Genetic relationships among strains of Xanthomonas campestrispv. campestrisrevealed by novel rep-PCR primers

Abstract

Novel primers for rep-PCR were developed with the original software and based on 'ancient diverged periodical sequences'. Rep-PCR with these primers was applied to study genetic relationships among 51 Xanthomonas campestris strains. The strains were collected from different countries including Russia, Japan, UK, Germany and Hungary. Reference strains of three X. campestris pathovars and five other Xanthomonas species were included. Based on qualitative differences in amplification profiles, the strains were divided into four major groups. Two subgroups recognised within X. campestris population were similar to RFLP haplotypes. The third subgroup included strains of two other pathovariants and Japanese isolates of X. campestris pv. campestris while the fourth group comprised the other species of Xanthomonas. The analysis of the diversity within X. campestris resulted in the conclusion that isolates belong to distinct clonal populations (subgroups). The differences between the subgroups of X. campestris were only slightly smaller than between species of Xanthomonas. A PCR fragment about 600 bp amplified by primer KRPN2 was found in nearly all tested strains of X. campestris. SCAR primers designed for this marker produced a single specific band for strains of X. campestris, but not for other Xanthomonas, Pseudomonas and Erwinia strains tested. Application of the new primer set for rep-PCR offers a rapid, simple and reproducible method for identification of bacterial strains. The X. campestris-specific SCAR primers may be used in diagnostics of this important plant pathogen.

Genetic Diversity in Populations ofXanthomonas campestrispv.campestrisin Cruciferous Weeds in Central Coastal California

“…The majority of the tested strains belonged to either race 6 (70%) or race 5 (18%). Less than 12% of the strains belonged to the races 1, 3, and 4, or races differed from the previously recognized ones (26). The more uncommon races were found only at sites 29 (races 1, 3, 5, and 6), 33 (races 1, 3, and 5), 51 (races 4 and 5), and 54 (races 1, 4, 5, and 6) ( Table 2).…”

“…Races 1 and 4 of X. campestris are predominant among the strains from cultivated brassicas all over the world (6,26), whereas races 5 and 6 (formerly race 0, designated by Kamoun et al) (8) are found mostly in B. rapa and mustard in locations with vast native populations of brassicas, such as Portugal (27). Thus, presence of X. campestris races 5 and 6 on weedy populations with resistance similar to Rxcc1 in B. nigra, B. carinata, and B. juncea (6,25) was expected from previous reports, but the frequency of those races was unexpectedly high.…”

“…Zhao et al (31) found that the majority of 45 local strains of X. campestris from Oklahoma belonged to a single BOX genotype similar to a known crop strain, PHW117, representative for the haplotype 1 (1,26). Group B was similar to the type strain NCPPB 528 T of the haplotype 3 (1,26), and five strains belonged to "exotic" groups C, D, and E Fig. 4.…”

“…3). Crop strains were separated into two groups containing strains representative of genotypes (haplotypes) 1 and 3 recognized previously by restriction fragment length polymorphism (RFLP) (1) and repetitive element (rep)-PCR (26). Crop strain 11565, isolated in September 2005 near weed site 34, was in a group containing only known crop strains.…”

“…However, no information is available on the presence of X. campestris in crucifer weeds along the Pacific coast, which are geographically isolated from commercial crops. The degree of genetic diversity among X. campestris strains in commercial crucifer plants is well established (1,11,26,31); however, nothing is known about the amount of diversity in strains infecting cruciferous weeds. To determine the genetic diversity among strains of X. campestris in weeds in noncultivated and cultivated areas, strains of X. campestris were isolated from populations of cruciferous weeds growing in remote sites along the California central coast and from sites of current or previous fresh-market and seed-production or breeding areas of Lompoc, Salinas, Hollister, and San Juan Bautista.…”