Enhanced Plant Biomass Research Articles

The Multifunctional Anaphase Promoting Complex 7 (APC7) Gene Is Associated With Increased Plant Growth and Improved Resistance to DNA and RNA Viruses.

The anaphase promoting complex 7 (AtAPC7) is an APC/C subunit expressed in different organs of Arabidopsis thaliana and conserved among eukaryotes. A variant of the complete APC7 protein, containing its C-terminal region (named APC-CT), shows a high homology with a tobacco viral replication inhibitor (IVR-like) protein that reduces plant susceptibility to RNA viruses. Here, the role of the AtAPC7 gene was investigated by characterizing Arabidopsis plants overexpressing the full-length AtAPC7 (APC7OE) and the C-terminal portion (APC7-CTOE), by phenotypical, physiological and molecular approaches. APC7OE plants showed improved growth of vegetative organs, earlier flowering and increased photosynthetic efficiency, CO2 assimilation and productivity, compared with Col-0 control plants. Conversely, APC7-CTOE plants showed reduced susceptibility to both RNA and DNA viruses, along with an improvement in plant growth, although not surpassing APC7OE plants. Altogether, the data provide evidence for the role of the AtAPC7 in regulating cell division, expansion and differentiation, accompanied by an increase in photosynthetic capacity, resulting in enhanced plant biomass and seed yield. AtAPC7-CT might reduce growth-defence trade-offs, enabling plants to simultaneously defend themselves while promoting better growth. Our findings highlight the multifunctional role of AtAPC7, unveiling the potential of its orthologous genes as valuable biotechnological tools in important crops.

Citric acid-driven cadmium uptake and growth promotion mechanisms in Brassica napus

Citric acid (CA) is well-known for mitigating cadmium (Cd) toxicity in plants. Yet, the underlying mechanisms driving growth promotion, Cd detoxification/tolerance, and enhanced phytoremediation processes remain incompletely understood. This study investigated the effects of CA application (2.5 mM) on Brassica napus grown in Cd-contaminated (30 mg kg−1) growth medium through a controlled pot experiment. Cd exposure alone significantly impaired various plant physiological parameters in B. napus. Whereas CA application significantly (p < 0.05) enhanced physiological attributes, Cd detoxification and tolerance by modulating key genes involved in photosynthesis and Cd transport, including the metal-transporting P1B-type ATPases (Cd/zinc heavy metal-transporting ATPase 1; HMA1) and light-harvesting chlorophyll a/b-binding 3 (LHCB3). Notably, CA application increased Cd accumulation in stems and leaves by 4% and 35%, respectively, enhancing bioconcentration factors (BCF) by 12% in stems and 40% in leaves while reducing root BCF by 10%. This translocation was facilitated by the upregulation of HMA4, HMA2, and plant Cd resistance (PCR2) genes in plant leaves, improving Cd mobility within the plant. Furthermore, CA induced a 34% increase in phytochelatins and a 32% upregulation in metallothioneins, accompanied by a significant reduction in oxidative stress markers, including a 40% decrease in hydrogen peroxide and a 44% decline in malondialdehyde levels in leaves. Enhanced antioxidant enzyme activity and osmolyte accumulation further contributed to improved Cd detoxification/sequestration in leaves, reduced oxidative stress, and improved photosynthetic efficiency, resulting in enhanced plant biomass production and Cd tolerance. Transcriptomic analysis showed that CA treatment substantially influenced the expression of 12,291 differentially expressed genes (DEGs), with 750 common genes consistently downregulated in CK vs Cd treatment group but upregulated in Cd vs Cd-CA treatment group. Additionally, CA modulated 11 DEGs associated with 32 gene ontologies in the citrate pathway under Cd stress, highlighting its targeted regulatory effect on metabolic pathways involved in Cd stress response. This study offers novel insights into the synergistic role of CA in promoting plant growth and regulating Cd uptake in B. napus, highlighting its potential to enhance phytoremediation strategies.

The pivotal role of arbuscular mycorrhizal fungi in enhancing plant biomass and nutrient availability under drought stress conditions: A global meta-analysis

Drought is a serious threat to crop productivity and global food security. About 40 % of the worldwide land is considered arid dryland soil because of a lack of rainfall, high solar radiation, and temperature fluctuations. Though rhizobacteria, particularly mycorrhizal fungi (MF), assist plants in coping with drought stress, an intensive quantitative assessment of their effects on plant growth and nutrient availability is still limited. We systematically carried out a global meta-analysis using 122 peer-reviewed publications comprising 3534 observations to investigate the effects of MF on plant biomass (PB) and nutrient availability (nitrogen: N and phosphorus: P) under drought-stress conditions. The results show that the MF inoculation significantly increased mycorrhizal colonization (MC), N and P uptakes, and plant biomass (PB) at a C:N ratio > 15 by 2171.44 %, 23.74 %, 135.61 %, and 220.91 %, respectively. The MF species Claroideoglomus etunicatum and Glomus significantly influenced the MC, N, and PB concentrations by 2541.68 %, 40.35 %, and 110.85 %, respectively. Moreover, the concentrations of MC, N, and PB were considerably affected by the soil texture categories, with the maximum levels of 4940.04 %, 127.05 %, and 84.04 % found in sandy, clay, and clay loam soils, respectively. In addition, soil pH, crop types, soil textural class, and MF species were identified as vital pedologic factors affecting plant growth and nutrient availability during fungal inoculation. Overall, this meta-analysis addresses gaps in understanding the effects of MF inoculation on plant development and nutrient availability under drought stress.

Growth, phytochemical, and phytohormonal responses of basil to different light durations and intensities under constant daily light integral

Horticulture in controlled environments has been increasingly used to tackle limitations on crop production. As a crucial environmental factor, light regulate plant growth and metabolism. In the present study, basil plants were subjected to different light durations and intensities considering constant daily light integral (DLI). The lighting environment included 200, 300, and 400 µmol m− 2 s− 1 intensities for 18, 12, and 9 h, respectively. DLI amounted to 12.96 mol m− 2 d− 1 among all light treatments (LI200 for 18 h, LI300 for 12 h, and LI400 for 9 h). Half of the plants under each light treatment were exposed to 30 µmol m− 2 s− 1 of far-red light. The results indicated the general negative impact of LI400/9 on the growth of basils. Exposure to far-red light hurt the growth of the shoot, while it enhanced stem and petiole elongation. This effect was due to higher gibberellin accumulation, which resulted in shade avoidance responses. Exposure to far-red light also reduced anthocyanin and flavonoid contents, as two important nutritional components. Soluble carbohydrates increased, while storage carbohydrates decreased by increasing lighting duration/decreasing light intensity or by far-red light inclusion. The lowest antioxidant activity was detected in LI400/9. In the LI200/18, the highest level of auxin and the lowest level of cytokinin were detected, while the LI300/12 exhibited the highest level of gibberellin hormone. Low light intensity and long photoperiod enhanced plant biomass and phytochemical production and are recommended for basil production in controlled environments.

Interactions between arbuscular mycorrhizal fungi and phosphate-soluble bacteria affect ginsenoside compositions by modulating the C:N:P stoichiometry in Panax ginseng.

The biomass production as well as the accumulation of secondary metabolites of plant is highly determined by the absorption of nutritional elements, in particular nitrogen (N) and phosphorus (P). Arbuscular mycorrhizal fungi (AMF) can absorb soluble P and transport it to plants, while phosphate solubilizing bacteria (PSB) can increase the content of solubilizing P in soil. Previous studies have identified the effects of either AMF or PSB inoculation on altering plant C:N:P stoichiometry, whether AMF interact with PSB in promoting plant growth and changing elemental concentration and composition of secondary metabolites by altering plant C:N:P stoichiometry remains ambiguous. In this study, we investigated the effects of inoculation of AMF, PSB, and their co-inoculation AMP (AMF and PSB) on the biomass growth, the C:N:P stoichiometry, the core microorganisms of rhizosphere soil, and the ginsenoside compositions of ginseng (Panax ginseng). The results showed that compared to control or single inoculation of AMF or PSB, co-inoculation of AMF and PSB significantly increased the AMF colonization rate on ginseng roots, increased the biomass of both above and under-ground parts of ginseng. Similarly, co-inoculation of AMF and PSB substantially increased the concentrations of N and P, reduced the ratios of C:P and N:P in the above-ground part of ginseng. The co-inoculation of AMF and PSB also increased concentrations of total ginsenosides and altered the compositions of ginsenosides in both the above and under-ground parts of ginseng. Analysis the rhizosphere microorganism showed that the co-inoculation of AMF and PSB recruited distinct core microorganisms that differ from the control and treatments with single inoculation of AMF or PSB. Our results suggested that PSB inoculation enhanced the positive effect of AMF in improving the absorption of nutrimental elements, altered the C:N:P stoichiometry and, ginsenosides concentration and composition of ginseng, influenced the plant rhizosphere microbial community. These findings offer valuable insights into enhancing plant biomass production and promoting secondary metabolites by improving the plant-fungi-bacterial relationships.

Lime-assisted cultivation of Erigeron breviscapus: enhancing plant biomass production and scutellarin content in cadmium-contaminated soil

Lime-assisted cultivation of Erigeron breviscapus: enhancing plant biomass production and scutellarin content in cadmium-contaminated soil

Jasmonate and salicylic sprays improve cherry tomato fruit productivity and quality in unheated greenhouses

Introduction. Arable regions often have insufficient soil nutrients, which means that fertilizers must be used. However, using fertilizers excessively can harm the environment, human health, and food safety. Natural growth regulators derived from plants are environmentally friendly and reasonably priced. Salicylic acid (SA) and methyl jasmonate (MeJA) phytohormones are crucial for enhancing plant biomass, quality, productivity, and resistance to environmental stresses. Objective. To evaluate the foliar effect of MeJA and SA on fruit quality and production of cvs. colorful tomato under greenhouse conditions. Materials and methods. The trial was carried out in the University of Diyala, Iraq, from 1 December, 2022 to 5 June 2023. Foliar of 0, 200 mg/L SA and or 200 mg/L MeJA was evaluated to determine effects on fruit quality and production of colorful cherry tomato cultivars indeterminate: LA4013, LA353, LA2921, LA3899 and IQ2, with a randomized complete block design with each treatment having three replicates. Results. The cv. IQ2 had the heaviest fruit (82.13 g), highest yield (4.56 kg/plant), total yield (4.56 t/house) and highest treatable acidity (0.62 %). The cv. LA4013 had a higher fruit number (612.88 fruit/plant) and the highest total soluble solids (2.933 %). Foliar of SA at 200 mg/L had the highest chlorophyll index (36.68 SPAD) highest fruits per plant (373.73), highest yield (3.15 kg/plant) and total yield (3.93 t/house). Conclusion. When considering all variables together, the best genotypes were IQ2 and LA4013, which were found to be superior to the other genotypes in quality and yield trials. The 200 mg/L foliar SA improved the yield and quality of cherry tomatoes under greenhouse conditions.

CLONING OF CDNA-GENE OF ARABIDOPSIS THALIANA RIBOSOMAL PROTEIN S6, ITS EXPRESSION IN ESCHERICHIA COLI AND PURIFICATION OF ATRPS6B1 RECOMBINANT PROTEIN

Living organisms must adapt their growth and development in response to external factors like stress and nutrient availability throughout their lifespan. Consequently, they have evolved various regulatory pathways to enhance environmental perception and facilitate necessary metabolic adjustments. These pathways involve key proteins that, under stress and nutrient limitation, initiate anabolic and catabolic cellular processes. One critical pathway present in all eukaryotes involves the protein kinase TOR (Target of rapamycin), a large kinase that governs numerous biological processes, including the activation of S6K kinase, which phosphorylates the S6 protein (RPS6). Crystal structures have revealed the precise location of RPS6 within the 40S ribosomal subunit, highlighting structural features such as the C-terminal helix containing multiple phosphorylation sites. RPS6 primarily regulates mechanisms controlling cell growth and division. In plants, eS6 is encoded by two conserved genes, and its activation and phosphorylation are closely linked to S6Ks. Recent studies emphasize the significance of S6 protein phosphorylation as a key event in signaling pathways related to cell growth and survival factors, crucially regulating translation initiation and protein synthesis. S6 protein can be phosphorylated on various serine and threonine residues by S6K kinase, and further research shows its interaction with other molecules and proteins, expanding its functional roles in cell signaling. Further exploration of ribosomal protein S6 could unveil new insights into its molecular interactions, roles in cellular physiology and pathophysiology, and potential applications in enhancing plant biomass and yield. This study involved cloning and site-directed mutagenesis of cDNA for the second isoform of AtRPS6 protein (AtRPS6B), followed by expression of natural and phosphomimetic forms of the protein in E. coli ArcticExpress (DE3) cells. The proteins were then purified using metal-chelate affinity chromatography (IMAC), and their presence and degree of purification were confirmed via Western blotting. These findings contribute to the broader research context surrounding ribosomal protein S6. RPS6, a key effector in the TOR signaling pathway, plays a crucial role in regulating ribosome biosynthesis by controlling transcription and translation processes. Phosphorylation of RPS6, indicative of S6K activity, is associated with actively dividing cells. However, the precise role of RPS6 in ribosome biosynthesis regulation remains a subject of ongoing investigation. The data obtained from the study on AtRPS6B expand our understanding of the molecular mechanisms underlying ribosomal biosynthesis regulation. These insights may significantly contribute to our knowledge of the interplay between signaling pathways, ribosomal proteins, cellular metabolism, and offer new perspectives for therapeutic interventions targeting cellular processes associated with ribosomes.

IAA is more effective than EDTA in enhancing phytoremediation potential for cadmium and copper contaminated soils

Enhanced phytoremediation offers a rapid and eco-friendly approach for cleaning agricultural soil contaminated with copper and cadmium which pose a direct threat to food scarcity and security. The current study aimed to compare the effectiveness of the two commonly used additives, IAA and EDTA, for the remediation of copper (Cu) and cadmium (Cd) contaminated soils using sunflower and maize. The plants were cultivated in pots under controlled conditions with four sets of treatments: control (0), Cu50/Cd50, Cu50/Cd50 + EDTA, and Cu50/Cd50 + IAA. The results showed that Cu50/Cd50 mg/kg drastically compromised the phytoremediation potential of both plants, as evident by reduced shoot and root length, and lower biomass. However, the augmentation of Cu50/Cd50 with EDTA or IAA improved the tested parameters. In sunflower, EDTA enhanced the accumulation of Cu and Cd by 58% and 21%, respectively, and improved plant biomass by 41%, compared to control treatment. However, IAA exhibited higher accumulation of Cu and Cd by 64% and 25%, respectively, and enhanced plant biomass by 43%. In case of maize, IAA was superior to EDTA which enhanced the accumulation of Cu and Cd by 87% and 32% respectively, and increased the plant biomass by 57%, compared to control treatment. Our findings demonstrate that foliar IAA is more effective than EDTA in enhancing the phytoremediation potential of sunflower and maize for Cu and Cd.

Comparative role of calcium oxide nanoparticles and calcium bulk fertilizer to alleviate cadmium toxicity by modulating oxidative stress, photosynthetic performance and antioxidant-defense genes expression in alfalfa

Cadmium (Cd) toxicity poses a significant threat to soil health and sustainable food production. Its bioaccumulation in plant tissues induces phytotoxicity by affecting physiological and biochemical attributes, leading to a reduction in plant biomass and production. Recently, nanotechnology has emerged as a promising approach for addressing heavy metal toxicity in an eco-friendly manner to enhance crop production. However, the comparative role of foliar applied calcium oxide nanoparticles (CaO-NPs) and bulk calcium fertilizer under Cd stress in alfalfa remains unexplored. Herein, we studied the ameliorative role of CaO-NPs and bulk calcium (50 and 100 mg L−1) to alleviate Cd stress (30 mg kg−1) in alfalfa seedlings. Plants exposed to Cd exhibited significant decreases in morpho-physiological traits, gas exchange attributes, and pigment contents as well as increase in Cd bioaccumulation in plant tissues. Notably, exogenous application of CaO-NPs ameliorates the toxic impact of Cd by enhancing plant biomass (45%), fluorescence efficiency and gaseous exchange attributes. The maximum dose of CaO-NPs induced Cd-tolerance response accompanied by a significant increase in antioxidative enzyme activities, such as superoxide dismutase (SOD; 29%), peroxidase (POD; 41%), catalase (CAT; 36%) and ascorbate peroxidase (APX; 49%), which play positive roles in ROS scavenging. TEM examination further revealed the protective role of these NPs in averting Cd-induced damage to leaf ultrastructure and mesophyll cells. Furthermore, CaO-NPs had a substantial influence on both Cd and Ca2+ accumulation in plant tissues, while qRT‒PCR analysis demonstrated higher expression of antioxidant defense genes viz. Cu/ZnSOD (0.38 fold change (FC)), MtPOD (0.51 FC), MtCAT (0.61 FC) and MtAPX (0.79 FC) under CaO-NPs application, over Cd control. Overall, our findings suggested that exogenous CaO-NPs could be effective in alleviating the adverse effects of Cd on alfalfa seedlings to ensure food safety and support sustainable agriculture.

Impact of allelochemicals from shade trees bark on the performance of cocoa seedlings

AbstractShade trees are important in cocoa agroforestry systems; however, they release allelochemicals from various parts that affect understory plants. Unfortunately, information on allelochemicals produced by shade tree bark in cocoa plantation remain scarce. This study investigates the effect of allelochemicals from bark of shade trees on cocoa seedlings growth. The experiment was a 4 × 11 factorial study, and the treatments were four different concentrations from each of the 11 tree species. The treatments were laid out in a completely randomized design with four replicates. Data were collected at 30, 60, 90, 120, and 150 days after treatment applications. The tree species alone and bark extract concentrations alone significantly impacted plant height from 90 to 150 days after application. Albizia ferruginea (Guill. &amp; Perr.) Benth, Celtis mildbraedii Engl., and Triplochiton scleroxylon K. Schum produced the highest cocoa seedling heights. All concentrations also influenced stem diameter of cocoa seedlings. Albizia ferruginea enhanced stem diameter significantly among tree species and the control. Tree species and bark extract concentrations interacted to increase fresh root weights and dry plant biomass. Albizia ferruginea consistently increased dry plant biomass, while C. mildbraedii produced the highest enhancement for fresh roots. All concentrations enhanced plant biomass, with the 75 mg mL−1 concentration consistently producing the highest plant fresh and dry weights. Albizia ferruginea and C. mildbraedii can be potential tree species in the cocoa agroforestry when 2‐month‐old cocoa seedlings are to be transplanted on the field. Bark extract of 75 mg mL−1 concentration can be used as a growth stimulant on cocoa seedlings.

Appropriate supply of sulfur alleviates lead toxicity and stimulates its accumulation in hyperaccumulator Arabis alpina

Widespread lead (Pb) contamination of agricultural soils is a global issue stemming from human activities. The remediation of Pb-contaminated soils used for agricultural purposes is critically important to safeguard food crop safety. Despite the modulating effects of sulfur (S) on plant responses to toxic heavy metals, the ecological, physiological, and molecular mechanisms driving such modulation in the Pb hyperaccumulator Arabis alpina L. remain unclear. Here, we investigated the effects of five S concentrations (0, 50, 100, 150, and 200 mg kg−1) on A. alpina grown in Pb-contaminated soil from a lead-zinc mining area. Under S50 (i.e., 50 mg kg−1) and S100 treatments, the Pb concentration in both shoots and roots of A. alpina significantly decreased compared to the control (S0). Specifically, the S50 treatment significantly enhanced Pb accumulation, plant biomass, and plant height, indicating that low S applications facilitate Pb accumulation from the soil and alleviate Pb toxicity. Additionally, S50, S100, and S150 treatments significantly improved photosynthetic rate, stomatal conductance, and intercellular CO2 concentration in A. alpina. Transcriptomic analysis showed that S50 and S100 treatments increased the expression of the LHCA, LHCB, psa, and psb genes, which had a significant impact on photosynthetic efficiency. S50 and S100 boosted glutathione (GSH) levels in A. alpina roots, and the increased expression of GST gene enhanced tolerance to environmental stress. In summary, these results suggest that an appropriate supply of S (S50 and S100) not only alleviates Pb toxicity by enhancing plant biomass, height, photosynthetic features, and sulfur metabolites but also stimulates Pb accumulation in the hyperaccumulator A. alpina. Our study elucidated the specific concentrations of sulfur that optimally enhance both Pb accumulation and stress tolerance in the hyperaccumulator A. alpina, providing novel insights into the practical application of sulfur in phytoremediation strategies and advancing our understanding of the underlying molecular mechanisms.

Cladosporium psychrotolerans strain T01 enhances plant biomass and also exhibits antifungal activity against pathogens.

An increasing number of microorganisms are being identified to enhance plant growth and inhibit phytopathogens. Some Cladosporium species form beneficial associations with plants, either as endophytes or by colonizing the rhizosphere. Herein, we evaluated the influence of the Cladosporium psychrotolerans (T01 strain) fungus on the in vitro growth of Arabidopsis thaliana plantlets through direct and split interactions. After 9 days post-inoculation with C. psychrotolerans, Arabidopsis plantlets exhibited a notable increase in fresh weight and lateral roots, particularly in split interactions. Chlorophyll content increased in both plant-fungus interaction conditions, whereas the primary root was inhibited during direct interaction. We observed an increase in the GUS signal from the Arabidopsis auxin-inducible DR5:uidA marker in lateral root tips in both contact and split fungal interactions, and primary root tips in a split interaction. Arabidopsis and tomato plants cultivated in soil pots and inoculated with C. psychrotolerans (T01 strain) showed a positive effect on biomass production. GC/MS analysis detected that the T01 strain emitted volatile organic compounds (VOCs), predominantly alcohols and aldehydes. These VOCs displayed potent inhibitory effects, with a 60% inhibition against Botrytis cinerea and a 50% inhibition against C. gloeosporioides. Our study demonstrates that C. psychrotolerans T01 has the potential to enhance biomass production and inhibit pathogens, making it a promising candidate for green technology applications.

Mild to moderate drought stress reinforces the role of functional microbiome in promoting growth of a dominant forage species (Neopallasia pectinata) in desert steppe.

Desert steppe ecosystems are prone to drought stress, which influences the ecological balance and sustainable development of grasslands. In addition to directly restrict plant growth, drought stress indirectly impacts plant fitness by altering the diversity and function of root-associated microbiomes. This begs the question of whether the functional microbiome of forage plants, represented by synthetic microbial communities (SynComs), can be leveraged to mitigate drought stress in desert steppes and promote the ecological restoration of these fragile ecosystems. A pot experiment was conducted to evaluate the role of SynComs in improving the plant growth and drought stress resistance of Neopallasia pectinata (Pall.) Poljak in desert steppe in Inner Mongolia, China. Six SynComs were derived from the rhizosphere and root endosphere of 12 dominant forage species in the desert steppe. Each SynCom comprised two to three bacterial genera (Bacillus, Protomicromonospora, and Streptomyces). We examined the capacities of different SynComs for nutrient solubilization, phytohormone secretion, and enzymatic activity. Under no water stress (75% soil water holding capacity, WHC), single strains performed better than SynComs in promoting plant growth in terms of stem diameter, root length, and plant dry weight, with the greatest effects observed for Streptomyces coeruleorubidus ATCC 13740 (p < 0.05). However, under mild to moderate drought stress (55% and 35% WHC), SynComs outperformed single strains in enhancing plant biomass accumulation and inducing the production of resistance-related substances (p < 0.05). No significant effect of single strains and SynComs emerged under extreme drought stress (20% WHC). This study underscores the potential of SynComs in facilitating forage plants to combat drought stress in desert steppe. Mild to moderate drought stress stimulates SynComs to benefit the growth of N. pectinata plants, despite a soil moisture threshold (21% WHC) exists for the microbial effect. The use of SynComs provides a promising strategy for the ecological restoration and sustainable utilization of desert steppes by manipulating the functional microbiome of forage plants.

Modulation of rhizosphere microbial community and metabolites by bio-functionalized nanoscale silicon oxide alleviates cadmium-induced phytotoxicity in bayberry plants

Cadmium (Cd) is an extremely toxic heavy metal that can originate from industrial activities and accumulate in agricultural soils. This study investigates the potential of biologically synthesized silicon oxide nanoparticles (Bio-SiNPs) in alleviating Cd toxicity in bayberry plants. Bio-SiNPs were synthesized using the bacterial strain Chryseobacterium sp. RTN3 and thoroughly characterized using advanced techniques. A pot experiment results demonstrated that Cd stress substantially reduced leaves biomass, photosynthesis efficiency, antioxidant enzyme activity, and induced oxidative damage in bayberry (Myrica rubra) plants. However, Bio-SiNPs application at 200 mg kg−1 significantly enhanced plant biomass, chlorophyll content (26.4 %), net photosynthetic rate (8.6 %), antioxidant enzyme levels, and mitigated reactive oxygen species production under Cd stress. Bio-SiNPs modulated key stress-related phytohormones by increasing salicylic acid (13.2 %) and abscisic acid (13.7 %) contents in plants. Bio-SiNPs augmented Si deposition on root surfaces, preserving normal ultrastructure in leaf cells. Additionally, 16S rRNA gene sequencing demonstrated that Bio-SiNPs treatment favorably reshaped structure and abundance of specific bacterial groups (Proteobacteria, Actinobacteriota, and Acidobacteriota) in the rhizosphere. Notably, Bio-SiNPs application significantly modulated the key metabolites (phenylacetaldehyde, glycitein, maslinic acid and methylmalonic acid) under both normal and Cd stress conditions. Overall, this study highlights that bio-nanoremediation using Bio-SiNPs enhances tolerance to Cd stress in bayberry plants by beneficially modulating biochemical, microbial, and metabolic attributes.

Improving plant adaptation to soil antimony contamination: the synergistic contribution of arbuscular mycorrhizal fungus and olive mill waste

BackgroundThis study aimed to investigate the alterations in biochemical and physiological responses of oat plants exposed to antimony (Sb) contamination in soil. Specifically, we evaluated the effectiveness of an arbuscular mycorrhizal fungus (AMF) and olive mill waste (OMW) in mitigating the effects of Sb contamination. The soil was treated with a commercial strain of AMF (Rhizophagus irregularis) and OMW (4% w/w) under two different levels of Sb (0 and 1500 mg kg−1 soil).ResultsThe combined treatment (OMW + AMF) enhanced the photosynthetic rate (+ 40%) and chlorophyll a (+ 91%) and chlorophyll b (+ 50%) content under Sb condition, which in turn induced more biomass production (+ 67–78%) compared to the contaminated control plants. More photosynthesis in OMW + AMF-treated plants gives a route for phenylalanine amino acid synthesis (+ 69%), which is used as a precursor for the biosynthesis of secondary metabolites, including flavonoids (+ 110%), polyphenols (+ 26%), and anthocyanins (+ 63%) compared to control plants. More activation of phenylalanine ammonia-lyase (+ 38%) and chalcone synthase (+ 26%) enzymes in OMW + AMF-treated plants under Sb stress indicated the activation of phenylpropanoid pathways in antioxidant metabolites biosynthesis. There was also improved shifting of antioxidant enzyme activities in the ASC/GSH and catalytic pathways in plants in response to OMW + AMF and Sb contamination, remarkably reducing oxidative damage markers.ConclusionsWhile individual applications of OMW and AMF also demonstrated some degree of plant tolerance induction, the combined presence of AMF with OMW supplementation significantly enhanced plant biomass production and adaptability to oxidative stress induced by soil Sb contamination.

N limitation may inhibit the effectiveness of close-to-nature restoration measures for degraded alpine meadows on the northern Qinghai‒Tibet Plateau

As important terrestrial ecosystems on the Qinghai‒Tibet Plateau with important ecological and economic value, alpine meadows in some regions are in a degraded state due to climate change and unsustainable grazing. Due to the fragile ecological environment, exploring sustainable restoration models of degraded alpine meadows using close-to-nature restoration measures is the direction of ongoing efforts. Thus, in this study, three close-to-nature restoration measures, namely, manure application (M), Poa annua, Elymus dahuricus, and Puccinellia distans mixed with non-tillage reseeding (R), and the combined treatments (MR), were used to restore degraded alpine meadows from 2019 to 2021. The results showed that the M and MR treatments significantly enhanced plant biomass and reduced forbs dominance, thus improving community structure. Moreover, the M and MR treatments significantly affected plant and bacterial alpha diversity. However, the three restoration measures did not alter the correlation between the plant and bacterial communities. Furthermore, these three measures resulted in a significant increase in the plant carbon:nitrogen ratio and a significant decrease in the nitrogen:phosphorus ratio, while neither the plant carbon:phosphorus ratio nor the soil stoichiometric ratio changed significantly, indicating that nitrogen limitation was an important factor that limited the recovery process of the alpine meadows. The structural equation model indicated that the plant nitrogen:phosphorus ratio may regulate the response of plant and bacterial diversity to different restoration measures in alpine meadows. Our findings emphasize that the management of degraded alpine meadows using close-to-nature restoration measures should be a long-term effort, with more attention given to changes in the nitrogen content of meadow ecosystems.

Halotolerant Pseudomonas koreensis S4T10 mitigate salt and drought stress in Arabidopsis thaliana.

Salt and drought are documented among the most detrimental and persistent abiotic stresses for crop production. Here, we investigated the impact of Pseudomonas koreensis strain S4T10 on plant performance under salt and drought stress. Arabidopsis thaliana Col-0 wild type and atnced3 mutant plants were inoculated with P. koreensis or tap water and exposed to NaCl (100 mM) for five days and drought stress by withholding water for seven days. P. koreensis significantly enhanced plant biomass and photosynthetic pigments under salt and drought stress conditions. Moreover, P. koreensis activated the antioxidant defence by modulating glutathione (GSH), superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activities to scavenge the reactive oxygen species produced due to the stress. In addition, the application of P. koreensis upregulated the expression of genes associated with antioxidant responses, such as AtCAT1, AtCAT3, and AtSOD. Similarly, genes linked to salt stress, such as AtSOS1, AtSOS2, AtSOS3, AtNHX1, and AtHKT1, were also upregulated, affirming the positive role of P. koreensis S4T10 in streamlining the cellular influx and efflux transport systems during salt stress. Likewise, the PGPB inoculation was observed to regulate the expression of drought-responsive genes AtDREB2A, AtDREB2B, and ABA-responsive genes AtAO3, AtABA3 indicating that S4T10 enhanced drought tolerance via modulation of the ABA pathway. The results of this study affirm that P. koreensis S4T10 could be further developed as a biofertilizer to mitigate salt and drought stress at the same time.

AsHSP26.2, a creeping bentgrass chloroplast small heat shock protein positively regulates plant development.

The creeping bentgrass small heat shock protein AsHSP26.2 positively regulates plant growth and is a novel candidate for use in crop genetic engineering for enhanced biomass production and grain yield. Small heat shock proteins (sHSPs), a family of proteins with high level of diversity, significantly influence plant stress tolerance and plant development. We have cloned a creeping bentgrass chloroplast-localized sHSP gene, AsHSP26.2 responsive to IAA, GA and 6-BA stimulation. Transgenic creeping bentgrass overexpressing AsHSP26.2 exhibited significantly enhanced plant growth with increased stolon number and length as well as enlarged leaf blade width and leaf sheath diameters, but inhibited leaf trichomes initiation and development in the abaxial epidermis. These phenotypes are completely opposite to those displayed in the transgenic plants overexpressing AsHSP26.8, another chloroplast sHSP26 isoform that contains additional seven amino acids (AEGQGDG) between the consensus regions III and IV (Sun et al., Plant Cell Environ 44:1769-1787, 2021). Furthermore, AsHSP26.2 overexpression altered phytohormone biosynthesis and signaling transduction, resulting in elevated auxin and gibberellins (GA) accumulation. The results obtained provide novel insights implicating the sHSPs in plant growth and development regulation, and strongly suggest AsHSP26.2 to be a novel candidate for use in crop genetic engineering for enhanced plant biomass production and grain yield.

Interactive mode of biochar-based silicon and iron nanoparticles mitigated Cd-toxicity in maize

Cadmium contamination poses severe environmental and health threats, necessitating effective mitigation strategies. Rice husk biochar (BC) and nanoparticle (NP) treatments are emerging strategies with limited research on their synergistic benefits. This study assesses BC, silicon NPs (nSi), and iron NPs (nFe) modifications (B-nSi, B-nFe, and B-nSi-nFe) to reduce Cd-bioavailability in soil and its toxicity in maize, not reported before. Characterization of amendments validated, nSi and nFe attachment to BC, forming new mineral crystals to adsorb Cd. We found that B-nSi-nFe induced Cd-immobilization in soil by the formation of Cd-ligand complexes with the effective retention of NPs within microporous structure of BC. B-nSi-nFe increased soil pH by 0.76 units while reducing bioavailable Cd by 49 %, than Ck-Cd. Resultantly, B-nSi-nFe reduced Cd concentrations in roots and shoots by 51 % and 75 %, respectively. Moreover, the application of B-nSi-nFe significantly enhanced plant biomass, antioxidant activities, and upregulated the expression of antioxidant genes [ZmAPX (3.28 FC), ZmCAT (3.20 FC), ZmPOD (2.58 FC), ZmSOD (3.08 FC), ZmGSH (3.17 FC), and ZmMDHAR (3.80 FC)] while downregulating Cd transporter genes [ZmNramp5 (3.65 FC), ZmHMA2 (2.92 FC), and ZmHMA3 (3.40 FC)] compared to Ck-Cd. Additionally, confocal microscopy confirmed the efficacy of B-nSi-nFe in maintaining cell integrity due to reduced oxidative stress. SEM and TEM observations revealed alleviation of Cd toxicity to stomata, guard cells, and ultracellular structures with B-nSi-nFe treatment. Overall, this study demonstrated the potential of B-nSi-nFe for reducing Cd mobility in soil-plant system, mitigating Cd-toxicity in plants and improving enzymatic activities in soil.