (PAMDB) was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of <i>gyrB</i>, <i>rpoD</i>, and <i>gap1</i> gene sequences showed that <i>P. syringae</i> pv. <i>syringae</i> causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for <i>P. syringae</i> control.