Karyotype analysis of the southernmost South American species of Stemodia (Scrophulariaceae)

MARÍA DE LAS MERCEDES SOSA; PANSERI, ANDREA FLORENCIA; FERNÁNDEZ, AVELIANO

PLANT BIOSYSTEMS

TAYLOR & FRANCIS LTD

Lugar: Roma; Año: 2011 vol. 145 p. 472 - 477

1126-3504

The aim of the present study was to examine the somatic chromosomes of seven species of Stemodia (Scrophulariaceae). The karyotypes of Stemodia ericifolia (2n=22=20m+2sm), S. hassleriana (2n=22=20m+2sm), S. hyptoides (2n=22=20m+2sm), S. hyptoides (2n=44=40m+4sm), S. lobelioides (2n=44=40m+4sm) and S. stricta (2n=22=20m+2sm) were analyzed for the first time. All the species studied showed a predominance of metacentric chromosomes, and a lower proportion of submetacentric pairs. The chromosomes in all the species were found to be small with a mean chromosome length  of 1.42 µm, varying from 0.77 µm in S. hyptoides (2n=66) to 2.10 µm in S. lanceolata. The differences in the asymmetry of the karyotypes were small, for which it is possible to assume that the great diversification of the genus has been accompanied by very small changes in the structure of the chromosomes.