Species of Orchidaceae are under severe threat of extinction mainly due to overcollection and habitat destruction; accurate identification of orchid species is critical in conservation biology and sustainable utilization of orchids as plant resources. We examined 647 sequences of the cpDNA regions rbcL, matK, atpF-atpH IGS, psbK-psbI IGS and trnH-psbA IGS from 89 orchid species (95 taxa) and four outgroup taxa to develop an efficient DNA barcode for Orchidaceae in Korea. The five cpDNA barcode regions were successfully amplified and sequenced for all chlorophyllous taxa, but the amplification and sequencing of the same regions in achlorophyllous taxa produced variable results. psbK-psbI IGS showed the highest mean interspecific K2P distance (0.1192), followed by matK (0.0803), atpF-atpH IGS (0.0648), trnH-psbA IGS (0.0460) and rbcL (0.0248). The degree of species resolution for individual barcode regions ranged from 60.5% (rbcL) to 83.5% (trnH-psbA IGS). The degree of species resolution was significantly enhanced in multiregion combinations of the five barcode regions. Of the 26 possible combinations of the five regions, six provided the highest degree of species resolution (98.8%). Among these, a combination of atpF-atpH IGS, psbK-psbI IGS and trnH-psbA IGS, which comprises the least number of DNA regions, is the best option for barcoding of the Korean orchid species.
Invasive giant knotweed (Fallopia sachalinensis) is native to northeastern Asia. In Korea, F. sachalinensis is confined to two volcanic islands, Ullung and Dok islands, where it occurs as dodecaploids (2n = 132). We investigated the molecular variation in 104 accessions from 94 populations of F. sachalinensis and its relatives throughout their native range to elucidate the origin of these island populations. All F. sachalinensis plants on Ullung and Dok islands were uniquely dodecaploid, whereas other populations were tetraploid (2n = 44). Among the 39 cpDNA haplotypes identified, the accessions from these islands shared two unique haplotypes, and were resolved as a well-supported monophyletic clade. However, this clade was sister to a clade comprising F. japonica accessions from southwestern Japan and separated from the clade comprising F. sachalinensis from other areas; this relationship is inconsistent with morphological evidence. The monophyly of the F. sachalinensis populations on Ullung and Dok islands suggests a single colonization event. The progenitor was likely from Japan, where it possibly captured F. japonica var. japonica cpDNA via introgression. The Ullung Island populations subsequently differentiated through polyploidization and mutations post-introduction. Our results also indicate that giant knotweed in Europe and North America likely originated from northern Japan and/or Sakhalin Island.
Interspecific hybridization has been suggested to occur frequently in Rumex (Polygonaceae). Several hypothesized combinations of parental species of hybrids based on their intermediate morphology have been suggested in the genus, but few of them have been phylogenetically tested. We analyzed nuclear and chloroplast DNA sequence data of a putative natural hybrid between Rumex crispus and Rumex obtusifolius from Korea to confirm its hybrid status and to determine the maternal parent. Analysis of the nuclear DNA pgiC region revealed that R. crispus and R. obtusifolius have contributed to the nuclear genome of the putative hybrids. The haplotype distribution pattern inferred from the combined sequence data set of five chloroplast DNA regions (matK, rbcL-accD IGS, trnK-rps16 IGS, ycf6-psbM IGS and psbA-trnH IGS) indicated bidirectional hybridization events between R. crispus and R. obtusifolius. This paper provides the first molecular evidence for interspecific hybridization between R. crispus and R. obtusifolius. In addition, our findings strongly suggested that Korean populations of Rumex japonicus have a hybrid origin, and R. crispus may represent one of the parental taxa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.