Determination of Chromosome Number and Ploidy Level in Five Species of Agave from Mexico

Cytogenetic analysis was carried out on five species of Agave genus collected in Mexico. Meristematic root cells were analyzed cytogenetically using a modified steam-drop method for chromosome counting. The analysis showed that in A. guiengola, A. geminiflora, A. attenuata, and A. victoriae-reginae species, the chromosome number was 2n=60 with bimodal karyotypes composed of five pairs of large chromosomes and 25 pairs of small chromosomes. On the other hand, A. salmiana also showed a bimodal karyotype consisting of 30 large + 150 small chromosomes. Considering the basic number x=30, A. salmiana is a hexaploid species (2n=6x=180), whereas the other four species analyzed are diploid (2n=2x=60). This is the first report on the chromosome number of A. guiengola.