Traditional Eastern Spanish varieties of tomato

Despite the importance of traditional varieties of tomato (Solanum lycopersicum L.) as sources of variation in breeding programs and varieties targeted to high-price quality markets that value their exceptional organoleptic quality, little is known regarding the structure of these materials at the morphological level. In this study, a collection of 166 populations (137 of them during two years) of traditional varieties of tomato from the east coast of Spain has been characterized using 41 descriptors. The characterization revealed a considerable variation. The segregation observed in several populations (28 %) suggests that apart from the configuration as population varieties, the high variation present in these landraces may be partially due to possible seed mixing and spontaneous cross-pollination. Only nine fruit descriptors were required to represent the variation present in the collection analyzed. It seems that after spontaneous cross-pollinations, farmers applied strong selection to a small number of traits, though even in these traits a high level of variation is maintained. The variation observed may hinder clear recognition by the consumer, an attribute required for the consolidation of quality markets. Additionally, a registry of these materials as conservation varieties would be complicated considering the actual levels of variation. Therefore, a varietal depuration would be interesting in order to promotein situ conservation of these resources. Finally, the high levels of variation in the intra-varietal scale may justify the collection and maintenance of more populations of the same variety as the risk of conserving duplicates would not be so high.

Traditional Eastern Spanish varieties of tomato

Despite the importance of traditional varieties of tomato (Solanum lycopersicum L.) as sources of variation in breeding programs and varieties targeted to high-price quality markets that value their exceptional organoleptic quality, little is known regarding the structure of these materials at the morphological level. In this study, a collection of 166 populations (137 of them during two years) of traditional varieties of tomato from the east coast of Spain has been characterized using 41 descriptors. The characterization revealed a considerable variation. The segregation observed in several populations (28 %) suggests that apart from the configuration as population varieties, the high variation present in these landraces may be partially due to possible seed mixing and spontaneous cross-pollination. Only nine fruit descriptors were required to represent the variation present in the collection analyzed. It seems that after spontaneous cross-pollinations, farmers applied strong selection to a small number of traits, though even in these traits a high level of variation is maintained. The variation observed may hinder clear recognition by the consumer, an attribute required for the consolidation of quality markets. Additionally, a registry of these materials as conservation varieties would be complicated considering the actual levels of variation. Therefore, a varietal depuration would be interesting in order to promotein situ conservation of these resources. Finally, the high levels of variation in the intra-varietal scale may justify the collection and maintenance of more populations of the same variety as the risk of conserving duplicates would not be so high.(AU)

Variation revealed by SNP genotyping and morphology provides insight into the origin of the tomato.

Tomato, Solanum lycopersicum, is divided into two widely distributed varieties: the cultivated S. lycopersicum var. lycopersicum, and the weedy S. lycopersicum var. cerasiforme. Solanum pimpinellifolium is the most closely related wild species of tomato.The roles of S. pimpinellifolium and S. l. cerasiforme during the domestication of tomato are still under debate. Some authors consider S. l. cerasiforme to be the ancestor, whereas others think that S. l. cerasiforme is an admixture of S. pimpinellifolium and the cultivated S. l. lycopersicum. It is also not clear whether the domestication occurred in the Andean region or in Mesoamerica. We characterized 272 accessions (63 S. pimpinellifolium, 106 S. l. cerasiforme, 95 S. l. lycopersicum and 8 derived from hybridization processes) were morphologically and genetically using the SolCap platform (7,414 SNPs). The two species were distinguished in a PCA analysis and displayed a rich geographic structure. Solanum lycopersicum var. cerasiforme and S. l. lycopersicum were also differentiated in the PCA and Structure analyses, which supports maintaining them as different varieties. Solanum pimpinellifolium and the Andean S. l. cerasiforme were more diverse than the non-Andean S. lycopersicum. Solanum lycopersicum var. cerasiforme was morphologically and molecularly intermediate between S. pimpinellifolium and tomato. Solanum lycopersicum var. cerasiforme, with the exception of several Ecuadorian and Mexican accessions, is composed of the products of admixture processes according to the Structure analysis. The non-admixtured S. l. cerasiforme might be similar to the ancestral cultivars from which the cultivated tomato originated, and presents remarkable morphological diversity, including fruits of up to 6 cm in diameter. The data obtained would fit a model in which a pre-domestication took place in the Andean region, with the domestication being completed in Mesoamerica. Subsequently, the Spaniards took plants from Mesoamerica to Spain and from there they were exported to the rest of the world.