Genomic Relatedness of Xanthomonas campestris Strains Causing Diseases of Citrus

Abstract

Xanthomonas campestris strains that cause disease in citrus were compared by restriction endonuclease analysis of DNA fragments separated by pulsed-field gel electrophoresis and by DNA reassociation. Strains of X. campestris pv. citrumelo, which cause citrus bacterial spot, were, on average, 88% related to each other by DNA reassociation, although these strains exhibited diverse restriction digest patterns. In contrast, strains of X. campestris pv. citri groups A and B, which cause canker A and canker B, respectively, had relatively homogeneous restriction digest patterns. The groups of strains causing these three different citrus diseases were examined by DNA reassociation and were found to be from 55 to 63% related to one another. Several pathovars ofX. campestris, previously shown to cause weakly aggressive symptoms on citrus, ranged from 83 to 90% similar to X. campestris pv. citrumelo by DNA reassociation. The type strain ofX. campestris pv. campestris ranged from 30 to 40% similar in DNA reassociation experiments to strains of X. campestis pv. citrumelo and X. campestris pv. citri groups A and B. Whereas DNA reassociation quantified the difference between relatively unrelated groups of bacterial strains, restriction endonuclease analysis distinguished between closely related strains.

Xanthomonas axonopodis pv. citri: factors affecting successful eradication of citrus canker

“…Analysis of the lrp gene furthermore reveals that A strains are most closely associated with strains of X. axonopodis pv. malvacearum that affect cotton, confirming the results obtained by other techniques (Egel et al, 1991), while Xanthomonas producing citrus bacterial spot are more related with strains affecting dieffenbachia, ficus, tomato or pepper. These results suggest that citrus bacterial spot, as well as other xanthomonad diseases cited above, resulted from the adaptation of very closely related xanthomonad strains to a different host.…”

“…(Brunings and Gabriel, 2003). This idea is supported by the fact that citrus bacterial spot is a disease caused by a diversity of strains with differential aggressiveness that represent a heterogeneous group, while the citrus canker group displays a higher homology among its members (Egel et al, 1991).…”

Characterization of Erwinia chrysanthemi, the soft‐rot pathogen of white‐flowered calla lily, based on pathogenicity and PCR‐RFLP and PFGE analyses

“…Since PCR-RFLP could only find genetic variation of a single gene, macrorestriction analysis by PFGE was used to reveal the entire genomic diversity within E. chrysanthemi and to determine whether white-flowered calla lily isolates are distinctive. A number of PFGE protocols have been developed for interspecies and intraspecies differentiation of plant pathogenic bacteria, such as Pseudomonas syringae and Xanthomonas campestris pathovars (Egel et al, 1991;Grothues & Rudolph, 1991). However, with similar protocols, E. coli and Erwinia amylovora could not be analysed by PFGE, because restriction digests in the presence of Tris buffer produced a smear of DNA fragments.…”

“…Macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) has been used successfully for strain differentiation of plant pathogenic bacteria (Egel et al ., 1991;Grothues & Rudolph, 1991;Zhang & Geider, 1997). However, with similar protocols, E. chrysanthemi isolates could not be analysed by PFGE, because a smear of DNA fragments was produced.…”

Ligation-mediated PCR, a fast and reliable technique for insertion sequence-based typing ofXanthomonas citripv.citri

“…Restriction fragment length polymorphism (RFLP), pulsed field gel electrophoresis (PFGE) and rep-PCR-based molecular fingerprinting techniques were used to distinguish between the pathovars of Xanthomonas pathogenic to citrus or pathotypes within X. citri pv. citri (Gabriel et al, 1988;Egel et al, 1991;Kanamori et al, 1999;Cubero & Graham, 2002). The high labor requirement for PFGE and RFLP and the lack of discriminatory power of rep-PCR make these techniques unsuitable for extensive epidemiological surveillance and outbreak investigation (Struelens et al, 1998).…”