Genetic Diversity and Aggressiveness of Ralstonia solanacearum Strains Causing Bacterial Wilt of Potato in Uruguay

Abstract

Bacterial wilt, caused by Ralstonia solanacearum, is a major disease affecting potato (Solanum tuberosum) production worldwide. Although local reports suggest that the disease is widespread in Uruguay, characterization of prevalent R. solanacearum strains in that country has not been done. In all, 28 strains of R. solanacearum isolated from major potato-growing areas in Uruguay were evaluated, including 26 strains isolated from potato tubers and 2 from soil samples. All strains belonged to phylotype IIB, sequevar 1 (race 3, biovar 2). Genetic diversity of strains was assessed by repetitive-sequence polymerase chain reaction, which showed that the Uruguayan strains constituted a homogeneous group. In contrast, inoculation of the strains on tomato and potato plants showed, for the first time, different levels of aggressiveness among R. solanacearum strains belonging to phylotype IIB, sequevar 1. Aggressiveness assays were also performed on accessions of S. commersonii, a wild species native to Uruguay that is a source of resistance for potato breeding. No significant interactions were found between bacterial strains and potato and S. commersonii genotypes, and differences in aggressiveness among R. solanacearum strains were consistent with previously identified groups based on tomato and potato inoculations. Moreover, variation in responses to R. solanacearum was observed among the S. commersonii accessions tested.

The sequevar distribution of Ralstonia solanacearum in tobacco-growing zones of China is structured by elevation

“…Biovar classification has been defined by their ability to utilize disaccharides and to oxidize hexose alcohols (He et al 1983;Hayward 1964Hayward , 1991Genin and Denny 2012). Although both classification schemes have been used to describe the diversity of R. solanacearum for a long time, several disadvantages have been revealed with our increasing knowledge of pathogen diversity, such as the lack of discriminating power, additional time required, and lack of correlation with the phylogenetic origin of different strains (Siri et al 2011;Genin and Denny 2012).…”

A Novel, Sensitive Method to Evaluate Potato Germplasm for Bacterial Wilt Resistance Using a LuminescentRalstonia solanacearumReporter Strain

“…Moreover, IIB1 strains have the ability to produce symptomless latent infections, which facilitates the dissemination of the pathogen worldwide, hindering disease control (Janse 1996;Swanson et al 2005;Williamson et al 2002). UY031 is a highly aggressive strain that belongs to this sequevar and was isolated from potato tubers in 2003 in Uruguay (Siri and Pianzzola 2011;Siri et al 2009). …”

“…An advantage of this system is that the reporter is stably inserted in monocopy in the bacterial chromosome, avoiding reporter loss in competitive conditions (e.g., during plant infection) and variations in reporter copy number. Here, we have improved the reporter system to ensure its continuous expression and introduced it in the highly aggressive R. solanacearum UY031 (Siri and Pianzzola 2011;Siri et al 2009), which has been genetically modified for the first time to constitutively emit light while maintaining its virulence on potato. As shown by the data presented here, the modified strain can be efficiently used to follow bacterial multiplication in potato plants.…”

Rapid Method for Isolation of PCR Amplifiable Genomic DNA of <i>Ralstonia solanacearum</i> Infested in Potato Tubers

“…Resistant varieties, field sanitation, crop rotation and use of bactericides have met, if at all, with only limited successes [5]. Furthermore, the high variability of strains of R. solanacearum [5,6] coupled with the influence of environmental factors on host pathogen interactions often restrict the expression of resistance in specific regions.…”

“…Furthermore, the high variability of strains of R. solanacearum [5,6] coupled with the influence of environmental factors on host pathogen interactions often restrict the expression of resistance in specific regions.…”