Levels Of Biological Organization Research Articles

AOP report: Development of an adverse outcome pathway for deposition of energy leading to cataracts.

Cataracts are one of the leading causes of blindness, with an estimated 95 million people affected worldwide. A hallmark of cataract development is lens opacification, typically associated not only with aging but also radiation exposure as encountered by interventional radiologists and astronauts during the long-term space mission. To better understand radiation-induced cataracts, the adverse outcome pathway (AOP) framework was used to structure and evaluate knowledge across biological levels of organization (e.g., macromolecular, cell, tissue, organ, organism and population). AOPs identify a sequence of key events (KEs) causally connected by key event relationships (KERs) beginning with a molecular initiating event to an adverse outcome (AO) of relevance to regulatory decision-making. To construct the cataract AO and retrieve evidence to support it, a scoping review methodology was used to filter, screen, and review studies based on the modified Bradford Hill criteria. Eight KEs were identified that were moderately supported by empirical evidence (e.g., dose-, time-, incidence-concordance) across the adjacent (directly linked) relationships using well-established endpoints. Over half of the evidence to justify the KER linkages was derived from the evidence stream of biological plausibility. Early KEs of oxidative stress and protein modifications had strong linkages to downstream KEs and could be the focus of countermeasure development. Several identified knowledge gaps and inconsistencies related to the quantitative understanding of KERs which could be the basis of future research, most notably directed to experiments in the range of low or moderate doses and dose-rates, relevant to radiation workers and other occupational exposures.

Resistance of an intertidal oyster(Saccostrea mordax)to marine heatwaves and the implication for reef building

Marine heatwaves (MHWs) have a significant impact on intertidal bivalves and the ecosystems they sustain, causing the destruction of organisms' original habitats. Saccostrea mordax mainly inhabits the intertidal zone around the equator, exhibiting potential tolerance to high temperatures and maybe a species suitable for habitat restoration. However, an understanding about the tolerance mechanism of S. mordax to high temperatures is unclear. It is also unknown the extent to which S. mordax can tolerate repeated heatwaves of increasing intensity and frequency. Here, we simulated the effects of two scenarios of MHWs and measured the physiological and biochemical responses and gene expression spectrum of S. mordax. The predicted responses varied greatly across heatwaves, and no heatwave had a significant impact on the survival of S. mordax. Specifically, there were no statistically significant changes apparent in the standard metabolic rate and the activities of enzymes of the oyster during repeated heatwaves. S. mordax exposed to high-intensity heatwaves enhanced their standard metabolic rate to fuel essential physiological maintenance and increasing activity of SOD and expression of HSP70/90. These strategies are presumably at the expense of functions related to immunity and growth, as best exemplified by significant depressions in activities of enzymes (NaK, CaMg, T-ATP, and AKP) and expression levels of genes (Rab, eEF-2, HMGR, Rac1, SGK, Rab8, etc.). The performance status of S. mordax tends to improve by implementing a suite of less energy-costly compensatory mechanisms at various levels of biological organization when re-exposed to heatwaves. The adaptive abilities shown by S. mordax indicate that they can play a crucial role in the restoration of oyster reefs in tropical seas.

Thermo-priming triggers species-specific physiological and transcriptome responses in Mediterranean seagrasses

Heat-priming improves plants' tolerance to a recurring heat stress event. The underlying molecular mechanisms of heat-priming are largely unknown in seagrasses. Here, ad hoc mesocosm experiments were conducted with two Mediterranean seagrass species, Posidonia oceanica and Cymodocea nodosa. Plants were first exposed to heat-priming, followed by a heat-triggering event. A comprehensive assessment of plant stress response across different levels of biological organization was performed at the end of the triggering event. Morphological and physiological results showed an improved response of heat-primed P. oceanica plants while in C. nodosa both heat- and non-primed plants enhanced their growth rates at the end of the triggering event. As resulting from whole transcriptome sequencing, molecular functions related to several cellular compartments and processes were involved in the response to warming of non-primed plants, while the response of heat-primed plants involved a limited group of processes. Our results suggest that seagrasses acquire a primed state during the priming event, that eventually gives plants the ability to induce a more energy-effective response when the thermal stress event recurs. Different species may differ in their ability to perform an improved heat stress response after priming. This study provides pioneer molecular insights into the emerging topic of seagrass stress priming and may benefit future studies in the field.

Parental exposure to antidepressants has lasting effects on offspring? A case study with zebrafish

Fish have common neurotransmitter pathways with humans, exhibiting a significant degree of conservation and homology. Thus, exposure to fluoxetine makes fish potentially susceptible to biochemical and physiological changes, similarly to what is observed in humans. Over the years, several studies demonstrated the potential effects of fluoxetine on different fish species and at different levels of biological organization. However, the effects of parental exposure to unexposed offspring remain largely unknown. The consequences of 15-day parental exposure to relevant concentrations of fluoxetine (100 and 1000 ng/L) were assessed on offspring using zebrafish as a model organism. Parental exposure resulted in offspring early hatching, non-inflation of the swimming bladder, increased malformation frequency, decreased heart rate and blood flow, and reduced growth. Additionally, a significant behavioral impairment was also found (reduced startle response, basal locomotor activity, and altered non-associative learning during early stages and a negative geotaxis and scototaxis, reduced thigmotaxis, and anti-social behavior at later life stages). These behavior alterations are consistent with decreased anxiety, a significant increase in the expression of the monoaminergic genes slc6a4a (sert), slc6a3 (dat), slc18a2 (vmat2), mao, tph1a, and th2, and altered levels of monoaminergic neurotransmitters. Alterations in behavior, expression of monoaminergic genes, and neurotransmitter levels persisted until offspring adulthood. Given the high conservation of neuronal pathways between fish and humans, data show the possibility of potential transgenerational and multigenerational effects of pharmaceuticals’ exposure. These results reinforce the need for transgenerational and multigenerational studies in fish, under realistic scenarios, to provide realistic insights into the impact of these pharmaceuticals.

Assessing combined effects of long-term exposure to copper and marine heatwaves on the reef-forming serpulid Ficopomatus enigmaticus through a biomarker approach

Sessile benthic organisms can be affected by global changes and local pressures, such as metal pollution, that can lead to damages at different levels of biological organization. Effects of exposure to marine heatwaves (MHWs) alone and in combination with environmentally relevant concentration of copper (Cu) were evaluated in the reef-forming tubeworm Ficopomatus enigmaticus using a multi-biomarker approach. Biomarkers of cell membrane damage, enzymatic antioxidant defences, metabolic activity, neurotoxicity, and DNA integrity were analyzed. The exposure to Cu alone did not produce any significant effect. Exposure to MHWs alone produced effects only on metabolic activity (increase of glutathione S-transferase) and energy reserves (decrease in protein content). MHWs in combination with copper was the condition that most influenced the status of cell homeostasis of exposed F. enigmaticus. The combination of MHWs plus Cu exposure induced increase of protein carbonylation and glutathione S-transferase activity, decrease in protein/carbohydrate content and carboxylesterase activity. This study on a reef-forming organism highlighted the additive effect of a climate change-related stressor to metals pollution of marine and brackish waters.

Combined effects of polyethylene microplastics and carbendazim on Eisenia fetida: A comprehensive ecotoxicological study

Microplastic (MP) pollution is becoming an emerging environmental concern across aquatic and terrestrial ecosystems. Plastic mulching and the use of pesticides in agriculture can lead to microplastics and agrochemicals in soil, which can result in unintended exposure to non-target organisms. The combined toxicity of multiple stressors represents a significant paradigm shift within the field of ecotoxicology, and its exploration within terrestrial ecosystems involving microplastics is still relatively limited. The present study investigated the combined effects of polyethylene MP (PE-MP) and the agrochemical carbendazim (CBZ) on the earthworm Eisenia fetida at different biological levels of organization. While E. fetida survival and reproduction did not exhibit significant effects following PE-MP treatment, there was a reduction in cocoon and hatchling numbers. Notably, prolonged exposure revealed delayed toxicity, leading to substantial growth impairment. Exposure to CBZ led to significant alterations in the endpoints mentioned above. While there was a decrease in cocoon and hatchling numbers, the combined treatment did not yield significant effects on earthworm reproduction except at higher concentrations. However, lower concentrations of PE-MP alongside CBZ induced a noteworthy decline in biomass content, signifying a form of potentiation interaction. In addition, concurrent exposure led to synergistic effects, from oxidative stress to modifications in vital organs such as the body wall, intestines, and reproductive structures (spermathecae, seminal vesicles, and ovarian follicles). The comparison of multiple endpoints revealed that seminal vesicles and ovarian follicles were the primary targets during the combined exposure. The research findings suggest that there are variable and complex responses to microplastic toxicity in terrestrial ecosystems, especially when combined with other chemical stressors like agrochemicals. Despite these difficulties, the study implies that microplastics can alter earthworms' responses to agrochemical exposure, posing potential ecotoxicological risks to soil fauna.

Spatial factors overcome seasonality regulating the consumption of allochthonous food resources by fishes from tropical lotic ecosystems

Abstract In lotic ecosystems, a higher availability of allochthonous food resources is expected during floods and rainfall events, which may yield a higher consumption of these resources by consumers. However, allochthonous input and seasonality in environmental conditions are locally dependent. Thus, dietary responses of freshwater consumers to seasonality should also be locally dependent. Herein, we applied a meta‐analytical approach to identify the spatial and seasonal environmental variables associated with the relative consumption of allochthonous food resources by fishes from tropical lotic ecosystems in different seasons. We gathered 566 observations of the diet of fish populations (i.e., restricted to the same sampling event) from 38 studies conducted in 70 localities across the tropics during flood and drought periods (hereafter, high‐water and low‐water periods, respectively). We retrieved latitude, seasonal channel width, elevation and two proxies for allochthonous input for each locality: terrestrial biomass (without considering seasonality) and the normalised difference vegetation index (NDVI; considering seasonality). Then, we applied meta‐regression models using these environmental variables as predictors and the proportion of allochthonous food resources in each consumer's diet (%Allo) as the response variable. Our models revealed that the diet of fishes from tropical lotic ecosystems is mostly autochthonous‐based, independent of the hydrological period (high‐water or low‐water), and aquatic invertebrates were the most consumed food items. Terrestrial vegetation biomass and elevation predicted increasing allochthony in the diet of tropical fishes for high‐water, but only terrestrial biomass predicted allochthony at low‐water periods. We found no relationship between latitude, channel width or NDVI with allochthony. Our study highlights the importance of considering the hierarchical level of biological organisation and fish trophic guilds for understanding seasonal patterns of relative consumption of allochthonous and autochthonous food resources by fishes. We also argue that variations in seasonality across the tropics are likely to have undermined its influence on allochthony in fish diets. The absence of a non‐relationship between channel width and allochthony provides evidence that the River Continuum Concept is better suited to temperate lotic ecosystems. Our results provide novel insights and the big‐picture of seasonal pattern in the diets of tropical fishes for use in future local empirical studies, improving forecasting of the relationship between the factors underpinning the availability of allochthonous and autochthonous food resources, and the diet of freshwater fishes.

Exploring the Relationship Among Lipid Profile Changes, Growth, and Reproduction in Folsomia candida Exposed to Teflubenzuron Over Time.

The integration of untargeted lipidomics approaches in ecotoxicology has emerged as a strategy to enhance the comprehensiveness of environmental risk assessment. Although current toxicity tests with soil microarthropods focus on species performance, that is, growth, reproduction, and survival, understanding the mechanisms of toxicity across all levels of biological organization, from molecule to community is essential for informed decision-making. Our study focused on the impacts of sublethal concentrations of the insecticide teflubenzuron on the springtail Folsomia candida. Untargeted lipidomics was applied to link changes in growth, reproduction, and the overall stress response with lipid profile changes over various exposure durations. The accumulation of teflubenzuron in organisms exposed to the highest test concentration (0.035 mg a.s. kg-1 soil dry wt) significantly impacted reproductive output without compromising growth. The results suggested a resource allocation shift from reproduction to size maintenance. This hypothesis was supported by lipid shifts on day 7, at which point reductions in triacylglycerol and diacylglycerol content corresponded with decreased offspring production on day 21. The hypermetabolism of fatty acids and N-acylethanolamines on days 2 and 7 of exposure indicated oxidative stress and inflammation in the animals in response to teflubenzuron bioaccumulation, as measured using high-performance liquid chromatography-tandem mass spectrometry. Overall, the changes in lipid profiles in comparison with phenotypic adverse outcomes highlight the potential of lipid analysis as an early-warning tool for reproductive disturbances caused by pesticides in F. candida. Environ Toxicol Chem 2024;43:1149-1160. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The Effects of Wastewater Reuse on Smallmouth Bass (Micropterus dolomieu) Relative Abundance in the Shenandoah River Watershed, USA.

Municipal and industrial wastewater effluent is an important source of water for lotic systems, especially during periods of low flow. The accumulated wastewater effluent flows-expressed as a percentage of total streamflow (ACCWW%)-contain chemical mixtures that pose a risk to aquatic life; fish may be particularly vulnerable when chronically exposed. Although there has been considerable focus on individual-level effects of exposure to chemical mixtures found in wastewater effluent, scaling up to population-level effects remains a challenging component needed to better understand the potential consequences of exposure in wild populations. This may be particularly important under a changing climate in which wastewater reuse could be essential to maintain river flows. We evaluated the effects of chronic exposure to wastewater effluent, as measured by ACCWW%, on the relative abundance of young-of-year (YOY), juvenile, and adult smallmouth bass (Micropterus dolomieu) populations in the Shenandoah River Watershed (USA). We found that increases in ACCWW% in the previous year and during the prespawn period were negatively correlated with the relative abundance of YOY, resulting in an average 41% predicted decrease in abundance (range = 0.5%-94% predicted decrease in abundance). This lagged effect suggests that adult fish reproductive performance may be compromised by chemical exposure during periods of high ACCWW%. No relationships between ACCWW% and juvenile or adult relative abundance were found, suggesting that negative effects of ACCWW% on YOY abundance may be offset due to compensatory mechanisms following higher ACCWW% exposure. Understanding the effects of wastewater effluent exposure at multiple levels of biological organization will help in the development of management strategies aimed at protecting aquatic life. Environ Toxicol Chem 2024;43:1138-1148. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Freshwater systems in the Anthropocene: why we need to evaluate microplastics in the context of multiple stressors

Microplastics are a diverse contaminant with complex physical and chemical properties. While microplastics have varying effects, most studies to date have focused on evaluating microplastics as a single stressor under stable environmental conditions. In reality, organisms are exposed to more than microplastics, and thus, it will be increasingly important to evaluate the effects of microplastics in the context of multiple anthropogenic stressors. Here, we highlight the need to assess the physical and chemical effects of microplastics, as well as their interactions with other anthropogenic stressors, at multiple levels of biological organization (i.e., sub-organismal, individual, population, community, ecosystem). We also outline research priorities and recommendations that will facilitate ecotoxicological assessments to better encompass the multidimensionality of microplastics as environmental conditions continue to change. By taking a multi-stressor ecotoxicological approach, we can work toward a better understanding of microplastic and other stressor effects at multiple levels of biological organization to help inform robust, evidenced-based policy and management decisions.

Parallel evolution of gravity sensing.

Omnipresent gravity affects all living organisms; it was a vital factor in the past and the current bottleneck for future space exploration. However, little is known about the evolution of gravity sensing and the comparative biology of gravity reception. Here, by tracing the parallel evolution of gravity sensing, we encounter situations when assemblies of homologous modules result in the emergence of non-homologous structures with similar systemic properties. This is a perfect example to study homoplasy at all levels of biological organization. Apart from numerous practical implementations for bioengineering and astrobiology, the diversity of gravity signaling presents unique reference paradigms to understand hierarchical homology transitions to the convergent evolution of integrative systems. Second, by comparing gravisensory systems in major superclades of basal metazoans (ctenophores, sponges, placozoans, cnidarians, and bilaterians), we illuminate parallel evolution and alternative solutions implemented by basal metazoans toward spatial orientation, focusing on gravitational sensitivity and locomotory integrative systems.

Investigating students’ meaning-making of multiple visual representations of epigenetics at different levels of biological organisation

ABSTRACT The aim of this study is to investigate students’ meaning–making of multiple visual representations of epigenetics at different levels of biological organisation, and to discern what visual aspects of the multiple visual representations might influence students’ reasoning. Adopting an exploratory approach, we analysed how students made meaning of visually communicated epigenetics phenomena while pointing at and reasoning about the multiple visual representations as part of semi-structured focus groups. We investigated students’ meaning-making of the multiple visual representations by analysing their indications through physical pointing and accompanying verbal utterances. The analysis revealed meaning-making and the nature of linking between levels of organisation in four distinct patterns, namely intra horizontal linking, inter horizontal linking, one level vertical linking and two level vertical linking. In addition, five different visual characteristics of the multiple visual representations emerged as influencing students’ reasoning while linking between different organisation levels: multiple visual representations, salient visual features, analogous visual features, familiar visual elements, and textual adjuncts. The study shows that multiple visual representations at different levels of organisation can support students’ meaning-making of epigenetics, indicating that this way of communicating can be transferable to other biological domains. Potential implications for future research and teaching practice are provided.

Marine protected areas promote stability of reef fish communities under climate warming

Protection from direct human impacts can safeguard marine life, yet ocean warming crosses marine protected area boundaries. Here, we test whether protection offers resilience to marine heatwaves from local to network scales. We examine 71,269 timeseries of population abundances for 2269 reef fish species surveyed in 357 protected versus 747 open sites worldwide. We quantify the stability of reef fish abundance from populations to metacommunities, considering responses of species and functional diversity including thermal affinity of different trophic groups. Overall, protection mitigates adverse effects of marine heatwaves on fish abundance, community stability, asynchronous fluctuations and functional richness. We find that local stability is positively related to distance from centers of high human density only in protected areas. We provide evidence that networks of protected areas have persistent reef fish communities in warming oceans by maintaining large populations and promoting stability at different levels of biological organization.

Does Behavior Evolve First? Correlated Responses to Selection for Voluntary Wheel-Running Behavior in House Mice.

AbstractHow traits at multiple levels of biological organization evolve in a correlated fashion in response to directional selection is poorly understood, but two popular models are the very general "behavior evolves first" (BEF) hypothesis and the more specific "morphology-performance-behavior-fitness" (MPBF) paradigm. Both acknowledge that selection often acts relatively directly on behavior and that when behavior evolves, other traits will as well but most with some lag. However, this proposition is exceedingly difficult to test in nature. Therefore, we studied correlated responses in the high-runner (HR) mouse selection experiment, in which four replicate lines have been bred for voluntary wheel-running behavior and compared with four nonselected control (C) lines. We analyzed a wide range of traits measured at generations 20-24 (with a focus on new data from generation 22), coinciding with the point at which all HR lines were reaching selection limits (plateaus). Significance levels (226 P values) were compared across trait types by ANOVA, and we used the positive false discovery rate to control for multiple comparisons. This meta-analysis showed that, surprisingly, the measures of performance (including maximal oxygen consumption during forced exercise) showed no evidence of having diverged between the HR and C lines, nor did any of the life history traits (e.g., litter size), whereas body mass had responded (decreased) at least as strongly as wheel running. Overall, results suggest that the HR lines of mice had evolved primarily by changes in motivation rather than performance ability at the time they were reaching selection limits. In addition, neither the BEF model nor the MPBF model of hierarchical evolution provides a particularly good fit to the HR mouse selection experiment.

Eco-evolutionary emergence of macroecological scaling in plankton communities.

Macroecological scaling patterns, such as between prey and predator biomass, are fundamental to our understanding of the rules of biological organization and ecosystem functioning. Although these scaling patterns are ubiquitous, how they arise is poorly understood. To explain these patterns, we used an eco-evolutionary predator-prey model parameterized using data for phytoplankton and zooplankton. We show that allometric scaling relationships at lower levels of biological organization, such as body-size scaling of nutrient uptake and predation, give rise to scaling relationships at the food web and ecosystem levels. Our predicted macroecological scaling exponents agree well with observed values across ecosystems. Our findings explicitly connect scaling relationships at different levels of biological organization to ecological and evolutionary mechanisms, yielding testable hypotheses for how observed macroecological patterns emerge.

Metamicrobiome diversity promotes the evolution of host-microbial mutualisms.

Ecological theory suggests that a host organism's internal spatial structure can promote the persistence of mutualistic microbes by allowing for the turnover of tissue occupied by non-beneficial or cheating microbes. This type of regulation, whereby a host preferentially rewards tissue occupied by beneficial members of its microbiome but sanctions tissue occupied by non-beneficial cheaters, is expected to generate a competition-extinction trade-off by allowing beneficial microbes to experience a lower extinction rate than competitively dominant cheaters. Using an adaptive dynamics approach, we demonstrate that although ecologically stable, microbial regulation via sanctioning is not stable in any evolutionary sense, as each individual host will be under pressure to reduce the costs incurred from cheater suppression in order to maximize its own fitness at the expense of the rest of the host population. However, increasing the diversity of non-beneficial cheaters in the host population metamicrobiome can lead to an increase in the relative fitness of hosts that actively sanction non-performing tissue, thus facilitating the evolutionary emergence and persistence of such strategies in host-microbial systems. These counter-intuitive results demonstrate how diversity at multiple levels of biological organization and spatiotemporal scales can interact to facilitate the establishment and maintenance of mutualistic relationships.

How does temperature rise affect a freshwater catfish Rhamdia quelen? A proteomic approach

Outside of scientific circles, climate change is a hotly debated topic due to all its consequences. Changes in the temperature can affect aquatic organisms and it is important to understand and to detect earlier signals. This study aimed to analyze how a Neotropical fish species responds to temperature increases, using proteomic analysis as a tool. For this, fish of the species Rhamdia quelen, male and female, were exposed to two temperatures: 25 °C and 30 °C. After 96 h, the animals were anesthetized, euthanized and the liver was collected for proteomic analysis. Using freely available online software and databases (e.g. MetaboAnalyst, Gene Ontology and UniProt), we define the altered proteins in both sexes: 42 in females and 62 in males. Data are available via ProteomeXchange with identifier PXD046475. Differences between the two temperatures were observed mainly in the amino acid metabolic pathways. The cellular process and the immune response was altered, indicating that effects at lower levels of biological organization could serve as a predictor of higher-level effects when temperature rise affects wildlife populations. Thus, we conclude that the increase in temperature is capable of altering important cellular and physiological processes in R. quelen fish, with this response being different for males and females.

Life Is Uncertain: Inherent Variability Exhibited by Organisms, and at Higher Levels of Biological Organization.

Organisms act stochastically. A not uncommon view in the ecological literature is that this is mainly due to the observer having insufficient information or a stochastic environment-and not partly because organisms themselves respond with inherent unpredictability. In this study, I compile the evidence that contradicts that view. Organisms generate uncertainty internally, which results in irreducible stochastic responses. I consider why: for instance, stochastic responses are associated with greater adaptability to changing environments and resource availability. Over longer timescales, biologically generated uncertainty influences behavior, evolution, and macroecological processes. Indeed, it could be stated that organisms are systems defined by the internal generation, magnification, and record-keeping of uncertainty as inputs to responses. Important practical implications arise if organisms can indeed be defined by an association with specific classes of inherent uncertainty: not least that isolating those signatures then provides a potential means for detecting life, for considering the forms that life could theoretically take, and for exploring the wider limits to how life might become distributed. These are all fundamental goals in astrobiology.

Stability/Flexibility: the tightly coupled homeostasis generator is at the same time the driver of change.

There is "no Flexibility without Stability and no Stability without Flexibility": this is a crucial feature common to any system interacting with its environment. This tight link between two apparently opposite features is at the basis of the time-honoured concept of homeostasis (the tendency of any adaptive system to go back to its "comfort zone" contrasting the incoming perturbations) and is widely recognized since long time. On the contrary, the fact that the escape from a stable attractor state is a consequence of the same homeostasis mechanisms is often overlooked. In this brief note, we will try to give a proof-of-concept of the relation existing between stability/flexibility based homeostasis and the state changes at all the levels of biological organization. The ubiquity of the same principles across very different systems is a signature of a new attitude to look at scientific enterprise from a network-based viewpoint.

The soil-microbe-plant resistome: A focus on the source-pathway-receptor continuum.

The One World, One Health concept implies that antibiotic resistance (AR) in the soil-microbe-plant resistome is intricately linked to the human resistome. However, the literature is mainly confined to sources and types of AR in soils or microbes, but comprehensive reviews tracking AR in the soil-microbe-plant resistome are limited. The present review applies the source-pathway-receptor concept to understand the sources, behaviour, and health hazards of the soil-microbe-plant resistome. The results showed that the soil-microbe-plant system harbours various antibiotic-resistance genes (ARGs), antibiotic-resistant bacteria (ARB), and mobile genetic elements (MGEs). Anthropogenic sources and drivers include soil application of solid waste, wastewater, biosolids, and industrial waste. Water-, wind-, and human-driven processes and horizontal gene transfer circulate AR in the soil-microbe-plant resistome. The AR in bulk soil, soil components that include soil microorganisms, soil meso- and macro-organisms, and possible mechanisms of AR transfer to soil components and ultimately to plants are discussed. The health risks of the soil-microbe-plant resistome are less studied, but potential impacts include (1) the transfer of AR to previously susceptible organisms and other resistomes, including the human resistome. Overall, the study tracks the behaviour and health risks of AR in the soil-plant system. Future research should focus on (1) ecological risks of AR at different levels of biological organization, (2) partitioning of AR among various phases of the soil-plant system, (3) physico-chemical parameters controlling the fate of AR, and (4) increasing research from low-income regions particularly Africa as most of the available literature is from developed countries.