Karyotypes and chromosome morphology in the genus Salvia Linn.

Abstract

Karyotypes of 11 species and varieties of Salvia were studied. Chromosomes show certain remarkable peculiarities. Karyotypes are characterized by chromosomes of relatively small and uniform sizes. In the species S. farinacea (2n=18), chromosomes are the longest among all the species studied. Here two pairs of the longest chromosomes have secondary constrictions. Another pair of chromosomes are also long but without any secondary constriction. The remaining chromosomes are more or less of same size. The karyotype is strictly asymmetrical. The species S. grahamii (2n=22) has a relatively symmetrical karyotype. The longest chromosome pair has the secondary constriction. Three varieties of S. coccinea, all having 2n=22 chromosomes were studied. The karyotypes are symmetrical with only the longest pairs possessing the secondary constrictions. The species S. tiliifolia (2n=22) and S. leucantha (2n=22) also have a symmetrical karyotype with one pair of longest chromosomes having secondary constrictions. The species S. nemorosa (2n=14), S. horminum (2n=16) and S. reflexa (2n=20) show symmetrical karyotypes with median primary constrictions. In all the species, only the longest chromosome pairs have secondary constrictions. In the species S. officinalis (2n=14) an asymmetrical karyotype was found. One pair of chromosomes has secondary constrictions, but this is not the longest pair as noted in all other species.In a few species with very small chromosomes, only chromosome morphology was studied. It was not possible to locate the primary as well as the secondary constrictions. In the species S. splendens (2n=44), chromosomes are very small and are of equal sizes. In S. verbenacea (2n=54) 10 chromosomes are comparatively longer than the rests. Of the 10 chromosomes, 8 showed secondary constrictions. Here the karyotype is an asymmetrical one. In S. aegyptica (2n=26), all the chromosomes are more or less of same length with median primary constrictions. In S. pratensis (2n=16), chromosomes are more or less rod shaped. In the species S. hispanica (2n=12), lowest number of chromosomes was noted. Here also the chromosomes are rod like. In S. aethiopis (2n=22), 4 chromosomes are long and the rests are very short. Interrelationships among the species on the basis of chromosome morphology as well as evolution in karyotypes have been discussed in detail.