Abstract Vietnam features extensive ethnolinguistic diversity and occupies a key position in Mainland Southeast Asia. Yet, the genetic diversity of Vietnam remains relatively unexplored, especially with genome-wide data, because previous studies have focused mainly on the majority Kinh group. Here, we analyze newly generated genome-wide single-nucleotide polymorphism data for the Kinh and 21 additional ethnic groups in Vietnam, encompassing all five major language families in Mainland Southeast Asia. In addition to analyzing the allele and haplotype sharing within the Vietnamese groups, we incorporate published data from both nearby modern populations and ancient samples for comparison. In contrast to previous studies that suggested a largely indigenous origin for Vietnamese genetic diversity, we find that Vietnamese ethnolinguistic groups harbor multiple sources of genetic diversity that likely reflect different sources for the ancestry associated with each language family. However, linguistic diversity does not completely match genetic diversity: There have been extensive interactions between the Hmong-Mien and Tai-Kadai groups; different Austro-Asiatic groups show different affinities with other ethnolinguistic groups; and we identified a likely case of cultural diffusion in which some Austro-Asiatic groups shifted to Austronesian languages during the past 2,500 years. Overall, our results highlight the importance of genome-wide data from dense sampling of ethnolinguistic groups in providing new insights into the genetic diversity and history of an ethnolinguistically diverse region, such as Vietnam.

Vietnam exhibits great cultural and linguistic diversity, yet the genetic history of Vietnamese populations remains poorly understood. Previous studies focused mostly on the majority Kinh group, and thus the genetic diversity of the many other groups has not yet been investigated. Here we analyze complete mtDNA genome sequences and~2.3 Mb sequences of the male-specific portion of the Y chromosome from the Kinh and 16 minority populations, encompassing all five language families present in Vietnam. We find highly variable levels of diversity within and between groups that do not correlate with either geography or language family. In particular, the Mang and Sila have undergone recent, independent bottlenecks, while the majority group, Kinh, exhibits low levels of differentiation with other groups. The two Austronesian-speaking groups, Giarai and Ede, show a potential impact of matrilocality on their patterns of variation. Overall, we find that isolation, coupled with limited contact involving some groups, has been the major factor influencing the genetic structure of Vietnamese populations, and that there is substantial genetic diversity that is not represented by the Kinh.

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BackgroundThe economic value of ginseng in the global medicinal plant trade is estimated to be in excess of US$2.1 billion. At the same time, the evolutionary placement of ginseng (Panax ginseng) and the complex evolutionary history of the genus is poorly understood despite several molecular phylogenetic studies. In this study, we use a full plastome phylogenomic framework to resolve relationships in Panax and to identify molecular markers for species discrimination.ResultsWe used high-throughput sequencing of MBD2-Fc fractionated Panax DNA to supplement publicly available plastid genomes to create a phylogeny based on fully assembled and annotated plastid genomes from 60 accessions of 8 species. The plastome phylogeny based on a 163 kbp matrix resolves the sister relationship of Panax ginseng with P. quinquefolius. The closely related species P. vietnamensis is supported as sister of P. japonicus. The plastome matrix also shows that the markers trnC-rps16, trnS-trnG, and trnE-trnM could be used for unambiguous molecular identification of all the represented species in the genus.ConclusionsMBD2 depletion reduces the cost of plastome sequencing, which makes it a cost-effective alternative to Sanger sequencing based DNA barcoding for molecular identification. The plastome phylogeny provides a robust framework that can be used to study the evolution of morphological characters and biosynthesis pathways of ginsengosides for phylogenetic bioprospecting. Molecular identification of ginseng species is essential for authenticating ginseng in international trade and it provides an incentive for manufacturers to create authentic products with verified ingredients.Electronic supplementary materialThe online version of this article (10.1186/s12862-018-1160-y) contains supplementary material, which is available to authorized users.

Proteinase A is a papain-like cysteine endopeptidase of vetch (Vicia sativu L.) which was assumed to initiate storage-globulin breakdown just after the onset of seed germination. This enzyme was purified from cotyledons of vetch seedlings. On gelatin-containg SDS gels, active proteinase A migrated with an apparent molecular mass of 21 kDa, whereas after heat denaturation its molecular size on SDSPAGE was 29 kDa. Although proteinase A is capable of hydrolyzing storage globulins in vitro it could not be localized in the protein-body fraction of cotyledons from germinating seeds. cDNA clones encoding proteinase A precursor have been obtained by PCR. The precursor is composed of an N-terminal signal sequence followed by a propeptide, the region encoding mature proteinase A, and a C-terminal KDEL sequence. Mature proteinase A with a derived molecular mass of 25244 Da does not have the KDEL sequence. The derived amino acid sequence of the proteinase A precursor is 78.2% identical to sulfhydrylendopeptidase (SH-EP), a cysteine endopeptidase from germinating Vigna tnungo seedlings. Northern blot analysis indicated that proteinase A mRNA appears de novo in cotyledons of I-day-germinated vetch seeds, where its amount increases up to day 6. No proteinase A mRNA was detected in other vetch organs, not even in the embryo axis, which contains stored globulins. By means of antibodies raised against the purified and against recombinantly produced proteinase A, the 29-kDa bands of mature proteinase A were detected in cotyledon extracts of 6-day-germinated seeds when globulin degradation has already far proceeded. The reported data do not agree with the proposed triggering role of proteinase A in storage-globulin breakdown during germination.Keywords: triggering cysteine endopeptidase ; seed germination; Vicia sativa L. ; endoplasmic reticulum retention signal.The beginning of storage-protein degradation is indicated by slight mobility changes of globulins from cotyledon extracts of germinating dicotyledonous seeds on electrophoresis (Shutov and Vaintraub, 1973;Lichtenfeld et al., 1979Lichtenfeld et al., , 1981Boylan and Sussex, 1987; Dunaevsky and Belozersky, 1989). During this first stage of breakdown the holoproteins remain assembled, which is reflected by nearly unchanged positions in the sucrosedensity gradient after centrifugation and in gels after electrophoresis under non-denaturing conditions. Only small trichloroacetic-acid-soluble peptides are lost as the result of limited proteolysis (Shutov and Vaintraub, 1987). These first modifications are thought to be catalyzed either by stored endopeptidases that have to be activated just after imbibition, as in buckwheat (Elpidino et al., 1991), or by newly formed endopeptidases, as assumed for the majority of legumes (Chrispeels et al., 1976; Lichtenfeld et al., 1979;Muntz et al., 1985; Shutov and Vaintraub, 1987). Only after 3-6 days depending on the species and germination conditions, a second stage with rapid storageglobulin degradation begins, accompanied by strong increa...