Strong Genetic Differentiation of Submerged Plant Populations across Mountain Ranges: Evidence from Potamogeton pectinatus in Iran

Mutational Dynamics of Aroid Chloroplast Genomes II

The co-occurrence among single nucleotide polymorphisms (SNPs), insertions-deletions (InDels), and oligonucleotide repeats has been reported in prokaryote, eukaryote, and chloroplast genomes. Correlations among SNPs, InDels, and repeats have been investigated in the plant family Araceae previously using pair-wise sequence alignments of the chloroplast genomes of two morphotypes of one species, Colocasia esculenta belonging to subfamily Aroideae (crown group), and four species from the subfamily Lemnoideae, a basal group. The family Araceae is a large family comprising 3,645 species in 144 genera, grouped into eight subfamilies. In the current study, we performed 34 comparisons using 27 species from 7 subfamilies of Araceae to determine correlation coefficients among the mutational events at the family, subfamily, and genus levels. We express strength of the correlations as: negligible or very weak (0.10–0.19), weak (0.20–0.29), moderate (0.30–0.39), strong (0.40–0.69), very strong (0.70–0.99), and perfect (1.00). We observed strong/very strong correlations in most comparisons, whereas a few comparisons showed moderate correlations. The average correlation coefficient was recorded as 0.66 between “SNPs and InDels,” 0.50 between “InDels and repeats,” and 0.42 between “SNPs and repeats.” In qualitative analyses, 95–100% of the repeats at family and sub-family level, while 36–86% of the repeats at genus level comparisons co-occurred with SNPs in the same bins. Our findings show that such correlations among mutational events exist throughout Araceae and support the hypothesis of distribution of oligonucleotide repeats as a proxy for mutational hotspots.

A Biogeographic Barrier Test Reveals a Strong Genetic Structure for a Canopy-Emergent Amazon Tree Species

Wallace's (1854) Riverine Barrier hypothesis is one of the earliest explanations for Amazon biotic diversification. Despite the importance of this hypothesis for explaining speciation in some animal groups, it has not been studied extensively for plant species. In this study we use a prominent Amazon tree, Buchenavia oxycarpa (Mart.) Eichler (Combretaceae), to evaluate Wallace's hypothesis along the Rio Negro, a major Amazon tributary that has driven allopatric speciation for several animal taxa. We sampled six individuals from sixteen localities along both river banks, and used a modified ddRADseq protocol to identify SNP markers. Our population genomic data revealed strong genetic structure for B. oxycarpa sampled across banks of the Rio Negro (ϕ_CT = 0.576, P < 0.001), supporting the hypothesis that the Rio Negro acted as a significant genetic barrier for B. oxycarpa. Our study shows that gene flow for this large and well-dispersed Amazon tree is impeded by riverine barriers, though this has not yet resulted in speciation. Future studies focused on species with different life histories, including species restricted to non-flooded forests, are needed to further advance our understanding of Amazon rivers as drivers of biotic diversification.

Regression model, artificial neural network, and cost estimation for biosorption of Ni(II)-ions from aqueous solutions by Potamogeton pectinatus

This study investigated the application of Potamogeton pectinatus for Ni(II)-ions biosorption from aqueous solutions. FTIR spectra showed that the functional groups of -OH, C-H, -C = O, and -COO- could form an organometallic complex with Ni(II)-ions on the biomaterial surface. SEM/EDX analysis indicated that the voids on the biosorbent surface were blocked due to Ni(II)-ions uptake via an ion exchange mechanism. For Ni(II)-ions of 50 mg/L, the adsorption efficiency recorded 63.4% at pH: 5, biosorbent dosage: 10 g/L, and particle-diameter: 0.125-0.25 mm within 180 minutes. A quadratic model depicted that the plot of removal efficiency against pH or contact time caused quadratic-linear concave up curves, whereas the curve of initial Ni(II)-ions was quadratic-linear convex down. Artificial neural network with a structure of 5 - 6 - 1 was able to predict the adsorption efficiency (R²: 0.967). The relative importance of inputs was: initial Ni(II)-ions > pH > contact time > biosorbent dosage > particle-size. Freundlich isotherm described well the adsorption mechanism (R²: 0.974), which indicated a multilayer adsorption onto energetically heterogeneous surfaces. The net cost of using P. pectinatus for the removal of Ni(II)-ions (4.25 ± 1.26 mg/L) from real industrial effluents within 30 minutes was 3.4 $USD/m³.

Population Genetics of the Endangered and Wild Edible Plant Ottelia acuminata in Southwestern China Using Novel SSR Markers

Ottelia acuminata is an edible aquatic plant species that is endemic to southwestern China. This plant has experienced habitat degradation resulting from environmental change and extensive human disturbance. Determining the genetic variation and genetic structure of O. acuminata populations could help develop strategies to collect, evaluate, utilize and conserve the species. To this end, we genotyped 183 individuals sampled throughout the species distribution using twelve novel nuclear microsatellite loci (nSSRs). Eight of these nSSRs exhibited low average levels of genetic diversity (H_E = 0.351, Ho = 0.376) and showed evidence of significant inbreeding across several populations. A high degree of genetic differentiation was identified among populations (F_ST = 0.457), probably resulting from limited pollen and seed-mediated gene flow. Only 17.8% of variation existed between O. acuminata var. acuminata and other O. acuminata varieties. Bayesian analysis and a UPGMA dendrogram based on Nei's genetic distance also revealed notably low genetic differentiation among the varieties. This low genetic differentiation is possibly attributed to shared ancestral polymorphisms since their divergence. Additional taxonomic and phylogenetic studies with additional molecular markers are needed to determine the population genetic relationship between O. acuminata varieties. Conservation of this species depends on in situ and ex situ actions, such as controlling habitat water pollution and overexploitation and creating a germplasm bank based on the population genetic differences. To the best of our knowledge, this study represents the first attempt to understand the population genetics of O. acuminata in China using novel nSSR markers developed from transcriptome sequencing and could contribute to the conservation management of this economic plant.