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

Abstract

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 2nϭ14 (in both populations), the great uniformity in the total haploid chromosomal length, the karyotypic formula (8 mϩ6 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.

Abnormal meiotic behavior in three species of Crotalaria

“…Information on chromosome number, quantitative karyotype parameters, chromosome banding patterns and rRNA gene mapping have been used for phylogenetic and chromosome evolution inferences in Crotalaria (Oliveira & Aguiar-Perecin, 1999;Mondin, 2003;Tapia-Pastrana et al, 2005;Almada et al, 2006;Flores et al, 2006;Mondin et al, 2007).…”

Citogenética de Calochortus barbatus (Liliaceae: Calochortoideae) de la Reserva Ecológica del Pedregal de San Ángel, en México, Distrito Federal

“…1 y 2). Cabe señalar que algunas constricciones separan notablemente los satélites y aunque este evento es común en especies vegetales (Tapia-Pastrana et al, 2005;Tapia-Pastrana, 2007), podría ocasionar que éstos sean confundidos con fragmentos cromosómicos, más aún cuando se trata de satélites grandes como los presentes en C. barbatus. Esto podría explicar algunas descripciones anteriores sobre la presencia de fragmentos en células de individuos que por lo demás en nada difieren de aquellos en los que no fueron observados (Beal, 1939).…”

Karyotype characterization reveals an up and down of 45S and 5S rDNA sites in Crotalaria (Leguminosae-Papilionoideae) species of the section Hedriocarpae subsection Macrostachyae

“…Most of the cytogenetic studies in the genus Crotalaria have been concentrated on chromosome counting (Boulter et al 1970;Flores et al 2006), karyotype description (Almada et al 2006; Gupta and Gupta 1978;Oliveira and Aguiar-Perecin 1999;Raina and Verma 1979;), and karyotype variability among populations (Palomino and Vázquéz 1991;Tapia-Pastrana et al 2005). Cytogenetically, the genus presents a decrease in chromosome size according to the level of flower specialization (Boulter et al 1970), with the non-specialized floral species having bigger chromosomes than specialized species.…”