First genome size assessments for Marshallia and Balduina (Asteraceae, Helenieae) reveal significant cytotype diversity

Abstract

The genus Marshallia is made up by seven to ten species of perennial herbs growing mainly in open habitats, whereas the genus Balduina is represented by three sympatric species; two perennial herbs and one annual, growing in open pine forest habitats. Both genera belong to the family Asteraceae, tribe Helenieae, and are endemic to the southeast United States, in North America. Cytogenetic studies concerning these two genera are scarce and genome size data is lacking for both. The main goals of this study were to (i) generate novel insights into the evolution of the genome size and (ii), contribute to filling existing gaps on our knowledge of the Asteraceae family from this point of view. Nuclear DNA contents range from 11.42 pg/2C in Marshallia trinervia to 31.58 pg/2C in Marshallia mohrii. The combination of genome size with chromosome data (and inferred cytotypes) suggests the existence of multiple cytotypes, and provides interesting insights into the potential impact of polyploidy in the evolution of these genera in general, and the shaping of genome size diversity, in particular.

Keywords

• Barbara’s buttons
• chromosome counts
• Compositae
• nuclear DNA content
• karyology
• polyploidy