Indole-3-acetic Acid Research Articles

The Promotion of Dark Septate Endophytes on the Performance and Active Ingredients Accumulation of Dendranthema morifolium Under Cd Stress

Dark septate endophytes (DSE) may facilitate plant growth and stress tolerance in stressful ecosystems. However, little is known about the response of medicinal plants to DSE, especially under heavy metal stress. This study aimed to investigate how DSE affects the growth of Dendranthema morifolium in medicinal plants under cadmium (Cd) stress. In this investigation, the sterile and non-sterile inoculations were carried out to evaluate the effect of three DSE strains on D. morifolium stressed with Cd. For the root, DSE15 sterile or non-sterile inoculation resulted in enhanced root biomass, root volume, the Cd content of roots, and the indoleacetic acid (IAA) levels in D. morifolium under Cd stress. DSE7 non-sterile inoculation significantly enhanced the Cd content of roots at 1 and 5 mg Cd/kg soil. Regarding impact stems and leaves, under sterile conditions, DSE7 and DSE15 effectively regulated the shoot biomass, plant height, chlorophyll level, and superoxide dismutase (SOD) content. Under sterile conditions, DSE15 positively influenced shoot biomass and plant height, while DSE7 had no significant effect on them when subjected to Cd stress. For effects on flowers under non-sterile conditions, DSE7 and DSE15 significantly increased the flower biomass under Cd stress, while DSE7 reduced the Cd transfer coefficient of flowers at 1 and 5 mg Cd/kg soil. Importantly, at 1 mg Cd/kg soil, DSE7 and DSE15 non-sterile inoculations promoted the 1, 5-dicaffeoylquinic acid content by 18.29% and 21.70%. The interaction between DSE and soil factors revealed that DSE species had significant effects on soil organic carbon and available nitrogen in D. morifolium non-sterile soil. The DSE15 inoculation enhanced soil organic carbon content, while the inoculation of DSE7 and DSE15 reduced soil available nitrogen content under Cd stress. These results contribute to a better understanding of DSE-plant interactions in habitats contaminated by heavy metals and demonstrate the potential utility of DSE strains for cultivating medicinal plants.

Plant Growth Promoting Fungi (PGPF) for Ecologically Sound Agriculture and its Market Trend Evolution

Amidst the escalating concerns regarding the detrimental impact of harmful agrochemicals, the development of organic fertilizers has assumed paramount importance in curbing reliance on syntheticcounterparts within agricultural practices. Plant growth promoting fungi (PGPF) has emerged as a promising solution, owing to its capacity to enhance plant development via many pathways, including siderophore synthesis, phosphate solubilizationand indole-3-acetic acid (IAA) production, along side other beneficial traits such as stress tolerance and biocontrol activity. The increasing awareness of the adverse consequences of harsh agrochemicals has prompted a shift towards organic biofertilizers, aligning with the principles of sustainable agriculture. Numerous countries have already begun implementing stringent regulations on use of harmful chemicals while actively promoting the adoption of microbe-based products to enhance plant growth. While it’s not feasible to completely eliminate synthetic agrochemicals overnight, the incorporation of biofertilizers can substantially reduce their usage. The principal goal of this comprehensive review is to delve into the pivotal role of PGPF in fostering environmentally responsible agriculture. Additionally, it digs into the emerging market trends linked with products based on PGPF.

Molecular Characterization and Plant Growth Promotion Potential of Paenibacillus Dendritiformis Endophyte Isolated from Tecomella Undulata (Roheda)

In this study, we have isolated a bacterial endophyte Paenibacillus dendritiformis strain RAE13 (Accession number: OR259131) from the leaves of Tecomella undulata (Roheda) plant. The identification of bacterial species was carried out using 16s-rDNA ribotyping. Subsequently, the isolated bacterial strain was gauged for its potential to endorse plant growth through various mechanisms such as nitrogen fixation, IAA production, HCN synthesis, siderophore generation, and ammonia production. Furthermore, the evaluation focused on the endophyte's capacity for producing extracellular enzymes, including cellulase, chitinase, protease, amylase, and catalase. The endophyte exhibited to synthesize an average of 18±0.375 μg/ml of indole-3-acetic acid (IAA) after being subjected to a concentration of 5 mg/ml of tryptophan over a 14-day incubation period. The endophytic isolate RAE 13 produced an average of 42.4±0.004 μg/ml of Gibberellin, solubilized phosphate in the range of 70.2 μg/ml to 135.5 μg/ml, and produced an average of 45.5 μg/ml of ammonia. The phylogenetic analysis unveiled that the isolated strain RAE13 had a common ancestor and had a maximum nucleotide sequence similarity of 98.30% with Paenibacillus sp isolates of Uttar Pradesh, India. To diminish the consumption of chemicals in conventional farming, the results indicated that the isolated endophyte had great potential as a plant growth-stimulating inoculant. Henceforward, utilization of these extracellular enzymes for medical and industrial applications will be highly beneficial. Additionally, it could enhance plant tolerance to challenging environmental circumstances including drought and high temperatures.

Maternal Gut Inflammation Aggravates Acute Liver Failure Through Facilitating Ferroptosis via Altering Gut Microbial Metabolism in Offspring.

Microbial transmission from mother to infant is important for offspring microbiome formation and health. However, it is unclear whether maternal gut inflammation (MGI) during lactation influences mother-to-infant microbial transmission and offspring microbiota and disease susceptibility. In this study, it is found that MGI during lactation altered the gut microbiota of suckling pups by shaping the maternal microbiota in the gut and mammary glands. MGI-induced changes in the gut microbiota of suckling pups lasted into adulthood, resulting in the exacerbation of acute liver failure (ALF) caused by acetaminophen (APAP) in offspring. Specifically, MGI reduced the abundance of Lactobacillus reuteri (L. reuteri) and its metabolite indole-3-acetic acid (IAA) level in adult offspring. L. reuteri and IAA alleviated ALF in mice by promoting intestinal IL-22 production. Mechanistically, IL-22 limits APAP-induced excessive oxidative stress and ferroptosis by activating STAT3. The intestinal abundances of L. reuteri and IAA are inversely associated with the progression of patients with ALF. Overall, the study reveals the role of MGI in mother-to-infant microbial transmission and disease development in offspring, highlighting potential strategies for intervention in ALF based on the IAA-IL-22-STAT3 axis.

Unlocking olive rhizobacteria: harnessing biocontrol power to combat olive root rot and promote plant growth.

Olive trees are susceptible to various diseases, notably root rot caused by Pythium spp., which presents significant challenges to cultivation. Conventional chemical control methods have limitations, necessitating exploration of eco-friendly alternatives like biological control strategies. This study aims to evaluate the potential of rhizobacteria in managing Pythium schmitthenneri-induced root rot in olive trees. We screened 140 bacteria isolated from olive tree rhizospheres for antifungal activity against the pathogen in vitro. Twelve isolates exhibited promising antifungal activity, identified through 16S rDNA gene sequencing as primarily Bacillus, Pseudomonas, Stenotrophomonas, and Alcaligenes species. Particularly, Pseudomonas koreensis (A28 and A29), Pseudomonas reinekei (A16), and Bacillus halotolerans (A10) were the highest effective strains. Mechanistic investigations revealed positive protease production in all twelve isolates, with eight producing amylase and cellulase. Chitinase activity was absent, while five solubilized tricalcium phosphate. Furthermore, eight secreted hydrocyanic acid (HCN), ten synthesized indole-3-acetic acid (IAA), and nine produced siderophores. Variability existed in antimicrobial substance production, including bacillomycin (seven isolates), iturin (eleven isolates), fengycin (two isolates), and surfactin (three isolates). Plant growth-promoting rhizobacteria (PGPR) capabilities were assessed using canola (Brassica napus) seedlings, showing enhanced growth in treated seedlings compared to controls. Greenhouse experiments confirmed the biocontrol efficacy of P. koreensis A28 and Bacillus subtilis C6 against root rot disease. These findings suggest these strains could serve as promising tools for managing olive tree root rot, offering a sustainable alternative to hazardous agrochemicals.

Cultivation of Siberian Motherwort Plants (Leonurus sibiricus L.) in In Vitro Culture

In this study, an attempt was made to micropropagate the Siberian motherwort (Leonurus sibiricus L.) in in vitro cultures. The aim of this study was to compare methods of sterilization of seeds, which served as a source of initial explants to induce in vitro culture and to multiply shoots from explants isolated from them. The primary explants in the experiment were seeds. The seeds were placed on ½ MS medium without PGR and enriched with GA3 at a concentration of 1 mg∙dm−3. The addition of GA3 to the medium stimulated their germination. Sodium hypochlorite (NaClO) and 70% ethanol (C2H5OH) were used to sterilize the seeds. NaClO was used for proper sterilization in concentrations: 0.0% (1), 1.5% (2), 2% (3), and 2.5% (4) for 11 min. As secondary explants in the experiment, single-node fragments of sterile seedlings derived from sterile seeds were used, which were placed on MS medium, with the addition of plant growth regulators (PGR) from the group of auxins and cytokinins. The largest number of sterile and live Siberian motherwort seedlings was obtained in the variant in which 2.5% NaClO was used for proper sterilization of the seeds. To optimize the procedure of in vitro micropropagation, the axillary shoots of Leonurus sibiricus L. were transferred during the third passage onto nine different combinations of MS medium: PGR-free medium, with different concentrations of BAP (6-benzylaminopurine) (0.0, 2.0, 3.0, 4.0, 5.0 mg∙dm−3) and BAP (0.0, 2.0, 3.0, 4.0, 5.0 mg∙dm−3) with NAA (1-naphthaleneacetic acid) (1.0 mg∙dm−3). The largest number of shoots (9.62) forming was obtained on the medium supplemented with 4 mg∙dm−3 BAP and 1 mg∙dm−3 NAA, while the longest shoots were on the medium without PGR. Induction of rhizogenesis of Siberian motherwort plants in in vitro cultures was achieved on MS medium with the addition of 0.5 mg∙dm−3 IAA (indole-3-acetic acid). At the stage of adaptation to ex vitro conditions, high plant survival of 90% was achieved by using a solution with MS salts (25%) for irrigation.

Use of Light-Emitting Diodes on the In Vitro Rooting of Apple Tree Rootstocks

This study presents a pioneering investigation into the use of Light Emitting Diodes (LEDs) for in vitro rooting of ‘Marubakaido’ apple tree rootstocks, marking the first report of this approach in the literature. The research evaluates the effects of four distinct light sources: blue LED (450 nm), red LED (660 nm), a combination of red and blue LEDs, and traditional fluorescent lamps as a control. Mini-cuttings were inoculated in Murashige and Skoog (MS) medium with reduced nutrient concentrations, supplemented with indoleacetic acid (IAA) and sucrose. The explants were incubated under controlled conditions for 30 days, enabling a comprehensive assessment of the impact of different light sources on various growth metrics. The results revealed that blue LEDs significantly enhanced dry mass accumulation in seedlings compared to both red LEDs and fluorescent lamps, demonstrating their superior effectiveness in promoting plant growth. The use of LEDs not only improves seedling development but also offers economic advantages over fluorescent lamps. LEDs are characterized by high luminous efficiency, low energy consumption, and a long operational lifespan, which collectively reduce costs in plant production systems. This research advances the understanding of light-mediated effects on plant tissue culture and highlights the potential of combining blue and red LEDs as a viable alternative to fluorescent lighting. These findings could revolutionize practices in horticulture and plant propagation, providing a more efficient and sustainable approach to in vitro cultivation.

Evaluation of In Vitro Production Capabilities of Indole Derivatives by Lactic Acid Bacteria

Lactic acid Bacteria (LAB) convert tryptophan to indole derivatives and induce protective IL-22 production in vivo. However, differences in metabolizing capabilities among LAB species have not been widely investigated. In the present study, we compared the capabilities of 186 LAB strains to produce four kinds of indole derivatives, including indole-3-carboxaldehyde (IAId), indole-3-lactic acid (ILA), indole-3-propanoic acid (IPA), and indole-3-acetic acid (IAA). These strains were isolated from fermented foods, dairy products, and the feces of healthy individuals, as well as from fish and shrimp from Shanxi and Jiangsu provinces. They represent 15 genera, including Bifidobacterium, Enterococcus, Lacticaseibacillus, Lactiplantibacillus, Lactobacillus, Lactococcus, Limosilactobacillus, Pediococcus, Streptococcus, Weissella, Latilactobacillus, Levilactobacillus, Ligilactobacillus, and Loigolactobacillus. The results indicate widespread IAId-producing capabilities in LAB strains, with positive rates of approximately 90% (106/117) and 100% (69/69) among strains from Shanxi and Jiangsu provinces, respectively. The concentrations of IAId ranged from 72.42 ng/mL to 423.14 ng/mL in all positive strains from Shanxi Province and from 169.39 ng/mL to 503.51 ng/mL in strains from Jiangsu Province. Intriguingly, we also observed specific ILA-producing capabilities in Lactiplantibacillus strains, with positive rates of 55.17% (16/29) and 80.95% (17/21) among strains isolated from Shanxi and Jiangsu provinces, respectively. The overall detection rates of ILA among all tested strains (including both Lactiplantibacillus and other genus strains) were 17.9% (21/117) and 26.1% (18/69). The concentrations of ILA in positive strains ranged from 12.22 ng/mL to 101.86 ng/mL and from 5.75 ng/mL to 62.96 ng/mL from Shanxi and Jiangsu provinces, respectively. IPA and IAA were not detected in any strains. Finally, these indole derivative-producing capabilities were not related to their geographical origins or isolation sources. The current study provides insights into the species- or genus-dependent capabilities for metabolizing indole derivatives. Defining the specific roles of LAB in indole derivative metabolism will uncover the exact physiological mechanisms and be helpful for functional strain screening.

Transcriptome Analysis and Phytohormone Profile Reveal Core Phytohormone Regulating Parthenocarpy in Fingered Citron

Background: Parthenocarpy, the development of fruit without fertilization, is a significant trait in fingered citron (Citrus medica L. var. sarcodactylis Swingle). This study aims to elucidate the regulatory mechanisms underlying parthenocarpy through comparative transcriptome analysis and phytohormone profiling between fingered citron and its non-parthenocarpic counterpart, citron. Results: A total of 66 differentially expressed hormone-related genes were identified, with the auxin pathway emerging as the most prominent in fingered citron. Protein–protein interaction analysis revealed a potential interaction between auxin and abscisic acid (ABA). Phytohormone content analysis indicated that fingered citron exhibited higher levels of indole-3-acetic acid (IAA) and lower levels of ABA compared to citron. A weighted gene co-expression network analysis (WGCNA) suggested that the interplay between auxin and ABA is crucial for triggering parthenocarpy. Virus-induced gene silencing (VIGS) experiments demonstrated that silencing CmsABI5 led to decreased ABA levels, while auxin levels remained unchanged, resulting in disrupted parthenocarpy and increased ethylene levels, indicating a secondary hormonal response. Additionally, gene expression changes associated with failed parthenocarpy showed down-regulation of SAUR50 and up-regulation of PP2C 56, linking these changes to ABA signaling. Conclusions: Our findings highlight the central regulatory role of auxin in parthenocarpy in fingered citron, with ABA acting as a critical modulator. The suppression of ABA alone disrupts parthenocarpy despite stable auxin levels, emphasizing the necessity of balanced hormone interactions. This research underscores the significant role of auxin, rather than gibberellin (GA), in regulating parthenocarpy in fingered citron, contributing valuable insights to the understanding of fruit development mechanisms.

The response of Petunia × atkinsiana 'Pegasus Special Burgundy Bicolor’ to mechanical stress encompassing morphological changes as well as physiological and molecular factors

In 1973, Jaffe identified and characterized the phenomenon of thigmomorphogenesis, also referred to as mechanical stress (MS) or mechanical stimulation in plants. Previous studies on petunia plants demonstrated that MS significantly affects growth dynamics. As a response to MS, petunias exhibit increased levels of indole-3-acetic acid (IAA) oxidase and peroxidase, although the active transport of endogenous IAA remains unaffected. Furthermore, earlier research has shown that MS inhibits the synthesis of IAA and gibberellin (GA3), with noticeable effects on the 14th day of mechanical stimulation. The current experiment made on Petunia × atkinsiana 'Pegasus Special Burgundy Bicolor’ focused on evaluating the morphological and physiological responses to MS, along with the expression of specific touch-responsive genes such as GH3.1, which is involved in auxin metabolism, and calmodulins (CaMs), playing an important role in stress responses. GH3.1 expression was found to be negatively correlated with IAA synthesis while positively correlated with GAs synthesis and IAA oxidase activity. Variable expression patterns were observed in the calmodulins: CAM53 and CAM81 expression positively correlated with IAA synthesis and plant height, whereas CAM72 expression was positively associated with GAs levels and IAA oxidase activity in plants touched 80× per day, but all of them were negatively related to IAA content and shoot increment, while positively related to GAs synthesis and IAA oxidase activity.

Improvement of plant growth and fruit quality by introducing a phosphoribosylpyrophosphate synthetase mutation into Methylorubrum populi.

The aim of this study was to evaluate the impact of the introduction of a phosphoribosylpyrophosphate synthetase (PRS) mutation into a plant growth-promoting strain of Methylorubrum on the enhancement of phyllosphere colonization, with the ultimate goal of improving plant growth and quality. A strain of Methylorubrum populi (named HS04) was isolated from the groundnut leave and found to process the plant-promoting traits, including the ability to produce indole acetic acid, siderophore, 1-aminocyclopropane-1- carboxylate deaminase, and to fix nitrogen. The application via foliar spray significantly increased the fresh weight of cucumber seedlings cultivated in a standard growth chamber, with 43.0% higher than the control group. Genomic analysis revealed that the presence of an array of genes involved in plant growth promotion, including accD, aldB, ltaE as well as potential nitrogen-fixation-related genes, including nifA, bchlLNB and bchXYZ, in the HS04 strain. The introduction of the PRS mutation (an aspartic acid to an asparagine residue, D38N) in the HS04 strain (named HS04PTR) enhanced the utilization capacity of low concentrations of methanol and multi-carbon sources (C2 to C5 carbon sources). The HS04PTR strain indicated a notable enhancement in the phyllosphere colonization, with the subsequent application further promoting the growth of cucumber seedlings. An agricultural solar greenhouse experiment was thus performed to assess the efficiency of the HS04PTR strain, sprayed at low abundance, in improving the growth and quality of cucumber plants, including vitamin C, reducing sugars, and total sugars. Our findings provide insights into the potential of Methylorubrum/ Methylobacterium strains with the PRS mutations as an efficient inoculant for advantageous agricultural applications.

Phytohormonal homeostasis, chloroplast stability, and heat shock transcription pathways related to the adaptability of creeping bentgrass species to heat stress.

Creeping bentgrass (Agrostis stolonifera) is a cool-season perennial turfgrass and is frequently utilized in high-quality turf areas. However, a poor to moderate resistance to heat stress limits its promotion and utilization in transitional and worm climate zones. The objectives of the study were to assess the heat tolerance of 18 creeping bentgrass genotypes in the field and to further uncover differential mechanisms of heat tolerance between heat-tolerant and heat-sensitive genotypes. The results showed that 18 different genotypes had different heat tolerance during summer months of 2021 and 2022. Among them, 13M was identified as the best heat-tolerant cultivar based on the subordinate function values analysis of five physiological indicators. Under controlled growth conditions, heat stress significantly inhibited photosynthetic capacity and also accelerated oxidative damage and chlorophyll (Chl) degradation in both heat-tolerant 13M and heat-sensitive PA4. However, as compared with heat-sensitive PA4, 13M maintained significantly higher net photosynthetic rate, water use efficiency, and total antioxidant capacity as well as less Chl degradation and damage to chloroplast ultrastructure. Significantly higher contents of abscisic acid, cytokinin, gibberellin, and polyamines (spermine, spermidine, and putrescine) were also detected in 13M than that in PA4 in the later stage of heat stress, but 13M exhibited significantly lower indoleacetic acid content than PA4 during heat stress. In addition, heat-upregulated genes involved in heat shock transcriptional pathways were more pronounced in 13M than in PA4. These findings indicated that better heat tolerance of 13M could be related to more stable Chl metabolism, better photosynthetic and antioxidant capacities, endogenous hormonal homeostasis, and more effective heat shock transcriptional pathway. 13M is more appropriate for planting in transitional and subtropical zones instead of widely used PA4.

Systems analysis of long-term heat stress responses in the C4 grass Setaria viridis.

Many C4 plants are used as food and fodder crops and often display improved resource use efficiency compared to C3 plants. However, the response of C4 plants to future extreme conditions such as heatwaves is less understood. Here, Setaria viridis, an emerging C4 model grass, was grown under long-term high temperature stress for two weeks (42°C, compared to 28°C). This resulted in stunted growth, but surprisingly had little impact on leaf thickness, leaf area-based photosynthetic rates and bundle sheath leakiness. Dark respiration rates increased and there were major alterations in carbon and nitrogen metabolism in the heat-stressed plants. Abscisic acid and indole-acetic acid-amino acid conjugates accumulated in the heat-stressed plants, consistent with transcriptional changes. Leaf transcriptomics, proteomics and metabolomics analyses were carried out and mapped onto the metabolic pathways of photosynthesis, respiration, carbon/nitrogen metabolism and phytohormone biosynthesis and signaling. An in-depth analysis of correlations between transcripts and their corresponding proteins revealed strong differences between groups in the strengths and signs of correlations. Overall, many stress signaling pathways were upregulated, consistent with multiple signals leading to reduced plant growth. A systems-based model of the plant response to long-term heat stress is presented based on the oxidative stress, phytohormone and sugar signaling pathways.

Assessment of the Effects of Temperature and Time on the Bacteriological Quality and Heavy Metal of Digestate as a Safe Biofertiliser

The chemical composition and microbial diversity influence the safety, quality and utility of digestate. This study investigated the minimum temperature and time for conversion of digestate to a safe biofertilizer. Digestate, a byproduct of anaerobic digestion was treated at various temperatures, 28 ± 2, 55, 60, 70 and 80 °C at varying durations, 0, 20, 30, 40 and 60 minutes. The potential for rhizobacteria was examined and essentially, at 70 °C and 40 min bacterial counts were 8.05 ± 0.71 × 102 cfu/ml and less than the 1000 cfu/ml permissible limits. At this temperature and time, there were no recorded counts of Salmonella or Escherichiae. Identified species were Pseudomonas sp, Proteus spp., Enterobacter sp., Escherichia coli, Citrobacter sp., Klebsiella sp, Enterococcus sp., Streptococcus sp., Bacillus sp., Yersinia sp., Salmonella sp and Shigella sp. Physicochemical result suggests that digestate processed at 70 °C and 40 mins possess pH, total nitrogen, nitrate and total phosphorus within defined standards while heavy metal concentration was below permissible limits. The rhizobacterial screening showed that Pseudomonas sp., Proteus sp., Bacillus sp. and Streptococcus sp. tested positive for phosphate solubilization, nitrogen fixation, ammonia production and induction of indole acetic acid. Overall, digestate may be successfully deployed as a safe biofertilizer when treated at suitable temperature and time for enhance plant growth.

Bioinformatics and Expression Profiling of the DHHC-CRD S-Acyltransferases Reveal Their Roles in Growth and Stress Response in Woodland Strawberry (Fragaria vesca).

Protein S-acyl transferases (PATs) are a family of enzymes that catalyze protein S-acylation, a post-translational lipid modification involved in protein membrane targeting, trafficking, stability, and protein-protein interaction. S-acylation plays important roles in plant growth, development, and stress responses. Here, we report the genome-wide analysis of the PAT family genes in the woodland strawberry (Fragaria vesca), a model plant for studying the economically important Rosaceae family. In total, 21 'Asp-His-His-Cys' Cys Rich Domain (DHHC-CRD)-containing sequences were identified, named here as FvPAT1-21. Expression profiling by reverse transcription quantitative PCR (RT-qPCR) showed that all the 21 FvPATs were expressed ubiquitously in seedlings and different tissues from adult plants, with notably high levels present in vegetative tissues and young fruits. Treating seedlings with hormones indole-3-acetic acid (IAA), abscisic acid (ABA), and salicylic acid (SA) rapidly increased the transcription of most FvPATs. A complementation assay in yeast PAT mutant akr1 and auto-S-acylation assay of one FvPAT (FvPAT19) confirmed its enzyme activity where the Cys in the DHHC motif was required. An AlphaFold prediction of the DHHC and the mutated DHHC155S of FvPAT19 provided further proof of the importance of C155 in fatty acid binding. Together, our data clearly demonstrated that S-acylation catalyzed by FvPATs plays important roles in growth, development, and stress signaling in strawberries. These preliminary results could contribute to further research to understand S-acylation in strawberries and plants in general.

Elucidating the Underlying Allelopathy Effects of Euphorbia jolkinii on Arundinella hookeri Using Metabolomics Profiling.

Euphorbia jolkinii dominates the subalpine meadows in Shangri-La (Southwest China) owing to its potent allelopathic effects. However, the effects underlying its allelopathy require further characterization at the physiological and molecular levels. In this study, the physiological, biochemical, and metabolic mechanisms underlying E. jolkinii allelopathy were investigated using Arundinella hookeri as a receptor plant. The treatment of A. hookeri seedlings with E. jolkinii aqueous extract (EJAE) disrupted their growth by inhibiting photosynthesis, disrupting oxidation systems, and increasing soluble sugar accumulation and chlorophyll synthesis. Collectively, this causes severe impairment accompanied by abnormal photosynthesis and reduced biomass accumulation. Moreover, EJAE treatment suppressed gibberellin, indoleacetic acid, zeatin, salicylic acid, and jasmonic acid levels while promoting abscisic acid accumulation. Further metabolomic analyses identified numerous differentially abundant metabolites primarily enriched in the α-linolenic, phenylpropanoid, and flavonoid biosynthesis pathways in EJAE-treated A. hookeri seedlings. This study demonstrated that E. jolkinii exhibits potent and comprehensive allelopathic effects on receptor plants, including a significant disruption of endogenous hormone synthesis, the inhibition of photosynthesis, an impairment of membrane and oxidation systems, and changes in crucial metabolic processes associated with α-linolenic, phenylpropanoid, and flavonoid biosynthesis. Thus, our study provides a solid theoretical foundation for understanding the regulatory mechanisms underlying E. jolkinii allelopathy.

Functional Analysis of Durum Wheat GASA1 Protein as a Biotechnological Alternative Against Plant Fungal Pathogens and a Positive Regulator of Biotic Stress Defense.

Plants are frequently challenged by a variety of microorganisms. To protect themselves against harmful invaders, they have evolved highly effective defense mechanisms, including the synthesis of numerous types of antimicrobial peptides (AMPs). Snakins are such compounds, encoded by the GASA (Gibberellic Acid-Stimulated Arabidopsis) gene family, and are involved in the response to biotic and abiotic stress. Here, we examined the function of the newly identified TdGASA1 gene and its encoded protein in Triticum durum subjected to different biotic stress-related simulants, such as mechanical injury, methyl jasmonate (MeJA), indole-3-acetic acid (IAA), salicylic acid (SA), hydrogen peroxide (H2O2), as well as infection with pathogenic fungi Fusarium graminearum and Aspergillus niger. We found that in durum wheat, TdGASA1 transcripts were markedly increased in response to these stress simulants. Isolated and purified TdGASA1 protein exhibited significant antifungal activity in the growth inhibition test conducted on eight species of pathogenic fungi on solid and liquid media. Transgenic Arabidopsis lines overexpressing TdGASA1 obtained in this study showed higher tolerance to detrimental effects of H2O2, MeJA, and ABA treatment. In addition, these lines exhibited resistance to Fusarium graminearum and Aspergillus niger, which was linked to a marked increase in antioxidant activity in the leaves under stress conditions. This resistance was correlated with the upregulation of pathogenesis-related genes (AtPDF1.2a, AtERF1, AtVSP2, AtMYC2, AtPR1, AtACS6, AtETR1, and AtLOX2) in the transgenic lines. Overall, our results indicate that TdGASA1 gene and its encoded protein respond ubiquitously to a range of biotic stimuli and seem to be crucial for the basal resistance of plants against pathogenic fungi. This gene could therefore be a valuable target for genetic engineering to enhance wheat resistance to biotic stress.

Continuous-flow chemo-enzymatic gram-scale synthesis of indole-3-acetic acid

In this work, a chemo-enzymatic reaction was developed to synthesize indole-3-acetic acid (IAA) in a continuous flow mode.

Elevated CO2 alleviates negative impacts of high temperature and salinity on phytohormones, photosynthesis, and redox reactions in leaves of Caragana korshinskii kom.

In this research, we sought to investigate how high temperature, salinity, and CO2 affect endogenous phytohormones, photosynthesis, and redox homeostasis in Caragana korshinskii Kom (C. korshinskii) leaves, as well as to comprehensively evaluate the plant's physiological response to multiple environmental stressors. The elevated temperature (e[T]), elevated Na+ (e[Na]), and elevated temperature and Na+ (e[T-Na]) treatments increased abscisic acid (ABA) and reduced zeatin-riboside (ZR), indole-3-acetic acid (IAA), and gibberellic acid (GA3). These changes induced stomatal closure, and the subsequent reduction in photosynthetic rate triggered the generation of superoxide anion (O2·-) and hydrogen peroxide (H2O2). In response, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity increased, and free proline and total soluble sugars were accumulated. However, membrane lipid peroxidation was still aggravated. Under elevated CO2 (e[CO2]), the dramatic hormonal fluctuations and photosynthetic inhibition resulting from e[T], e[Na], and e[T-Na] were alleviated. Moreover, e[CO2] reduced ROS generation caused by e[T], e[Na], and e[T-Na], and stabilized antioxidant enzyme activities and non-enzymatic compound concentrations. Compared with e[T], e[Na], and e[T-Na], the increased malondialdehyde (MDA) content was effectively alleviated under elevated CO2 and temperature (e[CO2-T]), elevated CO2 and Na+ (e[CO2-Na]), and elevated CO2, temperature, and Na+ (e[CO2-T-Na]). Overall, our research suggest that e[CO2] may alleviate the negative impacts of e[T] and e[Na] on plant physiology.

Nanoscale‑boron nitride positively alters rhizosphere microbial communities and subsequent cucumber (Cucumis sativa) growth: A metagenomic analysis.

Boron (B) deficiency affects over 132 crop species globally, making effective B supplement crucial for enhancing agricultural yield and health. This study explores an innovative application of nanoscale boron nitride (nano-BN) as a sustainable solution for addressing B deficiency in crops. Cucumber seedlings were treated with different contents of nano-BN under greenhouse conditions and both B and N ionic treatments were set as comparisons. Results show that soil application of 10mg/kg nano-BN achieved a remarkable 15.8% increase in fresh weight compared to the control. Notably, nano-BN exhibited superior efficiency in providing essential micronutrients without inducing toxicity as compared to traditional ionic B sources. Phytohormone correlation analysis reveals that nano-BN application significantly enhances levels of indole-3-acetic acid (IAA) and cytokinins while reducing abscisic acid (ABA), fostering optimal plant growth conditions. Furthermore, increases in dissolved organic matter (DOM) and dissolved organic carbon (DOC) levels in the rhizosphere improve nutrient availability and promote beneficial microbial activity in the soil as affected by nano-BN. Metagenomics techniques were used to investigate the impact of nano-BN on soil carbon and nitrogen cycling, alongside its effects on the soil microbiome. The upregulation of genes associated with fermentation pathways as affected by nano-BN suggests the enhanced carbon cycling. Additionally, nano-BN upregulated a number of functional genes involved in nitrogen-based processes, leading to a significant increase in microorganisms harboring nitrogen-fixing genes, including Phenylobacterium, Novosphingobium, and Reyranella. Overall, these findings provide valuable insight into the application of nano-BN in agriculture to sustainably increase crop productivity and enhance the efficiency of carbon and nitrogen cycling.