Phenotypic and transcriptomic shifts in roots and leaves of rice under the joint stress from microplastic and arsenic

Polyvinyl chloride and polybutylene adipate microplastics affect peanut and rhizobium symbiosis by interfering with multiple metabolic pathways

Microplastics (MPs), widely presented in cultivated soil, have caused serious stresses on crop growth. However, the mechanism by which MPs affect legumes and rhizobia symbiosis is still unclear. Here, peanut seedlings were inoculated with Bradyrhizobium zhanjiangense CCBAU 51778 and were grown in vermiculite with 3 %/5 % (w/w) addition of PVC (polyvinyl chloride)-MPs/PBAT (polybutylene adipate)-MPs. PVC-MPs and PBAT-MPs separately decreased nodule number by 33-100 % and 2.62-80.91 %. Transcriptome analysis showed that PVC-MPs affected more DEGs (differentially expressed genes) than PBAT-MPs, indicating PVC-MPs were more devastating for the symbiosis than PBAT-MPs. Functional annotation revealed that PVC-MPs and PBAT-MPs enriched DEGs related to biosynthesis pathways such as flavonoid, isoflavonoid, and phenylpropanoid, in peanut. And when the dose increased from 3 % to 5 %, PVC-MPs mainly enriched the pathways of starch and sucrose metabolism, alanine, aspartate and glutamate metabolism, diterpenoid biosynthesis, etc.; PBAT-MPs enriched cysteine and methionine metabolism, photosynthesis, MAPK signaling, and other pathways. These significantly enriched pathways functioned in reducing nodule number and promoting peanut tolerance to MPs stresses. This study reveals the effect of PVC-MPs and PBAT-MPs on peanut and rhizobium symbiosis, and provides new perspectives for legume production and environmental safety.

Unveiling the impact of microplastics and nanoplastics on vascular plants: A cellular metabolomic and transcriptomic review

With increasing plastic manufacture and consumption, microplastics/nanoplastics (MP/NP) pollution has become one of the world's pressing global environmental issues, which poses significant threats to ecosystems and human health. In recent years, sharp increasing researches have confirmed that MP/NP had direct or indirect effects on vegetative growth and sexual process of vascular plant. But the potential mechanisms remain ambiguous. MP/NP particles can be adsorbed and/or absorbed by plant roots or leaves and thus cause diverse effects on plant. This holistic review aims to discuss the direct effects of MP/NP on vascular plant, with special emphasis on the changes of metabolic and molecular levels. MP/NP can alter substance and energy metabolism, as well as shifts in gene expression patterns. Key aspects affected by MP/NP stress include carbon and nitrogen metabolism, amino acids biosynthesis and plant hormone signal transduction, expression of stress related genes, carbon and nitrogen metabolism related genes, as well as those involved in pathogen defense. Additionally, the review provides updated insights into the growth and physiological responses of plants exposed to MP/NP, encompassing phenomena such as seed/spore germination, photosynthesis, oxidative stress, cytotoxicity, and genotoxicity. By examining the direct impact of MP/NP from both physiological and molecular perspectives, this review sets the stage for future investigations into the complex interactions between plants and plastic pollutants.

Micro- and nanoplastics in agricultural soils: Assessing impacts and navigating mitigation

Micro-/nanoplastic contamination in agricultural soils raises concerns on agroecosystems and poses potential health risks. Some of agricultural soils have received significant amounts of micro-/nanoplastics (MNPs) through plastic mulch film and biosolid applications. However, a comprehensive understanding of the MNP impacts on soils and plants remains elusive. The interaction between soil particles and MNPs is an extremely complex issue due to the different properties and heterogeneity of soils and the diverse characteristics of MNPs. Moreover, MNPs are a class of relatively new anthropogenic pollutants that may negatively affect plants and food. Herein, we presented a comprehensive review of the impacts of MNPs on the properties of soil and the growth of plants. We also discussed different strategies for mitigating or eliminating MNP contamination. Moreover, perspectives for future research on MNP contamination in the agricultural soils are also highlighted.

The Oryza sativa transcriptome responds spatiotemporally to polystyrene nanoplastic stress

Nanoplastic represents an emerging abiotic stress facing modern agriculture, impacting global crop production. However, the molecular response of crop plants to this stress remains poorly understood at a spatiotemporal resolution. We therefore used RNA sequencing to profile the transcriptome expressed in rice (Oryza sativa) root and leaf organs at 1, 2, 4, and 8 d post exposure with nanoplastic. We revealed a striking similarity between the rice biomass dynamics in aboveground parts to that in belowground parts during nanoplastic stress, but transcriptome did not. At the global transcriptomic level, a total of 2332 differentially expressed genes were identified, with the majority being spatiotemporal specific, reflecting that nanoplastics predominantly regulate three processes in rice seedlings: (1) down-regulation of chlorophyll biosynthesis, photosynthesis, and starch, sucrose and nitrogen metabolism, (2) activation of defense responses such as brassinosteroid biosynthesis and phenylpropanoid biosynthesis, and (3) modulation of jasmonic acid and cytokinin signaling pathways by transcription factors. Notably, the genes involved in plant-pathogen interaction were shown to be successively modulated by both root and leaf organs, particularly plant disease defense genes (OsWRKY24, OsWRKY53, Os4CL3, OsPAL4, and MPK5), possibly indicating that nanoplastics affect rice growth indirectly through other biota. Finally, we associated biomass phenotypes with the temporal reprogramming of rice transcriptome by weighted gene co-expression network analysis, noting a significantly correlation with photosynthesis, carbon metabolism, and phenylpropanoid biosynthesis that may reflect the mechanisms of biomass reduction. Functional analysis further identified PsbY, MYB, cytochrome P450, and AP2/ERF as hub genes governing these pathways. Overall, our work provides the understanding of molecular mechanisms of rice in response to nanoplastics, which in turn suggests how rice might behave in a nanoplastic pollution scenario.

Influencing mechanisms of microplastics existence on soil heavy metals accumulated by plants

Microplastics (MPs) and heavy metals often coexist in soil, drawing significant attention to their interactions and the potential risks of biological accumulation in the soil-plant system. This paper comprehensively reviews the factors and biochemical mechanisms that influence the uptake of heavy metals by plants, in the existence of MPs, spanning from rhizospheric soil to the processes of root absorption and transport. The paper begins by introducing the origins and current situation of soil contamination with both heavy metals and MPs. It then discusses how MPs alter the physicochemical properties of rhizospheric soil, with a focus on parameters that affect the bioavailability of heavy metals such as aggregates, pH, Eh, and soil organic carbon (SOC). The paper also examines the effect of this pollution on soil organisms and plant growth and reviews the mechanisms by which MPs affect the bioavailability and movement-transformation of heavy metals in rhizospheric soil. This examination emphasizes the roles of rhizospheric microbes, soil fauna, and root physiological metabolism. Finally, the paper outlines the research progress on the mechanisms by which MPs influence the uptake and transport of heavy metals by plant roots. Through this comprehensive review, this paper provides aims to provide environmental managers with a detailed understanding of the potential impact of the coexistence of MPs and heavy metals on the soil-plant ecosystem.

Polystyrene nanoplastics exposure triggers spermatogenic cell senescence via the Sirt1/ROS axis

Polystyrene nanoplastics (PS-NPs) have been reported to accumulate in the testes and constitute a new threat to reproductive health. However, the exact effects of PS-NPs exposure on testicular cells and the underlying mechanisms remain largely unknown. The C57BL/6 male mice were orally administered with PS-NPs (80 nm) at different dosages (0, 10, and 40 mg/kg/day) for 60 days, and GC-1 cells were treated with PS-NPs in this study. Enlarged seminiferous tubule lumens and a loose and vacuolated layer of spermatogenic cells were observed in PS-NPs-exposed mice. Spermatogenic cells which may be one of the target cells for this reproductive damage, were decreased in the mice from PS-NPs group. PS-NPs caused spermatogenic cells to undergo senescence, manifested as elevated SA-β-galactosidase activity and activated senescence-related signaling p53-p21/Rb-p16 pathways, and induced cell cycle arrest. Mechanistically, Gene Ontology (GO) enrichment suggested the key role of reactive oxygen species (ROS) in PS-NPs-induced spermatogenic cell senescence, and this result was confirmed by measuring ROS levels. Moreover, ROS inhibition partially attenuated the senescence phenotype of spermatogenic cells and DNA damage. Using the male health atlas (MHA) database, Sirt1 was filtrated as the critical molecule in the regulation of testicular senescence. PS-NPs induced overexpression of the main ROS generator Nox2, downregulated Sirt1, increased p53 and acetylated p53 in vivo and in vitro, whereas these disturbances were partially restored by pterostilbene. In addition, pterostilbene intervention significantly alleviated the PS-NPs-induced spermatogenic cell senescence and attenuated ROS burst. Collectively, our study reveals that PS-NPs exposure can trigger spermatogenic cell senescence mediated by p53-p21/Rb-p16 signaling by regulating the Sirt1/ROS axis. Importantly, pterostilbene intervention may be a promising strategy to alleviate this damage.

Microplastics enhance the invasion of exotic submerged macrophytes by mediating plant functional traits, sediment properties, and microbial communities

Plant invasions and microplastics (MPs) have significantly altered the structure and function of aquatic habitats worldwide, resulting in severe damage to aquatic ecosystem health. However, the effects of MPs on plant invasion and the underlying mechanisms remain largely unknown. In this study, we conducted mesocosm experiments over a 90-day period to assess the effects of polystyrene microplastics on the invasion of exotic submerged macrophytes, sediment physicochemical properties, and sediment bacterial communities. Our results showed that PS-MPs significantly promoted the performance of functional traits and the invasive ability of exotic submerged macrophytes, while native plants remained unaffected. Moreover, PS-MPs addition significantly decreased sediment pH while increasing sediment carbon and nitrogen content. Additionally, MPs increased the diversity of sediment bacterial community but inhibited its structural stability, thereby impacting sediment bacterial multifunctionality to varying degrees. Importantly, we identified sediment properties, bacterial composition, and bacterial multifunctionality as key mediators that greatly enhance the invasion of exotic submerged macrophytes. These findings provide compelling evidence that the increase in MPs may exacerbate the invasion risk of exotic submerged macrophytes through multiple pathways. Overall, this study enhances our understanding of the ecological impacts of MPs on aquatic plant invasion and the health of aquatic ecosystems.

Exploration the interaction of cadmium and copper toxic effects in pakchoi (Brassica chinensis L) roots through combinatorial transcriptomic and weighted gene co-expression network analysis

The interaction between cadmium(Cd) and copper(Cu) during combined pollution can lead to more complex toxic effects on humans and plants.However, there is still a lack of sufficient understanding regarding the types of interactions at the plant molecular level and the response strategies of plants to combined pollution. To assess this, we investigated the phenotypic and transcriptomic patterns of pakchoi (Brassica chinensis L) roots in response to individual and combined pollution of Cd and Cu. The results showed that compared to single addition, the translocation factor of heavy metals in roots significantly decreased (p < 0.05) under the combined addition, resulting in higher accumulation of Cd and Cu in the roots. Transcriptomic analysis of pakchoi roots revealed that compared to single pollution, there were 312 and 1926 differentially expressed genes (DEGs) specifically regulated in the Cd2Cu20 and Cd2Cu100 combined treatments, respectively. By comparing the expression of these DEGs among different treatments, we found that the combined pollution of Cd and Cu mainly affected the transcriptome of the roots in an antagonistic manner. Enrichment analysis indicated that pakchoi roots upregulated the expression of genes involved in glucosetransferase activity, phospholipid homeostasis, proton transport, and the biosynthesis of phenylpropanoids and flavonoids to resist Cd and Cu combined pollution. Using weighted gene co-expression network analysis (WGCNA), we identified hub genes related to the accumulation of Cd and Cu in the roots, which mainly belonged to the LBD, thaumatin-like protein, ERF, MYB, WRKY, and TCP transcription factor families. This may reflect a transcription factor-driven trade-off strategy between heavy metal accumulation and growth in pakchoi roots. Additionally, compared to single metal pollution, the expression of genes related to Nramp, cation/H+ antiporters, and some belonging to the ABC transporter family in the pakchoi roots was significantly upregulated under combined pollution. This could lead to increased accumulation of Cd and Cu in the roots. These findings provide new insights into the interactions and toxic mechanisms of multiple metal combined pollution at the molecular level in plants.

Combined transcriptomics and metabolomics to analyse the response of Cuminum cyminum L. under Pb stress

Lead (Pb) can disrupt plant gene expression, modify metabolite contents, and influence the growth of plants. Cuminum cyminum L. is highly adaptable to adversity, but molecular mechanism by which it responds to Pb stress is unknown. For this study, transcriptomic and metabolomic sequencing was performed on root tissues of C. cyminum under Pb stress. Our results showed that high Pb stress increased the activity of peroxidase (POD), the contents of malondialdehyde (MDA) and proline by 80.03 %, 174.46 % and 71.24 %, respectively. Meanwhile, Pb stress decreased the activities of superoxide dismutase (SOD) and catalase (CAT) as well as contents of soluble sugars and GSH, which thus affected the growth of C. cyminum. In addition, Pb stress influenced the accumulation and transport of Pb in C. cyminum. Metabolomic results showed that Pb stress affected eight metabolic pathways involving 108 differentially expressed metabolites, primarily amino acids, organic acids, and carbohydrates. The differentially expressed genes identified through transcriptome analysis were mainly involved the oxidation reductase activity, transmembrane transport, phytohormone signaling, and MAPK signaling pathway. The results of this study will help to understand the molecular mechanisms of C. cyminum response to Pb stress, and provide a basis for screening seeds with strong resistance to heavy metals.

Integrated morphological, physiological and transcriptomic analyses reveal response mechanisms of rice under different cadmium exposure routes

Rice (Oryza sativa) is one of the major cereal crops and takes up cadmium (Cd) more readily than other crops. Understanding the mechanism of Cd uptake and defense in rice can help us avoid Cd in the food chain. However, studies comparing Cd uptake, toxicity, and detoxification mechanisms of leaf and root Cd exposure at the morphological, physiological, and transcriptional levels are still lacking. Therefore, experiments were conducted in this study and found that root Cd exposure resulted in more severe oxidative and photosynthetic damage, lower plant biomass, higher Cd accumulation, and transcriptional changes in rice than leaf Cd exposure. The activation of phenylpropanoids biosynthesis in both root and leaf tissues under different Cd exposure routes suggests that increased lignin is the response mechanism of rice under Cd stress. Moreover, the roots of rice are more sensitive to Cd stress and their adaptation responses are more pronounced than those of leaves. Quantitative PCR revealed that OsPOX, OsCAD, OsPAL and OsCCR play important roles in the response to Cd stress, which further emphasize the importance of lignin. Therefore, this study provides theoretical evidence for future chemical and genetic regulation of lignin biosynthesis in crop plants to reduce Cd accumulation.

Transcriptomics, proteomics, and metabolomics interventions prompt crop improvement against metal(loid) toxicity

The escalating challenges posed by metal(loid) toxicity in agricultural ecosystems, exacerbated by rapid climate change and anthropogenic pressures, demand urgent attention. Soil contamination is a critical issue because it significantly impacts crop productivity. The widespread threat of metal(loid) toxicity can jeopardize global food security due to contaminated food supplies and pose environmental risks, contributing to soil and water pollution and thus impacting the whole ecosystem. In this context, plants have evolved complex mechanisms to combat metal(loid) stress. Amid the array of innovative approaches, omics, notably transcriptomics, proteomics, and metabolomics, have emerged as transformative tools, shedding light on the genes, proteins, and key metabolites involved in metal(loid) stress responses and tolerance mechanisms. These identified candidates hold promise for developing high-yielding crops with desirable agronomic traits. Computational biology tools like bioinformatics, biological databases, and analytical pipelines support these omics approaches by harnessing diverse information and facilitating the mapping of genotype-to-phenotype relationships under stress conditions. This review explores: (1) the multifaceted strategies that plants use to adapt to metal(loid) toxicity in their environment; (2) the latest findings in metal(loid)-mediated transcriptomics, proteomics, and metabolomics studies across various plant species; (3) the integration of omics data with artificial intelligence and high-throughput phenotyping; (4) the latest bioinformatics databases, tools and pipelines for single and/or multi-omics data integration; (5) the latest insights into stress adaptations and tolerance mechanisms for future outlooks; and (6) the capacity of omics advances for creating sustainable and resilient crop plants that can thrive in metal(loid)-contaminated environments.

Microplastic interactions in the agroecosystems: methodological advances and limitations in quantifying microplastics from agricultural soil

The instantaneous growth of the world population is intensifying the pressure on the agricultural sector. On the other hand, the critical climate changes and increasing load of pollutants in the soil are imposing formidable challenges on agroecosystems, affecting productivity and quality of the crops. Microplastics are among the most prevalent pollutants that have already invaded all terrestrial and aquatic zones. The increasing microplastic concentration in soil critically impacts crop plants growth and yield. The current review elaborates on the behaviors of microplastics in soil and their impact on soil quality and plant growth. The study shows that microplastics alter the soil's biophysical properties, including water-holding capacity, bulk density, aeration, texture, and microbial composition. In addition, microplastics interact with multiple pollutants, such as polyaromatic hydrocarbons and heavy metals, making them more bioavailable to crop plants. The study also provides a detailed insight into the current techniques available for the isolation and identification of soil microplastics, providing solutions to some of the critical challenges faced and highlighting the research gaps. In our study, we have taken a holistic, comprehensive approach by analysing and comparing various interconnected aspects to provide a deeper understanding of all research perspectives on microplastics in agroecosystems.

Impacts of Plastics on Plant Development: Recent Advances and Future Research Directions

Plastics have inundated the world, with microplastics (MPs) being small particles, less than 5 mm in size, originating from various sources. They pervade ecosystems such as freshwater and marine environments, soils, and the atmosphere. MPs, due to their small size and strong adsorption capacity, pose a threat to plants by inhibiting seed germination, root elongation, and nutrient absorption. The accumulation of MPs induces oxidative stress, cytotoxicity, and genotoxicity in plants, which also impacts plant development, mineral nutrition, photosynthesis, toxic accumulation, and metabolite production in plant tissues. Furthermore, roots can absorb nanoplastics (NPs), which are then distributed to stems, leaves, and fruits. As MPs and NPs harm organisms and ecosystems, they raise concerns about physical damage and toxic effects on animals, and the potential impact on human health via food webs. Understanding the environmental fate and effects of MPs is essential, along with strategies to reduce their release and mitigate consequences. However, a full understanding of the effects of different plastics, whether traditional or biodegradable, on plant development is yet to be achieved. This review offers an up-to-date overview of the latest known effects of plastics on plants.

Microplastic stress in plants: effects on plant growth and their remediations

Microplastic (MP) pollution is becoming a global problem due to the resilience, long-term persistence, and robustness of MPs in different ecosystems. In terrestrial ecosystems, plants are exposed to MP stress, thereby affecting overall plant growth and development. This review article has critically analyzed the effects of MP stress in plants. We found that MP stress-induced reduction in plant physical growth is accompanied by two complementary effects: (i) blockage of pores in seed coat or roots to alter water and nutrient uptake, and (ii) induction of drought due to increased soil cracking effects of MPs. Nonetheless, the reduction in physiological growth under MP stress is accompanied by four complementary effects: (i) excessive production of ROS, (ii) alteration in leaf and root ionome, (iii) impaired hormonal regulation, and (iv) decline in chlorophyll and photosynthesis. Considering that, we suggested that targeting the redox regulatory mechanisms could be beneficial in improving tolerance to MPs in plants; however, antioxidant activities are highly dependent on plant species, plant tissue, MP type, and MP dose. MP stress also indirectly reduces plant growth by altering soil productivity. However, MP-induced negative effects vary due to the presence of different surface functional groups and particle sizes. In the end, we suggested the utilization of agronomic approaches, including the application of growth regulators, biochar, and replacing plastic mulch with crop residues, crop diversification, and biological degradation, to ameliorate the effects of MP stress in plants. The efficiency of these methods is also MP-type-specific and dose-dependent.