Multivariate analysis as a key tool in chemotaxonomy of brinjal eggplant, African eggplants and wild related species

The brinjal eggplant (Solanum melongena L.) is an important vegetable species worldwide, while African eggplants (S. aethiopicum L., S. macrocarpon L.) are indigenous vegetable species of local significance. Taxonomy of eggplants and their wild relatives is complicated and still unclear. Hence, the objective of the study was to clarify taxonomic position of cultivars and landraces of brinjal, its wild relatives and African eggplant species and their wild ancestors using chemotaxonomic markers and multivariate analysis techniques for data processing, with special attention paid to the recognition of markers characteristic for each group of the plants.The total of 34 accessions belonging to 9 species from genus Solanum L. were used in the study. Chemotaxonomic analysis was based on the profiles of cuticular n-alkanes and methylalkanes, obtained using gas chromatography-mass spectrometry and gas chromatography with flame ionization detector. Standard hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used for the classification, while the latter and two-way HCA allowed to identify markers responsible for the clustering of the species. Cultivars, landraces and wild forms of S. melongena were practically identical in terms of their taxonomic position. The results confirmed high and statistically significant distinctiveness of all African eggplant species from the brinjal eggplant. The latter was characterized mostly by abundant long chain hydrocarbons in the range of 34–37 carbon atoms. The differences between both African eggplant species were, however, also statistically significant; S. aethiopicum displayed the highest contribution of 2-methylalkanes to the total cuticular hydrocarbons, while S. macrocarpon was characterized by elevated n-alkanes in the range of 25–32 carbon atoms. Wild ancestors of both African eggplant species were identical with their cultivated relatives. Concluding, high usefulness of the chemotaxonomic approach in classification of this important group of plants was confirmed.