Abstract
Elettariopsis Baker is a small genus consisting of about 30 accepted species. It is distributed in China, Vietnam, Laos, Cambodia, Thailand, Malaysia with only a few species extending to Indonesia..
Morphological features as well as recent studies suggest that it is closely related to the paraphyletic genus Amomum Roxb., but not much research has been so far conducted. Our aim was to 1) examine the infrageneric structure in Elettariopsis and its relationship with Amomum, 2) investigate the patterns in absolute genome size and its correlation with phylogeny, and 3) discuss the relationship between the phylogeny of Elettariopsis and its geographical distribution.
Samples from most of the area of distribution were analysed by flow cytometry to obtain the absolute genome size (2C). The nuclear marker ITS, chloroplast matK and a single-copy nuclear gene, DCS (diketide CoA synthase) were sequenced.
Genome size evolution was reconstructed and mapped onto the phylogenetic trees. Localities of the samples were visualized.
The results supported by absolute genome size and geographical data imply that Elettariopsis consists of two distinct groups. However, Elettariopsis is only weakly supported as a monophyletic genus, although it is strongly supported together with Amomum subulatum, A. plicatum and A. repoeense.
The absolute genome size in Elettariopsis varies greatly (from 5.39 pg to 15.52 pg) but is not gradual throughout the genus, with two groups observed. A group with smaller absolute genome sizes consists of species distributed in the north (Indochinese region), whereas species with larger genomes are distributed in the south (Malesia).
This corresponds with the pattern observed in the whole family Zingiberaceae, where deciduous plants from monsoonal areas have smaller genomes than their evergreen relatives from evergreen tropics.