Hydroponic Experiment Research Articles

Responses to low phosphorus conditions of Triadic sebifera (Euphorbiaceae), an invasive plant species on Miyajima Island, southwest Japan

ABSTRACT Phosphorus (P) is a crucial nutrient for plant growth, but its availability in soils is often limited. Invasive plants have shown enhanced utilization of essential elements in soil, including P, compared to native plants, contributing to their success. This study investigated the responses of Triadic sebifera, an invasive species, to low P conditions. We compared T. sebifera with native Mallotus japonicus and other local plants in field conditions and further examined T. sebifera‘s response to low P availability using hydroponic systems and RNA-seq analysis. The hydroponic experiments involved three treatment groups with different P concentrations (0, 6.4, and 64 µM ). Field survey results revealed that T. sebifera exhibited higher P use efficiency and more efficient P resorption compared to other native plants on Miyajima Island. However, no significant differences in P concentrations were found between T. sebifera and native plant M. japonicus, another member of the Euphorbiaceae family. This suggests that the efficient use and resorption of P may not be unique to the invasive species T. sebifera, but rather a trait shared by members of the Euphorbiaceae family. Hydroponic experiments further demonstrated the response of T. sebifera to low P availability. Under 0 µM P treatment, T. sebifera showed enhanced secretion of acid phosphatase (AcPase). At 6.4 µM P treatment, the plant maintained growth, exhibited potential enhancement in root development, high chlorophyll content, and high root biomass, and demonstrated relatively high AcPase secretion, but displayed a P-deficient state compared to the 0 and 64 µM P treatments. RNA-seq analysis provided insights into the potential strategies of T. sebifera in low P environments. It revealed that T. sebifera under 0 µM P treatment exhibits upregulation of transcripts related to P acquisition, antioxidant activities, stress responses, and arsenate uptake risk or regulation. Additionally, T. sebifera showed upregulation of transcripts associated with secondary metabolism under 6.4 µM P treatment, suggesting mechanisms for more efficient P acquisition and environmental stress defense. This study highlights the strategies of T. sebifera under low P availability, suggesting a role in enhancing its own P utilization efficiency, which may contribute to its successful invasion.

Industrial hemp (Cannabis sativa L.) adapts to cadmium stress by reshaping rhizosphere fungal community

Increasing evidence indicates that plants under environmental stress can actively seek the help of microbes (‘cry-for-help’ hypothesis). However, empirical evidence underlying this strategy is limited under metal-stress conditions. Here, we employed integrated microbial community profiling in cadmium (Cd) polluted soil and culture-based methods to investigate the three-way interactions between the industrial hemp (Cannabis Sativa L.), rhizospheric microbes, and Cd stress. Results from the pot and three cycles of the successful hemp planting experiments showed that Cd stress significantly affected the composition of rhizosphere fungi in industrial hemp and induced enrichment of the fungal operational taxonomic unit (OTU)3 (Cladosporium). A representative of OTU3 (strain DM-2) was successfully isolated. In a hydroponic experiment, inoculation of DM-2 significantly increased the shoot length (by 25.84 %) and fresh weight (by 92.66 %) of hemp seedlings when compared to the absence of DM-2 under the Cd stress. The findings indicate that DM-2 inoculation could effectively alleviate the Cd stress in hemp seedlings. Metabolomic analysis of spent media with or without DM-2 revealed the association of DM-2 with the transformation of root exudates to melatonin, which may be a key chemical in plant-microbe interactions against abiotic stresses. The findings will inform efforts to manipulate the root microbiome to enhance plant growth in polluted environments.

Proline and Glycine Betaine: A Dynamic Duo for Enhancing Salt Stress Resilience in Maize by Regulating Growth, Stomatal size, and Oxidative Stress Responses

Osmolytes proline (Pro) and glycine betaine (GB) have been reported to impart tolerance against salinity stress in many plants. However, there is no report available on the combined application of Pro and GB to mitigate salinity-induced growth inhibition in maize. Consequently, the goal of the current study is to assess Pro's and GB's potential as priming and exogenous agents in maize under salt stress. Therefore, the present study was conducted using a petri dish and hydroponic pot experiment to evaluate the morpho-physiological and biochemical characteristics of maize plants subjected to salt stress, with the addition of Pro and GB. The seeds of maize were germinated under 20 mM of each Pro or GB, with or without 120 mM salinity stress. The findings demonstrated that salt stress lessened the final germination percentage (FGP) (52.9%), photosynthetic pigments (40.0%), relative water content (RWC) (20.2%), stomatal size (59.3%), and leaf and root K+/Na+ ratios of maize seedlings compared to control. In addition, compared to the control, higher levels of malondialdehyde (MDA) (24.2%) and hydrogen peroxide (H2O2) (25.7%) were observed, whereas lower levels of catalase (CAT) (43.8%) and peroxidase (POX) (30.4%) were noted. The priming with Pro, GB, Pro+GB significantly increased FGP, germination index (GI), shoot-root biomass, seed vigor index (SVI), and reduced mean germination time (MGT) under salt stress. Foliar application of Pro, GB, or Pro+GB resulted in a significant increment in chlorophyll contents, RWC, K+ absorption, and stomatal size under salt stress. Furthermore, supplementing with Pro, GB, or Pro+GB reduced the accumulation of H2O2 (24.0, 23.3, and 31.1%, respectively) and MDA (22.8, 17.2, and 32.1%, respectively) caused by salt and augmented the levels of CAT (33.3, 22.8, and 45.2%, respectively) and POX (36.4, 23.5, and 47.2%, respectively) in the leaves. Taken together, the current study's findings indicate that combining Pro and GB is one of the most effective techniques for improving the salinity-tolerant seed germination and seedling traits of maize plants. Consequently, this study recommends that Pro and GB can be used as seed priming and exogenous agents to help maize grow faster in salt-stress situations.

The paradoxical effects of beneficial bacteria on Solanum lycopersicum under Cd stress.

This study investigated the complex interactions between a novel consortium and tomato seedlings under cadmium (Cd) stress. The consortium consists of two bacteria, Pseudomonas sp. HS4 and Paenarthrobacter sp. AS8, both with proven plant growth-promoting (PGP) properties, isolated from Cd hyperaccumulators. Our research highlights the paradoxical effects of these bacteria, revealing their dual role in reducing Cd uptake while simultaneously inducing oxidative stress in plants. Hydroponic experiments showed that the consortium reduced Cd accumulation in tomato shoots by 52% compared to uninoculated controls. However, this reduction was accompanied by decreased plant biomass and increased oxidative stress, with malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels up to 80% and 160% higher, respectively, in inoculated plants. Root H₂O₂ production increased by 38% under 50 μM Cd without a corresponding rise in catalase (CAT) activity. Despite Cd exposure, the consortium promoted chlorophyll and carotenoid synthesis, restoring pigment levels to those of unstressed controls. Gene expression analysis revealed a complex impact on stress responses, with inoculation suppressing Sl1 gene expression in roots and upregulating the oxidative stress-related GR-1 gene in shoots. These findings highlight the complex and multifaceted relationship between beneficial bacteria and plant fitness under heavy metal stress, with significant implications for sustainable agriculture. The study raises new questions regarding the broader physiological and ecological impacts of applying hyperaccumulator-associated bacteria in crop management, emphasizing the necessity for deeper mechanistic insights into these interactions to fully harness their potential in improving crop resilience and productivity.

Pi-efficient wheat cultivars screened by using both functional marker CAPS-799 and field experiment

ContextIn our previous study, we identified TaPHT1;9–4B as a critical high-affinity phosphate (Pi) transporter that plays a significant role in Pi acquisition and transport. Subsequently, we developed the functional marker CAPS-799 to facilitate the identification of its Pi-efficient elite haplotype. ObjectiveThis study aimed to screen a variety of wheat cultivars using the CAPS-799 marker to identify those exhibiting Pi-efficient elite haplotypes. Additionally, we sought to elucidate the physiological mechanisms underlying these traits through both field and hydroponic experiments. MethodsField experiments over two successive years without phosphorus (P) fertilizer, along with a hydroponic experiment using low Pi (10 μM) were conducted. P concentration, biomass, grain yield, yield components, root growth parameters, and transcript levels of TaPHT1;9–4B were measured. Total P accumulation, P transport and utilization efficiency, and relative parameters were also calculated. ResultsEight Pi-efficient wheat cultivars with the Hap3 haplotype were identified using CAPS-799 from a group of 80 modern major cultivars. In two-year field experiments without P fertilizer, these Hap3 cultivars exhibited significantly higher grain yield, spike number, P uptake, and transport efficiency compared to Non-Hap3 haplotypes (Hap1, Hap2, and Hap4). As a result, these eight cultivars were classified as Pi-efficient elite haplotypes. In field experiments, TaPHT1;9–4B transcript levels in the roots during the early grain-filling stage, as well as root surface area, volume, and mean root diameter in hydroponic experiments, were significantly greater in Hap3 cultivars than in Non-Hap3 cultivars. ConclusionsOur field and hydroponic experiments demonstrated that CAPS-799 is a valuable functional marker for identifying Pi-efficient wheat cultivars. These Pi-efficient cultivars were characterized by higher TaPHT1;9–4B transcript levels and increased root growth. ImplicationsCAPS-799 can be used to screen or develop Pi-efficient wheat cultivars.

Synthetic communities derived from the core endophytic microbiome of hyperaccumulators and their role in cadmium phytoremediation

BackgroundAlthough numerous endophytic bacteria have been isolated and characterized from cadmium (Cd) hyperaccumulators, the contribution and potential application of the core endophytic microbiomes on facilitating phytoremediation were still lack of intensive recognition. Therefore, a 2-year field sampling in different location were firstly conducted to identify the unique core microbiome in Cd hyperaccumulators, among which the representative cultivable bacteria of different genera were then selected to construct synthetic communities (SynComs). Finally, the effects and mechanisms of the optimized SynCom in regulating Cd accumulation in different ecotypes of Sedum alfredii were studied to declare the potential application of the bacterial agents based on core microbiome.ResultsThrough an innovative network analysis workflow, 97 core bacterial taxa unique to hyperaccumulator Sedum was identified based on a 2-year field 16S rRNA sequencing data. A SynCom comprising 13 selected strains belonging to 6 different genera was then constructed. Under the combined selection pressure of the plant and Cd contamination, Alcaligenes sp. exhibited antagonistic relationships with other genera and plant Cd concentration. Five representative strains of the other five genera were further conducted genome resequencing and developed six SynComs, whose effects on Cd phytoremediation were compared with single strains by hydroponic experiments. The results showed that SynCom-NS comprising four strains (including Leifsonia shinshuensis, Novosphingobium lindaniclasticum, Ochrobactrum anthropi, and Pseudomonas izuensis) had the greatest potential to enhance Cd phytoremediation. After inoculation with SynCom-NS, genes related to Cd transport, antioxidative defense, and phytohormone signaling pathways were significantly upregulated in both ecotypes of S. alfredii, so as to promote plant growth, Cd uptake, and translocation.ConclusionIn this study, we designed an innovative network analysis workflow to identify the core endophytic microbiome in hyperaccumulator. Based on the cultivable core bacteria, an optimized SynCom-NS was constructed and verified to have great potential in enhancing phytoremediation. This work not only provided a framework for identifying core microbiomes associated with specific features but also paved the way for the construction of functional synthetic communities derived from core microbiomes to develop high efficient agricultural agents.5KavnCJpVp3k2g6uQCMsTeVideo

Preparation of calcium-based phosphate adsorbent and mineral-rich humic acid fertilizer from biomass ash and bamboo by hydrothermal-pyrolysis: Performance and mechanism

Biomass ash (BA) contains alkaline cations such as K, Ca, and Mg. Due to its high pH, direct application to the soil may result in soil salinization. Composting of BA with organic matter is an effective strategy, but the composting cycle is long and there is a large amount of insoluble residue in the product. Therefore, this research proposed for the first time using the hydrothermal method to rapidly convert BA and bamboo powder (BP) into water - soluble fertilizer (WSF) within 4 h. The insoluble hydrothermal residue was further converted into calcium - rich biochar phosphorus adsorption material by a simple pyrolysis process. WSF was neutral and contained humic acid and elements like K, Ca, Mg, and Si. A 14 - day wheat hydroponic experiment showed that the addition of 0.0125% WSF increased the fresh weight of wheat by 18.77% compared with deionized water. The calcium - based biochar adsorbent produced by pyrolysis had an ideal adsorption capacity of up to 113.6 mg P g−1 for phosphate in water, higher than many existing reports. The adsorption mechanisms mainly included surface precipitation, ion exchange, and electrostatic attraction. Moreover, the calcium - rich biochar sample slowly released phosphorus into water after adsorbing phosphate. When the pH was 3 or 4, the removal rate of Pb2+, Cd2+, and Cu2+ at 15 – 20 mg L−1 was as high as 99%. This indicated its potential as a slow - release fertilizer and heavy metal remediation agent. This research provided a new way of thinking for the treatment and disposal of BA.

Responses of glyoxalase system, ascorbate-glutathione cycle, and antioxidant enzymes in Pontederia cordata to lead stress and its capacity to remove lead

A hydroponic experiment was conducted to investigate the variations in membrane permeabilities, chlorophyll contents, antioxidase activities, the ascorbic acid (AsA)-glutathione (GSH) cycle, and the glyoxalase system in the leaves of Pontederia cordata with 0 ∼ 15.0 mg L−1 lead ion (Pb2+) exposure. The concentrations of Pb2+ accumulated in the plant roots, stems, and leaves were also evaluated. After 7 days of exposure, the plants maintained normal growth, and there was a significant increase in ascorbate peroxidase and dehydroascorbate reductase activities. With 5.0 mg L−1 Pb2+ exposure for 28 days, nearly 66.36% of Pb2+ accumulated in the roots, while excess Pb2+ immobilized in the leaves was not observed. Exposure to 10.0 and 15.0 mg L−1 Pb2+ for 28 days significantly increased Pb2+ contents in the leaves. This led to decrease in chlorophyll a, b, and carotenoid contents, and to increase in the methylglyoxal content in the leaves. With 10 and 15 mg L−1 Pb2+ exposure, NPT and PCs contents in leaves increased. however, the glyoxalase system did not function well in the plant tolerant to Pb2+ at higher concentrations. The AsA-GSH cycle did not cooperate with the glyoxalase system in the plant defense against Pb2+ exposure in the present investigation.

Growth promotion on maize and whole-genome sequence analysis of Bacillus velezensis D103.

In this study, we assessed the capacity of D103 to promote plant growth and examined the effects of hydroponic experiments inoculated with this strain on the growth of maize seedlings. We sequenced and analyzed the complete genome of D103, identifying several genes and gene clusters associated with plant growth promotion and resistance to pathogenic fungi, thus revealing the plant growth-promoting mechanisms of this strain. The isolation and characterization of new strains with beneficial traits are essential for expanding microbial resources available for biofertilizer production. Collectively, these findings highlight the promising potential of Bacillus velezensis D103 as a biofertilizer for agricultural applications.

Genome-Wide Association-Based Identification of Alleles, Genes and Haplotypes Influencing Yield in Rice (Oryza sativa L.) Under Low-Phosphorus Acidic Lowland Soils.

Rice provides poor yields in acidic soils due to several nutrient deficiencies and metal toxicities. The low availability of phosphorus (P) in acidic soils offers a natural condition for screening genotypes for grain yield and phosphorus utilization efficiency (PUE). The objective of this study was to phenotype a subset of indica rice accessions from 3000 Rice Genome Project (3K-RGP) under acidic soils and find associated genes and alleles. A panel of 234 genotypes, along with checks, were grown under low-input acidic soils for two consecutive seasons, followed by a low-P-based hydroponic screening experiment. The heritability of the agro-morphological traits was high across seasons, and Ward's clustering method identified 46 genotypes that can be used as low-P-tolerant donors in acidic soil conditions. Genotypes ARC10145, RPA5929, and K1559-4, with a higher grain yield than checks, were identified. Over 29 million SNPs were retrieved from the Rice SNP-Seek database, and after quality control, they were utilized for a genome-wide association study (GWAS) with seventeen traits. Ten quantitative trait nucleotides (QTNs) for three yield traits and five QTNs for PUE were identified. A set of 34 candidate genes for yield-related traits was also identified. An association study using this indica panel for an already reported 1.84 Mbp region on chromosome 2 identified genes Os02g09840 and Os02g08420 for yield and PUE, respectively. A haplotype analysis for the candidate genes identified favorable allelic combinations. Donors carrying the superior haplotypic combinations for the identified genes could be exploited in future breeding programs.

Characterizing the hysteretic effects of water and salinity stresses on root-water-uptake

Characterizing the effects of previous water and salinity stresses is critical for the evaluation of plant water status, which, in turn, is essential for understanding soil-plant water relations and optimizing irrigation schemes. Recent research has found that hysteresis of plant response following water stress alone can be described by an exponential function of the stress degree on the previous day. To explore and quantify the effects of hysteresis concerning salinity stress and combined water-salinity stress, a hydroponic experiment and a soil column experiment on winter wheat, and a field experiment on cotton were conducted. Like water stress, previous salinity stress and combined water-salinity stress also resulted in hysteretic effects on root-water-uptake. Leaf stomatal conductance and plant transpiration rate of stressed crops could only recover gradually from a previous stressed status after re-watering. When stress was mild, compensatory recovery was found, while incomplete recovery occurred when stress was severe. Although the recovery process was closely related to stress history and type, a recovery coefficient was quantified universally with an exponential function of the stress extent on the previous day (with a coefficient of determination R2 ≥ 0.60). Consideration of hysteresis for water and salinity stresses with a mathematical model led to significant improvement in the simulation of both relative transpiration rate (R2 = 0.94, root mean squared error RMSE = 0.04, maximal absolute error MAE = 0.12) and soil water content (R2 = 0.90, RMSE = 0.01 cm3 cm–3, MAE = 0.03 cm3 cm–3), especially during the recovery periods severely affected by historical stress. Consideration of hysteresis is expected to benefit regulation of soil water and salinity and thus enhance water use efficiency. However, the mechanisms underlying hysteresis, especially the compensatory recovery mechanisms, still need to be further investigated.

OsSTP1 mediates sucrose allocation to regulate rice responses to different nitrogen supply levels

Improving the nitrogen use efficiency is an effective way to increase the yield of rice, and maintaining carbon-nitrogen balance is essential for the normal growth and development of rice. To investigate the impact of the sucrose transporter protein OsSTP1 on nitrogen absorption in rice, in this study, we constructed transgenic lines overexpressing the sucrose transporter gene OsSTP1 (OsSTP1-OE1, OsSTP1-OE2) and mutant transgenic lines (osstp1-1, osstp1-2) from the wild type TB309. Further, we conducted a hydroponic experiment with four nitrogen supply levels of free nitrogen (FN, 0 mg/L), low nitrogen (LN, 10 mg/L), normal nitrogen (NN, 40 mg/L), and high nitrogen (HN, 80 mg/L) to study the responses of each line to different nitrogen supply levels during the seedling stage. The results showed that compared with the wild type and mutant lines in the LN group, the OsSTP1-overexpressing lines exhibited significantly increased biomass, root length, and plant height, decreased soluble sugar content in the leaves, and increased soluble sugar content in the roots. The results indicate that the soluble sugars produced by leaf photosynthesis are transported to the roots through the phloem to promote root growth and nitrogen uptake, thus increasing the aboveground biomass. This study has identified that OsSTP1 can affect the long-distance transport of carbohydrates from source to sink to promote root growth, ultimately influencing rice's absorption and accumulation of nitrogen, improving nitrogen use efficiency and providing reference for reducing nitrogen fertilizer application.

The Physiological Response of Salix matsudana for Water Pollution by 2,4-Dinitrophenol.

In this study, the effects of different concentrations of 2,4-dinitrophenol (2,4-DNP) stress on physiological parameters, as well as the uptake and removal of 2,4-DNP in Salix matsudana, were investigated using hydroponic simulation experiments to explore the potential of the use of Salix matsudana in the phytoremediation of wastewater polluted by 2,4-DNP. The results showed that PN (net photosynthetic rate), Tr (transpiration rate), Gs (stomatal conductance), Ls (stomatal limitation value), Fv/Fm (maximal quantum yield of PSII photochemistry), and qp (photochemical quenching coefficient) of Salix matsudana seedlings showed an overall decreasing trend, while Ci (intercellular CO2 concentration) showed an increasing trend with the increase in 2,4-DNP concentration. The net photosynthetic rate and intercellular carbon dioxide concentration showed an opposite trend in the leaves with the increase in 2,4-DNP stress concentration, and the inhibition of net photosynthesis by 2,4-DNP on Salix matsudana seedlings was mainly based on non-stomatal factors. In the 15 d incubation experiment, the values of SOD (superoxide dismutase), POD (peroxidase), and CAT (catalase) indexes were higher at low concentrations of 2,4-DNP stress, and all three enzymes reached their maximum values at 10 mg L-1 of 2,4-DNP and then decreased. Salix matsudana seedlings could tolerate 2,4-DNP stress well, which did not exceed 20 mg L-1. The toxicity of 2,4-DNP solution was significantly reduced after purification by Salix matsudana seedlings. The removal rate of 2,4-DNP was higher than 80% in each treatment group by Salix matsudana purified after 15 days. When the concentration of 2,4-DNP reached 20 mg L-1, the contents of MDA (malonicdialdehyde) were 55.62 mmol g-1, and the values of REC (relative conductivity) and LD (leaf damage) were 63.51% and 59.93%, respectively. The structure and function of the cell membrane in leaves were seriously damaged. With the increase in 2,4-DNP concentration, the removal of 2,4-DNP by Salix matsudana seedlings showed a decreasing trend. When the 2,4-DNP concentration was 5 mg L-1, the highest removal rate of 2,4-DNP by Salix matsudana seedlings was 95.98%, while when the 2,4-DNP concentration was 20 mg L-1, the highest removal rate was 86.76%. It is noted that the suitable, recommended concentration for the phytoremediation of 2,4-DNP contamination by Salix matsudana seedlings is between 8.81 and 13.78 mg L-1.

Decreased Sulfamethoxazole Uptake in Lettuce (Lactuca sativa L.) due to Transpiration Inhibition by Polypropylene Microplastics

Microplastics and antibiotics are emerging contaminants in agricultural soil that can have negative effects on crops. However, limited research has been conducted on the effects of the polypropylene (PP) microplastic and sulfamethoxazole (SMX) co-exposure on crops, specifically regarding the impact of PP microplastics on SMX uptake and transport in crops. In this study, hydroponic experiments were carried out using lettuce (Lactuca sativa L.), PP microplastics (1.0 g L−1), and SMX (0.5 mg L−1 or 2.5 mg L−1) to investigate the individual and co-exposure effects of PP microplastics and SMX on Lettuce growth, explore the uptake and translocation of SMX in lettuce and elucidate the underlying mechanism of PP microplastic impact on SMX uptake. Results demonstrated that co-exposure to 1.0 g L−1 of PP microplastics and 0.5 mg L−1 of SMX resulted in an enhanced toxic effect. However, no intensified toxic effect on the lettuce was observed when 1.0 g L−1 PP microplastics were added in the presence of 2.5 mg L−1 SMX, indicating that the SMX dominated the toxic effect on lettuce at high concentrations. Additionally, the study found that the water absorption process controlled by the aquaporin and transpiration contributed to the uptake and translocation of SMX in lettuce. When exposed to PP microplastics, no impact was observed on the aquaporin contents of the lettuce while the transpiration rate was significantly decreased by 31.6 % - 44.2 % resulting from microplastics adhered to the root surface. Therefore, in the presence of 2.5 mg L−1 SMX, the SMX uptake in the lettuce root was inhibited by 35.9 % (P < 0.05) when exposed to 1.0 g L−1 PP microplastic. This work deepens our understanding of the behaviour of microplastics and antibiotics in the terrestrial environment.

Combating wheat yellow mosaic virus through microbial interactions and hormone pathway modulations

BackgroundThe rhizosphere microbiome is critical for promoting plant growth and mitigating soil-borne pathogens. However, its role in fighting soil-borne virus-induced diseases, such as wheat yellow mosaic virus (WYMV) transmitted by Polymyxa graminis zoospores, remains largely underexplored. In this study, we hypothesized that during viral infections, plant microbiomes engage in critical interactions with plants, with key microbes playing vital roles in maintaining plant health. Our research aimed to identify microbial taxa that not only suppress the disease but also boost wheat yield by using a blend of techniques, including field surveys, yield assessments, high-throughput sequencing of plant and soil microbiomes, microbial isolation, hydroponic experiments, and transcriptome sequencing.ResultsWe found that, compared with roots and leaves, the rhizosphere microbiome showed a better performance in predicting wheat yield and the prevalence of P. graminis and WYMV across the three WYMV-impacted regions in China. Using machine learning, we found that healthy rhizospheres were marked with potentially beneficial microorganisms, such as Sphingomonas and Allorhizobium-Neorhizobium-Parararhizobium-Rhizobium, whereas diseased rhizospheres were associated with a higher prevalence of potential pathogens, such as Bipolaris and Fusicolla. Structural equation modeling showed that these biomarkers both directly and indirectly impacted wheat yield by modulating the rhizosphere microbiome and P. graminis abundance. Upon re-introduction of two key healthy rhizosphere biomarkers, Sphingomonas azotifigens and Rhizobium deserti, into the rhizosphere, wheat growth and health were enhanced. This was attributed to the up-regulation of auxin and cytokinin signaling pathways and the regulation of jasmonic acid and salicylic acid pathways during infections.ConclusionsOverall, our study revealed the critical role of the rhizosphere microbiome in combating soil-borne viral diseases, with specific rhizosphere microbes playing key roles in this process.9s7rr2_Gfui1KYKQgMf1m6Video

Physiological and biochemical responses in a cadmium accumulator of traditional Chinese medicine Ligusticum sinense cv. Chuanxiong under cadmium condition

Ligusticum sinense cv. Chuanxiong (L. Chuanxiong), one of the widely used traditional Chinese medicines (TCM), is currently facing the problem of excessive cadmium (Cd) content. This problem has significantly affected the quality and safety of L. Chuanxiong and become a vital factor restricting its clinical application and international trade development. Currently, to solve the problem of excessive Cd, it is essential to research the response mechanisms of L. Chuanxiong to Cd stress. However, there are few reports on its physiological and biochemical responses under Cd stress. In this study, we conducted the hydroponic experiment under 25 μM Cd stress, based on the Cd content of the genuine producing areas soil. The results showed that 25 μM Cd stress not only had no significant inhibitory effect on the growth of L. Chuanxiong seedlings but also significantly increased the chlorophyll a content (11.79%) and root activity (51.82%) compared with that of the control, which might be a hormesis effect. Further results showed that the absorption and assimilation of NH4+ increased in seedlings under 25 μM Cd stress, which was associated with high photosynthetic pigments. Here, we initially hypothesized and confirmed that Cd exceedance in the root system of L. Chuanxiong was due to the thickening of the root cell wall, changes in the content of the cell wall components, and chelation of Cd by GSH. There was an increase in cell wall thickness (57.64 %) and a significant increase in cellulose (25.48%) content of roots under 25 μM Cd stress. In addition, L. Chuanxiong reduced oxidative stress caused by 25 μM Cd stress mainly through the GSH/GSSG cycle. Among them, GSH-Px (48.26%) and GR (42.64%) activities were significantly increased, thereby maintaining a high GSH/GSSG ratio. This study preliminarily reveals the response of L. Chuanxiong to Cd stress and the mechanism of Cd enrichment. It provides a theoretical basis for solving the problem of Cd excessive in L. Chuanxiong.Graphical Physiological and biochemical mechanisms of L. Chuanxiong seedlings under Cd stress.

Exogenous N Supply on N Transportation and Reuse during the Rice Grain-Filling Stage and Its Relationship with Leaf Color-Changing Parameters

During the later reproductive period of rice growth, the chlorophyll in the leaves degraded, accompanied by the nitrogen (N) transportation from leaves to panicle, resulting in a change in leaf color from green to yellow. This study aimed to investigate the effects of exogenous N supply on leaf color-changing, N accumulation, N transportation, and N loss of indica-japonica hybrid rice during the grain-filling stage. Two indica-japonica hybrid rice cultivars, Chunyou 167 (CY167) and Chunyou 927 (CY927), which exhibited significant differences in leaf color-changing during the grain-filling stage, were selected as materials for field experiment and hydroponic experiment with low, medium, and high N treatments (LN, MN, and HN). The dynamic changes in SPAD value from heading to maturity were measured and fitted with quadratic function to extract leaf color-changing parameters; labeled 15N was used as N source after heading to trace the source of N in the panicle and the remobilization of vegetative organ N. The results showed that 67.37–72.38% of the panicle N was transported from vegetative organs, the N transport efficiency was the upper three leaves &gt; lower leaves &gt; stem, and about 3.1–35.0% of the transported N was lost via volatilization. The effects of exogenous N concentration on N harvest index, N dry matter/grain production efficiency, N reuse efficiency, and N loss were closely related to leaf color-changing parameters. In MN and HN treatment, the N loss was negatively correlated with the onset time of leaf color-changing (T0) and the final leaf color index (CIf), but positively correlated with the leaf color-changing rate (Rmean). Increasing the supply of exogenous N increased T0 and CIf, but decreased Rmean, N transport/reuse efficiency, N harvest index, and N dry matter/grain production efficiency. Compared to the cultivar CY167 with normal leaf color-changing, the “stay-green” cultivar CY927 had higher T0, CIf, and lower Rmean, resulting in less N volatilization loss, lower N harvest index and N transport efficiency, while higher N reuse efficiency. In conclusion, the exogenous N supply affects leaf color by influencing the transportation and reuse of leaf N during the grain-filling stage.

Amine-functionalized soy protein/graphene oxide aerogel for efficient removal of multiple sugar-derived contaminants (SDCs): Full life cycle exploration and interaction simulation

Sugar-derived contaminants (SDCs) pose significant environmental hazards and safety concerns, emerging as urgent issue. Using amine-modified soy protein (SPI) and graphene oxide (GO), an environment-friendly aerogel (PSPI/PGO) was synthesized to efficiently remove multiple SDCs. The equilibrium adsorption capacities of PSPI/PGO for melanoidins, caramels, and saccharin were 1124.2, 291.1, and 399.3 mg/g, respectively, surpassing those of previously proposed materials. A series of characterizations and experiments demonstrated that the porous PSPI/PGO exhibited high hydrophilicity, nontoxicity, excellent thermal stability, and sustainable capture properties. Emerging dynamic models (i.e., AOAS, EXT-INT, and LF-PC-AS) and multiple quantum chemical theory calculations (ESPL, ALIE, FMO, IGMH, and HSA) further revealed the capture of each SDC onto PSPI/PGO was driven predominantly by charge interactions, followed by H-bonding and intermolecular interactions. PSPI/PGO acts as an H-bonding acceptor in a diverse range of uptake processes for each SDC. The applicability of PSPI/PGO for treating real wastewater has been validated. The full lifecycle exploration of PSPI/PGO (including soil burial degradation tests, wastewater treatment, and garlic hydroponic experiments using depleted PSPI/PGO) underscores its considerable biocompatibility and potential for industrial applications.

Insights into the uptake, accumulation, and metabolism of UV-328 in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

2-(2H-benzotriazole-2yl)-4,6-di-t-pentylphenol (UV-328), a newly listed persistent organic pollutant (POP) under the Stockholm Convention, has garnered significant attention. It is imperative to understand the uptake, translocation and metabolic pathways of UV-328 in plants to assess its bioaccumulation capacity and potential human health risks. In this study, the absorption, accumulation, and metabolic characteristics of UV-328 in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.) were assessed by hydroponic experiments. In the hydroponics experiment, UV-328 was significantly absorbed by the roots of the plants, with average root concentration factors (RCFs) ranging from 58.5 to 400 mL/g for lettuce and 84.4–154 mL/g for radish. However, UV-328 was poorly translocated from roots to shoots, with a translocation factor (TF) below 0.055. Furthermore, UV-328 underwent transformation and metabolism within the plant. Utilizing a nontarget screening strategy, fourteen phase I metabolites of UV-328 were firstly identified. The metabolic pathways of UV-328 in plants including hydroxylation, demethylation, oxidation, acetylation and deoxygenation were also suggested. It was worth noting that UV-328 has a significant adverse impact on plant growth and quality. The concentration of chlorophyll in plants exposed to UV-328 was significantly reduced, as were the concentrations of water, flavonoids, vitamin C and amino acids.

Effect of Co-exposure to Additional Substances on the Bioconcentration of Per(poly)fluoroalkyl Substances: A Meta-Analysis Based on Hydroponic Experimental Evidence.

A consensus has yet to emerge regarding the bioconcentration responses of per(poly)fluoroalkyl substances under co-exposure with other additional substances in aqueous environments. This study employed a meta-analysis to systematically investigate the aforementioned issues on the basis of 1,085 published datasets of indoor hydroponic simulation experiments. A hierarchical meta-analysis model with an embedded variance covariance matrix was constructed to eliminate the non-independence and shared controls of the data. Overall, the co-exposure resulted in a notable reduction in PFAS bioaccumulation (cumulative effect size, CES = - 0.4287, p < 0.05) and bioconcentration factor (R2 = 0.9507, k < 1, b < 0) in hydroponics. In particular, the inhibition of PFAS bioconcentration induced by dissolved organic matter (percentage form of the effect size, ESP = - 48.98%) was more pronounced than that induced by metal ions (ESP = - 35.54%), particulate matter (ESP = - 24.70%) and persistent organic pollutants (ESP = - 18.66%). A lower AS concentration and a lower concentration ratio of ASs to PFASs significantly promote PFAS bioaccumulation (p < 0.05). The bioaccumulation of PFASs with long chains or high fluoride contents tended to be exacerbated in the presence of ASs. Furthermore, the effect on PFAS bioaccumulation was also significantly dependent on the duration of co-exposure (p < 0.05). The findings of this study provide novel insights into the fate and bioconcentration of PFAS in aquatic environments under co-exposure conditions.