Natural Plant Populations Research Articles

Effect of In Vitro Pretreatment with Ag-Containing Amino Acid Nanofibers on Biometrics and Antioxidant Activity in Drought-Stressed Ex Vitro-Adapted Stevia rebaudiana Bertoni

Biotechnological methods prevent the destruction of natural populations of medicinal plants due to climate change and developing agriculture. This study evaluates the effects of in vitro pretreatment with two types of silver-containing amino acid nanofibers (NF-1%Ag and NF1-Ag salt) on the drought tolerance of ex vitro soil-adapted Steviia rebaudiana Bertoni. The duration of the drought was five days. The data suggested that the pretreatment with the studied nanofibers during plant propagation enhanced the plant tolerance to drought stress manifested in a smaller decrease in plant biomass accumulation and a smaller increase in sugar content. The pretreatment with the two tested nanoparticles of well-watered plants increased the leaf fresh biomass accumulation of the ex vitro-adapted S. rebaudiana compared to the untreated WW control plants. The highest values were reported at 10 mg L−1 NF1-Ag salt. Five days of drought led to a decrease in the leaf fresh biomass compared to the WW plants, with the recorded lowest reduction again at 10 mg L−1 NF1-Ag salt. These observations correlate with antioxidant activity improvement. The results show that adding 10 mg L−1 NF1-Ag salt to the MS medium led to higher ex vitro-adapted S. rebaudiana resistance to water deficit than 100 mg L−1. This paper discusses the impact of the selected nanofibers on parameters characterizing plant growth and antioxidant activity of drought-stressed ex vitro-adapted Stevia rebaudiana plants.

Selection for domestication favored taxa characterized by fast growth and tolerance of high intraspecific density

Societal Impact StatementTo understand why certain plants have been domesticated into crops, we need to recognize that the environmental conditions plants experience in wild populations are totally different from those of agricultural fields. In this study, we investigated whether the characteristics that promote growth and survival in these different environments may have influenced domestication. Our results revealed that ancestral crops were selected because they developed better than other plants in dense single‐species stands, with selection for increased yield likely occurring after domestication. These insights shed light on the origins of agriculture and offer valuable guidance for future crop breeding efforts.Summary In spite of a large history of research, it is still unclear which functional traits may have mediated plant domestication. Solving this problem requires consideration of the ecological and demographic disparities between natural plant populations and cultivated fields. Since population density tends to be higher in the latter, we hypothesized that traits facilitating growth and survival in dense, monospecific populations might have been relevant for initial domestication. We investigated whether functional traits that respond to population density varied across three different domestication stages: undomesticated crop wild relatives, natural populations of crop progenitors, and landraces. To do this, we compared traits influencing competition (lodging; growth rate), resource acquisition (plant height; total aerial and root biomass) and yield (fruit number) in three annual legume crops—lentil, grasspea, and vetch—grown without resource limitation at three different densities. Our results showed clear differences among species, likely reflective of the distinct uses of the crops and their domestication pathways. Nevertheless, undomesticated relatives consistently differed from crop progenitors and landraces, producing smaller, slower‐growing plants that were more prostrate and allocated less biomass to roots. The effect of selection under domestication on these vegetative traits appeared to be largely negligible. Conversely, landraces produced more fruits. We conclude that early agriculturalists selected for domestication wild legumes that performed well in dense monocultures and were more effective in resource capture. Later domestication and breeding efforts likely had more significant effects on reproductive traits, such as fruit and seed production.

Study of Hyssop Essential Oil from Southeastern Serbia.

The aim of the present study was a chemical, microbiological and statistics analysis of Hyssopus officinalis L. subsp. aristatus (Godr.) Nyman essential oil during different stages of development from three natural populations of plant collected in southeastern Serbia. In addition, using statistical tools, we also tried to explain the effect of dominant components' content on antimicrobial activity. Oxygenated monoterpenes were the most abundant compound class in the H. officinalis oil during examined phenological stages (27.32-92.25 %). The four most abundant essential oil components are eucalyptol, cis-pinocamphone, β-pinene and β-ocimene. H. officinalis essential oils demonstrated minimum inhibitory concentrations and minimum microbicidal concentrations values from 2.4 to 160 mg/mL. Maximum antimicrobial activity, in total, was recorded in November, after the flowering stage. The percentage of dominant compounds of essential oils, eucalyptol, and cis-pinocamphone, affects essential oils' antibacterial activity. The essential oil with most closely matched research criteria was extracted from a plant in Kravlje village.

Sexual differetiation of Rhodiola rosea L. populations in the high-mountain zone of the Ukrainian Carpathians

Background. Individual (morphological) and group parameters (the number of male and female individuals, their sex ratio, and the range of sex ratio displacement) are an important indicator of sexual differentiation of Rhodiola rosea L. populations. To date, indicators of these parameters in natural plant populations have not been studied sufficiently. Therefore, for the analysis of the state of the populations of the species, it is important to study the parameters of their sexual differentiation and the main trends of changes that affect the ability to recover in high-mountain conditions. Methods. In order to obtain data, conventional stationary and route-based research methods were used. To record individuals of different sexes, long-term monitoring plots were used, which were laid in the characteristic habitats of the species’ populations in 2000–2022. The ratio of male and female individuals is determined based on their quantitative distribution per unit area. The sexual potential index that determines the proportion of females and their participation in generative reproduction was used. Results. The main differences in the morphological and quantitative parameters of male and female individuals in high-mountain conditions were determined. It was found that a characteristic feature during long-term research is a decrease in the number of generative individuals of both male and female sexes. In the studied populations, there is a shift in the sex ratio towards males (73 %) and this trend has been maintained over the last dozen of years. Therefore, the number of females compared to males is very small, which affects the sexual potential of populations. Conclusions. The ratio of male and female individuals, the range of its displacement and potential participation in the realization of sexual potential in R. rosea was determined. The present study showed that the general trend in the populations of the species is a decrease in the number of female individuals. Male biased sex ratio has an impact on sexual potential and ability to generative reproduction.

Impacts of assisted migration: An introduced herbivore has short‐term and long‐term effects on its native host plant population

AbstractAssisted migration consists of the introduction of a species to previously inhabited areas or to new suitable regions. Such introductions have been touted as a viable tool for conserving the earth's biodiversity. However, both the likely success of assisted migrations and the impacts on local communities are hotly debated. Empirical data on the local impacts of assisted migration are particularly lacking. We examined the short and long time‐scale effects of herbivory on Lonicera involucrata (Richards) Banks ex. Spreng (Caprifoliaceae) after an introduction of Euphydryas gillettii Barnes (Lepidoptera: Nymphalidae, Melitaeini) to Gunnison County, Colorado, USA, via an assisted migration in 1977. The plant is the primary larval host plant for the butterfly. We quantified plant seed production, plant survival, and population stage structure in two sets of observational experiments. We found that herbivory by E. gillettii increased L. involucrata reproduction on an annual time scale, independent of plant size and local microhabitat characteristics. Over the time since the butterfly's introduction, herbivory by E. gillettii resulted in a plant population structure biased toward smaller plants in the butterfly introduction and satellite sites compared with sites without the butterfly. Our results highlight the importance of studying the effects of assisted migrations on native populations at different temporal scales. As assisted migration becomes an indispensable tool for species conservation, our work adds to the understanding of the multi‐trophic impacts of assisted introductions on local populations and communities.

Environmental genome-wide association studies across precipitation regimes reveal that the E3 ubiquitin ligase MBR1 regulates plant adaptation to rainy environments

In an era characterized by rapidly changing and less-predictable weather conditions fueled by the climate crisis, understanding the mechanisms underlying local adaptation in plants is of paramount importance for the conservation of species. As the frequency and intensity of extreme precipitation events increase, so are the flooding events resulting from soil water saturation. The subsequent onset of hypoxic stress is one of the leading causes of crop damage and yield loss. By combining genomics and remote sensing data, it is now possible to probe natural plant populations that have evolved in different rainfall regimes and look for molecular adaptation to hypoxia. Here, using an environmental genome-wide association study (eGWAS) of 934 non-redundant georeferenced Arabidopsis ecotypes, we have identified functional variants of the gene MED25 BINDING RING-H2 PROTEIN 1 (MBR1). This gene encodes a ubiquitin-protein ligase that regulates MEDIATOR25 (MED25), part of a multiprotein complex that interacts with transcription factors that act as key drivers of the hypoxic response in Arabidopsis, namely the RELATED TO AP2 proteins RAP2.2 and RAP2.12. Through experimental validation, we show that natural variants of MBR1 have different effects on the stability of MED25 and, in turn, on hypoxia tolerance. This study also highlights the pivotal role of the MBR1/MED25 module in establishing a comprehensive hypoxic response. Our findings show that molecular candidates for plant environmental adaptation can be effectively mined from large datasets. This thus supports the need for integration of forward and reverse genetics with robust molecular physiology validation of outcomes.

The impact of insect herbivory on biogeochemical cycling in broadleaved forests varies with temperature

Herbivorous insects alter biogeochemical cycling within forests, but the magnitude of these impacts, their global variation, and drivers of this variation remain poorly understood. To address this knowledge gap and help improve biogeochemical models, we established a global network of 74 plots within 40 mature, undisturbed broadleaved forests. We analyzed freshly senesced and green leaves for carbon, nitrogen, phosphorus and silica concentrations, foliar production and herbivory, and stand-level nutrient fluxes. We show more nutrient release by insect herbivores at non-outbreak levels in tropical forests than temperate and boreal forests, that these fluxes increase strongly with mean annual temperature, and that they exceed atmospheric deposition inputs in some localities. Thus, background levels of insect herbivory are sufficiently large to both alter ecosystem element cycling and influence terrestrial carbon cycling. Further, climate can affect interactions between natural populations of plants and herbivores with important consequences for global biogeochemical cycles across broadleaved forests.

Transcriptome variations in hybrids of wild emmer wheat (Triticum turgidum ssp. dicoccoides)

BackgroundWild emmer wheat is a great candidate to revitalize domesticated wheat genetic diversity. Recent years have seen intensive investigation into the evolution and domestication of wild emmer wheat, including whole-genome DNA and transcriptome sequencing. However, the impact of intraspecific hybridization on the transcriptome of wild emmer wheat has been poorly studied. In this study, we assessed changes in methylation patterns and transcriptomic variations in two accessions of wild emmer wheat collected from two marginal populations, Mt. Hermon and Mt. Amasa, and in their stable F4 hybrid.ResultsMethylation-Sensitive Amplified Polymorphism (MSAP) detected significant cytosine demethylation in F4 hybrids vs. parental lines, suggesting potential transcriptome variation. After a detailed analysis, we examined nine RNA-Seq samples, which included three biological replicates from the F4 hybrid and its parental lines. RNA-Seq databases contained approximately 200 million reads, with each library consisting of 15 to 25 million reads. There are a total of 62,490 well-annotated genes in these databases, with 6,602 genes showing differential expression between F4 hybrid and parental lines Mt. Hermon and Mt. Amasa. The differentially expressed genes were classified into four main categories based on their expression patterns. Gene ontology (GO) analysis revealed that differentially expressed genes are associated with DNA/RNA metabolism, photosynthesis, stress response, phosphorylation and developmental processes.ConclusionThis study highlights the significant transcriptomic changes resulting from intraspecific hybridization within natural plant populations, which might aid the nascent hybrid in adapting to various environmental conditions.

Equivalent mating system parameters in post‐mining and undisturbed native plant populations confirms restitution of bird‐pollinator function

Abstract The restoration of diverse self‐sustaining ecosystems requires re‐establishment of functional interactions among species. For plant communities, pollinators are usually essential for pollination, seed set and seed quality. A common assumption in ecological restoration for plants pollinated by animals is one of ‘build it and they will come’, which is rarely tested. Beyond seed set, there may be negative genetic consequences for seed quality if pollinators and their behaviour do not reflect those in reference populations. Here, we conduct an ecological genetic assessment of seed quality via mating system parameters in Lambertia multiflora (Proteaceae), a species dependent on nectar‐feeding birds for pollination. Four populations of L. multiflora in disturbed sites that were rehabilitated following mineral sands mining were compared with four native reference populations, near Eneabba, Western Australia. In each population, approximately 10 offspring from each of 10 maternal plants were genotyped with 11 highly polymorphic microsatellite markers. From these data, genetic diversity and mating system parameters were assessed, and found to be equivalent across all populations. Mean allelic diversity and heterozygosity across loci were very high. All populations were completely outcrossing with no bi‐parental inbreeding. Mean correlated paternity, sibship and effective population size estimates for restored and natural populations were not significantly different and reflected uniformly high paternal diversity and wide outcrossing. Equivalent genetic results for restored and natural reference populations indicate successful restitution of bird‐pollinator services for L. multiflora in these post‐mining rehabilitation sites. Synthesis and applications. Reviewing our results with other published studies to date suggests a resilience of bird‐pollinator services in restored plant communities. These findings provide some reassurance to restoration practitioners working in these global south systems where bird pollination is a feature, at least for similar landscape scenarios. Our study also highlights the global contribution of ecological genetics to the objective assessment of functional species interactions in ecological restoration, an increasingly important goal of land managers and regulators seeking to improve restoration standards.

Adaptive responses to living in stressful habitats: Do invasive and native plant populations use different strategies?

Plants inhabit stressful environments characterized by a variety of stressors, including mine sites, mountains, deserts, and high latitudes. Populations from stressful and reference (non-stressful) sites often have performance differences. However, while invasive and native species may respond differently to stressful environments, there is limited understanding of the patterns in reaction norms of populations from these sites. Here, we use phylogenetically controlled meta-analysis to assess the performance of populations under stress and non-stress conditions. We ask whether stress populations of natives and invasives differ in the magnitude of lowered performance under non-stress conditions and if they vary in the degree of performance advantage under stress. We also assessed whether these distinctions differ with stress intensity. Our findings revealed that natives not only have greater adaptive advantages but also more performance reductions than invasives. Populations from very stressful sites had more efficient adaptations, and performance costs increased with stress intensity in natives only. Overall, the results support the notion that adaptation is frequently costless. Reproductive output was most closely associated with adaptive costs and benefits. Our study characterized the adaptive strategies used by invasive and native plants under stressful conditions, thereby providing important insights into the limitations of adaptation to extreme sites.

Exploring the complex pre-adaptations of invasive plants to anthropogenic disturbance: a call for integration of archaeobotanical approaches.

Pre-adaptation to anthropogenic disturbance is broadly considered key for plant invasion success. Nevertheless, empirical evidence remains scarce and fragmentary, given the multifaceted nature of anthropogenic disturbance itself and the complexity of other evolutionary forces shaping the (epi)-genomes of recent native and invasive plant populations. Here, we review and critically revisit the existing theory and empirical evidence in the field of evolutionary ecology and highlight novel integrative research avenues that work at the interface with archaeology to solve open questions. The approaches suggested so far focus on contemporary plant populations, although their genomes have rapidly changed since their initial introduction in response to numerous selective and stochastic forces. We elaborate that a role of pre-adaptation to anthropogenic disturbance in plant invasion success should thus additionally be validated based on the analyses of archaeobotanical remains. Such materials, in the light of detailed knowledge on past human societies could highlight fine-scale differences in the type and timing of past disturbances. We propose a combination of archaeobotanical, ancient DNA and morphometric analyses of plant macro- and microremains to assess past community composition, and species' functional traits to unravel the timing of adaptation processes, their drivers and their long-term consequences for invasive species. Although such methodologies have proven to be feasible for numerous crop plants, they have not been yet applied to wild invasive species, which opens a wide array of insights into their evolution.

Proteomic and physiological signatures of altitude adaptation in a Myrsine coriacea population under common garden conditions

Plants exhibit phenotypic plasticity in response to environmental variations, which can lead to stable genetic and physiological adaptations if exposure to specific conditions is prolonged. Myrsine coriacea demonstrates this through its ability to thrive in diverse environments. The objective of the article is to investigate potential differences in protein accumulation and physiological responses of M. coriacea by cultivating plants from seeds collected from four populations at different altitudes in a common garden experiment. Additionally, we aim to evaluate whether these differences exhibit genetic fixation. Through integrated physiological and proteomic analyses, we identified 170 differentially accumulated proteins and observed significant physiological differences among the populations. The high-altitude population (POP1) exhibited a unique proteomic profile with significant down-regulation of proteins involved in carbon fixation and energy metabolism, suggesting a potential reduction in photosynthetic efficiency. Physiological analyses showed lower leaf nitrogen content, net CO2 assimilation rate, specific leaf area, and relative growth rate in stem height for POP1, alongside higher leaf carbon isotopic composition (δ13C) and leaf carbon (C) content. These findings provide insight into the complex interplay between proteomic and physiological adaptations in M. coriacea and underscore the importance of local adaptations. SignificanceWe investigate the adaptive responses of M. coriacea, a shrub with a broad phenotypic range, by cultivating plants from seeds collected at four different altitudes in a common garden experiment. These findings provide insight into the complex interplay between proteomic and physiological adaptations in M. coriacea and underscore the importance of local adaptations in the face of climate change. This study contributes to advancing our understanding of the influence of altitude-specific selection pressures on the molecular biology and physiology of plants in natural populations. Our findings provide valuable insights that enhance our ability to predict and comprehend how plants respond to climate change.

Effects of floral display size, local open raceme density, patch size, and distance between patches on pollinator behaviour in Salvia nipponica

Flowers cluster at various spatial scales, so pollinators use information from multiple scales when foraging in natural plant populations. Little is known about the effects of interactions between scales or their relative strength. We examined bumblebee foraging behaviour in a natural population of Salvia nipponica in 10 and 7 patches in 2019 and 2020, respectively. We recorded within-patch factors (display size of racemes and local open raceme densities) and patch-level factors (patch size and distance from the nearest patch) and analysed their relationships with pollinator behaviour. The numbers of visits per raceme and flower were mainly affected by the interaction of patch size and raceme density; they were higher in locations with lower raceme density in larger patches. The ratio of flowers visited to all open flowers in a raceme during a raceme visit, which relates to a bumblebee’s choice to leave a raceme, was mainly affected by the interaction of display size and local open raceme density; in 2019 it was higher in racemes with smaller display sizes, while in 2020 the strength and direction of the relationship depended on the open raceme density. These results suggest that pollinators relied on the sizes of flower clusters at different spatial scales when visiting and leaving racemes and adjusted their responses to the sizes of flower clusters depending on the distances between clusters. Therefore, it is important to evaluate factors at various spatial scales and their interactions to fully understand pollinator behaviour in natural plant populations.

A Trip Back Home: Resistance to Herbivores of Native and Non-Native Plant Populations of Datura stramonium.

When colonizing new ranges, plant populations may benefit from the absence of the checks imposed by the enemies, herbivores, and pathogens that regulated their numbers in their original range. Therefore, rates of plant damage or infestation by natural enemies are expected to be lower in the new range. Exposing both non-native and native plant populations in the native range, where native herbivores are present, can be used to test whether resistance mechanisms have diverged between populations. Datura stramonium is native to the Americas but widely distributed in Spain, where populations show lower herbivore damage than populations in the native range. We established experiments in two localities in the native range (Mexico), exposing two native and two non-native D. stramonium populations to natural herbivores. Plant performance differed between the localities, as did the abundance of the main specialist herbivore, Lema daturaphila. In Teotihuacán, where L. daturaphila is common, native plants had significantly more adult beetles and herbivore damage than non-native plants. The degree of infestation by the specialist seed predator Trichobaris soror differed among populations and between sites, but the native Ticumán population always had the lowest level of infestation. The Ticumán population also had the highest concentration of the alkaloid scopolamine. Scopolamine was negatively related to the number of eggs deposited by L. daturaphila in Teotihuacán. There was among-family variation in herbivore damage (resistance), alkaloid content (scopolamine), and infestation by L. daturaphila and T. soror, indicating genetic variation and potential for further evolution. Although native and non-native D. stramonium populations have not yet diverged in plant resistance/constitutive defense, the differences between ranges (and the two experimental sites) in the type and abundance of herbivores suggest that further research is needed on the role of resource availability and adaptive plasticity, specialized metabolites (induced, constitutive), and the relationship between genealogical origin and plant defense in both ranges.

Географические особенности возобновления Pinus sibirica Du Tour

One of the main problems of forest ecology is to identify the patterns of the dynamics of natural populations of woody plants at the stage of their renewal, which programs the entire subsequent structure and development of plant ecosystems. The process of reforestation is determined by both the dynamics of seed production and the peculiarities of the seed distribution of forest-forming tree species. The renewal of five-needled pines of the Cembrae subsection with wingless seeds is due to their close trophic relationships with birds of the genus Nucifraga sp., which spread seeds, creating soil forage stocks. The purpose of this study is to reveal geographical features of the relationship between seed production and renewal of Siberian stone pine (Pinus sibirica Du Tour) with the intermediary participation of the thin-billed nutcracker (Nucifraga caryocatactes macrorhynchos Brehm C.L.). The research was carried out in 3 geographical regions of Pinus sibirica forests: in the forests of the Aldan Highlands in Southern Yakutia (59º40´ N., 125º24´ E.), the Northern Urals in the area of the Denezhkin Kamen mountain (60º25´ N., 59º32´ E.), and the Khamar-Daban Mountain range in the South-Eastern Baikal region (51º32´ N., 103º32´ E.). It is shown that each region of the Pinus sibirica growth differs in the dynamics of both seed production and renewal. It was found that the abundance of Pinus sibirica seedlings in the forests of the Aldan Highlands is positively associated (R2 = 0.46) with the yield of cones the previous year. The number of seedlings in the Northern Urals and Khamar-Daban is negatively related to the yield of cones of last year but is positively (R2 = 0.48–0.49) associated with the yield of cones of the year before last. We believe that seedlings in any case appear from the seeds of last year's yield. But the visible connection is due to the activity of the nutcracker. As a result of the stationary studies conducted in the Northern Urals, we identified a constant close (R2 = 0.81) positive relationship between the number of Pinus sibirica seedlings and the number of nutcrackers during the period of seed storage and dispersal in August-September of the previous year. It is assumed that the nature of the dynamics of seed production in the region affects the change in the number of nutcrackers during the seed harvesting period, which in turn determines the abundance of Pinus sibirica seedlings next year. This determines the revealed differences in the dynamics of Pinus sibirica renewal and its dependence on the yields of tree cones in the regions under consideration. For citation: Tantsyrev N.V., Sannikov S.N., Usoltsev V.А. Geographical Features of Pinus sibirica Du Tour Renewal. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 6, pp. 44–56. (In Russ.). https://doi.org/10.37482/0536-1036-2023-6-44-56

Combining the resurrection approach with transplant experiments to investigate adaptation of plant populations to environmental change

Recent climatic changes, such as more frequent droughts and heatwaves, can lead to rapid evolutionary adaptations in plant populations. Such rapid evolution can be investigated using the resurrection approach by comparing plants raised from stored ancestral and contemporary seeds from the same population. This approach has so far only been used in common garden experiments, allowing to reveal genetic differentiation but not adaptation. In this study, we performed a novel approach by testing for evolutionary adaptation in natural plant populations using a resurrection study in combination with in situ transplantations. We cultivated seedlings from ancestors (23–26 years old) and contemporary descendants of three perennial species (Melica ciliata, Leontodon hispidus and Clinopodium vulgare) from calcareous grasslands in the greenhouse and transplanted them back to their collection sites. In addition, we sowed seeds of ancestors and descendants of two species (L. hispidus and C. vulgare) to the collection sites in order to investigate germination rates. In transplanted M. ciliata seedlings, we observed lower mortality and larger plant size in descendants compared to ancestors. This indicates that descendants are better adapted than ancestors to the current environmental conditions, which proved to be exceptionally hot and dry during the study period. Descendants of C. vulgare seedlings tended to be smaller and descendants of L. hispidus seedlings produced fewer leaves compared to their ancestors in their contemporary environmental conditions. In C. vulgare and L. hispidus, we found evolution towards faster germination, and especially descendant seeds of C. vulgare were better adapted to the unfavourable conditions during the experimental period. Concluding, we demonstrate that our novel approach to combine resurrection ecology with transplant experiments is a promising avenue to rigorously test for evolutionary adaptations in changing environments.

Features of Seed Reproduction of <i>Saposhnikovia divaricata</i> (Apiaceae)

Abstract—Saposhnikovia divaricata (Turcz. ex Ledeb.) Schischk. (Apiaceae) is a useful medicinal plant, which contain a number of substances with a wide range of pharmacological activity; chromones, in particular, are found in the roots. For this reason, plants are heavily harvested from the wild, resulting in the population low density. S. divaricata is a taproot perennial monocarpic that reproduces by seeds only. The introduction of the species, the study of seed productivity and seed reproduction is a vital task for the development of industrial plant cultivation and the restoration of natural populations. The purpose of this work is to study seed production and biology of seed propagation. The generative shoot of S. divaricata is a synflorescence (a panicle of double umbels) with a floral unit being a double umbel. Plants from natural habitat and cultivated ones were studied. A comparative analysis of the seed production of double umbels, depending on their position on the rachis was carried out. The proportion of seed set (seed number/ovule number) and fruit set (fruit number/flower number) in a simple umbel, the potential and real seed productivity of a simple umbel, double umbel, and an individual plant were determined. Fruit of S. divaricata is a cremocarp consisting of two single-seeded mericarps. The seeds have a thin spermoderm, so they were stored and germinated with the pericarp. Seeds (mericarps) for germination were collected from natural populations and cultivated plants considering their position on the rachis, and stored for eight months under laboratory conditions (+23–25 °C). The results of the experiment included data on the duration of the period from the beginning of the experiment to the seed germination, the duration of the germination period (from the beginning of germination), laboratory germination of seeds (%), germination energy (%), rate of germination energy (%). All cultivated plants were monocarpic. The diameter of the synflorescence reaches 124 cm; on average, about 70 double umbels with fruits are formed on it. It was found that in introduced plants, seeds from the branches of the third order make up more than 50% of the real seed production, and from the second and fourth order branches – 21 and 26%, respectively. In natural populations, seeds from the fourth order branches account for 45% of the real seed production, of the third – 30%, of the 2nd – 15%. In the introduced plants, the real seed production of the second generation was about 6000 seeds per individual, which is higher than that of plants in natural populations, where the seed set is 65%. The seeds exhibit non-deep dormancy, and the period before germination does not exceed 10 days. Seed germination is dynamic; more than 50% of the germinated seeds have sprouted within seven days. Laboratory germination was higher in the seeds from the natural population, than from the introduced plants. The highest laboratory germination in introduced plants was found in seeds from double umbels of the second or third order branches – 72–73%, and from the natural populations – in seeds from the shoots of the third or fourth order branches – more than 90%.

A pathogen's spatial range is not constrained by geographical features in the flax rust pathosystem.

Climate change and shifting environmental conditions can allow pathogens to spread into previously unburdened areas. For plant pathogens, this dynamic has the potential to disrupt natural ecosystem equilibria and human agriculture, making predicting plant pathogen range shifts increasingly important. Although such predictions will hinge on an accurate understanding of the determinants of pathogen range-namely the environmental, geographical, and host range characteristics that modulate local pathogen habitation-few studies to date have probed these in natural plant populations. Here, we characterize range determinants for the model system of Lewis flax (Linum lewisii) and its pathogen, flax rust (Melampsora lini), in the Rocky Mountains. Transect surveys were performed to assess three relationships: (i) the effect of geographical features-elevation, slope aspect, slope grade, and land cover-on flax presence and density, (ii) the effect of geographical features on flax rust presence and prevalence, and (iii) the effects of flax's local population density and metapopulation structure on flax rust presence and prevalence. We found that flax population density, but not host metapopulation structure, influences the distribution of flax rust. Additionally, we showed that, while the distribution of flax was broadly constrained to a relatively narrow range of geographical and resulting environmental features, flax rust was evenly distributed across the full range of settings measured. These results indicate that a warming environment, which is expected to modulate such features, may restrict the optimal range of the plant more than that of its pathogen. Importantly, our results also suggest that even if flax shifts its spatial range to escape increasing climatic pressures, flax rust will not face any significant barriers to track this movement.

Telomere sequence variability in genotypes from natural plant populations: unusual block-organized double-monomer terminal telomeric arrays

BackgroundTelomeres are the nucleoprotein complexes that physically cap the ends of eukaryotic chromosomes. Most plants possess Arabidopsis-type telomere sequences (TSs). In addition to terminal TSs, more diverse interstitial TSs exists in plants. Although telomeres have been sufficiently studied, the actual diversity of TSs in land plants is underestimated.ResultsWe investigate genotypes from seven natural populations with contrasting environments of four Chenopodium species to reveal the variability in TSs by analyzing Oxford Nanopore reads. Fluorescent in situ hybridization was used to localize telomeric repeats on chromosomes. We identified a number of derivative monomers that arise in part of both terminal and interstitial telomeric arrays of a single genotype. The former presents a case of block-organized double-monomer telomers, where blocks of Arabidopsis-type TTTAGGG motifs were interspersed with blocks of derivative TTTAAAA motifs. The latter is an integral part of the satellitome with transformations specific to the inactive genome fraction.ConclusionsWe suggested two alternative models for the possible formation of derivative monomers from telomeric heptamer motifs of Arabidopsis-type. It was assumed that derivatization of TSs is a ubiquitous process in the plant genome but occurrence and frequencies of derivatives may be genotype-specific. We also propose that the formation of non-canonical arrays of TSs, especially at chromosomal termini, may be a source for genomic variability in nature.

Application of Various Concentrations of Mixed Extracts of Calotropis gigantea and Crescentia cujete Against Population and Attack Intensity of Leptocorisa acuta, Nephotettix virescens and Natural Enemy Populations of Rice Plants

Changes in land and pesticide are the main drivers of changes in the biodiversity of agricultural land, particularly natural enemies of insect pests. Leptocorisa acuta and Nephotettix virescens are the main pests of rice plants in Indonesia which are mostly controlled with pesticides. The use of extracts of natural ingredients Calontropis gigantea leaves and Crescentia cujete fruit is an alternative for controlling rice pests. The purpose of the study was to determine the mixed extracts of C. gigantea and C. cujete with various concentrations on the population and the attack intensity of Leptocorisa acuta and Nephotettix virescens as well as natural enemies population. This study consisted of six treatments, namely a concentration of 1%; 2.5%; 4%; 5.5%; 7% and farmer treatment. Observations were made visually and sweep net by taking samples diagonally in one plot was taken five plant sample points were and in one point consisted of four clumps of rice. The results showed that, in comparison to the farmers treatment, the population and attack intensity were low for all extract concentration treatments, and statistical analysis did not reveal any statistically significant differences between concentrations. In comparison to farmer treatment, the population of natural enemies was high in all extract treatments. When mixed extracts of C. gigantea and C. cujete are used for pest management of rice plants, the number and severity of pest attacks can be reduced without affecting natural enemies.