Promote Plant Development Research Articles

Study of Endophytic Bacteria in Pearl Millet [Pennisetum glaucum (L.) R. Br.] Roots

Aims: The current investigation aims to isolate and identify the root endophytic bacteria from Pearl millet (Pennisetum glaucum) variety MSH-1970, as well as evaluate the qualities that promote plant growth. Study Design: The study involves isolating endophytic bacteria, performing biochemical and molecular characterization, and evaluating their ability to stimulate plant development through biochemical tests. Place and Duration of Study: Departmentof Bioscience and Biotechnology, Banasthali Vidyapith, Tonk, Niwai, Rajasthan, 2022–2023. Methodology: Pearl millet MSH-1970 was planted in pots in the greenhouse of the Department of Bioscience and Biotechnology and endophytic bacterial strains were isolated. The isolates' morphological features were recorded using Bergey's Manual of Systemic Bacteriology, and biochemical testing was done. 16s rRNA gene PCR was used to do molecular characterization of the potential endophyte, and the PCR product was sequenced. Ammonia production, phosphate solubilization, and HCN production were used to identify the properties that promote plant development. Results: The initial culture of endophytic bacteria isolated from the pearl millet variety MSH-1970 yielded 14 colonies on Nutrient agar medium. One of the colonies, BVCA-16 could solubilize phosphate, and generate hydrogen cyanide, and ammonia. Using 16f-16r and 63f-1244r primers, a molecular analysis of BVCA16 revealed 99.92% similarity with Pseudomonas sp. AUS22.The sequence was submitted to Genebank NCBI as Pseudomonas sp. strain BVCA-16, accession number OR350932. Conclusion: In the Pearl millet variety MSH-1970, the endophytic bacteria Pseudomonas sp. strain BVCA-16 was identified and it showed potential to promote plant growth.

Insect frass from upcycling vegetable by-products with cereals: Effects on the soil properties, plant development and soil invertebrate fitness

The use of insects in organic management systems is expanding due to their ability to recycle waste into valuable co-products for agriculture, notably frass, constituted by the insect's excrements, larval exuviae, and remaining undigested feedstock. This study aimed to assess the effects of different application rates of frass (0.16, 0.32, 0.64, 1.28, 2.56 and 5.12%) produced by black soldier fly Hermetia illucens larvae (BSFL) on the survival and reproduction of two non-target invertebrate species, the enchytraeid Enchytraeus crypticus and the collembolan Folsomia candida, and early development of three representative species of crops as onion Allium cepa, turnip Brassica rapa and tomato Solanum lycopersicum. Chemical analyses were conducted to evaluate changes in the soil properties. Results showed that BSFL frass did not impact the invertebrates' survival while significantly enhancing the production of E. crypticus juveniles (after 21 days). F. candida juveniles remained similar (after 28 days). Seed germination decreased at the highest frass rate (5.12%), while the development was promoted at intermediate rates (0.64%–1.28%). The different outcomes may be linked to changes in certain soil parameters, such as the soil pH and electrical conductivity, the soil organic matter, and the availability of nutrients. In summary, frass posed no risk to the tested invertebrate species but may hinder seed germination at high rates, representing a risk for agricultural production. Nevertheless, intermediate rates of BSFL frass promoted plant development, showing potential as a sustainable alternative to conventional fertilizers. Further research is needed to ensure its safe and efficient application in agriculture.

Deciphering Whether Illite, a Natural Clay Mineral, Alleviates Cadmium Stress in Glycine max Plants via Modulation of Phytohormones and Endogenous Antioxidant Defense System

Globally, cadmium (Cd) stress dramatically reduces agricultural yield. Illite, a natural clay mineral, is a low-cost, environmentally acceptable, new promising method of reducing the heavy metal (HM) stress of cereal crops. In research statistics, there is little research on stress tolerance behavior of Illite (IL) on an experimental soybean plant. In the present study, we took IL and examined it for tolerance to Cd, as well as for other plant-growth-promoting (PGP) characteristics in Glycine max (soybean). The results showed that applying clay minerals in different concentrations enhanced the level of SA (defense hormone) and reduced the level of ABA (stress hormone). Cd 1 mM significantly reduces plant growth by altering their morphological characteristics. However, the application of IL significantly enhanced the seedling characteristics, such as root length (RL), 29.6%, shoot length (SL), 14.5%, shoot fresh biomass (SFW), 10.8%, and root fresh biomass (RFB), 6.4%, in comparison with the negative control group. Interestingly, IL 1% also enhanced the chlorophyll content (C.C), 15.5%, and relative water content (RWC), 12.5%, in all treated plants. Moreover, it resulted in an increase in the amount of superoxide dismutase (SOD), phenolics, and flavonoids in soybean plants, while lowering the levels of peroxidase (POD) and H2O2. Furthermore, compared to control plants, soybean plants treated with the Illite exhibited increased Si absorption and lower Cd levels, according to inductively coupled plasma mass spectrometry (ICP-MS). Thus, the IL can operate as an environmentally beneficial biofertilizer and sustainable approach under Cd stress by promoting plant development by activating signaling events.

Mixed Grass Species Enhances Root Production and Plant–Soil Reinforcement

ABSTRACTVegetation is a widely used eco‐friendly approach for slope reinforcement and ecological restoration. As a potential planting strategy, mixed planting of plants is often recommended to improve biodiversity, but the effects of mixed planting on soil reinforcement and slope stability are not yet clear. To address this issue, a study on two typical herbaceous slope protection plants, Chrysopogon zizanioides and Cynodon dactylon, were conducted. The biomechanical characteristics of different herbaceous plants were analyzed, and their root distribution and soil reinforcement performance under single and mixed planting were explored. Results show that mixed planting could significantly increase the number and root area ratio of root systems. At 0.1 cm depth after 42 days, the root number under mixed planting increased by 111.42% compared to vetiver grass monoculture and by 19.57% compared to bermuda grass monoculture. Mixed planting can provide stronger soil reinforcement by increasing apparent cohesion, with a maximum increase in apparent cohesion of 47.9%. The results of slope stability analysis showed that vegetation mainly relied on mechanical reinforcement in the root zone and hydrological reinforcement outside the root zone. After 42 days of growth, mixed planting at 0.1 m depth increased slope stability by 11.94% compared to vetiver grass monoculture and by 27.12% compared to bermuda grass monoculture, with both mechanical and hydrological effects of vegetation significantly enhanced. These findings suggest that mixed planting can promote plant development and growth, improve root production, and enhance plant–soil reinforcement and slope stability during the early establishment of vegetation. Therefore, in formulating slope reinforcement and ecological restoration strategies, more consideration can be given to mixed planting of plants, maximizing the utilization of competition characteristics between plants, and reducing the risk of shallow landslides while improving biodiversity.

Scrutinizing harsh habitats endophytic fungi and their prospective effect on water-stressed maize seedlings.

Drought constitutes a significant abiotic stressor that hinders plant growth and productivity in many countries. Habitat-adapted endophytic fungi offer an environmentally sustainable approach to address this issue by promoting plant development and enhancing resilience against abiotic stresses. In this study, 30 endophytic fungal isolates were recovered from some wild plants in the extreme habitats of Port Said Governorate, Egypt, and evaluated for their drought tolerance using polyethylene glycol (PEG-6000). Only eight isolates demonstrated drought tolerance properties and were further evaluated for their plant growth-promoting biochemical activities and ability to improve maize germination under simulated drought conditions. All eight isolates exhibited enzyme activity for endo-1,4-β-glucanase, amylase, and pectinase, and most displayed significant nutrient mobilization, with siderophores production ranging from 4 to 89%, ammonia production from 1 to 7μmol/ml, and phosphate solubilization from 129to 256µg/ml. Additionally, all isolates showed strong antioxidant activity and high total phenolic content, with some also producing notable levels of indole acetic acid (IAA) and gibberellic acid (GA3) as plant growth hormones. Coating maize grains with spore suspensions of the eight fungal isolates, in general, significantly increased their germination parameters and seedling vigor in vitro under 8% PEG-6000. This enhancement was particularly pronounced with Neurospora sitophila (P8L4M1) and Penicillium tardochrysogenum (P15L4M1), which increased the vigor of maize seedlings by approximately 308% compared to untreated control. Molecular identification of P8L4M1 and P15L4M1 was performed by amplifying the 28S rRNA gene. This study disclosed unique endophytic fungal isolates with promising potential for enhancing drought resistance in maize.

Mechanism of a novel Bacillus subtilis JNF2 in suppressing Fusarium oxysporum f. sp. cucumerium and enhancing cucumber growth.

Cucumber Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerium (FOC), is a prevalent soil-borne disease. In this study, Bacillus subtilis JNF2, isolated from the high incidence area of cucumber Fusarium wilt in Luoyang, demonstrated significant inhibitory effects on FOC and promoted cucumber seedling growth. The biocontrol mechanism of strain JNF2 were elucidated through morphological observation, physiological and biochemical experiments, and whole genome sequence analysis. Pot experiments revealed an 81.33 ± 0.21% control efficacy against Fusarium wilt, surpassing the 64.10 ± 0.06% efficacy of hymexazol. Seedlings inoculated with JNF2 exhibited enhanced stem thickness and leaf area compared to control and hymexazol-treated plants. Physiological tests confirmed JNF2's production of indole-3-acetic acid (IAA), siderophores, and hydrolytic enzymes, such as β-1,3-glucanase, amylase, and protease, which inhibited FOC growth and promoted plant development. Genome analysis identified genes encoding antimicrobial peptides and hydrolases, as well as a novel glycocin synthetic gene cluster. These findings underscore B. subtilis JNF2's potential as a biocontrol agent for sustainable cucumber cultivation.

Isolation of Heavy Metal-Tolerant and Anti-Phytopathogenic Plant Growth-Promoting Bacteria from Soils.

In this study, by isolating multifunctional soil bacteria that can promote plant development, resist heavy metals, exhibit anti-phytopathogenic action against plant diseases, and produce extracellular enzymes, we hope to improve the effectiveness of phytoremediation techniques. To isolate multifunctional soil bacteria, we used soils with diverse characteristics as isolation sources. To look into the diversity and structural traits of the bacterial communities, We conducted amplicon sequencing of the 16S rRNA gene on five types of soils and predicted functional genes using Tax4Fun2. The isolated bacteria were evaluated for their multifunctional capabilities, including heavy metal tolerance, plant growth promotion, anti-phytopathogenic activity, and extracellular enzyme activity. The genes related to plant growth promotion and anti-phytopathogenic activity were most abundant in forest and paddy soils. Burkholderia sp. FZ3 and FZ5 demonstrated excellent heavy metal resistance (≤ 1 mM Cd and ≤ 10 mM Zn), Pantoea sp. FC24 exhibited the highest protease activity (24.90 μmol tyrosine·g-DCW-1·h-1), and Enterobacter sp. PC20 showed superior plant growth promotion, especially in siderophore production. The multifunctional bacteria isolated using traditional methods included three strains (FC24, FZ3, and FZ5) from the forest and one strain (PC20) from paddy field soil. These results indicate that, for the isolation of beneficial soil microorganisms, utilizing target gene information obtained from isolation sources and subsequently exploring target microorganisms is a valuable strategy.

Combined Application of High-Throughput Sequencing and Metabolomics to Evaluate the Microbial Mechanisms of Plant-Growth-Promoting Bacteria in Enhancing the Remediation of Cd-Contaminated Soil by Hybrid Pennisetum

The contamination of soil with the heavy metal cadmium (Cd) is increasingly prominent and severely threatens food security in China. Owing to its low cost, suitable efficacy, and ability to address the shortcomings of plant remediation by enhancing the ability of plants to take up Cd, plant–microbe combination remediation technology has become a research hotspot in heavy metal pollution remediation. A pot experiment was performed to examine the effects of inoculation with the plant-growth-promoting bacterium Brevibacillus sp. SR-9 on the biomass, Cd accumulation, and soil nutrients of hybrid Pennisetum. The purpose of this study was to determine how Brevibacillus sp. SR-9 alleviates stress caused by heavy metal contamination. High-throughput sequencing and metabolomics were used to determine the effects of inoculation on the soil bacterial community composition and microbial metabolic functions associated with hybrid Pennisetum. The results suggest that mutation of Brevibacillus sp. SR-9 effectively alleviates Cd pollution stress, leading to increased biomass and accumulation of Cd in hybrid Pennisetum. The aboveground biomass and the root weight increased by 12.08% and 27.03%, respectively. Additionally, the accumulation of Cd in the aboveground sections and roots increased by 21.16% and 15.50%, respectively. Measurements of the physicochemical properties of the soil revealed that the strain Brevibacillus sp. SR-9 slightly increased the levels of available phosphorus, total nitrogen, total phosphorus, and available potassium. High-throughput DNA sequencing revealed that Brevibacillus sp. SR-9 implantation modified the composition of the soil bacterial community by increasing the average number of Actinobacteria and Bacillus. The total nitrogen content of the soil was positively correlated with the Actinobacteria abundance, total phosphorus level, and available phosphorus level. Metabolomic analysis revealed that inoculation affected the abundance of soil metabolites, and 59 differentially abundant metabolites were identified (p < 0.05). Among these, 14 metabolites presented increased abundance, whereas 45 metabolites presented decreased abundance. Fourteen metabolic pathways were enriched in these metabolites: the folate resistance pathway, the ABC transporter pathway, D-glutamine and D-glutamic acid metabolism, purine metabolism, and pyrimidine metabolism. The abundance of the metabolites was positively correlated with the levels of available phosphorus, total potassium, total phosphorus, and total nitrogen. According to correlation analyses, the development of hybrid Pennisetum and the accumulation of Cd are strongly associated with differentially abundant metabolites, which also impact the abundance of certain bacterial populations. This work revealed that by altering the makeup of microbial communities and their metabolic processes, bacteria that promote plant development can mitigate the stress caused by Cd. These findings reveal the microbiological mechanisms through which these bacteria increase the ability of hybrid Pennisetum to take up the Cd present in contaminated soils.

Potential Nitrogen Fixing Rhizobia Isolated from Some Wild Legumes of Nagaland Based on RAPD with Nif-directed Primer and Their Biochemical Activities

Wild legumes are widely dispersed and can survive in challenging environments as bacteria dwell in their nodules and help each other. Although Nagaland is home to many wild legume varieties, research on the microbial diversity that goes along with them is still in its infancy. This work aimed to characterize several wild legume root nodules and distinguish possible rhizobial isolates using RAPD and nif-directed RPO1 primer. Nodule bacteria were isolated in Yeast extract culture media. Based on their colony morphology, 150 isolates were selected for performing RAPD with nif-directed RPO1 primer. Eighty-four isolates were bonded with RPO1 primer, and a few biochemical tests were conducted on RPO1-positive isolates. Activities that promoted plant development were also investigated for these isolates. Of all the isolates, 18 exhibited phosphate solubilization capacity, while 38 isolates were found to produce IAA. This study entails a large variety of rhizobia in the nodules, which were able to promote growth. Hence, these isolates promise to be bio-fertilizers that could improve agricultural operations.

Effects of Plant Growth Promoting Bacteria on Growth and Essential Oil Production of Peppermint

Peppermint is abundant with organic compounds having therapeutic, coloring, preservative, and other uses for humans. Moreover, peppermint is used in food and perfume industry and as medicine in every corner over the world. Considering the economic and medicinal value of peppermint, there is a significant gap between supply and demand. Therefore, an analysis of the impact of bacteria that promote plant development was carried out on peppermints (Pseudomonas putida and Curtobacterium sp. strain LUW) essential oil production. Under the study, the plant growth parameters, essential oil, chlorophyll and carotenoids, and free proline of leaves were measured. The outcomes demonstrated that the use of both Pseudomonas and Curtobacterium (Plant Growth Promoting Bacteria) in the soil significantly increased root diameter, leaf area, leaf number, plant height, quantity of stems, root length, root volume, dry weight of leaf, and peppermint plants' relative water content by 34.29, 23.34, 36.57, 21.08, 87.5, 12.28, 20.37, 42.62, and 6.46 compared to the control conditions respectively. Furthermore, the application of bacteria in the soil that promotes plant growth raised the total quantity of essential oil, proline, and chlorophyll concentration in the leaf by 50.90, 20.90, and 33.35%, respectively, compared to the control conditions. Moreover, essential oil and proline content increased with Curtobacterium sp. strain application compared to Pseudomonas putida.

THE POTENTIAL OF TEQUIL, A PLANT EXTRACT BASED ON QUILLAJA SAPONARIA, IN SUSTAINABLE AGRICULTURE

More attention is being given to researches of eco-sustainable solutions to be implemented in agriculture, particularly in the presence of plant parasitic nematodes, whose damages have significant global importance. Unsustainable practices, such as fumigation and monoculture, have led to depletion of biodiversity, allowing harmful trophic groups (bacteria, fungi, and nematodes) to prevail, and their negative synergistic action further exacerbating yield losses. Considering the notable and progressive restriction of usable molecules, nematode control strategies must necessarily consider the appropriate integration of methods. The main objective of control is to limit pathogen populations below the damage threshold, rather than aiming at their eradication as mistakenly pursued in the past. This goal can be achieved with the help of solutions that promote plant development through biostimulation of root systems, which are often affected by various organisms in the biosphere. Tequil, through its well-documented synergy of saponins, tannins, and polyphenols, produces invigorating, biostimulating, and strengthening effects on the root system. Indeed, in vitro tests and field trials have highlighted Tequil’s appreciable activity in containing trophic groups, particularly root-knot nematodes of the Meloidogyne genus. Therefore, its use could indirectly contribute to nematode control and limit yield losses. Key Words: Quillaja saponaria, nematodes, bio stimulation, biocontrol, abiotic stresses resistance.

Effectiveness of some plant extracts in biocontrol of induced onion basal rot disease in greenhouse conditions

One of Egypt’s most notable and historically significant vegetable crops is the Liliaceae plant, Allium cepa L. In this study, the effectiveness of methanolic extracts of Artemisia absinthium leaves, Calotropis procera latex, Moringa oleifera seeds, and Syzygium aromaticum clove was investigated in vitro and, in a greenhouse, setting against Fusarium oxysporum, the pathogen that causes onion basal rot in Assiut Governorate, Egypt. The S. aromaticum extract exhibited the inhibition peak (63.3%), whereas the A. absinthium extract had the lowest inhibition impact against F. oxysporum growth (41.1%). The gas chromatography-mass spectroscopy (GC–MS) analysis revealed that 82 important compounds, with abundances ranging from low to high, were present in the tested S. aromaticum’s methanolic extract. The primary components were acetaldehyde, hydroxy- and 2-propanone, 1,1,3,3-tetrachloro-(42.71%), 1,2-ethanediol, and methyl alcohol (34.01%). In comparison to the infected control, the disease severity was significantly reduced by 20% with the use of a plant extracts mixture and Dovex 50% and increased by 62.22% with the use of an extract from A. absinthium. When compared to the infected control, onion plant fresh weight and dry weight were considerably higher under the clove extract therapy. The plant extracts used in this study’s testing contain a number of active ingredients, including amino acids, vitamins, minerals, antioxidants, and enzymes, which is probably why they have such positive impacts. The application of a combination of plant extracts was suggested as a feasible strategy for improving the growth and productivity of onion plants by the study’s findings. More research is needed to comprehend the mechanisms by which plant extracts promote plant development and to optimize the concentration and timing of administration.

Unveiling resilience: coelomic fluid bacteria’s impact on plant metabolism and abiotic stress tolerance

ABSTRACT Earthworms’ coelomic fluid (CF) has been discovered to possess properties that promote plant development. In particular, the earthworm’s coelomic fluid-associated bacteria (CFB) are the primary factor influencing the plants’ response. To investigate this, we used bacteria isolated from the CF and selected based on different plant growth-promoting traits, in a mesocosm ecosystem that includes plants. This experiment aimed to assess their impact on the metabolism of plants growing under abiotic stress environments (alkaline soil and nitrogen (N), phosphate (P), and potassium (K) deficit) and compare the lipid profiles of plants under the various treatments. We used seven different bacterial species isolated from the CF of Aporrectodea molleri and as a plant model Zea mays L. For the metabolomic analysis method, we used gas chromatography-mass spectrometry lipidomic. After observing the metabolomic profiles, we found that a few molecular pathways are involved in how plants react to bacterial biostimulants. The bacterial isolates belonging to Pantoea vagans, Pseudomonas aeruginosa, Bacillus paramycoides, and Bacillus thuringiensis have led to a significant increase in synthesizing several metabolites belonging to various chemical categories. Contrary to predictions, abiotic stress did not cause a drop in the composition and concentration of lipids in plants treated with the CFB, demonstrating the rigidity of the protective mechanisms. The statistical analysis based on the Pearson method revealed a positive significant correlation between plant growth parameters (length of the aerial part, surface of the leaves, and biomass) and some metabolites belonging to fatty acids, carboxylic acids, benzene derivatives, and alkanes. Moreover, the standard metabolic components of all treatments in much higher concentrations during bacterial treatments than the control treatment suggests that the bacteria have stimulated the overexpression of these metabolic components. According to these results, we could assume that plants treated with CFB exhibit an adaptability of abiotic stress defense mechanisms, which may be attributed to the upregulation of genes involved in lipid biosynthesis pathways.

ArPAOs from A. roxburghii showed essential roles in polyamine mediating water stress tolerance

Anoectochilus roxburghii is a precious Chinese herb with excellent pharmacological effects. When meet stress, plants produced polyamines (PAs) which are identified in active tissues and play crucial roles in stress responses. Nevertheless, the molecular mechanism of PAs responding to stress in A. roxburghii were largely unknown. Here, for the first time, three PAOs in A. roxburghii were identified from transcriptome data and functionally analyzed. Expression analysis was performed using fluorescence quantitative PCR and eventually, transgenic Arabidopsis thaliana were created to confirm the biological function of ArPAOs. It was found that the highest expression was in young flower buds and the expression levels of three ArPAO genes in various tissues were also different, which indicated their different catalytic preferences and functions. Under the treatment of exogenous spermine and spermidine, the expression of three ArPAOs fluctuated and the overall expression level increased. Overexpression (OE) of ArPAOs could enhance water stress tolerance through mediating polyamine catabolism. It might because the excessive expression of ArPAOs reduce the content of spermine and spermidine, creating a negative feedback regulation upstream and causes plants manufacturing PAs which reinforce water stress tolerance. Taken together, the study firstly reported the overexpression of ArPAOs enhance plant water stress tolerance and regulate the content of polyamines. This work will provide a vital theoretical foundation for uncovering the operation and regulatory mechanism of ArPAOs in promoting plant development and managing stress.

Increasing the Growth and Production of Eggplant (Solanum melongena L) by Providing Wood Biochar

The cultivation of eggplant (Solanum melongena L.) is a significant aspect of horticultural production in Indonesia. However, the productivity of eggplant remains minimal due to inadequate cultivation practices. An encouraging approach involves utilizing wood biochar as a supplement to improve soil fertility and promote plant development. This study aimed to assess the impact of varying levels of wood biochar application on the development and productivity of eggplant. The study utilized a Randomized Block Design (RBD) to investigate the effects of four different treatments: no biochar, 50 g of biochar per polybag, 100 g of biochar per polybag, and 150 g of biochar per polybag. The findings indicated that the incorporation of wood biochar had a notable impact on the growth and yield of the plants, as evidenced by the increase in plant height, leaf width, fruit weight per fruit, number of fruits per plant, and fruit weight per plant. Among the different treatments, B3 exhibited the most favorable outcomes. The analysis of variance (ANOVA) revealed that there were statistically significant differences between the various treatments (p < 0.05). In summary, using wood biochar has proven to successfully improve eggplant yield in Indonesian soil.

Phytomelatonin maintained chromium toxicity induced oxidative burst in Brassica juncea L. through improving antioxidant system and gene expression

Chromium (Cr) contamination in soils reduces crop yields and poses a remarkable risk to human and plant system. The main objective of this study was to observe the protective mechanisms of exogenously applied melatonin (Mel- 0.05, 0.1, and 0.15 μM) in seedlings of Brassica juncea L. under Cr (0.2 mM) stress. This was accomplished by analysing the plant's morpho-physiological, biochemical, nuclear, membrane, and cellular characteristics, as well as electrolyte leakage. Superoxide, malondialdehyde, and hydrogen peroxide increased with Cr toxicity. Cr also increased electrolyte leakage. Seedlings under Cr stress had 86.4% more superoxide anion and 27.4% more hydrogen peroxide. Electrolyte leakage increased 35.7% owing to Cr toxicity. B. juncea L. cells with high radical levels had membrane and nuclear damage and decreased viability. Besides this, the activities of the antioxidative enzymes, as POD, APOX, SOD, GST, DHAR, GPOX and GR also elevated in the samples subjected to Cr toxicity. Conversely, the activity of catalase was downregulated due to Cr toxicity. In contrast, Mel reduced oxidative damage and conserved membrane integrity in B. juncea seedlings under Cr stress by suppressing ROS generation. Moreover, the activity of antioxidative enzymes that scavenge reactive oxygen species was substantially upregulated by the exogenous application of Mel. The highest concentration of Mel (Mel c- 0.15 μM) applied showed maximum ameliorative effect on the toxicity caused by Cr. It causes alleviation in the activity of SOD, CAT, POD, GPOX, APOX, DHAR, GST and GR by 51.32%, 114%, 26.44%, 48.91%, 87.51%, 149%, 42.30% and 40.24% respectively. Histochemical investigations showed that Mel increased cell survival and reduced ROS-induced membrane and nuclear damage. The findings showed that Mel treatment upregulated several genes, promoting plant development. Its supplementation decreased RBOH1 gene expression in seedling sunder stress. The results supported the hypothesis that Mel concentrations reduce Cr-induced oxidative burst in B. juncea.

Colonization of Solanaceous crops by endophytic and rhizospheric plant growth-promoting bacteria from the native Solanaceae Solanum hindsianum Benth

Plant-associated bacteria are an important tool for sustainable agriculture since the have been shown to play a significant role in the health and productivity of plants through various mechanisms. However, commercial inoculants often fail to produce desired effects due to colonization issues and lack of adaptation to local conditions. In this study, we aimed to evaluate the potential of plant growth-promoting bacteria (PGPB) isolated from Solanum hindsianum, a native plant from the Sonoran Desert, to colonize and promote growth in Solanaceae crops under different irrigation conditions. First, endophytic bacteria were screened for various plant growth-promoting traits, and selected strains were identified as Bacillus, Brevibacillus, Pseudomonas, Acinetobacter, and Siccibacter. Then, endophytic and rhizospheric Pseudomonas isolates, were tested for their tolerance to salinity and osmotic stress and for their ability to induce auxin-responsive gene expression and promote plant development in Arabidopsis. All strains induced strong expression of an auxin reporter gene, while significantly improving root and plant morphology, and showed tolerance to osmotic and salinity stress. In colonization experiments, these strains successfully colonized the root crown and rhizosphere of chili, tomatillo, and tomato plants. However, the endophytic strain showed better colonization ability, especially under low irrigation conditions. Overall, this study demonstrates the potential of native PGPR strains to colonize and promote growth in Solanaceae crops under specific environmental conditions.

Endophytic Fungal Diversity in Hardwickia binata: Bridging the Gap between Traditional and Modern Techniques

Endophytic fungus is crucial for maintaining plant health and defense mechanisms, acting as protective barriers against pathogens, and producing medicinally beneficial bioactive compounds. Genome sequencing and metagenomics have significantly enhanced the understanding of fungal diversity and metabolic capabilities, enabling the identification of new genes and substances. Traditional culture-dependent methods have been complemented by culture-independent techniques, offering a more comprehensive view of fungal diversity. Using both culture-dependent and culture-independent techniques, the present research investigation explored the diversity of endophytic fungi encountered in the foliage of Hardwickia binata. The study examined the topographical characteristics and nutritional content of soil samples collected from the locality of the selected plant sample, H. binata, to better comprehend the effects on the plant’s growth. The balanced nutrient constituted approximately a pH of 7.2, which suggested an alkaline nature and promoted plant development. The ratio of nitrogen, phosphorous, and potassium remained 3:1:1. A total of 25 fungal isolates, categorized into 17 morphotypes, were obtained using the culture-dependent approach; Curvularia and Nigrospora emerged as the most common genera. Furthermore, the prediction of the ITS2 secondary structure supports the identification of species, highlighting a wide variety of fungal species present in H. binata. The culture-independent approach generated 69,570 high-quality sequences, identifying 269 Operational Taxonomic Units (OTUs). The dominant Ascomycota phylum, along with various genera, indicated a rich fungal community associated with H. binata. This study advances the understanding of the endophytic fungus communities that are associated with H. binata and the nature of soil ecology. The findings emphasize the significance of holistic techniques in the study of microbial dynamics within plant systems as well as their implications for ecosystem management and plant health.

Effect of Siderophore Producing Cadmium Tolerant Streptomyces pactum OR958669 on Plant Growth of Groundnut (Arachis hypogaea L.)

Cadmium is a dangerous environmental contaminant that disturbs numerous ecological and environmental systems while being poisonous to plants and the microbial life. The present research attempted to utilize previously isolated Streptomyces pactum OR958669 from polluted soil to promote plant development and prevent cadmium's detrimental impacts. Streptomyces pactum OR958669 was chosen for this because it was the highly Cd-tolerant isolate and produced a significant amount of siderophore (43.94%). It was isolated from agricultural soil that had been polluted by pesticides. The impact of Cd (1000ppm) and Streptomyces pactum OR958669 on some physiological traits of the Groundnut plants grown for 10 weeks were determined. Plant’s root and shoot development (length, fresh and dry masses), number of leaves, N, P, K, and Mg concentrations all diminished when they were irrigated with water that included heavy metals. Heavy metals reduced the amount of chlorophyll (Chl) in the leaves and the number of soluble proteins in the shoots, but it raised the amounts of total soluble carbohydrates and proline. Utilizing Streptomyces pactum OR958669 to the test soil increased the plant's resistance to heavy metals, which had an impact on the majority of the test characteristics. In order to increase agricultural productivity, it was determined that adding Streptomyces pactum OR958669 to the soil produced siderophores effectively and inexpensively.

Valorization of steelmaking slag and coal fly ash as amendments in combination with Betula pubescens for the remediation of a highly As- and Hg-polluted mining soil

Soil pollution by As and Hg is a pressing environmental issue given their persistence. The intricate removal processes and subsequent accumulation of these elements in soil adversely impact plant growth and pose risks to other organisms in the food chain and to underground aquifers. Here we assessed the effectiveness of non-toxic industrial byproducts, namely coal fly ash and steelmaking slag, as soil amendments, both independently and in conjunction with an organic fertilizer. This approach was coupled with a phytoremediation technique involving Betula pubescens to tackle soil highly contaminated. Greenhouse experiments were conducted to evaluate amendments' impact on the growth, physiology, and biochemistry of the plant. Additionally, a permeable barrier made of byproducts was placed beneath the soil to treat leachates. The application of the byproducts reduced pollutant availability, the production of contaminated leachates, and pollutant accumulation in plants, thereby promoting plant development and survival. Conversely, the addition of the fertilizer alone led to an increase in As accumulation in plants and induced the production of antioxidant compounds such as carotenoids and free proline. Notably, all amendments led to increased thiolic compound production without affecting chlorophyll synthesis. While fertilizer application significantly decreased parameters associated with oxidative stress, such as hydrogen peroxide and malondialdehyde, no substantial reduction was observed after byproduct application. Thermal desorption analysis of the byproducts revealed Hg immobilization mechanisms, thereby indicating retention of this metalloid in the form of Hg chloride. In summary, the revalorization of industrial byproducts in the context of the circular economy holds promise for effectively immobilizing metal(loid)s in heavily polluted soils. Additionally, this approach can be enhanced through synergies with phytoremediation.