Indole-3-acetic Acid Research Articles

Isolation, identification, characterization and in vitro assay of saline tolerant endophytes against groundnut root rot caused by Rhizoctonia bataticola (Taub.) Butler

Groundnut, known as Arachis hypogaea L., is India's significant oil seed crop. Dry root rot, caused by Rhizoctonia bataticola, poses a substantial challenge to cultivating groundnuts. During the roving survey, 60.50% dry root rot disease incidence was recorded in Namakkal district, Tamil Nadu. This study aims to acquire salt-tolerant endophytic bacteria residing in groundnuts with significant antagonistic activity against R. bataticola. A total of 27 bacterial strains were isolated from groundnuts. Among these strains, RMV 3 and RMV 2 are the most effective isolates, exhibiting 60.1% and 50% inhibition zones, respectively. The effective isolates were characterized through morphological, biochemical and phytostimulation activities and 16S rDNA sequencing. Among the isolates, RMV 3 and RMV 2 showed positive results for siderophore, indole acetic acid (IAA) and cellulase test. The strain RMV 3 was identified as Bacillus subtilis through 16S rDNA sequencing. GC-MS analysis identified twenty bioactive compounds produced by B. subtilis RMV 3, such as pyrrolo [12-a] pyrazine-14-dione hexahydro-3 (2-methylpropyl) and hexadecanoic acid methyl ester. The crude metabolite assay demonstrated a 96.6% inhibition of R. bataticola by RMV 3. This study demonstrated that Bacillus subtilis RMV 3, which exhibits a robust antagonistic effect on R. bataticola, can potentially be an effective biocontrol agent for groundnut dry root rot.

The Effects of Lead and Cross-Talk Between Lead and Pea Aphids on Defence Responses of Pea Seedlings.

The main goal of this study was to investigate the effect of lead (Pb) at various concentrations, as an abiotic factor, and the cross-talk between Pb and pea aphid (Acyrthosiphon pisum (Harris)) (Hemiptera: Aphididae), as a biotic factor, on the defence responses of pea seedlings (Pisum sativum L. cv. Cysterski). The analysis of growth parameters for pea seedlings demonstrated that Pb at a low concentration, i.e., 0.025-0.0625 mM Pb(NO3)2, caused a hormesis effect, i.e., stimulation of seedling growth, whereas Pb at higher concentrations, i.e., 0.01-0.325 mM Pb(NO3)2, inhibited growth, which manifested as the inhibition of length and fresh biomass. The differences in the level of the main defence-related phytohormones, such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA), and indole-3-acetic acid (IAA)-an auxin stimulating plant cell growth-depended on the dose of Pb, aphid infestation and direct contact of the stress factor with the organ. A high accumulation of soluble sugars in the organs of pea seedlings both at sublethal doses and hormetic doses at early experimental time points was observed. At 0 h and 24 h of the experiment, the hormetic doses of Pb significantly stimulated invertase activities, especially in the roots. Moreover, an increase was observed in the pisatin concentration in pea seedlings growing in the presence of different concentrations of Pb and in the case of cross-talk between Pb and A. pisum in relation to the control. Additionally, a significant induction of the expressions of isoflavone synthase (IFS) and 6α-hydroxymaackiain 3-O-methyltransferase (HMM) genes, which participate in the regulation of the pisatin biosynthesis pathway, in pea seedlings growing under the influence of sublethal 0.5 mM Pb(NO3)2 and hormetic 0.075 mM Pb(NO3)2 doses of Pb was noted. The obtained results showed that the response of P. sativum seedlings depends on the Pb dose applied, direct contact of the stress factor with the organ and the duration of contact.

Prospects of iron solubilizing Bacillus species for improving growth and iron in maize (Zea mays L.) under axenic conditions

Iron (Fe) deficiency in calcareous soils is a significant agricultural challenge, affecting crop productivity and nutritional quality. This study aimed to isolate, characterize, and evaluate Fe solubilizing rhizobacterial isolates from maize rhizosphere in calcareous soils as potential biofertilizers. Forty bacterial isolates coded as SG1, SG2, …, SG40 were isolated and screened for siderophore production, with ten showing significant Fe solubilizing capabilities. These isolates were further assessed for phosphate solubilization and exopolysaccharides production. The selected bacterial isolates were also screened under axenic conditions for their ability to improve maize growth. The isolates SG8, SG13, SG24, SG30 and SG33 significantly enhanced growth parameters of maize. Notably, SG30 showed highest increment in shoot length (58%), root length (54%), root fresh and dry biomass (67% and 76%), SPAD value (67%), relative water contents (69%), root surface area (61%), and Fe concentration in shoots (79%) as compared to control. The biochemical characterization of these strains showed that all these strains have capability to solubilize insoluble phosphorus, produce indole-3-acetic acid (IAA), and ammonia with catalase, urease and protease activity. Molecular identification through 16s rRNA gene sequencing confirmed high similarity (99.7–100%) of the selected isolates to various Bacillus species, including B. pyramidoids, B. firmicutes, and B. cereus. The study provides a strong base for developing eco-friendly, cost-effective biofertilizers to address Fe deficiency in crops and promote sustainable agriculture.

Suppression of Thielaviopsis ethacetica wilt and root rot, the emerging pathogen on bell pepper (Capsicum annuum), and plant growth promotion properties by the safety indigenous Streptomyces SBcT04

Thielaviopsis ethacetica is an emerging pathogen responsible for wilt and root rot in bell peppers, significantly impacting crop yield. Biological control of the fungal pathogen provides significant advantages as a safe and efficient alternative to excessive chemical fungicides for managing plant diseases. Studying the screened and selected potential actinomycete strain from the indigenous collection is a quick and efficient measure to protect the yield of local bell pepper crops. The research assessed the indigenous actinomycete's ability to inhibit plant pathogens and promote plant growth both in vitro and in vivo. The Streptomyces SBcT04 was the most effective against T. ethacetica TROC-2 pathogen in vitro. The inhibition percentage reached 89.15 ± 0.46%. SBcT04 also effectively promoted plant growth properties in vitro. This strain fixed nitrogen and produced substantial amounts of indole-3-acetic acid (IAA), siderophores, and enzymes. Furthermore, the safety characteristics of SBcT04 for both the host plant (in vivo) and animals (in vitro) were confirmed. Streptomyces SBcT04 significantly processed pathogens, resulting in a reduction of approximately 40% in disease severity. Additionally, SBcT04 significantly promoted the host plant's growth, even in the presence of T. ethacetica TROC-2 infection. The indigenous Streptomyces SBcT04 efficiently inhibited T. ethacetica and significantly enhanced bell pepper plant growth. These advantageous characteristics of SBcT04 indicate its potential to foster secure and sustainable local bell pepper agricultural output.

ОПТИМИЗАЦИЯ СОСТАВА ПИТАТЕЛЬНОЙ СРЕДЫ И УСЛОВИЙ КУЛЬТИВИРОВАНИЯ ДЛЯ МИКРОРАЗМНОЖЕНИЯ IN VITRO THYMUS SERPYLLUM L. И THYMUS CAUCASICUS WILLD.

The study was conducted to optimize the cultivation conditions for the second stage of clonal micropropagation of Thymus caucasicus Willd. and Thymus serpullum L. Stem segments with one node (8…10 mm), obtained by microcutting of shoots, were cultured on 10 different Murashige and Skoog (MS) nutrient media containing 2% sucrose and 0.8% agar-agar, with the addition of kinetin, thidiazuron, benzylaminopurine (BAP), indoleacetic and gibberellic acids. Various culture vessels (jars, flasks, test tubes) were used for micropropagation. The duration of the cultivation cycle varied from 40 to 70 days. The highest reproduction coefficient of T. serpyllum was noted on the MS medium containing 1.0 mg/l BAP and was 6.7, while that of T. caucasicus was on the MS medium containing 1.0 mg/l kinetin (16.1). The highest efficiency of culturing both thyme species was achieved in jars, with the use of which the reproduction coefficient was 1.4…2.1 times higher than when grown in test tubes or flasks. It is advisable to cultivate the studied thyme species with a standard cycle of 40 days. The best combinations of various thyme reproduction factors contributed to the maximum manifestation of the morphogenetic potential in in vitro experiments. The greatest influence on the multiplication coefficient was exerted by the type of culture vessel, the interaction of the composition of the nutrient medium and the genotype, as well as the composition of the nutrient medium (the shares of the influence of factors ranged from 20.0% to 25.3%). The results of the studies served as the basis for the development of a protocol that can be used for accelerated micropropagation of T. caucasicus and T. serpullum.

Physiological and transcriptomic responses of microalgal-bacterial co-culture reveal nutrient removal and lipid production during biogas slurry treatment.

Microalgal-bacterial consortia can treat biogas slurry and produce high-value products. This study found that co-cultures of Desmodesmus sp. and Bacillus megaterium improved nutrient removal, biomass production, and lipid accumulation in Desmodesmus sp. Dual transcriptomic analyses revealed that B. megaterium upregulated genes associated with glycolysis, the Calvin cycle, tricarboxylic acid cycle, indole acetic acid synthesis, and fatty acid biosynthesis in Desmodesmus sp. Under a high C/N ratio, key genes involved in fatty acid degradation were downregulated, promoting lipid accumulation in co-cultured Desmodesmus sp. Effective NH4+-N removal in the co-culture under a high C/N ratio was attributed to microbial interactions. Desmodesmus sp. downregulated the URE gene in bacteria, inhibiting urea hydrolysis, while B. megaterium upregulated the URE and gdhA genes in microalgae, promoting urea utilization and NH4+-N assimilation. This study provides new insights into the transcriptional regulation in nutrient assimilation and lipid metabolism in microalgal-bacterial consortia.

Copper sulfate-induced stress in Spinach: Metabolic pathway disruption and plant response

Copper sulfate (CuSO4) stress profoundly affects plant growth by interfering with key metabolic pathways. This disruption leads to significant alterations in various physiological parameters, ultimately impacting the overall health and productivity of the plant. This study assessed the impact of CuSO4 stress on spinach (Spinacia oleracea L.) through a pot experiment using CuSO4 concentrations of 0, 75, 125, and 175 ppm. We noticed that at 75 ppm, CuSO4 improved plant height and the concentration of soluble sugar and ascorbic acid compared to the control. Additionally, amino acid, phenol, proline, fresh weight, and moisture content peaked at 175 ppm. Conversely, at 125 and 175 ppm, plant height, dry weight, leaf area, and concentrations of ascorbic acid and sugar significantly decreased. Moreover, at 175 ppm, there were substantial decreases in chlorophyll a (14.8%), chlorophyll b (73.6%), carotenoids (15%), and photosynthetic rates compared to the control. However, the chlorophyll a to chlorophyll b ratio increased by 29.53% at 175 ppm. In addition, protein and phenol contents diminished at 75 and 125 ppm. Elevated CuSO4 levels increased non-protein thiol levels while reducing the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase. Stress hormones such as abscisic acid, jasmonic acid, and ethylene increased with CuSO4 stress, whereas growth hormones indol-acetic acid and gibberellic acid declined. This study demonstrates that spinach shows improved growth and metabolic function at 75 ppm CuSO4, indicating tolerance to mild stress. However, higher CuSO4 concentrations (125 and 175 ppm) significantly reduce growth parameters, chlorophyll content, and enzyme activities, highlighting the need for careful CuSO4 management in agriculture to avoid adverse effects on plant health and productivity.

Engineering peroxisomal surface display for enhanced biosynthesis in the emerging yeast Kluyveromyces marxianus

The non-conventional yeast Kluyveromyces marxianus is a promising microbial host for industrial biomanufacturing. With the recent development of Cas9-based genome editing systems and other novel synthetic biology tools for K. marxianus, engineering of this yeast has become far more accessible. Enzyme colocalization is a proven approach to increase pathway flux and the synthesis of non-native products. Here, we engineer K. marxianus to enable peroxisomal surface display, an enzyme colocalization technique for displaying enzymes on the peroxisome membrane via an anchoring motif from the peroxin Pex15. The native KmPex15 anchoring motif was identified and fused to GFP, resulting in successful localization to the surface of the peroxisomes. To demonstrate the advantages for pathway localization, the Pseudomonas savastanoi IaaM and IaaH enzymes were co-displayed on the peroxisome surface; this increased production of indole-acetic acid 7.9-fold via substrate channeling effects. We then redirected pathway flux by displaying the violacein pathway enzymes VioE and VioD from Chromobacterium violaceum, increasing selectivity of proviolacein to prodeoxyviolacein by 2.5-fold. Finally, we improved direct access to peroxisomal acetyl-CoA and increased titers of the polyketide triacetic acid lactone (TAL) by 2-fold through concurrent display of the proteins Cat2, Acc1, and the type III PKS 2-pyrone synthase from Gerbera hybrida relative to the same three enzymes diffusing in the cytosol. We further improved TAL production by up to 2.1-fold through engineering peroxisome morphology and lifespan. Our findings demonstrate that peroxisomal surface display is an efficient enzyme colocalization strategy in K. marxianus and applicable for improving production of a wide range of non-native products.

Establishment of the auxin inducible degron system for Babesia duncani: a conditional knockdown tool to study precise protein regulation in Babesia spp.

BackgroundBabesia duncani is a pathogen within the phylum Apicomplexa that causes human babesiosis. It poses a significant threat to public health, as it can be transmitted not only through tick bites but also via blood transfusion. Consequently, an understanding of the gene functions of this pathogen is necessary for the development of drugs and vaccines. However, the absence of conditional gene knockdown tools has hindered the research on this pathogen. The auxin-inducible degron (AID) system is a rapid, reversible conditional knockdown system widely used in gene function studies. Thus, there is an urgent need to establish the AID system in B. duncani to study essential gene functions.MethodsThe endogenous genes of the Skp1-Cullin-F-box (SCF) complex in B. duncani were identified and confirmed through multiple sequence alignment and conserved domain analysis. The expression of the F-box protein TIR1 from Oryza sativa (OsTIR1) was achieved by constructing a transgenic parasite strain using a homologous recombination strategy. Polymerase chain reaction (PCR), western blot, and indirect immunofluorescence assay (IFA) were used to confirm the correct monoclonal parasite strain. The degradation of enhanced green fluorescent protein (eGFP) tagged with an AID degron was detected through western blot and live-cell fluorescence microscopy after treatment of indole-3-acetic acid (IAA).ResultsIn this study, Skp1, Cul1, and Rbx1 of the SCF complex in B. duncani were identified through sequence alignment and domain analysis. A pure BdTIR1 strain with expression of the OsTIR1 gene was constructed through homologous recombination and confirmed. This strain showed no significant differences from the wild type (WT) in terms of growth rate and proportions of different parasite forms. The eGFP tagged with an AID degron was successfully induced for degradation using 500 μM IAA. Grayscale analysis of western blot indicated a 61.3% reduction in eGFP expression levels, while fluorescence intensity analysis showed a 77.5% decrease in fluorescence intensity. Increasing the IAA concentration to 2 mM accelerated eGFP degradation and enhanced the extent of degradation.ConclusionsThis study demonstrated the functionality of the AID system in regulating protein levels by inducing rapid degradation of eGFP using IAA, providing an important research tool for studying essential gene functions related to invasion, egress, and virulence of B. duncani. Moreover, it also offers a construction strategy for apicomplexan parasites that have not developed an AID system.Graphical

Microbe-Friendly Plants Enable Beneficial Interactions with Soil Rhizosphere Bacteria by Lowering Their Defense Responses.

The use of plant growth-promoting rhizobacteria presents a promising addition to conventional mineral fertilizer use and an alternative strategy for sustainable agricultural crop production. However, genotypic variations in the plant host may result in variability of the beneficial effects from these plant-microbe interactions. This study examined growth promotion effects of commercial vegetable crop cultivars of tomato, cucumber and broccoli following application with five rhizosphere bacteria. Biochemical assays revealed that the bacterial strains used possess several nutrient acquisition traits that benefit plants, including nitrogen fixation, phosphate solubilization, biofilm formation, and indole-3-acetic acid (IAA) production. However, different host cultivars displayed genotype-specific responses from the inoculations, resulting in significant (p < 0.05) plant growth promotion in some cultivars but insignificant (p > 0.05) or no growth promotion in others. Gene expression profiling in tomato cultivars revealed that these cultivar-specific phenotypes are reflected in differential expressions of defense and nutrient acquisition genes, suggesting that plants can be categorized into "microbe-friendly" cultivars (with little or no defense responses against beneficial microbes) and "microbe-hostile" cultivars (with strong defense responses). These results validate the notion that "microbe-friendly" (positive interaction with rhizosphere microbes) should be considered an important trait in breeding programs when developing new cultivars which could result in improved crop yields.

Sustainable bioconversion of rice straw into indole-3-acetic acid by Streptomyces coelicoflavus using response surface methodology

AbstractRice straw is an abundant agricultural waste that poses environmental disposal challenges and can be utilized for biotechnological applications. This study investigates the potential of actinobacteria to enhance rice straw biodegradation and sustainable indole-3-acetic acid (IAA) production, addressing the need for sustainable agricultural practices. Certain actinobacteria strains can effectively degrade rice straw while optimizing IAA production under controlled fermentation conditions. Twenty actinobacteria isolates were screened for lignocellulolytic enzyme activity, and ten were selected for rice straw biodegradation. IAA production was further optimized using response surface methodology based on temperature, pH, and agitation speed (RPM). Isolate S16 achieved a degradation rate of 68.75%, while S18 produced the highest IAA concentration (1040.625 μg/mL) under optimized conditions (25 °C, pH 9, 160 RPM). The purified IAA significantly improved Medicago sativa L. growth. Furthermore, the 16S rRNA gene sequence of isolate S18 was identified it as Streptomyces coelicoflavus strain NSH24 with accession number PP 320383.1. These findings underscore the potential of actinobacteria to efficiently convert agricultural waste into valuable bioproducts and promote sustainable farming practices. By transforming rice straw into high-value products like IAA, this approach contributes to a circular economy, offering an environmentally friendly solution for biomass utilization and agricultural sustainability.

The Adaptive Mechanism of Ginseng Rhizomes in Response to Habitat Changes

Panax ginseng, a perennial medicinal plant, utilizes its dried roots and rhizomes for medicinal purposes. Currently, in China, ginseng cultivation employs two methods: under-forest and farmland planting. These methods create distinct habitats, significantly influencing the ginseng’s rhizome morphology and, consequently, its economic value. In this study, two-year-old ginsengs were transplanted into farmland (TCG), a larch forest (TLCG) and a Quercus mongolica forest (TQCG) to analyze the differences in rhizome phenotypes caused by habitat changes. The results showed that there were significant differences in light intensity and the soil’s available phosphorus and potassium contents between farmland and forest environments. The differences in habitats led to different adaptability of the ginseng’s rhizome morphology. Compared with TCG, the rhizomes of TLCG and TQCG were significantly elongated by 48.36% and 67.34%, respectively. After the rhizomes’ elongation in TLCG and TQCG, there was an increase in indole-3-acetic acid (IAA) contents and a decrease in lignin contents. By analyzing the expression of key genes, we found that, compared with TCG, the expression of key enzymes of lignin biosynthesis genes such as PgCOMT and PgCCR4 were down-regulated. The difference in ginseng’s rhizome length is related to the signal transduction pathway of auxin and gibberellin. In addition, we preliminarily screened out transcription factors PgWRKY75, PgDIV, and PgbHLH93.1, which can actively respond to habitat changes and play important roles in the elongation of ginseng rhizomes. In summary, this study elucidates the phenotypic plasticity strategy of ginseng rhizomes in response to habitat changes and delineates the regulatory mechanism behind phenotypic adaptation, offering novel insights into ginseng’s morphogenesis.

Synergistic effects of SAP and PGPR on physiological characteristics of leaves and soil enzyme activities in the rhizosphere of poplar seedlings under drought stress.

Super absorbent polymers (SAP) provide moisture conditions that allow plant growth-promoting rhizobacteria (PGPR) to enter the soil for acclimatization and strain propagation. However, the effects of SAP co-applied with PGPR on the physiological characteristics of leaves and rhizosphere soil enzyme activities of poplar seedlings are not well understood. Here, a pot experiment using one-year-old poplar seedlings with five treatments, normal watering, drought stress (DR), drought stress + SAP (DR+SAP), drought stress + Priestia megaterium (DR +PGPR) and drought stress + SAP + P. megaterium (DR+S+P), was performed to analyze the contents of non-enzymatic antioxidants, osmotic regulators and hormones in leaves, as well as rhizosphere soil enzyme activities. Compared with normal watering, the DR treatment significantly decreased the contents of dehydroascorbate (DHA; 19.08%), reduced glutathione (GSH; 14.18%), oxidized glutathione, soluble protein (26.84%), indoleacetic acid (IAA; 9.47%), gibberellin (GA) and zeatin (ZT), the IAA/abscisic acid (ABA), GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (34.67%) ratios in leaves, and the urease and sucrase activities in the rhizosphere soil. Additionally, it significantly increased the soluble sugar, proline and ABA contents in leaves. However, in comparison with the DR treatment, the DR+S+P treatment significantly increased the DHA (29.63%), GSH (15.13%), oxidized glutathione, soluble protein (29.15%), IAA (12.55%) and GA contents, the IAA/ABA, GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (46.85%) ratios in leaves, and the urease, sucrose and catalase activities in rhizosphere soil to different degrees. The soluble sugar, proline and ABA contents markedly reduced in comparison to the DR treatment. The effects of the DR+SAP and DR+PGPR treatments were generally weaker than those of the DR+S+P treatment. Thus, under drought-stress conditions, the simultaneous addition of SAP and P. megaterium enhanced the drought adaptive capacities of poplar seedlings by regulating the non-enzymatic antioxidants, osmotic regulators, and endogenous hormone content and balance in poplar seedling leaves, as well as by improving the rhizosphere soil enzyme activities.

Ginsenoside Rg1 enriches gut microbial indole-3-acetic acid to alleviate depression-like behavior in mice via oxytocin signaling

Background and purposeAlthough a large collection of data has shown that ginsenosides, the major active ingredients from Ginseng, have neuroprotective and anti-depressant effect, the mechanism of action is incompletely understood. This study aims to elucidate the antidepressant mechanism of ginsenoside Rg1 (Rg1), a poorly absorbed ginsenoside, from the perspective of gut microbe to brain signaling. MethodsA mouse model of depression was induced by unpredictable mild stress (UMS). Behavioral and neurochemical tests were conducted to evaluate the effect and mechanism of Rg1 on depressive behavior. Non-target and target metabolomics were performed to identify the signaling metabolites underlying the antidepressant efficacy of Rg1. Gut microbial structure was analyzed by 16S rRNA sequencing and the potential functional strains associated with Rg1 action were investigated by in vitro bacterial culture. Chemical intervention was used to explore the mechanism of Rg1 and signaling metabolite. ResultsRg1 improved UMS-induced despair, anxiety-like and social avoidance behaviors in mice, which were accompanied by increased hypothalamic oxytocin secretion and restored neural proliferation in the hippocampus. Metabolomic analysis of the gut-brain axis revealed that Rg1 increased the concentration of serum and brain indole-3-acetic acid (IAA), a bacterial metabolite that was partially attributed to the enrichment of Lactobacillus murinus in the gut microbiome. Oral supplementation of IAA mimicked the anti-depressant action of Rg1, while oxytocin receptor antagonist abrogated the anti-depressant effects of both Rg1 and IAA. ConclusionOur work provides a new gut-to-brain signaling mechanism for the antidepressant effects of Rg1. In particular, Rg1 enriches the abundance of Lactobacillus murinus, which in turn increases the level of brain IAA and potentiates hypothalamic oxytocin signal. These findings suggest a promising pathway for producing antidepressant effects through gut-brain crosstalk.

Overexpression of wheat C2H2 zinc finger protein transcription factor TaZAT8-5B enhances drought tolerance and root growth in Arabidopsis thaliana.

TaZAT8-5B, a C2H2 zinc finger protein transcription factor, positively regulates drought tolerance in transgenic Arabidopsis. It promotes root growth under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. C2H2 zinc finger proteins (C2H2-ZFPs) represent the largest but relatively unexplored family of transcription factors in plants. This is particularly evident in wheat, where the functions of only a few C2H2-ZFP genes have been confirmed. In this study, we identified a novel C2H2-ZFP gene, TaZAT8-5B. This gene shows high expression in roots and flowers and is significantly induced by heat, drought, and salt stress. Under drought stress, overexpressing TaZAT8-5B in Arabidopsis resulted in increased proline content and superoxide dismutase (SOD) activity in leaves. It also led to reduced stomatal aperture and water loss, while inducing the expression of P5CS1, RD29A, and DREB1A. Consequently, it alleviated drought stress-induced malondialdehyde (MDA) accumulation and improved drought tolerance. Additionally, TaZAT8-5B promoted lateral root initiation under mannitol stress and enhanced both lateral and primary root growth under long-term drought stress. Moreover, TaZAT8-5B was induced by indole-3-acetic acid (IAA). Overexpressing TaZAT8-5B under drought stress significantly inhibited the expression of auxin signaling negative regulatory genes IAA12 and IAA14. Conversely, downstream genes (ARF7, LBD16, LBD18, and CDKA1) of IAA14 and IAA12 were upregulated in TaZAT8-5B overexpressing plants compared to wild-type (WT) plants. These findings suggest that TaZAT8-5B regulates root growth and development under drought stress via the Aux/IAA-ARF module in the auxin signaling pathway. In summary, this study elucidates the role of TaZAT8-5B in enhancing drought tolerance and its involvement in root growth and development through the auxin signaling pathway. These findings offer new insights into the functional analysis of homologous genes of TaZAT8-5B, particularly in Gramineae species.

The Ability of Endophytic Bacteria in Phosphate Solubilization and IAA Production on Chili Plant Growth

Biofertilizer is considered an alternative to chemical fertilizers for enhancing plant productivity while minimizing ecological damage. Endophytic bacteria have the ability to solubilize phosphate and produce IAA (indole acetic acid). The aim of this research is to assess the phosphate solubilization and IAA production abilities of bacterial isolates applied to chili plants. Seven bacterial isolates collection from the Microbiology Laboratory, Universitas Sumatera Utara, were tested. In quantitative tests conducted in vitro, isolates MB10 and MB11 demonstrated the highest phosphate solubilization capabilities, yielding solubilization indices of 16.2 mm and 9.5 mm, respectively. Additionally, the ability of bacterial isolates to produce IAA in vitro was evaluated using calorimetry, revealing that isolates MB8 and MB2 produced the highest concentrations of IAA, measuring 58.58 ppm and 54.64 ppm, respectively. Furthermore, in vivo application involved the inoculation of isolates MB10 and MB11 on chili plants for 30 days. Seed treatment with suspensions of isolates MB10 and MB11 resulted in decreased plant performance compared to the control. These findings indicate that some endophytic bacteria originating from the mangrove root Avicennia marina have potential for producing relatively high levels of secondary metabolites. However, direct application did not significantly enhance plant growth performance.

An Efficient System for Agrobacterium-Mediated Transformation of Elite Cultivars in Brassica juncea

Efficient genetic transformation approaches play pivotal roles in both gene function research and crop breeding. However, stable transformation in mustard, particularly for different horticultural types, has not been systematically studied and well-established so far. In this study, we optimized the key factors in the genetic transformation of mustard, including the optical density value of Agrobacterium suspension, the age of explants, and the combination of phytohormones at different concentrations. As a result, the optimal conditions for the genetic transformation of leaf and stem mustard included hypocotyl explants derived from 4-day-old seedlings, infection by 0.8 OD600nm Agrobacterium suspension, and then re-differentiation on a medium containing 4 mg/L trans-zeatin (tZ) and 0.1 mg/L indoleacetic acid (IAA) for leaf mustard, and for stem mustard, re-differentiation on a medium containing 2 mg/L tZ and 0.4 mg/L IAA, with positive rates of 4.74% and 5.26%, respectively. Those for root mustard were hypocotyl explants derived from 8-day-old seedlings, infection by 0.2 OD600nmAgrobacterium suspension, and a medium containing 2 mg/L tZ and 0.1 mg/L IAA, with a positive rate of 4.42%. Overall, this work provides an effective tool for both the theoretical study and genetic improvement of Brassica juncea.

Isolation and Identification of Multi-Traits PGPR for Sustainable Crop Productivity Under Salinity Stress

High salinity poses a significant threat to arable land globally and contributes to desertification. Growth-promoting rhizobacteria assist plants in mitigating abiotic stresses and enhancing crop productivity through the production of siderophores, exopolysaccharides (EPS), solubilisation of phosphate, indole-3-acetic acid (IAA), and other secondary metabolites. This study aimed to isolate, identify, and characterise bacteria that exhibit robust growth-promoting properties. A total of 64 bacterial isolates from the rhizosphere of Miscanthus sinensis were evaluated for plant growth-promoting (PGP) traits, including IAA, EPS, siderophores, and solubilisation of phosphate. Among them, five isolates were selected as plant growth-promoting rhizobacteria (PGPR) based on their PGP features and identified via 16S rRNA sequencing: Enterococcus mundtii strain INJ1 (OR122486), Lysinibacillus fusiformis strain INJ2 (OR122488), Lysinibacillus sphaericus strain MIIA20 (OR122490), Pseudomonas qingdaonensis strain BD1 (OR122487), and Pseudomonas qingdaonensis strain MIA20 (OR122489), all documented in NCBI GenBank. BD1 demonstrated a higher production of superoxide dismutase (SOD) (17.93 U/mg mL), catalase (CAT) (91.17 U/mg mL), and glutathione (GSH) (0.18 U/mg mL), along with higher concentrations of IAA (31.69 µg/mL) and salicylic acid (SA) (14.08 ng/mL). These isolates also produced significant quantities of amino and organic acids. BD1 exhibited superior PGP traits compared to other isolates. Furthermore, the NaCl tolerance of these bacterial isolates was assessed by measuring their growth at concentrations ranging from 0 to 200 mM at 8-h intervals. Optical density (OD) measurements indicated that BD1 and INJ2 displayed significant tolerance to salt stress. The utilisation of these isolates, which enhances plant growth and PGP traits under salt stress, may improve plant development under saline conditions.

Synergizing Bacillus halotolerans, Pseudomonas sihuiensis and Bacillus atrophaeus with folic acid for enhanced drought resistance in wheat by metabolites and antioxidants

Drought stress imposes a serious challenge to cultivate wheat, restricting its growth. Drought reduces the capability of plant to uptake essential nutrients. This causes stunted growth, development and yield. Traditional ways to increase wheat growth under drought stress have shortcomings. Using plant-growth-promoting rhizobacteria (PGPR) has proved feasible and eco-friendly way to enhance wheat growth even under the drought stress. Combining PGPR in consortiums further boosts up their effects. In this study, we have checked the efficacy of drought-tolerant Bacillus halotolerans, Pseudomonas sihuiensis and Bacillus atrophaeus in combination. These strains were allowed to grow on PEG 6000 with concentrations (-0.15, -0.49, -0.73 and − 1.2) Mega Pascal (MPa) alone and in combination. Furthermore, Fourier transmission infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used. Their biochemical traits such as solubilization of K, P and Zn and the synthesis of siderophore, indole acetic acid (IAA), protease, amylase, hydrogen cyanide (HCN) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase were done. In addition to this, we investigated the optimum folic acid concentration i.e 150 ppm for wheat against drought stress. We conducted a pot experiment to check the growth-enhancing and drought-mitigating effects of consortium and folic acid alone and in combination. As a result, we found a significantly increased wheat biomass, relative water content (RWC), chlorophyll content, antioxidants including glutathione reductase and total soluble sugars and protein content under all treatments. However, the combined treatment of bacterial consortium and folic acid showed maximum potential to boost wheat growth and survival even under drought. We also investigated the minerals uptake by wheat after the treatments and found maximum nutrient uptake under the co-effect of folic acid and bacterial consortium We believe this is the first study that has investigated the optimal dose of folic acid for wheat. Our research is also novel in that we seek to investigate the effects of folic acid along with a bacterial consortium comprising Bacillus halotolerans, Pseudomonas sihuiensis and Bacillus atrophaeus on wheat grown under the drought stress.

Evaluating the efficacy of endophytic bacteria in controlling rice sheath blight: In vitro and In vivo studies

Rice production is highly susceptible to various pathogens, including Rhizoctonia solani, Curvularia lunata, and Epicoccum rostratum, which are major threats in Asia. Exploring biological control methods using endophytic bacteria offers promising opportunities to enhance rice resilience against these lethal diseases. Using 16S RNA sequencing, we identified four endophytic isolates of Bacillus spp. from rice roots, stems, and leaves. We evaluated the antagonistic activity of these endophytic bacterial isolates against rice pathogens both in vitro and in vivo. These isolates inhibited the growth of C. lunata by 82 %, R. solani by 79 %, and E. rostratum by 88 % in vitro. The detached leaf assay for sheath blight (ShB) disease severity in strains ranged from 10.4 % to 73.3 %. In vivo results showed that B. amyloliquefaciens (R-19) exhibited the lowest disease intensity at 7.2 % and the highest disease suppression at 78.8 %. The fungicide propiconazole at 0.1 % treatment showed the lowest disease intensity of 7.7 % and the highest disease suppression of 73.4 %, compared to the infected control. Besides biocontrol efficacy, endophytic isolates enhance plant growth parameters, including shoot height, root length, fresh and dry weights, number of tillers, and grains per tiller. Plant hormones abscisic acid (ABA) and gibberellic acids (GA3) increased by 35 % and 53 %, respectively, due to B. subtilis (R-20) and B. amyloliquefaciens (R-19), while flavonoid and indole acetic acid (IAA) concentrations surged by 30%–80 %. Similarly, chlorophyll (a, b), carotenoids, antioxidant enzymatic activity, phenolic content, carbohydrates, and proline contents were higher compared to the control. This study provides a foundation for future studies on novel and eco-friendly biocontrol agents. In addition, our study recommends the integration of endophytic bacteria into sustainable agriculture for enhancing rice production and reducing disease impacts.