Cadmium (Cd) in soil and water streams is now recognized as a significant environmental issue that harms plants and animals. Plants damaged by Cd toxicity experience various effects, from germination to yield reduction. Plant- and animal-based goods are allowing more Cd to enter our food chain, which could harm human health. Therefore, this urgent global concern must be addressed by implementing appropriate remedial measures. Plantbased phytoremediation is one safe, economical, and environmentally acceptable way to remove hazardous metals from the environment. Hyperaccumulator plants possess specialized transport proteins, such as metal transporters located in membranes of roots, as well as they facilitate Cd uptake from soil. This review outlines the latest findings about these membrane transporters. Moreover, we also discuss how innovative modern tools such as microbiomes, omics, nanotechnology, and genome editing have revealed molecular regulators connected to Cd tolerance, which may be employed to develop Cd-tolerant future plants. We can develop effective solutions to enhance tolerance of plant to Cd toxicity by leveraging membrane transporters and modern biotechnological tools. Additionally, implementing strategies to increase tolerance of Cd and restrict its bioavailability in plants' edible parts is crucial for improving food safety. These combined efforts will lead to the cultivation of safer food crops and support sustainable agricultural practices in contaminated environments.

Drought stress significantly inhibits the growth of Astragalus mongholicus, leading to reduced biomass, decreased photosynthetic efficiency, and exacerbated oxidative damage. In our study, the accumulation of saponins and flavonoids in Astragalus roots markedly increased under moderate drought stress. These secondary metabolites further reshaped the rhizosphere microbial community structure, significantly increasing its diversity and interaction network complexity. Notably, drought stress enriched beneficial bacterial genera such as Rhizobium and Pseudomonas in the rhizosphere soil. Combined with the isolation of culturable microorganisms and the cooccurrence network of the rhizosphere bacterial community, we constructed a 13-strain synthetic community (SynCom) and simplified it to 7 strains. Compared with the noninoculated control, under moderate drought stress, inoculation with the simplified SynCom significantly increased plant growth, increasing the aboveground fresh weight by 50.10 %, dry weight by 55.29 %, and underground fresh weight by 76.40 %. Similarly, plants treated with the synthetic community presented significant increases in aboveground fresh weight and dry weight compared with those of the noninoculated control, with increases of 46.98 % and 61.54 %, respectively. Moreover, inoculation with the simplified community significantly reduced the content of malondialdehyde (MDA) and improved the catalase (CAT) and peroxidase (POD) activities and leaf photosynthetic parameters (Fv/ Fm and Y(II)) of Astragalus. Our findings provide new insight into improving the yield and quality of Astragalus and highlight the potential of synthetic rhizosphere microbial communities for assisting plants in coping with abiotic stress.

Salinity stress poses a critical threat to global crop productivity, driven by factors such as saline irrigation, low precipitation, native rock weathering, high surface evaporation, and excessive fertilizer application. This abiotic stress induces oxidative damage, osmotic imbalance, and ionic toxicity, severely affecting plant growth and leading to crop failure. Silicon (Si) has emerged as a versatile element capable of mitigating various biotic and abiotic stresses, including salinity. This review offers a comprehensive analysis of Si's multifaceted role in alleviating salinity stress, elucidating its molecular, physiological, and biochemical mechanisms in plants. It explores Si uptake, transport, and accumulation in plant tissues, emphasizing its contributions to maintaining ionic balance, enhancing water uptake, and reinforcing cell structural integrity under saline conditions. Additionally, this review addresses Si transformations in saline soils and the factors influencing its bioavailability. A significant focus is placed on silicon-solubilizing microorganisms (SSMs), which enhance Si bioavailability through mechanisms such as organic acid production, ligand exchange, mineral dissolution, and biofilm formation. By improving nutrient cycling and mitigating salinity-induced stress, SSMs offer a sustainable alternative to synthetic silicon fertilizers, promoting resilient crop production in salt-affected soils.

Hordeum jubatum L. is a perennial herb with high ornamental value and strong stress tolerance. Nitrogen deposition and cold stress are key environmental factors that affect stability of ecosystems in cold regions of northeast China. These factors significantly affect plant growth and development. Arbuscular mycorrhizal fungi (AMF) are symbiotic soil fungi that can increase plant resistance and growth. However, research on impacts of nitrogen deposition and cold stress on roots of H. jubatum-AM symbionts remains limited. Root biomass (dry and fresh weight), architecture (length, surface area, volume, forks, number of fourth-order roots, and root fractal dimension), and ultrastructure of H. jubatum were assessed, both in the presence and absence of AMF, under conditions of nitrogen deposition and cold stress. Cold stress inhibited all indicators of root architecture and disrupted root ultrastructure, with greater inhibition shown in the N2 (NH4+/NO3- = 1:1) treatment under cold stress, indicating nitrogen deposition increased sensitivity of H. jubatum to cold stress. Inoculation with AMF significantly reduced damage caused by nitrogen deposition and cold stress on H. jubatum roots compared with the non-inoculation treatment. Our results demonstrate different effects of the interaction of nitrogen deposition and cold stress versus single stress (nitrogen deposition or cold stress) on plant root development and provide a scientific basis for the use of mycorrhizal technology to improve resistance and productivity of cold-tolerant plants in cold regions under stress conditions.

Soil contamination with arsenic (As) is becoming a serious concern for living organisms. Arsenic is a nonessential metalloid for plants, humans, and other living organisms. Biochar (BC) is a very effective amendment to remediate polluted soils and it received great attention owing to its appreciable results. Arsenic toxicity negatively affects plant morph-physiological and biochemical functioning and upsurges the generation of reactive oxygen species (ROS), which negatively affect cellular structures. Arsenic toxicity also reduces seed germination and impedes plant growth by decreasing nutrient uptake, causing oxidative damage and disrupting the photosynthetic efficiency. Plants use different strategies like antioxidant defense and increased osmolyte synthesis to counteract As toxicity; nevertheless, this is not enough to counter the toxic impacts of As. Thus, applying BC has shown tremendous potential to counteract the As toxicity. Biochar application to As-polluted soils improves water uptake, maintains membrane stability and nutrient homeostasis, and increases osmolyte synthesis, gene expression, and antioxidant activities, leading to better plant performance. Additionally, BC modulates soil pH, increases nutrient availability, causes As immobilization, decreases its uptake and accumulation in plant tissues, and ensures safer production. The present review describes the sources, toxic impacts of As, and ways to lower As in the environment to decrease its toxic impacts on humans, the ecosystem, and the food chain. It concentrates on different mechanisms mediated by BC to alleviate As toxicity and remediate As-polluted soils and different research gaps that must be fulfilled in the future. Therefore, the current review will help to develop innovative strategies to minimize As uptake and accumulation and remediate As-polluted soils to reduce their impacts on humans and the environment.

Restoration of coastal dunes following tropical storm events often requires renourishment of sand substrate dredged from offshore sources, although dredging has well-described negative ecological impacts and high economic costs. As a potential solution, recycled glass sand (cullet) made from crushed glass bottles has been proposed as a potential replacement for dredging. However, glass sand substrates may have limited ability to provide support to coastal plant communities due to the absence of native soil microbial communities. To explore the potential use of glass sand as a substrate for dune plants in the Northern Gulf of Mexico, we compared the growth of Sea oats (Uniola paniculata), Beach morning-glory (Ipomoea imperati), and Railroad vine (I. pes-caprae) in glass sand to growth in live beach sand. To determine if inoculation of glass sand with native soil microbial communities improved survival, growth, and biomass production, we also tested plant growth in glass sand with native microbial amendments. Overall, we found no difference in the survival of the three dune species across three soil treatments and weak differences in plant growth and biomass production across our soil substrates. Our results suggest that glass sand substrates may be a viable option for coastal dune restoration, with limited differences between live beach sand, glass sand, and glass sand inoculated with native soil microbes. Restoration and replenishment of coastal dunes using glass sand as a substrate following tropical storms or sea-level rise may allow coastal managers to reduce the economic and ecological damage associated with offshore sediment dredging.

Aims The effects of a tropical forest logging road on soil C and N, and the compositions of Actinobacteria, Acidobacteria, and wood rot/lignin-degrading fungal (WRT/LD) decomposer communities were evaluated.Methods and results Soils from a healthy Costa Rican old growth forest before Hurricane Otto and from an adjacent, recently formed logging road built after Hurricane Otto were collected over 4 years and assessed for C and N metrics, and characteristics of the three decomposer communities determined by Illumina amplicon sequencing methods. The Logging Road negatively impacted the soil total organic C, respiration, biomass C, qCO2, and total N, while the Actinobacterial and Acidobacterial communities changed from stable compositions of copiotrophic taxa in the rich forest soil to stable compositions of oligotrophic taxa in the poor logging road soil, and the WRT/LD community changed from stable compositions of copiotrophic taxa in the forest soils to an unstable community of oligotrophic taxa with almost no overlap in genera between logging road soils.Conclusions The logging road negatively influenced 3 decomposer communities and associated C and N metrics, with the two bacterial communities taxonomically stabilizing, but the fungal community taxonomically diverging into an unstable composition over time. Monitoring efforts are on-going to provide local forest land managers with potential indicators of soil ecosystem damage and recovery.

Background and aims Locally produced bio-inoculant consortium and plant bioactive extract were studied as sustainable management options to boost maize production. Methods The field study was conducted from 13th April to 15th July 2021 and repeated on another field site from 5th May to 4th August 2023 to avoid residual effects while validating reliability of the treatments. Experiments were set up as randomized complete block design with 5 treatments including a Control (No input), Chemical (NPK fertilizer + synthetic insecticide), Organic (Poultry manure + Piper guineense), and locally produced or commercial bio-inoculant of plant growth-promoting bacteria, with 4 replicates. Results Local inoculum significantly (P < 0.05) increased maize grain yield than untreated control. Microbial and organic amendments produced comparable maize grain yield to chemical input, which were significantly higher than the untreated control (P < 0.05). The local inoculum reduced fall armyworm (FAW) infestation of maize cobs by 18% and 31% in 2021 and 2023, respectively, compared to untreated control (P < 0.05). Stem borer infestation also reduced significantly (P < 0.05) across treatments for both years, with the lowest in local inoculum (6%), followed by commercial inoculum (31%), organic (52%), chemical (42%), and control (100%) in 2021, with a similar trend observed in 2023. In 2021, amounts of plant available phosphorus and exchangeable potassium were 71 mg kg(-1) and 1010 mg kg(-1) soil, respectively, in the locally produced bio-inoculant consortium, which were significantly (P < 0.05) higher than 30 mg kg(-1) and 374 mg kg(-1) in the control, respectively, and a similar trend was observed in 2023.

The use of plant growth-promoting microorganisms is an effective agricultural practice to improve plant growth, especially under abiotic stress. In this study, the combined impact of three plant growth-promoting bacteria (PGPB) namely Brevibacterium halotolerans (Sd-6), Burkholderia cepacia (Art-7), Bacillus subtilis (Ldr-2) were tested with Trichoderma harzianum (Th) (possessing ACC deaminase producing activity) in Ocimum basilicum L. cv. Saumya to reduce drought-induced damages to the plants under different level of drought stress [i.e. wellwatered (100 %), moderate (60 %), severe (40 %)]. These PGPB strains, along with Th, were found to be tolerant against osmotic stress when tested in growth media containing different concentrations of polyethylene glycol (PEG 8000), and all were found to endure -0.99 MPa water potential. Compared to non-inoculated control, Th+Ldr-2 treatment improved fresh herb weight (62.45 %) and oil content (61.54 %) and higher photosynthetic rate under severe drought. Besides, in relation to control, the above treatment enhanced nutrient uptake, reduced ABA, ACC as well as ethylene levels and increased IAA content in addition to an increase in important constituents of essential oil, indicating better performance in terms of plant growth under drought. Higher RWC, decreased MDA, and reduced antioxidant activities in Th+Ldr-2 treated plants compared to non-inoculated control under drought support the mechanism of the microbes providing tolerance against drought. Colony forming unit of microbes and scanning electron microscopy (SEM) study support the effective colonisation behaviour of Th+Ldr-2, which protects plants against drought stress. A consortium of diverse microbes, found to improve plant growth under drought through increased nutrient uptake, reducing the levels of ACC and ABA, improving the content of IAA, antioxidant enzymes probably reducing the effect of drought stress and improving plant biomass could be a useful tool to reduce drought-induced losses in crop plants.

To limit damage from insect herbivores, plants rely on a blend of defensive mechanisms that includes partnerships with beneficial microbes, particularly those inhabiting roots. While ample evidence exists for microbially mediated resistance responses that directly target insects through changing phytotoxin and volatile profiles, we know surprisingly little about the microbial underpinnings of plant tolerance. Tolerance defenses counteract insect damage via shifts in plant physiology that reallocate resources to fuel compensatory growth, improve photosynthetic efficiency, and reduce oxidative stress. Despite being a powerful mitigator of insect damage, tolerance remains an understudied realm of plant defenses. Here, we propose a novel conceptual framework that can be broadly applied across study systems to characterize microbial impacts on expression of tolerance defenses. We conducted a systematic review of studies quantifying the impact of rhizosphere microbial inoculants on plant tolerance to herbivory based on several measures-biomass, oxidative stress mitigation, or photosynthesis. We identified 40 studies, most of which focused on chewing herbivores (n = 31) and plant growth parameters (e.g., biomass). Next, we performed a meta-analysis investigating the impact of microbial inoculants on plant tolerance to herbivory, which was measured via differences in plant biomass, and compared across key microbe, insect, and plant traits. Thirty-five papers comprising 113 observations were included in this meta-analysis, with effect sizes (Hedges' d) ranging from -4.67 (susceptible) to 18.38 (overcompensation). Overall, microbial inoculants significantly reduce the cost of herbivory via plant growth promotion, with overcompensation and compensation comprising 25% of observations of microbial-mediated tolerance. The grand mean effect size 0.99 [0.49; 1.49] indicates that the addition of a microbial inoculant increased plant biomass by similar to 1 SD under herbivore stress, thus improving tolerance. This effect was influenced most by microbial attributes, including functional guild and total soil community diversity. Overall, results highlight the need for additional investigation of microbially mediated plant tolerance, particularly in sap-feeding insects and across a more comprehensive range of tolerance mechanisms. Such attention would round out our current understanding of anti-herbivore plant defenses, offer insight into the underlying mechanisms that promote resilience to insect stress, and inform the application of microbial biotechnology to support sustainable agricultural practices.