Characterization of the chromosomes of sotol (Dasylirion cedrosanum Trel.) using cytogenetic banding techniques

Sotol (Dasylirion cedrosanum Trel.) is a perennial species with numerous grayish-to-green leaves that grow symmetrically from the base of the stem outward. Its inflorescences can measure up to 3 m in height and contain membranous bracts that enclose seeds. It is a species that has been scarcely studied at the cytogenetic level, with only one report available in the literature. In Mexico, it has economic importance because it is used to prepare the alcoholic beverage sotol. In the present work, the chromosomes of Dasylirion cedrosanum Trel. were obtained and analyzed using different cytogenetic banding techniques and morphometric analysis to construct the first karyotype for this species. Chromosomes were obtained by germinating plant seeds collected in the locality of Las Adjuntas, Santiago, Nuevo León, Mexico. Treatment with colchicine as an antimitotic was performed, followed by enzymatic treatment with pectinase and cellulase, to eliminate the cell walls. Chromosome slides were stained with Giemsa, GTG banding technique, CBW banding, and the 4’,6-diamidino-2-phenylindole fluorescence dye, and observed under a microscope. A chromosomal number 2n of 38 chromosomes, as previously reported, was confirmed. Using the different banding techniques, we observed that all chromosomes exhibited a submetacentric morphology with a fundamental number of 76, and it was possible to visualize the pattern of GTG and CBW bands; these findings are reported for the first time for this species. Morphometric analysis established that the average length of the chromosomes was between 5.09 and 9.84 mm.