NUCLEAR GENOME SIZE AND KARYOTYPE OF Agave angustifolia AND A. rhodacantha FROM SONORA, MÉXICO

Abstract

The nuclear DNA content of leaf tissue from three wild populations of Agave angustifolia and two of Agave rhodacantha from Nácori Chico county in Sonora state, was determined by flow cytometry. All specimens studied in both species were diploids (2n = 2x = 60). The mean 2C nuclear DNA content was 8.499 pg (1Cx = 4165 Mbp) in A. angustifolia, and 8.415 pg (1Cx = 4124 Mbp) in A. rhodacantha. The mean 2C-DNA content among the three populations of A. angustifolia and one of A. rhodacantha (El Bajío) were the same, although statistically different from Los Mochomos population of A. rhodacantha. Plant karyotypes of two populations of A. angustifolia from Los Mochomos and El Chorro, showed the same cytotype (48m + 2 sm + 6st + 4t), which was different in El Bajío (42m + 4sm + 10st + 4t). The two populations of A. rhodacantha showed the same karyotype (40m + 6sm + 4st + 10t). The total genome length (LTG) and asymmetry index (TF %) varied significantly among populations of both species, except LTG among A. rhodacantha populations. LTG values were larger in A. rhodacantha as compared to A. angustifolia, while the contrary occurred with TF %. These results are considered basic information to develop biotechnological and breeding approaches for both species.