Genetic diversity and conservation of two endangered eggplant relatives (Solanum vespertilio Aiton and Solanum lidii Sunding) endemic to the Canary Islands

Solanum vespertilio Aiton and Solanum lidii Sunding are endemic, endangered wild species from the Canary Islands. These species are of potential value for eggplant (S. melongena) breeding, given that they are part of the secondary genepool of this crop. We study genetic diversity with amplified fragment length polymorphisms (AFLPs) markers from 5 populations of S. vespertilio (47 samples) and 3 of S. lidii (26 samples). Five related African species (S. dasyphyllum Schumach. et Thonn., S. delagoense Dunal, S. campylacanthum Hochst., S. panduriforme E. Mey, S. aff. violaceum Ortega) were also included in the analysis. A total of 235 AFLP markers included 178 and 156 that were polymorphic in S. vespertilio and S. lidii, respectively. Analysis of genetic distance, phenograms, and principal component plots showed that these rare Canarian species are differentiated (G _ST = 0.412) from the continental materials and that Solanum vespertilio is more distinct to its African congeners than is S. lidii. There is a relatively high level of differentiation between the two species (G _ST = 0.373), that presumably reflects geographic restrictions (S. lidii to Gran Canaria; S. vespertilio essentially to Tenerife). However, both species have similar levels of total diversity. We speculate that the combination of the many unusual reproductive features (andromonoecy, zygomorphy, heteranthery and weak enantiostyly in S. vespertilio) help explain genetic diversity that is high for self compatible species. The high genetic diversity may also indicate populations were larger in the past. A decrease in population size could contribute to the relatively low genetic differentiation among the populations. The data presented herein provide the foundation for initiation of ex situ and in situ conservation programs for these wild relatives of eggplant. This paper is dedicated to the memory of Dr. Richard N. Lester, who made significant contributions to the taxonomy, biosystematics and conservation of genetic resources of African species of Solanum.