Molecular marker diversity and bacterial wilt resistance in wild Solanum commersonii accessions from Uruguay

Abstract

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.

Improvement for Bacterial Wilt Resistance in Potato By Conventional and Biotechnological Approaches

“…The genetic variation and the relationships among individuals in this germplasm collection were studied by different molecular markers, viz. RAPD, AFLP and SSR [138]. All markers grouped S. commersonii accessions into two clusters regardless to the marker type.…”

“…Two different steps leading to resistance could be distinguished: (1) the disease is stopped at the recognition of the infection and (2) the development of symptoms is delayed and reduced. Recently, Siri et al [138] screened 30 accessions of S. commersonii, and different levels of resistance were found ranging from delayed wilting to asymptomatic reaction. The genetic variation and the relationships among individuals in this germplasm collection were studied by different molecular markers, viz.…”

“…The distribution into two main clusters showed high correlation with geographical origin of the accessions. These were further used for screening in polyhouse and 9 most promising lines were identified [138].…”

Distribución y variabilidad morfológica de poblaciones de Solanum commersonii (Solanaceae) en la región pampeana de la Argentina.

“…Resultados similares fueron encontrados por Galván et al, (2007) en esta misma especie a través del análisis de la presencia de lectinas, glicoalcaloides y resistencia a Ralstonia solanacearum, detectando variación intraespecífica que no se encontraba asociada a un patrón de distribución geográfica, en materiales coleccionados desde las Sierras de Lavalleja y Treinta y Tres hasta la costa del Río de la Plata, a pocos metros del mar. Siri et al, (2009), trabajando con materiales de S. commersonii del Uruguay, detectaron altos niveles de polimorfismo para tres distintos marcadores moleculares, pero no encontraron correlación entre resistencia a Ralstonia solanacearum, variación genética y distribución geográfica.…”

“…Becc., entre rocas marítimas y dunas costeras, desde el nivel del mar hasta los 400 msnm (Correll, 1962;Hawkes & Hjerting, 1969;Hawkes, 1990;Laterra et al, 2003;Ispizúa et al, 2004, Clausen et al, 2013. Es una especie que posee tolerancia a estreses bióticos y abióticos (Palta et al, 1981;Seppänen et al, 2000;Siri et al, 2009;González et al, 2013;Pino et al, 2013), de gran importancia para su utilización en el mejoramiento genético de la papa (Solanum tuberosum L.).…”