Cytotaxonomy of two species of genus Chrysolaena H. Robinson, 1988 (Vernonieae, Asteraceae) fromNortheast Paraguay.

Gisela M Via Do Pico,Massimiliano Dematteis

doi:10.3897/compcytogen.v8i2.7209

Abstract

Chromosome counts and karyotypes of two species of Chrysolaena H. Robinson 1988 are presented in this paper. Mitotic analysis revealed that both taxa have x=10, a basic chromosome number considered characteristic of the genus. The chromosome number and the karyotype of Chrysolaena cristobaliana are reported for the first time, as well as a new cytotype and the karyotype of Chrysolaena sceptrum. Chrysolaena cristobaliana showed heptaploid cytotype with 2n=7x=70 and a karyotype composed of 46 m + 24 sm chromosomes. On the other hand, Chrysolaena sceptrum presented tetraploid cytotype with 2n=4x=40 and a karyotype with 30 m + 10 sm chromosomes. Accessory chromosomes were observed in cells of both species. The chromosome analysis showed that these species differ in the chromosome number and the total chromosome length, although they showed similar chromosome morphology and asymmetry indexes. The results support the use of chromosome data in taxonomic treatments of the American members of the tribe Vernonieae.

Highlights

The genus Chrysolaena (Vernonieae, Asteraceae) includes 18 species mainly concentrated in southern Brazil and northeast of Argentina
Chrysolaena sceptrum showed a tetraploid cytotype with 2n=4x=40 (Fig. 1a, b), with a karyotype composed of 30 metacentric (m) and 10 submetacentric chromosomes (Figure 2a)
The chromosome number is considered one of the most important features, since Chrysolaena is the only American member of the tribe with the base number x=10, which is mainly present in the Old World Vernonieae

Summary

Introduction

The genus Chrysolaena (Vernonieae, Asteraceae) includes 18 species mainly concentrated in southern Brazil and northeast of Argentina. From this area, the genus extends to north Peru and the Amazon region of Brazil, and southward, to the center of the Copyright G.M.Via Do Pico, M. Dematteis / Comparative Cytogenetics 8(2): 125–137 (2014)

Methods

Results

Discussion

Conclusion