Root Absorption Research Articles

Utilization of Arbuscular Mycorrhizal Fungi for the Efficiency Development of Lead (Pb) Metal Absorption and Growth of Hanjuang Plants (Cordyline fruticosa)

Contamination of Pb metal into the soil is an environmental problem that has a serious impact on living things, so it needs to be addressed through phytoremediation, one of which is using hanjuang plants. Plant roots in symbiosis with arbuscular mycorrhizal fungi (AMF) can increase plant growth and the phytoremediation ability of plants growing in polluted soil. This research aims to determine the effect of AMF application on the growth of hanjuang plants and the ability of hanjuang roots to absorb Pb metal. The research design used a single treatment with a Completely Randomized Block Design (CRBD) of 4 doses of AMF with 6 replications, namely control; 10 g polybag-1; 20 g polybag-1; and 30 g polybag-1. Planting was carried out for 8 weeks to see the growth and planting of hanjuang and the efficiency of Pb absorption in plant roots. The results showed that AMF had a significant effect on plant height aged 5 to 8 weeks, plant biomass, root wet weight, and root dry weight, but had no significant effect on the efficiency of Pb absorption in the roots of hanjuang plants. An AMF dose of 30 g polybag-1 provides the best results for the growth of hanjuang plants.

Isolation and functional determination of inward-rectifier K+ channel PbrAKT1 in pear

ABSTRACT Potassium (K+) is essential to plant growth and development. The absorption and transport of K+ by plant roots occurs mainly through K+ channels or transporters. In this study, an AKT1-type channel named PbrAKT1 was successfully cloned and characterised by a series of detailed procedures, including protein sequence alignment, expression and subcellular localisation analysis, as well as functional verification by heterologous expression function validation in yeast mutant R5421, Arabidopsis akt1 mutant, and Xenopus oocytes. The results showed that PbrAKT1 is preferentially expressed in pear roots and exhibits plasma membrane localisation, but its expression is unaffected by low K+ treatment. PbrAKT1 exhibits the function of an inwardly-rectifying K+ channel, and its activity is autonomously regulated when expressed in Xenopus oocytes. In addition, a series of heterologous expression experiments confirmed that PbrAKT1 plays an indispensable role in the processes of K+ transport, as well as alleviating the low-K+ -sensitive phenotype of yeast mutant R5421 and Arabidopsis akt1 mutant. In summary, PbrAKT1 plays an indispensable role in the processes of K+ transport and provide new information on the molecular mechanism of K+ absorption in pear roots.

Accumulation of nanoplastics by wheat seedling roots: Both passive and energy-consuming processes

Nanoplastics can transfer from the environment to plants and potentially harm organisms. However, the mechanisms on how crop root systems absorb and transport nanoplastics are still unclear. Here, original and fluorescent labeled polystyrene and polyvinyl chloride nanoparticles (PS-NPs, PVC-NPs; 30 nm; 10 mg L−1) were employed to study the distribution and internalization pathways in wheat seedling roots. In the study, nanoplastics accumulated more in the root tip and surface, with PVC-NPs more prevalent than PS-NPs. After being treated with inhibitors (Na3VO4, chlorpromazine and amiloride), the nanoplastics mean fluorescence intensities were reduced by 4.0–51.1 %. During the uptake, both passive and energy-consuming pathways occurred. For the energy-consuming uptake pathway, macropinocytosis contributed more to cytoplasm than clathrin-mediated endocytosis. H+ influx was observed during nanoplastic transport into the cytoplasm, and the reduction in plasma membrane ATPase activity led to a decrease in nanoplastic internalization. These results elucidate the pathways of nanoplastics absorption and transport in wheat roots, provide crucial evidence for assessing nanoplastics' ecological risks and support the development of technologies to block nanoplastics absorption by crop roots, ensuring agricultural and ecosystem safety.

Biochar solutions: Slow and fast pyrolysis effects on chromium stress in rapeseed roots

Chromium (Cr) contamination in agricultural soils, largely due to industrial activities, poses a significant threat to plant growth and productivity. This study examines the effects of Cr stress at concentrations of 100 and 200 mg of K2Cr2O7 per kg soil on rapeseed (Brassica napus) roots and evaluates the mitigating potential of biochar. Biochar, produced through both slow and fast pyrolysis and applied at 30 g per kg soil, was investigated for its ability to neutralize Cr toxicity. Our findings indicate that Cr stress significantly decreased the growth and physiological functions of rapeseed roots. However, biochar application improved soil pH, cation exchange capacity, and the uptake of essential nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium. Additionally, biochar enhanced the production of osmotic regulators like glycine betaine and soluble proteins, as well as indole acetic acid, promoting better root growth and water uptake under Cr stress. Notably, biochar reduced Cr availability and absorption in rapeseed roots, leading to lower levels of stress-related hormones such as abscisic acid, salicylic acid, and jasmonic acid. Among the biochars tested, slow pyrolysis biochar was more effective than fast pyrolysis biochar in mitigating Cr toxicity. These results highlight the potential of slow pyrolysis biochar as a sustainable strategy to alleviate Cr pollution and enhance plant resilience in contaminated soils.

A Case Report of Root Resorption after Tooth Dislocation Replantation

The complete dislocation of the right upper central incisor lasted for more than 2 hours. After 2 weeks of replantation, the ligature was removed. After 1.5 months of reexamination, it was found that the internal and external root absorption of the affected tooth could be slowed down through infection control in the root canal and apical barrier. Reexamination 2.5 months later showed increased bone density around the root of the affected tooth.

The transcription factor ZmbHLH105 confers cadmium tolerance by promoting abscisic acid biosynthesis in maize

Cadmium (Cd), a highly toxic heavy metal, profoundly impacts crop productivity. The bHLH-type transcription factors regulate plant stress responses, yet their involvement in maize's Cd stress response remains unclear. Here, we studied ZmbHLH105, a maize bHLH gene induced by Cd exposure. Overexpression of ZmbHLH105 in maize seedlings, which were treated with 1.0 mM CdCl2 for 7 days, increased endogenous ABA levels, decreased Cd accumulation, and enhanced Cd stress tolerance. ZmbHLH105 directly bound to promoter regions of two key ABA biosynthesis genes ZmNCED1/2, activating their transcription, thus boosting ABA levels and Cd tolerance. ZmbHLH105-overexpression promoted lignin synthesis, while ZmbHLH105-RNAi attenuated this effect. Exogenous ABA supplementation increased lignin content in Cd-stressed maize roots, suggesting ZmbHLH105-mediated Cd tolerance involves ABA-induced lignin deposition and cell wall thickening. Moreover, Cd transport-related gene expression was suppressed in ZmbHLH105 overexpression lines. Our findings demonstrate that ZmbHLH105 decreases Cd accumulation, improving Cd tolerance by enhancing ABA biosynthesis, increasing lignin deposition, thickening cell walls, and inhibiting Cd absorption in maize roots. This study unveils ZmbHLH105's mechanisms in Cd tolerance, highlighting its potential in breeding low Cd-accumulating crops for food and environment safety.

Kinetics of uptake, translocation, and metabolism of organophosphate esters in japonica rice (Oryza sativa L.): Hydroponic experiment combined with model

Hydroponics combined with fugacity model was employed to investigate the kinetics of uptake, accumulation, and metabolism of organophosphate esters (OPEs) by japonica rice. The time-dependent process for uptake and accumulation of 5 OPEs and their diester-metabolites in both rice root and shoot fitted well with the pseudo-first-order kinetic model. The peak OPE accumulations in rice root and shoot were significantly positively or negatively correlated with their octanol-water partition coefficient (logKow) respectively, but not for their apparent accumulation rates. Root concentration factors (RCFs) and root-to-shoot translocation factors (TFs) of OPEs were found to be positively and negatively correlated with their logKow, respectively. Triphenyl phosphate with benzene ring substituents showed the highest RCF, but the lowest TF, because of its high potential for root adsorption due to the π electron-rich structures. Sterilized root exudates can hinder the root adsorption and absorption of OPEs from solution probably through competitive adsorption of OPEs with root surface. The first-hand transport and metabolism rates were also obtained by generating these rates to fit the dynamic fugacity model with the measurement values. The simulation indicated that the kinetics of OPE accumulation in rice plants may be controlled by multiple processes and physicochemical properties besides Kow.

Impact of the Plant Growth-promoting Rhizobacterium Streptomyces saraceticus Strain 31 on Berry Quality of ‘Benifuji’ Grape: Improvements through the Reconfiguration of Fine Root Morphology and Vessel Anatomy

In an effort to mitigate the environmental impact of chemical fertilizers, plant growth-promoting rhizobacteria (PGPR) have emerged as a more sustainable alternative. Streptomyces saraceticus 31 (‘SS31’), a new strain of biocontrol bacteria, was inoculated into rhizosphere soils of ‘Benifuji’ grape to evaluate its impact on grape roots and berries. The results indicated significant improvements in soil fertility, with higher levels of organic matter, phosphorus, potassium, and nitrate nitrogen compared with those of the controls. Moreover, ‘SS31’ application elicited a notable reduction in soil pH levels, along with a substantial augmentation in the enzymatic activities of both phosphatase and invertase. The grapes treated with ‘SS31’ exhibited a notable increase in the number, length, surface area, and volume of fine roots in both 0- to 10-cm and 10- to 20-cm soil profiles. The application of ‘SS31’ resulted in the observation of greater diameter, lower density, and larger lumen area, along with increased specific hydraulic conductivity in the vessels of roots with 1- to 2-mm diameters. Despite a slight reduction in berry weight compared with that of the controls, ‘Benifuji’ grape berries displayed higher total soluble solids and lower total titratable acidity after ‘SS31’ application. Furthermore, ‘SS31’ treatment elevated the levels of volatile compounds in berries, especially fatty acid-derived compounds. A network analysis revealed a robust positive correlation between the observed improvements in grape berry quality and the morphology as well as the hydraulic conductivity of the grape fine roots. In conclusion, these findings suggest that ‘SS31’ has the potential to enhance grape root function by expanding the root absorption area and facilitating water transportation. This, in turn, may improve the flavor and aroma of ‘Benifuji’ grape berries.

PIP family-based association studies uncover ZmPIP1;6 involved in Pb accumulation and water absorption in maize roots

Excessive lead (Pb) in the soil affects crop growth and development, thus threatening human beings via food chains. Plasma membrane intrinsic proteins (PIPs) facilitate the transport of substrates across cell membranes. Herein, we characterized maize PIPs and identified eight Pb accumulation-associated PIP genes using association studies. Among these, ZmPIP1;6 was simultaneously correlated with root Pb concentrations under various Pb treatment stages. Significant correlations were observed between the ZmPIP1;6 expression abundance and Pb accumulation in maize roots. Ectopic expression in yeast showed that ZmPIP1;6 conferred Pb accumulation in the cells and affected Pb tolerance in yeast. Overexpression in maize demonstrated that ZmPIP1;6 altered the Pb concentration performance and root moisture content under Pb stress. Meanwhile, protein interaction analyses suggested that ZmPIP1; 6 and three PIP2 members formed isoforms and facilitate water uptake in maize roots. However, ZmPIP1; 6 improved Pb absorption in maize roots probably by interacting with CASP-like protein 2C3 and/or another metal transporter. Moreover, the significant variants in the ZmPIP1;6 promoter caused the variations in ZmPIP1;6 expression level and Pb accumulation among various maize germplasms. Our study will contribute to understanding of PIP family-mediated Pb accumulation in crops and bioremediation of Pb-polluted soils.

Development of a novel critical nitrogen concentration–cumulative transpiration curve for optimizing nitrogen management under varying irrigation conditions in winter wheat

Accurate nitrogen (N) nutrition diagnosis is essential for improving N use efficiency in crop production. The widely used critical N (Nc) dilution curve traditionally depends solely on agronomic variables, neglecting crop water status. With three-year field experiments with winter wheat, encompassing two irrigation levels (rainfed and irrigation at jointing and anthesis) and three N levels (0, 180, and 270 kg ha−1), this study aims to establish a novel approach for determining the Nc dilution curve based on crop cumulative transpiration (T), providing a comprehensive analysis of the interaction between N and water availability. The Nc curves derived from both crop dry matter (DM) and T demonstrated N concentration dilution under different conditions with different parameters. The equation Nc = 6.43T−0.24 established a consistent relationship across varying irrigation regimes. Independent test results indicated that the nitrogen nutrition index (NNI), calculated from this curve, effectively identifies and quantifies the two sources of N deficiency: insufficient N supply in the soil and insufficient soil water concentration leading to decreased N availability for root absorption. Additionally, the NNI calculated from the Nc-DM and Nc-T curves exhibited a strong negative correlation with accumulated N deficit (Nand) and a positive correlation with relative grain yield (RGY). The NNI derived from the Nc-T curve outperformed the NNI derived from the Nc-DM curve concerning its relationship with Nand and RGY, as indicated by larger R2 values and smaller AIC. The novel Nc curve based on T serves as an effective diagnostic tool for assessing winter wheat N status, predicting grain yield, and optimizing N fertilizer management across varying irrigation conditions. These findings would provide new insights and methods to improve the simulations of water-N interaction relationship in crop growth models.

New insights into the role of the root system of epiphytic bromeliads: comparison of root and leaf trichome functions in acquisition of water and nutrients.

In epiphytic bromeliads, the roots used to be considered poorly functional organs in the processes of absorption and metabolization of water and nutrients, while the leaves always acted as protagonists in both functions. More recent discoveries have been changing this old view of the root system. In this review, we will address the old thoughts of the scientific community regarding the function performed by the roots of epiphytic bromeliads (mere holdfast structures with low physiological activity) and the importance of a reduced or lack of root system for the emergence of epiphytism. We will present indirect and direct evidence that contradicts this older hypothesis. Furthermore, the importance of the root absorptive function mainly for juvenile tankless epiphytic bromeliads and the characteristics of the root absorption process of adult epiphytic tank bromeliads will be thoroughly discussed in physiological aspects. Finally, some factors (species, substrate, environmental conditions) that influence the absorptive capability of the roots of epiphytic tank bromeliads will also be considered in this review, highlighting the importance that the absorptive role of the roots have for the plasticity of bromeliads that live on trees, which is an environment characterized by the intermittent availability of water and nutrients. The roots of tank-forming epiphytic bromeliads play important roles in the absorption and metabolization of nutrients and water. The importance of roots stands out mainly for juvenile tankless bromeliads since the root is the main absorptive organ. In larger plants with tank, although the leaves become the protagonists in the resource acquisition process, the roots complement the absorptive function of the leaf trichomes, resulting in a better growth of the bromeliad. The physiological and biochemical properties of the processes of absorption and distribution of resources in the tissues seem to differ between absorption by trichomes and roots.

Chitosan Coating as a Strategy to Increase Postemergent Herbicidal Efficiency and Alter the Interaction of Nanoatrazine with Bidens pilosa Plants.

The atrazine nanodelivery system, composed of poly(ε-caprolactone) (PCL+ATZ) nanocapsules (NCs), has demonstrated efficient delivery of the active ingredient to target plants in previous studies, leading to greater herbicide effectiveness than conventional formulations. Established nanosystems can be enhanced or modified to generate new biological activity patterns. Therefore, this study aimed to evaluate the effect of chitosan coating of PCL+ATZ NCs on herbicidal activity and interaction mechanisms with Bidens pilosa plants. Chitosan-coated NCs (PCL/CS+ATZ) were synthesized and characterized for size, zeta potential, polydispersity, and encapsulation efficiency. Herbicidal efficiency was assessed in postemergence greenhouse trials, comparing the effects of PCL/CS+ATZ NCs (coated), PCL+ATZ NCs (uncoated), and conventional atrazine (ATZ) on photosystem II (PSII) activity and weed control. Using a hydroponic system, we evaluated the root absorption and shoot translocation of fluorescently labeled NCs. PCL/CS+ATZ presented a positive zeta potential (25 mV), a size of 200 nm, and an efficiency of atrazine encapsulation higher than 90%. The postemergent herbicidal activity assay showed an efficiency gain of PSII activity inhibition of up to 58% compared to ATZ and PCL+ATZ at 96 h postapplication. The evaluation of weed control 14 days after application ratified the positive effect of chitosan coating on herbicidal activity, as the application of PCL/CS+ATZ at 1000 g of a.i. ha-1 resulted in better control than ATZ at 2000 g of a.i. ha-1 and PCL+ATZ at 1000 g of a.i. ha-1. In the hydroponic experiment, chitosan-coated NCs labeled with a fluorescent probe accumulated in the root cortex, with a small quantity reaching the vascular cylinder and leaves up to 72 h after exposure. This behavior resulted in lower leaf atrazine levels and PSII inhibition than ATZ. In summary, chitosan coating of nanoatrazine improved the herbicidal activity against B. pilosa plants when applied to the leaves but negatively affected the root-to-shoot translocation of the herbicide. This study opens avenues for further investigations to improve and modify established nanosystems, paving the way for developing novel biological activity patterns.

Anti-sulfatide antibody associated GBS with headache and abdominal pain: a case report

BackgroundGuillain‒Barre syndrome (GBS) is an acute inflammatory peripheral neuropathy caused by autoimmunity. Gangliosides and sulfatides are important components of peripheral nerves. Anti-sulfatide antibody-mediated complement is associated with acute sensorimotor peripheral neuropathy in GBS, which is characterized by pain and paresthesias.Case presentationThe child was a 7-year-old girl with headache and abdominal pain, followed by limb numbness and pain. Cranial imaging showed ventricular dilatation, peripheral nerve function conduction examination showed polyradiculopathy, and cerebrospinal fluid tests showed normal cell counts but elevated protein levels, all of which led to the diagnosis of GBS. After treatment with intravenous immunoglobulin (400 mg/kg × 5 days), the symptoms did not improve, and muscle strength progressively worsened, accompanied by paroxysmal complexion flushing, heart rate fluctuation, hyperhidrosis, and a progressive increase in cerebrospinal fluid protein (up to 3780.1 mg/L). On the basis of these findings combined with serum anti-sulfatide IgM positivity, anti-sulfatide antibody-related GBS was considered, and treatment with low-dose prednisolone (1 mg/kg/d) led to symptom improvement.ConclusionsAnti-sulfatide antibody-associated GBS is associated with small fiber peripheral neuropathy. The main manifestations are pain, paresthesias and autonomic dysfunction. In addition to the dysfunction of spinal nerve root absorption caused by increased cerebrospinal fluid protein, autonomic dysfunction may be involved in pain. When the therapeutic effect of immunoglobulin is not satisfactory, a low dose and short course of corticosteroids can be considered, and the prognosis is good.

Polystyrene microplastics enhanced the toxicity of cadmium to rice seedlings: Evidence from rice growth, physiology, and element metabolism

Microplastics (MPs) and cadmium (Cd) are toxic to rice; however, the effects and mechanisms of their combined exposure are unclear. The combined exposure effects of polystyrene microplastics (PS-MPs) with different particle sizes (1–10 μm, 50–150 μm) and concentrations (50, 500 mg·L−1) and Cd on rice were explored. PS-MPs combined with Cd amplifies the inhibition of each individual exposure on the height and biomass of rice seedlings, and they showed antagonistic effects. PS-MPs reduced the content of chlorophyll and increased the content of carotenoid rice seedlings significantly. High concentrations of PS-MPs enhanced the inhibition of Cd on chlorophyll content. Cd, PS-MPs single and combined exposures significantly altered the antioxidant enzyme (POD, CAT, SOD) activities in rice seedlings. Under PS-MPs exposure, overall, the MDA content in shoots and roots exhibited opposite trends, with a decrease in the former and an increase in the latter. In comparison with Cd treatment, the combined exposures' shoot and root MDA content was reduced. Cd and PS-MPs showed “low concentration antagonism, high concentration synergism” on the composite physiological indexes of rice seedlings. PS-MPs significantly increased the Cd accumulation in shoots. PS-MPs promoted the root absorption of Cd at 50 mg·L−1 while inhibited at 500 mg·L−1. Cd and PS-MPs treatments interfered with the balance of microelements (Mn, Zn, Fe, Cu, B, Mo) and macroelements (S, P, K, Mg, Ca) in rice seedlings; Mn was significantly inhibited. PS-MPs can enhance of Cd's toxicity to rice seedlings. The combined toxic effects of the two contaminants appear to be antagonistic or synergistic, relying on the particle size and concentration of the PS-MPs. Our findings offer information to help people understanding the combined toxicity of Cd and MPs on crops.

Understanding the complexities in glyphosate and ametryn interactions: Soil retention and transformation as influenced by their applications alone and mixture

The use of herbicide mixtures is widely adopted by farmers in agriculture worldwide. Glyphosate and ametryn are herbicides commonly applied in tank mixtures, increasing the spectrum of weed control in sugarcane crops. After application, herbicides can reach the soil layer, which is susceptible to retention, transport, and degradation processes. Herbicide interactions in mixtures may affect their bioavailability and persistence in soil, leading to different behavior in the environment compared to when applied alone. This study evaluated the sorption-desorption and transformation of 14C-glyphosate and 14C-ametryn in soil when applied alone or in a tank mixture. The sorption of 14C-ametryn in soil was increased by 25% when mixed with glyphosate (14C-ametryn + glyphosate). This increase in sorption was not evident for 14C-glyphosate when mixed with ametryn (14C-glyphosate + ametryn). The amount desorbed of 14C-ametryn (20%) applied alone was higher than in a mixture (10%). Both herbicide's mineralization half-live time (MT50) was influenced when applied in mixtures. 14C-glyphosate applied alone showed lower MT50 (55 days) compared to 14C-glyphosate + ametryn (119 days). 14C-ametryn also showed lower MT50 when applied alone than when applied with glyphosate (>120 days in both cases). These results suggest that the presence of ametryn in mixture with glyphosate decreases the desorption and mineralization of both herbicides, potentially affecting their bioavailability for weed root absorption and degradation in environment.

Application of Overground Rock Film Mulching (ORFM) Technology in Karst Rocky Desertification Farmland: Improving Soil Moisture Environment and Crop Root Growth

Overground rock is a prominent feature of rocky desertification landscape in karst farmland; however, people often pay attention to their adverse effects, leaving their positive effects on ecohydrological processes and plant growth as rarely studied and utilized. In this study, the effects of overground rock film mulching (ORFM) on soil water flow behavior, soil water content and temporal and spatial heterogeneity were investigated through a dye tracer test and soil moisture measurement. Moreover, the effects of this technology on the root characteristics of crops (maize and broad bean) were analyzed. The results showed that ORFM treatment significantly increased soil water content and its spatio-temporal heterogeneity by preventing preferential flow at the rock–soil interface. It suggested that this practice can provide a more favorable soil moisture environment for crop growth, which was confirmed by the differences in root characteristics of crops (maize and broad bean) under different treatments in this study. It was found that ORFM treatment reduced the root radial extent of crops but increased the root biomass and root bifurcation rate, which are widely considered to be key factors in improving the efficiency of fine root absorption. Therefore, we believe that ORFM has great potential to improve the effective use of soil water and agricultural water management in karst areas, which is essential for sustainable agricultural development in the region.

Replacing chemical fertilizers with biogas slurry is an environment friendly strategy to reduce the risk of soil nitrogen leaching: evidence from the HYDRUS model simulation

Excessive chemical fertilizer use leads to soil nitrogen leaching. Biogas slurry, which is rich in nitrogen, has been proposed as an organic substitute for chemical fertilizer via drip irrigation. However, the dynamics of nitrogen migration and potential threats to biogas slurry return remain unclear. Using a two-year field experiment and HYDRUS software, this study modeled soil moisture and nitrogen migration under biogas slurry drip irrigation. The validated model accurately simulates water and nitrogen migration, predicting nitrogen leaching dynamics. Compared to chemical fertilizer treatment, differences in soil hydraulic parameters under biogas slurry drip irrigation impact moisture and nitrate nitrogen distribution. Increasing biogas slurry proportion enhances nitrate nitrogen content in the root layer, promoting plant nitrogen absorption while reducing leaching by 49.66%. Optimizing the irrigation system involves high concentration substitution in early growth and low concentration in late growth, mitigating nitrogen leaching, and enhancing plant root absorption.

Physiological and Transcriptional Characteristics of Banana Seedlings in Response to Nitrogen Deficiency Stress

Nitrogen is a crucial element for the growth and development of plants, directly affecting crop growth and yield. To investigate the physiological and molecular mechanism of nitrogen-deficiency stress, we conducted an investigation into the effects of different nitrogen levels on the growth, photosynthetic characteristics, and gene transcription levels of banana seedlings. Compared with the control group with normal nitrogen levels (NN), the height of plants receiving Reduced-N (NR), Low-N (LN), and N-Free (NF) treatments was decreased by 0.45 cm, 2.5 cm, and 3.25 cm, respectively. Their dry weight was reduced by 1.63 g, 2.99 g, and 2.88 g, respectively. Conversely, the dry weight of the underground plant part in the LN and NF treatment groups exhibited an increase of 0.13 g and 0.16 g, respectively. Regarding photosynthetic characteristics, the Specialty Products Agricultural Division (SPAD) values of the NR, LN, and NF treatments showed reductions of 15.5%, 30.4%, and 35.9%, respectively, compared with those of the control treatments. The values of maximum photosynthetic efficiency (Fv/Fm), actual photosynthetic efficiency (Y(Ⅱ)), and relative electron transfer (ETR) of the banana seedlings decreased to different degrees after NR, LN, and NF treatment, and their values were positively correlated with N levels. Gene transcription analysis showed that N transport-related proteins, including NRT1.7, NRT2.3a, NRT2.3b, and NRT2.5, were significantly up-regulated to increase the nitrogen absorption capacity of plant roots. On the other hand, various transcription factors including GRAS, MYB, and WRKY were notably up-regulated, facilitating root growth and the expanding root absorption area, thereby enhancing nitrogen uptake. Furthermore, genes associated with endogenous hormone metabolic pathways such as gibberellin (GA), strigolactone (SL), and brassinosteroids (BR) were activated in banana plants subjected to low nitrogen stress, enhancing the plant’s ability to adapt to nitrogen-deficient conditions. These findings offer valuable insights into understanding the transcriptional regulatory mechanisms governing banana responses to low nitrogen stress and breeding new varieties with improved nutrient utilization.

Multiple isotopes reveal the impact of land use change on nitrate transport and transformation in deep loess deposits

The deep-rooted economic trees decrease water storage but increase nitrate-nitrogen (NO3–N) accumulation in the soil due to the root water uptake and excessive use of fertilizers. Knowing how the NO3 accumulates in the soil and to what extent it can be flushed out or transformed can provide insights on the processes controlling N flux to waterways. We sampled cultivated farmland and orchards with varying ages of apple and peach trees in the loess deposits to > 15 m depth to measure the contents and isotopes of water and NO3 in soils. The novelty of this study is that the water isotopes are used to analyze water and NO3 transport, while the NO3 isotopes are further employed for NO3 source and transformation analysis. The parabolic NO3–N profiles (258–3579 kg N ha−1) were mainly observed within 0–5 m under different land use types. The surface-aggregated NO3 reservoirs under old apple orchard were about six times of farmland due to the overuse of chemical fertilizers, while those of peach orchard were only half of farmland because of less fertilizer inputs and possible root absorption effects. Piston flow resulted in the overall slow water movement and low NO3 flux under different land use types in deep loess deposits. Despite the soil water recharge by precipitation and low surface evaporation, the strong transpiration effects further resulted in no water and NO3 fluxes in the deep layers under old apple orchard. Nitrate reservoirs were mainly contributed by soil organic N (44 % ± 26 %) and ammonium N fertilizer (36 % ± 20 %), but their transformation was dominated by nitrification under old apple orchard and by mineralization in deep layers. The risks of NO3 bombs are temporarily weakened by lower dried soil layers under deep rooted plants; however, with lower water movement rates and limited denitrification potential, NO3 would eventually reach the aquifers in a few hundred years or more. This study provides new insights for clarifying NO3 transport and transformation processes by combing multiple isotopes, and the NO3 bombs would chronically endanger the sustainable development of terrestrial ecosystems and the environment in arid regions.

Design, synthesis and bioactivity of a new class of antifungal amino acid-directed phthalide compounds.

Peanut southern blight disease, caused by Sclerotium rolfsii, is a destructive soil-borne fungal disease. The current control measures, which mainly employ succinate dehydrogenase inhibitors, are prone to resistance and toxicity to non-target organisms. As a result, it is necessary to explore the potential of eco-friendly fungicides for this disease. Fourteen novel phthalide compounds incorporating amino acid moieties were designed and synthesized. The in vitro activity of analog A1 [half maximal effective concentration (EC50) = 332.21 mg L-1] was slightly lower than that of polyoxin (EC50 = 284.32 mg L-1). It was observed that on the seventh day, the curative activity of A1 at a concentration of 600.00 mg L-1 was 57.75%, while the curative activity of polyoxin at a concentration of 300.00 mg L-1 was 42.55%. These results suggested that our compound exhibited in vivo activity. Peanut plants treated with A1 showed significant agronomic improvements compared to the untreated control. Several compounds in this series exhibited superior root absorption and conduction in comparison to the endothermic fungicide thifluzamide. The growth promotion and absorption-conduction experiments demonstrated the reason for the superior in vivo activity of the target compound. Cytotoxic assays have demonstrated that this series of targeted compounds exhibit low toxicity levels toward human lo2 liver cells. Our results provide a new strategy for the design and synthesis of novel green compounds. Furthermore, the target compound A1 can serve as a lead for further development of green fungicides. © 2024 Society of Chemical Industry.