Genomic DNA of 191 strains of the family Pseudomonadaceae, including 187 strains of the genus Xanthomonas, was cleaved by EcoRI endonuclease. After hybridization of Southern transfer blots with 2-acetylamino-fluorene-labelled Escherichia coli 16+23S rRNA probe, 27 different patterns were obtained. The strains are clearly distinguishable at the genus, species, and pathovar levels. The variability of the rRNA gene restriction patterns was determined for four pathovars ofXanthomonas campestris species. The 16 strains ofX. campestris pv. begoniae analyzed gave only one pattern. The variability of rRNA gene restriction patterns of X. campestris pv. manihotis strains could be related to ecotypes. In contrast, the variability of patterns observed for X. campestris pv. malvacearum was not correlated with pathogenicity or with the geographical origins of the strains. The highest degree of variability of DNA fingerprints was observed within X. campestris pv. dieffenbachiae, which is pathogenic to several hosts of the Araceae family. In this case, variability was related to both host plant and pathogenicity.

A new insertion sequence was isolated from Xanthomonas campestris pv. dieffenbachiae. Sequence analysis showed that this element is 1,158 bp long and has 15-bp inverted repeat ends containing two mismatches. Comparison of this sequence with sequences in data bases revealed significant homology with Escherichia coli IS5. IS1051, which detected multiple restriction fragment length polymorphisms, was used as a probe to characterize strains from the pathovar dieffenbachiae.

Strains presumed to be of Xanthomonas campestris pv. vasculorum (Cobb.) Dye, obtained from sugarcane and other gramineae in Reunion Island, were compared in terms of cultural aspects, pathogenic and physiological reactions, fatty acid profiles and restriction fragment length polymorphism (RFLP) of genomic DNA. The strains could be divided into two separate groups (Gl and G2). The Gl strains were identical to strains described as X. campestris pv. vasculorum; they showed an important variability in their cultural characteristics and in their aggressiveness. The G2 strains did not induce the usual symptoms of gumming disease on sugarcane cultivars infected under natural conditions or inoculated in the greenhouse. The G2 strains grew faster on agar medium, their colonies were more pigmented and less fluidal and had a different morphology on agar slant. Unlike the Gl strains, G2 strains hydrolyzed starch weakly and casein strongly; they utilized L-fucose and, to a lesser extent, melibioze. The fatty acid and genomic DNA profiles differed between the groups. Differences seemed large enough to support separation of Gl and G2 strains into distinct taxonomic entities, namely Gl as Xanthomonas campestris pv. vasculorum and G2 as a different pathovar of X. campestris. The taxonomic position of G2 strains is discussed. ZusammenfassungVariabilitat von Xanthomonas campestris pv. vasculorum aus Zuckerrohr und anderen Gramineae in Reunion. Charakterisierung eines anderen Xanthomonaden Verglichen wurden Stamme von Xanthomonas campestris pv. vasculorum (Cobb.) Dye., die von Zuckerrohrpflanzen und anderen Gramineae in Reunion isoliert wurden, in Bezug auf ihre Charakteristika in Kultur, ihre pathogene und physiologische Reaktionen, ihre Fettsaureprofile sowie restriction fragment length polymorphism (RFLP) der genomen DNS. Die Stamme konnten in zwei Gruppen (Gl und G2) getrennt werden. Die Gl-Stlmme waren mit den als X. campestris pv. vasculorum beschriebenen Stammen identisch: sie zeigten eine wichtige VariabiKtJlt ihrer Charakteristika in Kultur sowie in ihrer Aggressivitat. Die G2-St3nime dagegen riefen die normalen Symptome der gumming-Krankheit bei Zuckerrohr nicht hervor, weder nach einer Infektion unter natiirlichen Bedingungen noch bei Pflanzen die im Gewachshaus inokuliert worden waren. Die G2-Stamme hatten eine schnellere Wachstumsrate auf Agarnahrmedien, ihre Kolonien zeigten eine starkere Pigmentbildung und sie waren in ihrer Konsistenz fliissiger und hatten eine andere Morphologie in Schragagarkultur als die Gl-StSmme. Die G2-Stamme konnten Starke nur schwach hydrolysieren, Casein dagegen stark; L-Fucose und Melibiose, obwohl in reduziertem Umfang, wurden metabolisiert. Die Fettsaure und genomen DNS-Profile waren zwischen den Gruppen unterschiedlich. Die Unterschiede waren so grofi, da6 eine Trennung der Gl-und G2-Stamme in zwei taxonomisch getrennte Einheiten fiir sinnvoll erschien, und zwar die Gl-Stamme als Xanthomonas campestris pv. vasculorum und die G2-Stamme als ein anderes X. campestris-l^a-thovur. Die taxonom...

Strai ns presumed to be of Xanthomonas campestris pv. vascu lomm (Cobb.) Dye, obtained from sugarcane and other gramineae in Reunio n Island, were compared in terms of cultural aspects, pathoge ni c and ph ys iological reactions, fatty acid profiles and restriction fragment length polymorphism (RFLP) of genomi c DNA. The strains could be divided into two sepa rate groups (G I and G2). The G l stra.ins were id entical to strains described as X. campestris pv. vasmlorum; they showed an important varia bility in their cultural characteristi cs and in their aggressiveness. The G2 strains did not induce the usual symptoms of gumming disease on sugarcane cultiva rs infected under natural conditi ons or inocul ated in the gree nhouse. The G2 strains grew faster on agar medi um, their colonies were more pigmented and less fluidal and had a different morphology on agar slant. Unlike the G I strai ns, G2 strains hydrolyzed sta rch weakly and casei n strongly; they utilized L-fucose and, to a lesser extent, melibioze. The fatty aci d and genomi c DNA profiles differed between the groups. Differences seemed large enough to support separation of Gl and G2 strains into distinct taxonomic entities, namely G l as Xanthomonas campestris pv. vascttlorum and G2 as a different pathovar of X. campestris. The taxono mi c position of G2 strains is discussed.

The internal transcribed spacer (ITS) regions of ribosomal DNA were amplified by PCR and used to develop genetic markers for isolates of Puccinia carduorum being evaluated for biological control of Carduus thoermeri (musk thistle). Unique patterns were produced upon restriction of ITS DNA amplified from four separate Puccinia spp. Restriction patterns of ITS DNA of isolates of P. carduorum from Carduus acanthoides and C. thoermeri were distinct from those of P. carduorum from Carduus tenuiflorus and Carduus pycnocephalus. By this technique, isolates of P. carduorum from four different weed hosts can be differentiated from other Puccinia spp. and separated into two host groups.