Solanum commersonii is a wild tuber-bearing species native to Uruguay with high potential for use in potato breeding programs. Little is known about the genetic diversity within this wild species and the relationship with the resistance to the bacterial pathogen Ralstonia solanacearum. We studied 30 S. commersonii clonal accessions, 20 of which were collected from geographically diVerent areas across the country, while the other ten were grown from seeds from a single plant. Resistance against R. solanacearum was tested and diVerent levels of resistance were found, ranging from delayed wilting to asymptomatic reactions. The genetic variation and the relationships among individuals in this germplasm collection were studied by diVerent molecular markers: Random AmpliWed Polymorphic DNA (RAPD), AmpliWed Fragment Length Polymorphism (AFLP) and Microsatellites or Simple Sequence Repeats (SSR). AFLP markers generated the largest number of total and polymorphic fragments per assay unit while SSR revealed the highest frequency of polymorphic bands (100%), followed by AFLP (96.2%) and RAPD (89.4%). In contrast, when comparing the number of diVerent genetic proWles generated, the SSR markers exhibited the lowest discriminatory power. The clustering pattern obtained with the three marker systems showed a similar distribution of the S. commersonii germplasm revealing a high correlation between the three methods employed. All three dendrograms grouped most of the accessions into two main clusters, containing the same accessions regardless of the marker type. Bacterial wilt resistant accessions were present in both clusters. Accessions originated from diVerent seeds of the same plant were grouped within one of the major clusters, and diVered in the response to R. solanacearum revealing segregation of resistance. Furthermore, the distribution in two main clusters showed high correspondence with the geographical origin of the accessions, from the north and south of the country, and with the subspecies malmeanum and commersonii morphologically identiWed.

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Azospirillum sp promotes the growth of many important crop plants. We demonstrated lectin binding activity in outer-membrane protein extracts of A. brasilense Sp7 by hemagglutination assays. The lectin specifically recognised the exopolysaccharide (EPS) produced by aggregated cells. Affinity chromatography using EPS-Sepharose was used to identify a 67 kDa outer-membrane lectin (OML) that recognised a binding region in the extracellular polysaccharide. Results show the specific recognition and binding between EPS and OML. The potential relationship between cell-to-cell aggregation and the OML-EPS interaction is discussed.

We describe a rapid and efficient method for producing the capsular polysaccharide of Streptococcus pneumoniae by fermentation on tryptic soy broth and purification of this compound by using immobilized soybean lectin as an affinity adsorbent. In principle, the same strategy can be used to produce purified capsular polysaccharides from other streptococcal serotypes by selecting the appropriate lectin adsorbents.

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