Strengths of fertilizer and litter effects on seedling recruitment and growth of grassland species differ depending on functional groups and seed size.

Agricultural grasslands play an important role in conserving the biodiversity of the European cultural landscape. Both, litter cover and soil nutrient availability, change with grassland management, but it is not well-studied how seedling recruitment and growth of multiple grassland species are influenced by their single or combined effects. Therefore, we studied the effects of nitrogen fertilization (100 kg N per year and ha) and litter cover (250 gdw per m2) on seedling recruitment and growth of 75 temperate grassland species (16 graminoid species, 51 forb species, 8 legume species) in a full factorial microcosm experiment. Overall, fertilizer reduced seedling emergence, while litter cover increased it even when combined with fertilization. Fertilization increased seedling height and biomass, and the combination of fertilizer and litter resulted in even stronger responses. Litter cover alone did not influence seedling biomass or seedling height. While the overall direction of treatment effects was similar across functional groups, their strengths were mostly weaker in graminoids than in non-legume forbs and legumes. Positive litter effects on seedling emergence were stronger in large-seeded species. Positive fertilization effects on seedling growth were stronger in small-seeded species, while their seedling biomass was negatively affected by litter cover. In summary, our results show for multiple grassland species that the combination of litter cover and fertilization modulates their single effects. The varying sensitivity of how grassland species representing different functional groups and seed sizes respond with their seedling emergence and growth to litter cover and nitrogen fertilization indicates that the consequences of land-use change on grassland diversity and composition already start to manifest in the earliest stages of the plant life cycle.

CaAl-Layered Double Hydroxides-Modified Biochar Composites Mitigate the Toxic Effects of Cu and Pb in Soil on Pea Seedlings.

Compound contamination of soil with heavy metals copper (Cu) and lead (Pb) triggered by mining development has become a serious problem. To solve this problem, in this paper, corncob kernel, which is widely available and inexpensive, was used as the raw material of biochar and modified by loading CaAl-layered double hydroxides to synthesize biochar-loaded CaAl-layered double hydroxide composites (CaAl-LDH/BC). After soil remediation experiments, either BC or CaAl-LDH/BC can increase soil pH, and the available phosphorus content and available potassium content in soil. Compared with BC, CaAl-LDH/BC significantly reduced the available content of Cu and Pb in the active state (diethylenetriaminepentaacetic acid extractable state) in the soil, and the passivation rate of Cu and Pb by a 2% dosage of CaAl-LDH/BC reached 47.85% and 37.9%, respectively. CaAl-LDH/BC can significantly enhance the relative abundance of beneficial microorganisms such as Actinobacteriota, Gemmatimonadota, and Luteimonas in the soil, which can help to enhance the tolerance and reduce the enrichment ability of plants to heavy metals. In addition, it was demonstrated by pea seedling (Pisum sativum L.) growing experiments that CaAl-LDH/BC increased plant fresh weight, root length, plant height, catalase (CAT) activity, and protein content, which promoted the growth of the plant. Compared with BC, CaAl-LDH/BC significantly reduced the Cu and Pb contents in pea seedlings, in which the Cu and Pb contents in pea seedlings were reduced from 31.97 mg/kg and 74.40 mg/kg to 2.92 mg/kg and 6.67 mg/kg, respectively, after a 2% dosage of CaAl-LDH/BC, which was a reduction of 90.84% and 91.03%, respectively. In conclusion, compared with BC, CaAl-LDH/BC improved soil fertility and thus the plant growth environment, and also more effectively reduced the mobility of heavy metals Cu and Pb in the soil to reduce the enrichment of Cu and Pb by plants.

Methyl Jasmonate and Zinc Sulfate Induce Secondary Metabolism and Phenolic Acid Biosynthesis in Barley Seedlings.

This study aimed to reveal the impact of MeJA and ZnSO4 treatments on the physiological metabolism of barley seedlings and the content of phenolic acid. The results showed that MeJA (100 µM) and ZnSO4 (4 mM) treatments effectively increased the phenolic acid content by increasing the activities of phenylalanine ammonia-lyase and cinnamate-4-hydroxylase (PAL) and cinnamic acid 4-hydroxylase (C4H) and by up-regulating the expression of genes involved in phenolic acid synthesis. As a result of the MeJA or ZnSO4 treatment, the phenolic acid content increased by 35.3% and 30.9% at four days and by 33.8% and 34.5% at six days, respectively, compared to the control. Furthermore, MeJA and ZnSO4 treatments significantly increased the malondialdehyde content, causing cell membrane damage and decreasing the fresh weight and seedling length. Barley seedlings responded to MeJA- and ZnSO4-induced stress by increasing the activities of antioxidant enzymes and controlling their gene expression levels. Meanwhile, MeJA and ZnSO4 treatments significantly upregulated calcium-adenosine triphosphate, calmodulin-dependent protein kinase-related kinase, and calmodulin-dependent protein genes in barley seedlings. This suggested that Ca2+ may be the signaling molecule that promotes phenolic acid synthesis under MeJA and ZnSO4 treatment. This study deepens the understanding of the phenolic acid enrichment process in barley seedlings under MeJA and ZnSO4 treatments.

Physiological and Proteome Analysis of the Effects of Chitosan Oligosaccharides on Salt Tolerance of Rice Seedlings.

Rice (Oryza sativa L.) is an important social-economic crop, and rice seedlings are easily affected by salt stress. Chitosan oligosaccharide (COS) plays a positive role in promoting plant growth and development. To gain a better understanding of the salt tolerance mechanism of rice under the action of COS, Nipponbare rice seedlings were selected as the experimental materials, and the physiological and biochemical indexes of rice seedlings in three stages (normal growth, salt stress and recovery) were measured. Unlabelled quantitative proteomics technology was used to study differential protein and signaling pathways of rice seedlings under salt stress, and the mechanism of COS to improve rice tolerance to salt stress was elucidated. Results showed that after treatment with COS, the chlorophyll content of rice seedlings was 1.26 times higher than that of the blank group (CK). The root activity during the recovery stage was 1.46 times that of the CK group. The soluble sugar in root, stem and leaf increased by 53.42%, 77.10% and 9.37%, respectively. The total amino acid content increased by 77% during the stem recovery stage. Furthermore, the malondialdehyde content in root, stem and leaf increased by 21.28%, 26.67% and 32.69%, respectively. The activity of oxide dismutase (SOD), peroxidase (POD) and oxygenase (CAT) were increased. There were more differentially expressed proteins in the three parts of the experimental group than in the CK group. Gene Ontology (GO) annotation of these differentially expressed proteins revealed that the experimental group was enriched for more entries. Then, through the Kyoto Encyclopedia of Genes and Genomes (KEGG), the top ten pathways enriched with differentially expressed proteins in the two groups (COS and CK groups) were utilized, and a detailed interpretation of the glycolysis and photosynthesis pathways was provided. Five key proteins, including phosphofructokinase, fructose bisphosphate aldolases, glycer-aldehyde-3-phosphate dehydrogenase, enolase and pyruvate kinase, were identified in the glycolysis pathway. In the photosynthesis pathway, oxygen evolution enhancement proteins, iron redox proteins and ferredoxin-NADPH reductase were the key proteins. The addition of COS led to an increase in the abundance of proteins, a response of rice seedlings to salt stress. COS helped rice seedlings resist salt stress. Furthermore, using COS as biopesticides and biofertilizers can effectively increase the utilization of saline-affected farmland, thereby contributing to the alleviating of the global food crisis.

Mechanistic insights into the plant biostimulant activity of a novel formulation based on rice husk nanobiosilica embedded in a seed coating alginate film.

Seed coating ensures the targeted delivery of various compounds from the early stages of development to increase crop quality and yield. Silicon and alginate are known to have plant biostimulant effects. Rice husk (RH) is a significant source of biosilica. In this study, we coated mung bean seeds with an alginate-glycerol-sorbitol (AGS) film with embedded biogenic nanosilica (SiNPs) from RH, with significant plant biostimulant activity. After dilute acid hydrolysis of ground RH in a temperature-controlled hermetic reactor, the resulting RH substrate was neutralized and calcined at 650°C. The structural and compositional characteristics of the native RH, the intermediate substrate, and SiNPs, as well as the release of soluble Si from SiNPs, were investigated. The film for seed coating was optimized using a mixture design with three factors. The physiological properties were assessed in the absence and the presence of 50 mM salt added from the beginning. The main parameters investigated were the growth, development, metabolic activity, reactive oxygen species (ROS) metabolism, and the Si content of seedlings. The results evidenced a homogeneous AGS film formation embedding 50-nm amorphous SiNPs having Si-O-Si and Si-OH bonds, 0.347 cm3/g CPV (cumulative pore volume), and 240 m2/g SSA (specific surface area). The coating film has remarkable properties of enhancing the metabolic, proton pump activities and ROS scavenging of mung seedlings under salt stress. The study shows that the RH biogenic SiNPs can be efficiently applied, together with the optimized, beneficial alginate-based film, as plant biostimulants that alleviate saline stress from the first stages of plant development.

Replacing traditional nursery soil with spent mushroom substrate improves rice seedling quality and soil substrate properties.

Currently, large quantities of spent mushroom substrate (SMS) are produced annually. Because SMS has high water retention and nutrients, it has great potential to replace traditional topsoil for raising seedlings in agricultural production. However, few studies have examined the effects of substituting SMS for paddy soil on rice seedling growth and soil nutrients. SMS was mixed with rice soil in different proportions (20%, 50%, and 80%), and chemical fertilizer, organic fertilizer, and peat substrate were added in addition to equivalent nitrogen as a traditional seedling nursery method for comparison. Compared to traditional paddy soil (CK), the seedling qualities of the three SMS ratio treatments were all higher. Adding SMS at different ratios promoted rice seedling root growth, elevated the soluble protein concentration, and amplified the superoxide dismutase (SOD) enzymatic action in rice seedlings. Total porosity and aeration porosity of the soil increased by 17.40% and 32.90%, respectively. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) increased by 21.26-118.48%, 50.44-71.68%, and 23.08-80.17%, respectively. Besides, the relative abundance of Bacillus, Bacteroidetes, and other bacteria as well as the abundance of Ascomycota were all significantly increased. Adding 50% SMS increased the abundance of Pseudomonas by 8.42 times. The seedling quality of the 50% SMS treatment was even higher than chemical fertilizer and organic fertilizer treatments, only second to the peat substrate treatment. In summary, partial substitution of paddy soil with SMS can ameliorate substrate properties, improve seedling quality, and increase microbial diversity, indicating the suitability of SMS as a replacement for rice soil in seedling substrates. The 50% SMS ratio is the best. This study provides a basis for SMS to replace traditional rice soil in seedling cultivation.

Metabolic and Functional Interactions of H2S and Sucrose in Maize Thermotolerance through Redox Homeodynamics.

Hydrogen sulfide (H2S) is a novel gasotransmitter. Sucrose (SUC) is a source of cellular energy and a signaling molecule. Maize is the third most common food crop worldwide. However, the interaction of H2S and SUC in maize thermotolerance is not widely known. In this study, using maize seedlings as materials, the metabolic and functional interactions of H2S and SUC in maize thermotolerance were investigated. The data show that under heat stress, the survival rate and tissue viability were increased by exogenous SUC, while the malondialdehyde content and electrolyte leakage were reduced by SUC, indicating SUC could increase maize thermotolerance. Also, SUC-promoted thermotolerance was enhanced by H2S, while separately weakened by an inhibitor (propargylglycine) and a scavenger (hypotaurine) of H2S and a SUC-transport inhibitor (N-ethylmaleimide), suggesting the interaction of H2S and SUC in the development of maize thermotolerance. To establish the underlying mechanism of H2S-SUC interaction-promoted thermotolerance, redox parameters in mesocotyls of maize seedlings were measured before and after heat stress. The data indicate that the activity and gene expression of H2S-metabolizing enzymes were up-regulated by SUC, whereas H2S had no significant effect on the activity and gene expression of SUC-metabolizing enzymes. In addition, the activity and gene expression of catalase, glutathione reductase, ascorbate peroxidase, peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and superoxide dismutase were reinforced by H2S, SUC, and their combination under non-heat and heat conditions to varying degrees. Similarly, the content of ascorbic acid, flavone, carotenoid, and polyphenol was increased by H2S, SUC, and their combination, whereas the production of superoxide radicals and the hydrogen peroxide level were impaired by these treatments to different extents. These results imply that the metabolic and functional interactions of H2S and sucrose signaling exist in the formation of maize thermotolerance through redox homeodynamics. This finding lays the theoretical basis for developing climate-resistant maize crops and improving food security.

Conceptualization and development of a semi-automatic vegetable transplanter prototype for small landholdings.

The process of seedling transplantation has significant importance within the realm of mechanical vegetable production in contemporary agriculture. A prototype of a two-row tractor-mounted semi-automatic vegetable seedling transplanter (SVT) was conceptualized and developed for small agricultural holdings. The functional behaviour of the prototype was examined with computer-aided design tools, and the various units of the prototype have been finalized. To develop the prototype, the feeding, metering, transplanting, drive train, and soil compacting/covering unit of the machine were developed and constructed using materials readily accessible locally. The machine has a set row-to-row spacing of 600 mm, and it may alter the plant-to-plant spacing when the machine's forward speed changes. The pace was customized to achieve the required 450 mm plant-to-plant spacing. A 12:1 speed reduction gearbox was used for the proper metering of seedlings. The effect of independent factors, namely tray cell type, feeding mechanism, soil covering/compacting wheel angle, and age of seedling, on the machine's actual field capacity (AFC) was examined. The prototype underwent preliminary field testing to assess the functional viability, and the functioning was satisfactory. The main effect of the feeding mechanism and soil covering/compacting wheel angle on AFC was statistically significant at 5 % for tomato and brinjal whereas their first-order interaction was found statistically significant on AFC for tomatoes. The findings demonstrate that this study's prototype can be marketed or used to further vegetable production studies.

Microplastic influences the ménage à trois among the plant, a fungal pathogen, and a plant growth-promoting fungal species.

Microplastics (MP) can influence a plethora of fungal species within the rhizosphere. Nevertheless, there are few studies on the direct impacts of MPs on soil fungi and their intricate interplay with plants. Here, we investigated the impact of polyethylene microspheres (PEMS) on the ecological interactions between Fusarium solani, a plant pathogenic fungus, and Trichoderma viride, a fungal plant growth promotor, within the rhizosphere of Solanum lycopersicum (tomato). Spores of F. solani and T. viride were pre-incubated with PEMS at two concentrations, 100 and 1000 mg L-1. Mycelium growth, sporulation, spore germination, and elongation were evaluated. Tomato seeds were exposed to fungal spore suspensions treated with PEMS, and plant development was subsequently assessed after 4 days. The results showed that PEMS significantly enhanced the sporulation (106.0 % and 70.1 %) but compromised the spore germination (up to 27.3 % and 32.2 %) and radial growth (up to -5.2% and -21.7 %) of F. solani and T. viride, respectively. Furthermore, the 100 and 1000 mg L-1 concentrations of PEMS significantly (p<0.05) enhanced the mycelium density of T. viride (9.74 % and 22.30 %, respectively), and impaired the germ-tube elongation of F. solani after 4 h (16.16 % and 11.85 %, respectively) and 8 h (4 % and 17.10 %, respectively). In addition, PEMS amplified the pathogenicity of F. solani and boosted the bio-enhancement effect of T. viride on tomato root growth. Further, PEMS enhanced the bio-fungicidal effect of T. viride toward F. solani (p<0.05). In summary, PEMS had varying effects on F. solani and T. viride, impacting their interactions and influencing their relationship with tomato plants. It intensified the beneficial effects of T. viride and increased the aggressiveness of F. solani. This study highlights concerns regarding the effects of MPs on fungal interactions in the rhizosphere, which are essential for crop soil colonization and resource utilization.

Wheat seedlings extract ameliorates sarcopenia in aged mice by regulating protein synthesis and degradation with anti-inflammatory and mitochondrial biogenesis effects.

BACKGROUND: Chronic inflammation, which becomes more prevalent during aging, contributes to sarcopenia by reducing muscle mass and strength. PURPOSE: Wheat seedlings extract (WSE) is known for its various physiological activities, including anti-inflammation and antioxidant effects. However, its efficacy against sarcopenia is not well documented. STUDY DESIGN: 8-week-old and 50-week-old C57BL/6 J mice were used as young control (YC group) and aged controls (AC group), respectively. Then, aged mice were randomly divided into 5 groups (WSE100mg/kg, WSE200mg/kg, WSE400mg/kg, and schizandrin as a positive control) and fed each experimental diet for 10 weeks. METHOD: We investigated the effects of WSE on muscle quality and protein homeostasis pathways based on improvements in mitochondrial function and chronic inflammation. We then used TNFα-treated C2C12 to investigate the effects of isoorientin (ISO) and isoschaftoside (ISS), the active substances of WSE, on the myogenic pathway. RESULTS: We administered WSE to aging mice and observed an increase in muscle mass, thickness, protein content, and strength in mice treated with WSE at a dose of 200 mg/kg or 400 mg/kg. Furthermore, the administration of WSE led to a reduction in inflammatory factors (TNFα, IL-1, and IL-6) and an increase in mitochondrial biogenesis (p-AMPK/SIRT3/PGC1α) in muscle. This effect was also observed in TNFα-induced muscle atrophy in C2C12 cells, and we additionally identified the upregulation of myogenic regulatory factors, including Myf5, Myf6, MyoD, and myogenin, by WSE, ISO, and ISS. CONCLUSION: These findings suggest that WSE could function as a dietary anti-inflammatory factor and mitochondrial activator, potentially exerting modulatory effects on the metabolism and mechanical properties of skeletal muscles in the aging population. Furthermore, Our results demonstrate the potential value of ISO and ISS as functional food ingredients for preventing muscle atrophy.

Endosphere mycobiome in mature rice roots originate from both seedlings and soils.

Plant-fungus symbioses have functional relevance during plant growth and development. However, it is still unknown whether the endosphere fungi in mature plants originated from soils or seeds. To elucidate the origination of endosphere fungi in mature rice roots, the fungal communities in surface sterilized roots and shoots of mature rice plants germinated in soils, rhizosphere soils and seedlings germinated under sterile conditions were analyzed by Illumina-based sequencing and compared. Total 62 fungal OTUs shared in the seedlings, shoots and roots, 126 OTUs shared in the rhizosphere soils, shoots and roots. Fungal OTUs coexisted in the four types of samples belonged to genera of Rhizophagus, Trichoderma, Fusarium, Atractiella, Myrmecridium, Sporothrix, Microdochium, Massariosphaeria, and Phialemonium. The principle component analysis (PCA) and NMDS plot suggested that the fungal community structure in rhizosphere soils was different from that in seedlings significantly. Rhizosphere soil, shoot and root contained more similar fungal community. The fungal community in seedling was similar to that in shoot and root of mature plants. The results suggested that endophytic fungal communities in mature rice plants originated from both seedlings and rhizosphere soils, and more fungal taxa originated from rhizosphere soils. Mature rice plants contain mycobiome transmitted vertically from seeds, which suggests that inoculation of endophytic fungi isolated from seedlings might be an effective way to introduce beneficial fungal inoculants into rice plants successfully.

Maize miRNAs and their putative target genes involved in chilling stress response in 5-day old seedlings.

BACKGROUND: In the context of early sowing of maize as a promising adaptation strategy that could significantly reduce the negative effects of climate change, an in-depth understanding of mechanisms underlying plant response to low-temperature stress is demanded. Although microRNAs (miRNAs) have been recognized as key regulators of plant stress response, research on their role in chilling tolerance of maize during early seedling stages is scarce. Therefore, it is of great significance to explore chilling-responsive miRNAs, reveal their expression patterns and associated target genes, as well as to examine the possible functions of the conserved and novel miRNAs. In this study, the role of miRNAs was examined in 5d-old maize seedlings of one tolerant and one sensitive inbred line exposed to chilling (10/8 °C) stress for 6 h and 24 h, by applying high throughput sequencing. RESULTS: A total of 145 annotated known miRNAs belonging to 30 families and 876 potentially novel miRNAs were identified. Differential expression (DE) analysis between control and stress conditions identified 98 common miRNAs for both genotypes at one time point and eight miRNAs at both time points. Target prediction and enrichment analysis showed that the DE zma-miR396, zma-miR156, zma-miR319, and zma-miR159 miRNAs modulate growth and development. Furthermore, it was found that several other DE miRNAs were involved in abiotic stress response: antioxidative mechanisms (zma-miR398), signal transduction (zma-miR156, zma-miR167, zma-miR169) and regulation of water content (zma-miR164, zma-miR394, zma-miR396). The results underline the zma-miRNAs involvement in the modulation of their target genes expression as an important aspect of the plant's survival strategy and acclimation to chilling stress conditions. CONCLUSIONS: To our understanding, this is the first study on miRNAs in 5-d old seedlings' response to chilling stress, providing data on the role of known and novel miRNAs post-transcriptional regulation of expressed genes and contributing a possible platform for further network and functional analysis.

Effects and mechanisms of proanthocyanidins-derived carbon dots on alleviating salt stress in rice by muti-omics analysis.

Carbon dots (CDs) with different structures were prepared by electrolysis (PE-CDs) and hydrothermal (PH-CDs) methods using proanthocyanidins as precursors. The smaller size and lower zeta potential enabled the PE-CDs treated rice seedlings to exhibit greater resistance to salt stress. The fresh weight of rice seedlings under salt stress was significantly increased by spraying CDs every other day for two weeks. PE-CDs treated group exhibited a faster electron transport rate, and the SOD activity and flavonoid content were 2.5-fold and 0.23-fold higher than those of the salt stress-treated group. Furthermore, the metabolomics and transcriptomics analysis revealed that the PsaC gene of photosystem I was significantly up-regulated under PE-CDs treatment, which accelerated electron transfer in photosystem I. The up-regulation of BX1 and IGL genes encoding indole synthesis allowed rice to enhance stress tolerance through tryptophan and benzoxazine biosynthesis pathways. These findings offer help in purposefully synthesizing CDs and boosting food production.

Soil geochemistry and constraint of tree seedlings immediately after germination on Macrotermes termite mounds in the Kruger National Park, South Africa.

Macrotermes termite mounds in the Kruger National Park occupy a significant part of the savanna landscapes, occurring at densities of up to 70 km-2 and often exceeding 10 m in width and 4 m in height. The mounds are usually devoid of trees, but have dense grass cover in wet years. As a result, these mounds form large patches of grassland amongst the wooded savanna. To our knowledge, it is not known why trees are largely excluded from the mounds. We analysed soil surface nutrient concentrations on and off mounds (0-2 cm deep, n = 80) to ascertain whether the availability of nutrients could be influencing competition between grasses and tree seedlings. The results showed that potential deficiencies in P, Ca, Cu, Zn and B in soils off the mounds are likely to be constraining plant growth. Notably, only B, with an average concentration of 0.19 mg kg-1, was likely to be limiting plant growth on the mounds. Notwithstanding likely interactions with herbivory and fire, we hypothesise that because grasses are far less susceptible to deficiencies of B than dicotyledonous trees, it is likely that grass competition with tree seedlings is considerably greater on mounds than off mounds.

Effects of nitrogen forms on Cd uptake and tolerance in wheat seedlings.

Hydroponic experiment was conducted to explore the effects of two nitrogen (N) levels with five nitrate nitrogen (NO3--N) and ammonium nitrogen (NH4+-N) ratios on the growth status and Cd migration patterns of wheat seedlings under Cd5 and Cd30 level. Results showed that higher Cd were detrimental to the growth, absorption of K and Ca, expression of genes mediating NO3--N and NH4+-N transport, which also increased the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in shoots and roots of wheat seedlings. Higher N treatment alleviated the inhibitory effects of Cd stress on the biomass, root development, photosynthesis and increased the tolerance index of wheat seedlings. The ratio of NO3--N and NH4+-N was the main factor driving Cd accumulation in wheat seedlings, the combined application of NH4+-N and NO3--N was more conducive for the growth, nitrogen assimilation and Cd tolerance to the Cd stressed wheat seedlings. Increased NO3--N application rates significantly up-regulated the expression levels of TaNPF2.12, TaNRT2.2, increased NH4+-N application rates significantly up-regulated the expression levels of TaAMT1.1. The high proportion of NO3--N promoted the absorption of K, Ca and Cd in the shoots and roots of wheat seedlings, while NH4+-N was the opposite. Under low Cd conditions, the NO3--N to NH4+-N ratio of 1:1 was more conducive to the growth of wheat seedlings, under high Cd stress, the optimal of NO3--N to NH4+-N was 1:2 for inhibiting the accumulation of Cd in wheat seedlings. The results indicated that increasing NH4+-N ratio appropriately could inhibit wheat Cd uptake by increasing NH4+, K+ and Ca2+ for K and Ca channels, and promote wheat growth by promoting N assimilation process.

Exogenous application of 5-NGS increased osmotic stress resistance by improving leaf photosynthetic physiology and antioxidant capacity in maize.

Background: Drought is a critical limiting factor affecting the growth and development of spring maize (Zea mays L.) seedlings in northeastern China. Sodium 5-nitroguaiacol (5-NGS) has been found to enhance plant cell metabolism and promote seedling growth, which may increase drought tolerance. Methods: In the present study, we investigated the response of maize seedlings to foliar application of a 5-NGS solution under osmotic stress induced by polyethylene glycol (PEG-6000). Four treatment groups were established: foliar application of distilled water (CK), foliar application of 5-NGS (NS), osmotic stress + foliar application of distilled water (D), and osmotic stress + foliar application of 5-NGS (DN). Plant characteristics including growth and photosynthetic and antioxidant capacities under the four treatments were evaluated. Results: The results showed that under osmotic stress, the growth of maize seedlings was inhibited, and both the photosynthetic and antioxidant capacities were weakened. Additionally, there were significant increases in the proline and soluble sugar contents and a decrease in seedling relative water content (RWC). However, applying 5-NGS alleviated the impact of osmotic stress on maize seedling growth parameters, particularly the belowground biomass, with a dry mass change of less than 5% and increased relative water content (RWC). Moreover, treatment with 5-NGS mitigated the inhibition of photosynthesis caused by osmotic stress by restoring the net photosynthetic rate (Pn) through an increase in chlorophyll content, photosynthetic electron transport, and intercellular CO2 concentration (Ci). Furthermore, the activity of antioxidant enzymes in the aboveground parts recovered, resulting in an approximately 25% decrease in both malondialdehyde (MDA) and H2O2. Remarkably, the activity of enzymes in the underground parts exhibited more significant changes, with the contents of MDA and H2O2 decreasing by more than 50%. Finally, 5-NGS stimulated the dual roles of soluble sugars as osmoprotectants and energy sources for metabolism under osmotic stress, and the proline content increased by more than 30%. We found that 5-NGS played a role in the accumulation of photosynthates and the effective distribution of resources in maize seedlings. Conclusions: Based on these results, we determined that foliar application of 5-NGS may improve osmotic stress tolerance in maize seedlings. This study serves as a valuable reference for increasing maize yield under drought conditions.

Endophytic non-pathogenic Fusarium oxysporum reorganizes the cell wall in flax seedlings.

Introduction: Flax (Linum usitatissimum) is a crop producing valuable products like seeds and fiber. However, its cultivation faces challenges from environmental stress factors and significant yield losses due to fungal infections. The major threat is Fusarium oxysporum f.sp lini, causing fusarium wilt of flax. Interestingly, within the Fusarium family, there are non-pathogenic strains known as biocontrols, which protect plants from infections caused by pathogenic strains. When exposed to a non-pathogenic strain, flax exhibits defense responses similar to those seen during pathogenic infections. This sensitization process activates immune reactions, preparing the plant to better combat potential pathogenic strains. The plant cell wall is crucial for defending against pathogens. It serves as the primary barrier, blocking pathogen entry into plant cells. Methods: The aim of the study was to investigate the effects of treating flax with a non-pathogenic Fusarium oxysporum strain, focusing on cell wall remodeling. The infection's progress was monitored by determining the fungal DNA content and microscopic observation. The plant defense response was confirmed by an increase in the level of Pathogenesis-Related (PR) genes transcripts. The reorganization of flax cell wall during non-pathogenic Fusarium oxysporum strain infection was examined using Infrared spectroscopy (IR), determination of cell wall polymer content, and analysis of mRNA level of genes involved in their metabolism. Results and discussion: IR analysis revealed reduced cellulose content in flax seedlings after treatment with Fo47 and that the cellulose chains were shorter and more loosely bound. Hemicellulose content was also reduced but only after 12h and 36h. The total pectin content remained unchanged, while the relative share of simple sugars and uronic acids in the pectin fractions changed over time. In addition, a dynamic change in the level of methylesterification of carboxyl groups of pectin was observed in flax seedlings treated with Fo47 compared to untreated seedlings. The increase in lignin content was observed only 48 hours after the treatment with non-pathogenic Fusarium oxysporum. Analysis of mRNA levels of cell wall polymer metabolism genes showed significant changes over time in all analyzed genes. In conclusion, the research suggests that the rearrangement of the cell wall is likely one of the mechanisms behind flax sensitization by the non-pathogenic Fusarium oxysporum strain. Understanding these processes could help in developing strategies to enhance flax's resistance to fusarium wilt and improve its overall yield and quality.

Effects of exogenous glycine betaine on growth and development of tomato seedlings under cold stress.

Low temperature is a type of abiotic stress affecting the tomato (Solanum lycopersicum) growth. Understanding the mechanisms and utilization of exogenous substances underlying plant tolerance to cold stress would lay the foundation for improving temperature resilience in this important crop. Our study is aiming to investigate the effect of exogenous glycine betaine (GB) on tomato seedlings to increase tolerance to low temperatures. By treating tomato seedlings with exogenous GB under low temperature stress, we found that 30 mmol/L exogenous GB can significantly improve the cold tolerance of tomato seedlings. Exogenous GB can influence the enzyme activity of antioxidant defense system and ROS levels in tomato leaves. The seedlings with GB treatment presented higher Fv/Fm value and photochemical activity under cold stress compared with the control. Moreover, analysis of high-throughput plant phenotyping of tomato seedlings also supported that exogenous GB can protect the photosynthetic system of tomato seedlings under cold stress. In addition, we proved that exogenous GB significantly increased the content of endogenous abscisic acid (ABA) and decreased endogenous gibberellin (GA) levels, which protected tomatoes from low temperatures. Meanwhile, transcriptional analysis showed that GB regulated the expression of genes involved in antioxidant capacity, calcium signaling, photosynthesis activity, energy metabolism-related and low temperature pathway-related genes in tomato plants. In conclusion, our findings indicated that exogenous GB, as a cryoprotectant, can enhance plant tolerance to low temperature by improving the antioxidant system, photosynthetic system, hormone signaling, and cold response pathway and so on.

The Role of Snow-Related Environmental Variables in Plant Conservation Plans in the Mediterranean Mountains.

This study aims to analyze the effects that snow cover may have on the survival of one-year-old seedlings from 15 different taxa in the Mediterranean high mountains (Sierra Nevada National Park, SE Spain) in order to have clearer criteria for the planning and management of restoration efforts in these environments. Additionally, the influence of variables that have been scarcely explored up to now is also revised. We use the survival rates of the seedlings observed from the ecological restoration trial as reference values. The survival data analyzed are based on six variables to evaluate their effects. The results confirm that the permanence of snow is a favorable factor for seedlings, independent of the plant community. Contrastingly, a specific type of foundation (stones and rocks) stands out for being clearly unfavorable, regardless of other variables. For both altitude and solar radiation, a worsening of the survival ratio has been observed as they increase. The species' geographic ranges are all shown to be unfavorable for taxa of a boreo-alpine distribution. Finally, the plant community does not have a significant influence on the survival of seedlings. These results provide novel indications to improve the results of the first stages of restoration work in the Mediterranean high mountains. They are also valuable for the management and cataloging of threatened flora, as well as having direct applications in recovery plans and protection lists.

Antifungal Properties of Bio-AgNPs against D. pinodes and F. avenaceum Infection of Pea (Pisum sativum L.) Seedlings.

Ascochyta blight and Fusarium root rot are the most serious fungal diseases of pea, caused by D. pinodes and F. avenaceum, respectively. Due to the lack of fully resistant cultivars, we proposed the use of biologically synthesized silver nanoparticles (bio-AgNPs) as a novel protecting agent. In this study, we evaluated the antifungal properties and effectiveness of bio-AgNPs, in in vitro (poisoned food technique; resazurin assay) and in vivo (seedlings infection) experiments, against D. pinodes and F. avenaceum. Moreover, the effects of diseases on changes in the seedlings' metabolic profiles were analyzed. The MIC for spores of both fungi was 125 mg/L, and bio-AgNPs at 200 mg/L most effectively inhibited the mycelium growth of D. pinodes and F. avenaceum (by 45 and 26%, respectively, measured on the 14th day of incubation). The treatment of seedlings with bio-AgNPs or fungicides before inoculation prevented the development of infection. Bio-AgNPs at concentrations of 200 mg/L for D. pinodes and 100 mg/L for F. avenaceum effectively inhibited infections' spread. The comparison of changes in polar metabolites' profiles revealed disturbances in carbon and nitrogen metabolism in pea seedlings by both pathogenic fungi. The involvement of bio-AgNPs in the mobilization of plant metabolism in response to fungal infection is also discussed.