SUMMARY

The Germplasm Bank of The Institute of Conservation and Improvement of the Valencian Agrodiversity of the Polytechnical University of Valencia (COMAV) holds and maintains more than 7000 horticultural species accessions, including local landraces and wild species. 3500 of these accessions belong to the genus Solanum section Lycopersicon and 144 to the Basarthrum section.
To be able to use this resources efficiently it is necessary to know their genetic structure and taxonomy. Knowing their variability distribution rational criteria for the conservation of these resources can be established. 

The objectives of the present doctoral thesis are focused in the study of the sections of the Solanum genus previously mentioned. Both sections include cultivated species: tomato and pepino. The classification and phylogeny studies of the species belonging to these sections have been controversial and, in spite of the effort carried out, a definitive consensus has not been reached yet. This could be explained by a recent separation of these species, that remain closely related and with hybridization capacity, or by the lack of previous works including an appropriate representation of all the variability present in these sections.

With the purpose of studying section Lycopersicon taxonomy a broad representation of each species has been employed covering their entire range of distribution. The analyses identified 12 different species. These classification confirms some of the new species proposed recently, but not all. The new species S. huaylasense appears clearly separated of S. peruvianum. Also the separation of S. arcanum is confirmed, although in this case the molecular data suggests that S. arcanum could be composed by two cryptic species morphologically difficult to distinguish. Contrary, S. corneliomulleri, another of the new species, could not be genetically differenciated from S. peruvianum according to our analyses.

Based on the phylogenetic relationships 3 groups could be established in the section Lycopersicon: Arcanum (S. arcanum, S. chmielewskii, S. neorickii, S. huaylasense), Lycopersicon (S. lycopersicum, S. pimpinellifolium, S. cheesmaniae, S. galapagense) and Eriopersicon (S. peruvianum s.str., S. chilense). The other two species from this genus, S. habrochaites and S. pennellii appear in a basal position.

In the section Basarthrum the classification of the materials in 13 species is supported by the presented data. Two new species not previously described have been found in this study. Materials from these species are morphologically and molecularly different from the rest of species. Regarding to the phylogenetic relationships, it has been confirmed that S. canense is the most distant species and that S. suaveolens appears in an intermediate position between the latter and the series Caripensia. Within the series Caripensia, S. basendopogon, S. trachycarpum and S. tabanoense are observed as distinct species. The Caripense complex is formed by S. caripense, S. filiforme, S. fraxinifolium and S. heiseri.

Besides the general analysis of the taxonomy the genetic structure of a species from each section is also analyzed in detail. In the case of the section Lycopersicon, the variation distribution of S. pimpinellifolium is analyzed in the whole range of distribution of this species; including the materials from Ecuador previously not included in any study. The analysis of this species has great interest because it is the closest wild species to the cultivated tomato and it is often employed as source of interesting tomato agronomical characters.

A great differentiation is found in Solanum pimpinellifollium between the materials originated from Peru and Ecuador. In the case of the Ecuadorian accessions a strong differentiation is found, whereas in case of the Peruvian materials only a light differentiation between north and south is apreciated. These genetics differences could be related with the diferent climatic and ecological conditions present in both countries. The climate along the Peruvian coast is quite uniform, whereas in Ecuador a greater climatic and ecological variation between north and south is observed. On the other hand the information about the variability and heterocigosity suggest that the region of origin of this species could be located close to the northern Peru border. The populations from Ecuador and the south of Peru could be the result of posterior migrations.

In the case of the section Basarthrum, the genetic variability present in S. muricatum, the only one cultivated species of the section, has been analyzed. Unlike other cultivated species, pepino keeps a great diversity. Comparison between variability present in cultivated and wild species allows us to conclude that S. muricatum include genetic variability coming from several wild species of the complex Caripense.