Abstract
The wild species of Solanum are important genetic resources for the medicinal and vegetable crop species of the genus and reservoir of genes for developing new economic uses of Solanum species. In this article, the genetic diversity and systematics of 14 Solanum accessions representing 11 species growing in the southwestern highlands of Saudi Arabia were evaluated using morphological variations and molecular polymorphism generated by 13 ISSR primers. Substantial variations were scored in 26 morphological characters and reflected in the cluster analysis of the examined accessions based on morphological variation. In the cluster trees illustrating the relatedness of the examined accessions based on morphological variation and ISSR polymorphism, the accessions of S. villosum and S. nigrum were differentiated as one cluster and S. dulcamara was associated with S. sisymbriifolium. In the meantime, S. coagulans was clustered with S. macracanthum. The analysis of ISSR data confirms that S. villosum is related to S. nigrum and supports the grouping S. incanum and S. glabratum based on the morphological traits. Principle Component Analysis (PCA) analysis of morphological and ISSR data as a combined set, differentiated the examined species into four groups in a scatter plot. The differentiation of the species/populations in the PCA scatter diagram agrees with their separation in the cluster trees. The four groups are 1. S. macracanthum, S. coagulans and S. schimperianum. 2. S. glabratum and S. incanum. 3. S. dulcamara, S. sisymbriifolium and S. torvum, 4. S. nigrum, S. villosum, and S. villosum ssp. puniceum.