New Cytogenetic Information of Two Mexican Populations of Crotalaria incana L. (Leguminosae-Papilionoideae)

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Chromosomes in prometaphases and typical metaphases obtained from root meristems of samples of Crotalaria incana, collected in the Mexican municipalities of Tamasopo (San Luis Potosí) and Martínez de la Torre (Veracruz) were analyzed, paying special attention to the possible cytotypic variation due to differences in number and nature of the chromosomes with secondary constrictions and satellites. The chromosomal number 2n=14 (in both populations), the great uniformity in the total haploid chromosomal length, the karyotypic formula (8 m+6 sm), the chromosomal length interval, and a slight difference in the asymmetry index were corroborated with the use of the “air drying method” (splash). It was observed that the 14 chromosomes, particularly in prometaphase, exhibit uncoiled terminal regions which could be confused with secondary constrictions. These findings are compared to previous records on the fine chromosome morphology of C. incana and other species of the genus. The existence of proposed cytotypes for the species is discarded, and their evolution as a function of gene changes or genic complexes is discussed.