Chromosome Number, Ploidy Level, and Nuclear DNA Content in 23 Species of (Crassulaceae).

is a polyploid genus with a wide diversity of species and morphologies. The number of species registered for is approximately 170; many of them are native to Mexico. This genus is of special interest in cytogenetic research because it has a variety of chromosome numbers and ploidy levels. Additionally, there are no studies concerning nuclear DNA content and the extent of endopolyploidy. This work aims to investigate the cytogenetic characteristics of 23 species of collected in 9 states of Mexico, analyzing 2 chromosome numbers, ploidy level, nuclear DNA content, and endopolyploidy levels. Chromosome numbers were obtained from root tips. DNA content was obtained from the leaf parenchyma, which was processed according to the two-step protocol with Otto solutions and propidium iodide as fluorochrome, and then analyzed by flow cytometry. From the 23 species of analyzed, 16 species lacked previous reports of 2 chromosome numbers. The 2 chromosome numbers found and analyzed in this research for species ranged from 24 to 270. The range of 2C nuclear DNA amounts ranged from 1.26 pg in to 7.70 pg in , while the 1C values were 616 Mbp and 753 Mbp, respectively, for the same species. However, differences in the level of endopolyploidy nuclei were found, corresponding to 4 endocycles (8C, 16C, 32C and 64C) in , , and . In contrast, presented 3 endocycles (8C, 16C and 32C) and presented 2 endocycles (8C and 16C). It has been suggested that polyploidization and diploidization processes, together with the presence of endopolyploidy, allowed species to adapt and colonize new adverse environments.