EMA-based chromosome characterization and karyotype analysis in two wild spiny medicinally and nutritionally important Solanaceaous species ̶ Solanum sisymbriifolium Lam. and Solanum virginianum L.

Abstract

The nutritional and medicinal wealth found in wild Solanum species is abundant, yet frequently goes unnoticed. Solanum sisymbriifolium Lam. and S. virginianum L. are two spiny species found worldwide in the Solanum genus, offering various medicinal and nutritional benefits. Chromosomal analysis, an essential component of genomic research for preserving plant genetic resources, has been notably overlooked in these two species. To our current knowledge, there is a lack of adequate karyotype data for S. sisymbriifolium, and the information available for S. virginianum is nearly non-existent. The present study includes establishing a standardized process involving enzymatic maceration of the cell wall, subsequent staining using the non-fluorescent dye Giemsa, and employing a fluorescent stain, 4′,6-diamidino-2-phenylindole (DAPI). The standardized enzymatic maceration and air drying (EMA) method yields fine chromosome dispersion, effectively eliminating cytoplasmic background interference. Both species exhibit a somatic cell chromosome count of 2n=24. Their karyotypes are symmetric and classified under the 3A category in Stebbins' classification. DAPI staining reveals distinct positive bands in S. sisymbriifolium, whereas S. virginianum exhibits uniform staining. This investigation will significantly enhance the chromosomal database, proving invaluable for breeding programs aimed at enhancing the quality of these wild Solanum species.