Potentially virulent isolates of Xanthomonas campestris from agricultural soil of Ray and Karaj

The Xanthomonas genus is one of the most important groups of crop plant pathogenic bacteria and they are one of main causal agents of post-harvest spoilage and economical loss. In this research، 71 agricultural soil samples collected from suburb of Ray and Karaj cities. Screening of bacteria on semiselective SX agar medium، performing morphological and biochemical tests and evaluation of two specific virulence factors resulted in a number of X. campestris isolates among all putative growing bacteria. Relative percentage of X. campestris to total number of bacteria grown on SX agar was 0. 69%. Capability of exopolysaccharide production by average concentration of 10. 98 g l-1 and average viscosity of 1403 cP and presence of xanthomonadin pigment with maximum absorbance index within the range of 441. 0-444. 7 nm wavelengths، as two main virulence factors، was determined and confirmed. Molecular identification for 25% of the randomly selected isolates possessing virulence factors، indicated X. campestris species by confirming the presence of specific hrcC gene marker. This study indicates that despite lack of any report on prevalence of the related diseases، the potentially virulent X. campestris can be found in soil of cabbage farms in suburb of Ray and Karaj cities. As a case study، existence of these strains in soil is noticeable because of probability of losses caused by spoilage of agricultural products which is prevalent in Iran.