scholarly journals Genetic Diversity and Population Structure in Bryophyte With Facultative Nannandry

2021 ◽  
Vol 12 ◽  
Author(s):  
Annick S. Lang ◽  
Thies Gehrmann ◽  
Nils Cronberg
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Snp Markers ◽  
Small Scale ◽  
Southern Sweden ◽  
Gender Dimorphism ◽  
Relative Contribution ◽  
Dicranum Scoparium ◽  
Dwarf Males

Among plants, gender dimorphism occurs in about 10% of all angiosperms and more than 50% of all moss taxa, with dwarf males (DM) found exclusively in some unisexual mosses. In this study, we explore the role of male dwarfism as a reproductive strategy in the widespread acrocarpous moss Dicranum scoparium, which has facultative male dwarfism, having both dwarf males (DMs) and normal-sized males (NMs). We retrieved 119 SNP markers from transcriptomes which were used to genotype 403 samples from 11 sites at seven localities in southern Sweden. Our aims were to compare the genetic variability and genetic structure of sexually reproducing populations at different geographic levels (cushion, site, and locality) and compare in particular the relative contribution of females, dwarf males and normal-sized males to the observed genetic diversity. The numbers of DMs differed strongly between sites, but when present, they usually outnumbered both females and NMs. Low genetic differentiation was found at locality level. Genetic differentiation was strongest between cushions for females and NMs and within cushions for DMs indicating small scale structuring and sometimes inbreeding. NMs were more clonal than either DMs or females. Genetic diversity was similar between females and DMs, but lower for NMs. Two haplotypes were shared between females and DMs and one haplotype was shared between a DM and a NM. In conclusion, our results show that DMs and NMs play different roles in reproduction, inbreeding may occur at cushion level, but gene flow is high enough to prevent substantial genetic drift.

scholarly journals Influence of isolation by environment and landscape heterogeneity on genetic structure of wild rice Zizania latifolia along a latitudinal gradient

2020 ◽  
Author(s):  
Godfrey Kinyori Wagutu ◽  
Xiangrong Fan ◽  
Wenlong Fu ◽  
Wei Li ◽  
Yuanyuan Chen
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Local Adaptation ◽  
Landscape Heterogeneity ◽  
Maximum Temperature ◽  
Zizania Latifolia ◽  
Precipitation Seasonality ◽  
Isolation By Environment

AbstractGlobal aquatic habitats are undergoing rapid degradation and fragmentation as a result of land-use change and climate change. Understanding the genetic variability and adaptive potential of aquatic plant species is thus important for conservation purposes. In this study, we investigated the role of environment, landscape heterogeneity and geographical distance in shaping the genetic structure of 28 natural populations of Zizania latifolia (Griseb.) Turcz. Ex Stapf in China based on 25 microsatellite markers. Genetic structure was investigated by analysis of molecular variance (AMOVA), estimation of FST, Bayesian clustering and Thermodynamic Integration (TI) methods. Isolation by environment (IBE), isolation by resistance (IBR) and isolation by distance (IBD) hypotheses were compared using a reciprocal causal model (RCM). Further, generalized linear models and spatially explicit mixed models, by using geographic, landscape and genetic variables, were developed to elucidate the role of environment in driving Z. latifolia genetic diversity. The genetic differentiation across all populations was high: FST = 0.579; Øpt = 0.578. RCM exclusively supported IBE in shaping genetic structuring, only partial support for IBR, but not for IBD. Maximum temperature of the warmest month and precipitation seasonality were the plausible parameters responsible for genetic diversity. After controlling for spatial effect and landscape complexity, precipitation seasonality was significantly associated with genetic diversity. Based on these findings, genetic structure of Z. latifolia across China seem to be as a result of local adaptation. Environmental gradient and topographical barriers, rather than geographical isolation, influence genetic differentiation of aquatic species across China resulting in instances of local adaptation.

scholarly journals Genetic diversity analysis of a Flax (Linum usitatissimum L.) global collection

2020 ◽  
Author(s):  
Ahasanul Hoque ◽  
Jason D. Fiedler ◽  
Mukhlesur Rahman
Keyword(s):  
Genetic Diversity ◽  
Linkage Disequilibrium ◽  
Genetic Differentiation ◽  
Genetic Gain ◽  
Mantel Test ◽  
Snp Markers ◽  
Breeding Program ◽  
Neighbor Joining ◽  
Breeding Lines ◽  
The North

Abstract Background A sustainable breeding program requires a minimum level of germplasm diversity to provide varied options for the selection of new breeding lines. To maximize genetic gain of the North Dakota State University (NDSU) flax breeding program, we aimed to increase the genetic diversity of its parental stocks by incorporating diverse genotypes. For this purpose, we analyzed the genetic diversity, linkage disequilibrium, and population sub-structure of 350 globally-distributed flax genotypes with 6,200 SNP markers Results All the genotypes tested clustered into seven sub-populations (P1 to P7) based on the admixture model and the output of neighbor-joining (NJ) tree analysis and principal coordinate analysis were in line with that of structure analysis. The largest sub-population separation arose from a cluster of NDSU/American genotypes with Turkish and Asian genotypes. All sub-populations showed moderate genetic diversity (average H = 0.22 and I = 0.34). The pairwise F st comparison revealed a great degree of divergence ( F st > 0.25) between most of the combinations. A whole collection mantel test showed significant positive correlation (r = 0.30 and p < 0.01) between genetic and geographic distances, whereas it was non-significant for all sub-populations except P4 and P5 (r= 0.251, 0.349 respectively and p < 0.05). In the entire collection, the mean linkage disequilibrium was 0.03 and it decayed to its half maximum within < 21 kb distance. Conclusions To maximize genetic gain, hybridization between NDSU stock (P5) and Asian individuals (P6) are potentially the best option as genetic differentiation between them is highest ( F st > 0.50). In contrast, low genetic differentiation between P5 and P2 may enhance the accumulation of favorable alleles for oil and fiber upon crossing to develop dual purpose varieties. As each sub-population consists of many genotypes, a Neighbor-Joining tree assists to identify distantly related genotypes. These results also inform genotyping decisions for future association mapping studies to ensure the identification of a sufficient number of molecular markers to tag all linkage blocks.

scholarly journals Small-scale spatial genetic structure of Asarum sieboldii metapopulation in a valley

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Hyeon Jin Jeong ◽  
Jae Geun Kim
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Genetic Distance ◽  
Spatial Genetic Structure ◽  
Dispersal Distance ◽  
Forest Understory ◽  
Small Scale ◽  
Low Density ◽  
Stochastic Events

Abstract Background Asarum sieboldii Miq., a species of forest understory vegetation, is an herbaceous perennial belonging to the family Aristolochiaceae. The metapopulation of A. sieboldii is distributed sparsely and has a short seed dispersal distance by ants as their seed distributor. It is known that many flowers of A. sieboldii depend on self-fertilization. Because these characteristics can affect negatively in genetic structure, investigating habitat structure and assessment of genetic structure is needed. A total of 27 individuals in a valley were sampled for measuring genetic diversity, genetic distance, and genetic differentiation by RAPD-PCR. Results The habitat areas of A. sieboldii metapopulation were relatively small (3.78~33.60 m2) and population density was very low (five to seven individuals in 20×20 m quadrat). The habitat of A. sieboldii was a very shady (relative light intensity = 0.9%) and mature forest with a high evenness value (J = 0.81~0.99) and a low dominance value (D = 0.19~0.28). The total genetic diversity of A. sieboldii was quite high (h = 0.338, I = 0.506). A total of 33 band loci were observed in five selected primers, and 31 band loci (94%) were polymorphic. However, genetic differentiation along the valley was highly progressed (Gst = 0.548, Nm = 0.412). The average genetic distance between subpopulations was 0.387. The results of AMOVA showed 52.77% of variance occurs among populations, which is evidence of population structuring. Conclusions It is expected that a small-scale founder effect had occurred, an individual spread far from the original subpopulation formed a new subpopulation. However, geographical distance between individuals would have been far and genetic flow occurred only within each subpopulation because of the low density of population. This made significant genetic distance between the original and new population by distance. Although genetic diversity of A. sieboldii metapopulation is not as low as concerned, the subpopulation of A. sieboldii can disappear by stochastic events due to small subpopulation size and low density of population. To prevent genetic isolation and to enhance the stable population size, conservative efforts such as increasing the size of each subpopulation or the connection between subpopulations are needed.

scholarly journals Genetic diversity of local and introduced cassava germplasm in Burundi using DArTseq molecular analyses

2021 ◽  
Author(s):  
niyonzima pierre ◽  
Lydia Nanjala Wamalwa ◽  
William Maina Muiru ◽  
Bigirimana Simon ◽  
Edward Kanju ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Morphological Traits ◽  
Snp Markers ◽  
Mosaic Disease ◽  
Breeding Program ◽  
Cassava Mosaic Disease ◽  
Small Scale ◽  
Population Genetic Analysis ◽  
Local Conditions ◽  
Elite Germplasm

In Burundi, most of small-scale farmers still grow traditional cassava landraces that are adapted to local conditions and have been selected for consumer preferred attributes. They tend to be susceptible, in varying degrees, to devastating cassava viral diseases such as Cassava Brown Steak Disease (CBSD) and Cassava Mosaic Disease (CMD) with production annual losses of US$1 billion annually. For long term resistance to the disease, several breeding strategies have been proposed. A sound basis for a breeding program is to understand the genetic diversity of both landraces and elite introduced breeding cultivars. This will also assist in efforts to conserve landraces ahead of the broad distribution of improved varieties which have the possibility of replacing landraces. Our study aimed at determining the genetic diversity and relationships of local landraces and introduced elite germplasm using morphological and simple nucleotide polymorphism (SNP) markers as well as identifying a core set of germplasm from the local varieties to be used in the cassava breeding program. A total of 118 cultivars were characterized for morphological trait variation based on leaf, stem and root traits, and genetic variation using SNP markers. Results of morphological characterization based on Ward’s Method revealed three main clusters and five accessions sharing similar characteristics. Molecular characterization identified over 18,000 SNPs and six main clusters and three pairs of duplicates which should be pooled together as one cultivar to avoid redundancy. Results of population genetic analysis showed low genetic distance between populations and between local landraces and elite germplasm. Accessions that shared similar morphological traits were divergent at the molecular level indicating that clustering using morphological traits was inconsistent. Despite the variabilities found within the collection, it was observed that cassava germplasm in Burundi have a narrow genetic base.

scholarly journals The genetic diversity of Ethiopian barley genotypes in relation to their geographical origin

2021 ◽  
Author(s):  
Surafel Shibru Teklemariam ◽  
Kefyalew Negisho Bayissa ◽  
Andrea Matros ◽  
Klaus Pillen ◽  
Frank Ordon ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Geographic Distance ◽  
Snp Array ◽  
Farming Systems ◽  
Mantel Test ◽  
Snp Markers ◽  
Improvement Program ◽  
Climate Conditions ◽  
Breeding Lines

Ethiopia is recognized as a center of diversity for barley, and its landraces are known for the distinct genetic features compared to other barley collections. The genetic diversity of Ethiopian barley likely results from the highly diverse topography, altitude, climate conditions, soil types, and farming systems. To get detailed information on the genetic diversity a panel of 260 accessions, comprising 239 landraces and 21 barley breeding lines, obtained from the Ethiopian biodiversity institute (EBI) and the national barley improvement program, respectively were studied for their genetic diversity using the 50k iSelect single nucleotide polymorphism (SNP) array. A total of 983 highly informative SNP markers were used for structure and diversity analysis. Three genetically distinct clusters were obtained from the structure analysis comprising 80, 71, and 109 accessions, respectively. Analysis of molecular variance (AMOVA) revealed the presence of higher genetic variation (89%) within the clusters than between the clusters (11%), with moderate genetic differentiation (PhiPT=0.11) and adequate gene flow (Nm=2.02). The Mantel test revealed that the genetic distance between accessions is poorly associated with their geographical distance. Despite the observed weak correlation between geographic distance and genetic differentiation, for some regions like Gonder, Jimma, Gamo-Gofa, Shewa, and Welo, more than 50% of the landraces derived from these regions are assigned to one of the three clusters.

scholarly journals Estimation of the Genetic Diversity and Population Structure of Thailand’s Rice Landraces Using SNP Markers

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 995
Author(s):  
Wanchana Aesomnuk ◽  
Siriphat Ruengphayak ◽  
Vinitchan Ruanjaichon ◽  
Tanee Sreewongchai ◽  
Chanate Malumpong ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Mantel Test ◽  
Snp Markers ◽  
High Yield ◽  
Rice Varieties ◽  
Rice Landraces ◽  
Geographical Regions

Rice is a staple food for more than half of the world’s population. Modern rice varieties have been developed for high yield and quality; however, there has been a substantial loss of diversity. A greater number of genetically dynamic landraces could offer valuable and useful genetic resources for rice improvement. In this study, the genetic diversity and population structure of 365 accessions of lowland and upland landraces from four populations from different geographical regions of Thailand were investigated using 75 SNP markers. Clustering analyses using maximum likelihood, Principal Coordinate Analysis (PCoA), and Discriminant Analysis of Principal Components (DAPC) clustered these landraces into two main groups, corresponding to indica and japonica groups. The indica group was further clustered into two subgroups according to the DAPC and STRUCTURE analyses (K = 3). The analysis of molecular variance (AMOVA) analysis results revealed that 91% of the variation was distributed among individuals, suggesting a high degree of genetic differentiation among rice accessions within the populations. Pairwise FST showed the greatest genetic differentiation between the northeastern and southern populations and the smallest genetic differentiation between the northern and northeastern populations. Isolation-by-distance analysis based on a Mantel test indicated a significant relationship between the genetic distance and geographic distance among the Thai rice landraces. The results from this study provide insight into the genetic diversity of Thai rice germplasm, which will enhance the germplasm characterization, conservation, and utilization in rice genetics and breeding.

scholarly journals Phylogeography Reveals Geographic and Environmental Factors Driving Genetic Differentiation of Populus sect. Turanga in Northwest China

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhongshuai Gai ◽  
Juntuan Zhai ◽  
Xiangxiang Chen ◽  
Peipei Jiao ◽  
Shanhe Zhang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Environmental Factors ◽  
Genetic Differentiation ◽  
Populus Euphratica ◽  
Northwest China ◽  
Snp Markers ◽  
Habitat Destruction ◽  
Northwestern China ◽  
Conservation Strategies ◽  
Distribution Area

Populus sect. Turanga (hereafter referred to as “Populus”), including Populus euphratica and Populus pruinosa, are the predominant tree species in desert riparian forests in northwestern China. These trees play key roles in maintaining ecosystem balance, curbing desertification, and protecting biodiversity. However, the distribution area of Populus forests has been severely diminished and degraded in recent years due to increased habitat destruction and human activity. Understanding the genetic diversity among Populus individuals and populations is essential for designing conservation strategies, but comprehensive studies of their genetic diversity in northwest China are lacking. Here, we assessed the population structures and genetic diversity of 1,620 samples from 85 natural populations of Populus (59 P. euphratica and 26 P. pruinosa populations) covering all of northwestern China using 120 single nucleotide polymorphism (SNP) markers. Analysis of population structure revealed significant differentiation between these two sister species and indicated that strong geographical distribution patterns, a geographical barrier, and environmental heterogeneity shaped the extant genetic patterns of Populus. Both P. euphratica and P. pruinosa populations in southern Xinjiang had higher genetic diversity than populations in other clades, perhaps contributing to local geographic structure and strong gene flow. Analysis of molecular variance (AMOVA) identified 15% variance among and 85% variance within subpopulations. Mantel tests suggested that the genetic variation among P. euphratica and P. pruinosa populations could be explained by both geographical and environmental distance. The genetic diversity of P. euphratica showed a significant negative correlation with latitude and longitude and a positive correlation with various environmental factors, such as precipitation of warmest quarter and driest month, temperature seasonality, and annual mean temperature. These findings provide insights into how the genetic differentiation of endangered Populus species was driven by geographical and environmental factors, which should be helpful for designing strategies to protect these genetic resources in the future.

Assessment of Genetic Diversity in Traditional Landraces and Improved Cultivars of Rice

2020 ◽  
Author(s):  
Nageen Zahra ◽  
Muhammad Kashif Naeem ◽  
Bilal Saleem ◽  
Muhammad Aqeel ◽  
Wajya Ajmal ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Differentiation ◽  
Large Scale ◽  
Heading Date ◽  
Principal Component ◽  
Snp Markers ◽  
Rice Cultivars ◽  
Breeding Programs ◽  
Improved Cultivars ◽  
Traditional Landraces

Abstract Background: Rice is the staple food for more than half of the world's population. Rice cultivation needs expansion to meet the increasing food demands across the globe. Genetic diversity is desired for crop breeding because it serves as the backbone for improving cultivars. The process of domestication and modern plant breeding technologies applied to rice has contributed to the erosion of genetic diversity. Current breeding programs have extensively shaped the genetic diversity of elite rice cultivars to no small extent. Results: We explored the genetic diversity of traditional landraces and improved cultivars by inspecting the whole genome SNP markers of 20 rice accessions. We found a higher number of genetic variations (76.70%) and observed heterozygosity (0.024) in landraces than improved cultivars. The principal component analysis also revealed the higher genetic diversity among the landraces. While population structure based on the phylogenetic tree suggested the population's structure according to rice subspecies. The genetic diversity parameter, FST, was applied to estimate the genetic differentiation of rice, which revealed week genetic differentiation (0.121) and nucleotide diversity (0.314) in modern rice cultivars. Genome-wide genetic differentiation (FST) analysis identified the two domesticated genes: Kala4 (pericarp color) and Ghd7 (heading date), and eight improvement genes: Sd1, Ghd8, GW2, NRT1.1b, GW6a, and Hd3a, that coincide with the candidate selective sweeps. Inbreeding depression (0.68617) among the modern cultivars suggests no genetic gain in future breeding efforts and compels exotic material utilization in the breeding programs. Conclusion: These findings demonstrate that modern cultivars have a narrow genetic base compared to landraces. Therefore, exploring the genome of landraces at a large scale to identify the genes responsible for stability and adaptation to abiotic stresses can help design varieties that can survive vulnerable climates.

scholarly journals The role of environmental factors in the formation of the genetic structure of P. аbies populations

2017 ◽  
Vol 15 (2) ◽  
pp. 11-20
Author(s):  
Kseniia V Zakharova ◽  
Kirill S Seits
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Geographic Region ◽  
Genetic Differences ◽  
Environment Impact ◽  
Geographical Regions ◽  
Adult Trees ◽  
Isolation By Environment

Background. Norway spruce (Picea abies (L.) Karst.) is one of the main forest forming spruce species in Europe. Their populations are characterized by the genetic heterogeneity between individuals in population. The genetic structure of P. abies populations studied supported a hypothesis of an environment impact on the degree of genetic differentiation among populations. Materials and methods. Analysis of genetic diversity of natural populations in distinct geographical regions from North-West Russia, South-West Russia, South Norway were done using nuclear microsatellites. The needles were collected from the 20-30 adult trees in each geographical spot taking into account the local environment. The statistical calculations were performed with GenAlEx 6.5.03 and Structure 2.3.4. Results. The analysis highlighted the environmental impact on the genetic diversity. The genetic structure of spruce cenopopulations from poor conditions are extremely different from those of cenopopulations growing under rich environmental conditions in one geographic region. The genetic differences between them are comparable with the genetic differences between spatially remote populations. Conclusion. The role of the isolation by environment as a pattern in which genetic differentiation increases with environmental differences independent of the geographic distance is essential for genetic structure of spruce populations.

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