Karyotype studies in cultivars of Agave tequilana Weber.

Agave tequilana cultivars “Lineño”, “Azul Listado”, “Moraleño”, “Azul”, “Sigüin”and “Pata de Mula” were diploids with 2n=2x=60; “Bermejo” were triploid with 2n=3x=90, and “Chato” tetraploid with 2n=4x=120 (x= 30). A. tequilana show a bimodal karyotype consisting of 10 large + 50 small chromo-somes in diploids; 15 large + 75 small chromosomes in triploids and 20 large + 100 small chromosomes in tetraploids. In diploids they had secondary constriction in one pair of large chromosome and in the third or fourth largest homologous chromosome groups in triploids and tetraploids, respectively. The variation among cultivars was clearly evident in the arm ratio. The variation observed among Agave tequilana is possible due to rearrangements in the large and small chromosomes of the complement.