Cytotype diversity and genome size variation in eastern Asian polyploid Cardamine (Brassicaceae) species

Abstract

† Background and Aims Intraspecific ploidy-level variation is an important aspect of a species' genetic make-up, which may lend insight into its evolutionary history and future potential. The present study explores this phenomenon in a group of eastern Asian Cardamine species. † Methods Plant material was sampled from 59 localities in Japan and Korea, which were used in karyological (chromosome counting) and flow cytometric analyses. The absolute nuclear DNA content (in pg) was measured using propidium iodide and the relative nuclear DNA content (in arbitrary units) was measured using 4,6-diamidino-2-phenylindole fluorochrome. † Key Results Substantial cytotype diversity was found, with strikingly different distribution patterns between the species. Two cytotypes were found in C. torrentis sensu lato (4x and 8x, in C. valida and C. torrentis sensu stricto, respectively), which displays a north-south geographical pattern in Japan. Hypotheses regarding their origin and colonization history in the Japanese archipelago are discussed. In Korean C. amaraeiformis, only tetraploids were found, and these populations may in fact belong to C. valida. C. yezoensis was found to harbour as many as six cytotypes in Japan, ranging from hexa-to dodecaploids. Ploidy levels do not show any obvious geographical pattern; populations with mixed ploidy levels, containing two to four cytotypes, are frequently observed throughout the range. C. schinziana, an endemic of Hokkaido, has hexa-and octoploid populations. Previous chromosome records are also revised, showing that they are largely based on misidentified material or misinterpreted names. † Conclusions Sampling of multiple populations and utilization of the efficient flow cytometric approach allowed the detection of large-scale variation in ploidy levels and genome size variation attributable to aneuploidy. These data will be essential in further phylogenetic and evolutionary studies.

Genome-wide nucleotide diversity and associations with geography, ploidy level and glucosinolate profiles in Aethionema arabicum (Brassicaceae)

“…Andropogon gerardi (Poaceae) (Keeler 1992) and Artemisia incana (Asteraceae) (Dolatyari et al 2013). The Brassicaceae core group also contains many species with different ploidy levels: Cardamine yezoensis from eastern Asia (Marhold et al 2010), many Draba species (Brochmann 1993;Jordon-Thaden et al 2013), various Boechera species (Schranz et al 2005;Sharbel et al 2005), the European Biscutella laevigata (Tremetsberger et al 2002), Allysum montanum, Allysum repens and Arabidopsis arenosa (Španiel et al 2011;Wright et al 2014) all have populations with different ploidy levels. A distinct geographical pattern of ploidy levels can be due to ecological adaptations to small differences in environmental conditions.…”

FLOW CYTOMETRIC ANALYSIS OF NUCLEAR DNA BETWEEN OKRA LANDRACES (<i>ABELMOSCHUS ESCULENTUS</i> L.)

“…Ploidy level has traditionally been determined based on chromosome counts. Recent studies have estimated ploidy level based on assessments of nuclear DNA content using flow cytometry (Marhold et al, 2010). Flow cytometry is a relatively convenient and rapid method compared with chromosome counts .…”

Intraspecific Chromosome Number Variation and Prairie Restoration—A Case Study in Northeast Iowa, U.S.A

“…The potential for the introduction of novel cytotypes into native populations through restoration efforts is not a problem that is unique to the tallgrass prairie of North America. Intraspecific ploidal variation has been documented in a number of biomes throughout the world, some recent examples include deserts in India (Gupta et al 2009), mountains in Europe (Šmarda & Bureš 2006), South America (Schmidt‐Lebuhn et al 2010), Russia and Mongolia (Funamoto et al 2008), riparian areas in East Asia (Marhold et al 2009) and taxa ranging from bryophytes (Uniyal 1998), aquatic angiosperms (Les & Philbrick 1993), to grasses and trees (García‐Verdugo et al 2009). Restoration efforts should consider the possibility of ploidy variation in most circumstances, as there are very few cases (e.g.…”