Biochemical Defense Responses Research Articles

Biochemical Defence of Plants against Parasitic Nematodes.

Plant parasitic nematodes (PPNs), such as Meloidogyne spp., Heterodera spp. and Pratylenchus spp., are obligate parasites on a wide range of crops, causing significant agricultural production losses worldwide. These PPNs mainly feed on and within roots, impairing both the below-ground and the above-ground parts, resulting in reduced plant performance. Plants have developed a multi-component defence mechanism against diverse pathogens, including PPNs. Several natural molecules, ranging from cell wall components to secondary metabolites, have been found to protect plants from PPN attack by conferring nematode-specific resistance. Recent advances in omics analytical tools have encouraged researchers to shed light on nematode detection and the biochemical defence mechanisms of plants during nematode infection. Here, we discuss the recent progress on revealing the nematode-associated molecular patterns (NAMPs) and their receptors in plants. The biochemical defence responses of plants, comprising cell wall reinforcement; reactive oxygen species burst; receptor-like cytoplasmic kinases; mitogen-activated protein kinases; antioxidant activities; phytohormone biosynthesis and signalling; transcription factor activation; and the production of anti-PPN phytochemicals are also described. Finally, we also examine the role of epigenetics in regulating the transcriptional response to nematode attack. Understanding the plant defence mechanism against PPN attack is of paramount importance in developing new, effective and sustainable control strategies.

In vitro antifungal activity and in vivo edible coating efficacy of insect-derived chitosan against Botrytis cinerea in strawberry

Strawberry is a perishable fruit, susceptible to development of rot by a range of fungi, in particular Botrytis cinerea. Chitosan represents an alternative to agrochemicals for improving shelf-life and fighting fungal pathogens. A chitosan-based coating derived from pupal exuviae of Hermetia illucens has been recently formulated for improving shelf-life of strawberry stored at 4 °C and mixed condition (4 °C and room temperature). The effects of a decolored (PEDEC) and not decolored (PEND) chitosan from the black soldier fly were evaluated and compared with commercial chitosans from crustaceans (CCs), in vitro and in vivo. An inhibition/reduction of fungal growth and a disturbance of normal fungal morphology were observed, being MIC of 0.5 mg mL−1 and 1 mg mL−1 and growth inhibition of 70 % and 4% for PEND and PEDEC, respectively. Both edible coatings distributed via aerograph showed equal or better potential application than CCs in controlling B. cinerea in strawberry post-harvest treated. Different effects for chitosans depended on their different molecular weight and deacetylation degree distributions, and the presence or absence of melanin pigments in their structure. PEND could act directly against the fungus, with effects predominantly associated with fungitoxic properties; PEDEC might principally provide viable alternatives, such as the elicitation of biochemical defense responses in fruits, for example through total phenols, in particular the flavonoids.

Biochemical Defense Responses in Advanced Backcross-derived Rice Genotypes to Nilaparvata lugens (Stal) Infestation

BPH, Nilaparvata lugens (Delphacidae: Homoptera) infestation on most of the resistant and moderately resistant backcross derived rice genotypes and resistant checks (PTB 33 and BM 71) resulted in an increase in the phenolic content in the infested plants leaf sheath. The percentage increase in phenols in resistant and moderately resistant genotypes ranged from 14.8 % to 67.7 %. Upon infestation of BPH there was a decrease in total reducing sugars in all the resistant and moderately resistant genotypes. The highest quantity of reducing sugars was present in healthy susceptible check TN1 compared to all the resistant and moderately resistant backcross derived rice genotypes. The ascorbic acid content in the resistant and moderately resistant genotypes decreased after BPH infestation and percentage decrease ranged from 16% to 36%. The total N content in the infested resistant and moderately resistant genotypes decreased over healthy genotypes. Decrease in the N content was highest in the susceptible check TN1 (35.2%). In the resistant checks slight decrease in the N content was observed. Potassium and Phosphorous (%) increased in the resistant genotypes and resistant checks, but not in susceptible check TN1. The plants responded defensively upon infestation, resulting in production of higher amount of phenolics, potassium, phosphorous and reduced level of nitrogen, reducing sugars and ascorbic acid.

Interaction of melatonin and H2S mitigates NaCl toxicity summer savory (Satureja hortensis L.) through Modulation of biosynthesis of secondary metabolites and physio-biochemical attributes.

As versatile signaling molecules, melatonin (ML) and hydrogen sulfide (H2S) are well-known for their roles in response to abiotic stresses. However, their cross-talk to the regulation of biochemical defence responses and secondary metabolite synthesis during salinity has received less attention. Here, the role of ML-H2S interplay in inducing defensive responses and the biosynthesis of essential oil compounds in summer savoury plants under NaCl treatment was investigated. NaCl treatment, by increasing Na accumulation, disrupting nitrogen metabolism, and inducing oxidative stress, lowered photosynthetic pigments and savoury growth. NaCl treatment also resulted in a decrease in γ-terpinene (10.3%), α-terpinene (21.9%), and p-cymene (15.3%), while an increase in carvacrol (9.1%) was observed over the control. ML and ML + H2S increased the activity of antioxidant enzymes and the level of total phenols and flavonoids, resulting in decreased levels of hydrogen peroxide and superoxide anion and alleviation of oxidative damage under salinity. ML and ML + H2S increased K uptake and restored K/Na homeostasis, thus protecting the photosynthetic apparatus against NaCl-induced toxicity. ML and ML + H2S treatments also improved nitrate/ammonium homeostasis and stimulated nitrogen metabolism, leading to improved summer savoury adaptation to NaCl stress. ML and ML + H2S changed the composition of essential oils, leading to an increase in the monoterpene hydrocarbons and oxygenated monoterpenes in plants stressed with NaCl. However, the addition of an H2S scavenger, hypotaurine, inhibited the protective effects of the ML and ML + H2S treatments under NaCl stress, which could confirm the function of H2S as a signaling molecule in the downstream defence pathway induced by ML.

Nitrogen and Silicon Contribute to Wheat Defense's to Pyrenophora tritici-repentis, but in an Independent Manner.

Nitrogen (N) and silicon (Si) are mineral elements that have shown a reduction in the damage caused by tan spot (Pyrenophora tritici-repentis (Ptr)) in wheat. However, the effects of these elements were studied separately, and the N and Si interaction effect on wheat resistance to tan spot remains elusive. Histocytological and biochemical defense responses against Ptr in wheat leaves treated with Si (+Si) at low (LN) and high N (HN) inputs were investigated. Soil amendment with Si reduced the tan spot severity in 18% due to the increase in the leaf Si concentration (around 30%), but it was affected by the N level used. The superoxide dismutase (SOD) activity was higher in +Si plants and inoculated with Ptr, leading to early and higher H2O2 and callose accumulation in wheat leaf. Interestedly, phenylalanine ammonia-lyase (PAL) activity was induced by the Si supplying, being negatively affected by the HN rate. Meanwhile, catalase (CAT), and peroxidase (POX) activities showed differential response patterns according to the Si and N rates used. Tan spot severity was reduced by both elements, but their interaction does not evidence synergic effects in this disease's control. Wheat plants from -Si and HN and +Si and LN treatments recorded lower tan spot severity.

Transcriptional and physio-chemical responses of Tectona grandis L. triggered by teak defoliator

Tectona grandis (L) is a popular timber species cultivated in the Indian sub-continent and other countries because of its economic significance. However, the lack of quality planting material with special reference to defoliator herbivory is a major constraint because it negatively influences the establishment of thriving plantations. To address this, the so-called pest response in teak seedlings was investigated at the biochemical and molecular levels. The stress was levied by allowing defoliator infestation on 1-year-old seedlings for nine days at 3-day intervals, whereas control plants were maintained as uninfected. A considerable difference was observed for the considered traits among the infested plants at different intervals compared with the control. Total soluble protein, soluble sugars, tannin, and lignin accumulation increased with increasing stress intensity. Furthermore, catalase, polyphenol oxidase, and phenol content increased after defoliator feeding, whereas peroxidase activity decreased compared with control plants. In addition, six herbivory stress-responsive genes revealed the molecular response of teak. Among them, four genes viz. zinc finger protein (ZFP2), ethylene-responsive factor (ERF-1), catalase-1 (Cat1) and peroxidase super family protein (Psfp) were highly expressed in the infected plants as compared with the control plants. In contrast, the MYB-DNA binding domain gene was downregulated in infected plants compared to uninfected plants. Cytochrome P450 was up-regulated in T1 and T2 plants, while it was down-regulated in T3. Genes were highly expressed as the stress frequency increased. This study offers an improved understanding of biochemical and transcriptional defense responses against the teak defoliator, which could further support teak improvement for quality planting material production.

Silicon complements disease control by fungicides by enhancing the biochemical defense responses of barley against Bipolaris sorokiniana

Silicon complements disease control by fungicides by enhancing the biochemical defense responses of barley against Bipolaris sorokiniana

Biochemical Defense Responses in Red Rice Genotypes Possessing Differential Resistance to Brown Planthopper, Nilaparvata lugens (Stål).

The brown planthopper [Nilaparvata lugens (Stål.)] is one of the most destructive insect pests in all the rice-growing regions of the world. The pest is complicated to manage through the blanket application of chemical pesticides. The development of stable, durable N. lugens-resistant rice varieties is the most economical and efficient strategy to manage the pest. Landraces of red rice genotypes possess numerous nutritional and stress-resistant properties, though an exclusive study on the same is yet to be carried out. In the present study, we evaluated 28 red rice genotypes, along with two resistance checks and one susceptibility check, for their resistance to N. lugens. These promising lines revealed differential responses in the defense mechanism against the pest. The resistant accessions showed a greater accumulation of phenols, peroxidase, polyphenol oxidase, catalase, and superoxide dismutase under N. lugens-stressed conditions. However, the concentration of soluble proteins was substantially decreased in all the test genotypes. The concentration of crude silica was at maximum in highly resistant genotypes. Six red rice genotypes, namely Mata Meher, Manipuri Black, Hermonona, Sonahanan, Bavdi, and Bacharya Khuta fall under the highly resistant category, and can be utilized as valuable sources of resistance in breeding programs.

Infection of Metarhizium anisopliae Ma6 and defense responses of host Phyllotreta striolata adults.

Entomopathogenic fungus as biological control agent plays a crucial role in the integrated management of insect pests. Metarhizium anisopliae Ma6 has been identified as a highly pathogenic strain against Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae), one of the most economically important and dominant insect pests damaging Brassica plants. The infection of M. anisopliae Ma6 on P. striolata was observed under stereomicroscopy and scanning electron microscopy (SEM), and biochemical defense responses of P. striolata adults after infection were investigated. The changes in total amino acids and free fatty acids, and the activities of protective enzymes, including catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), in P. striolata adults were measured. In stereomicroscopy and SEM observations, a large number of mycelia were observed on the body surface of P. striolata on the 5th day after treatment by M. anisopliae. Many conidia were germinated and covered the body of P. striolata on the 7th day after treatment. The free fatty acid, total amino acid, CAT, POD, and SOD activities all showed an increased and then decreased trend. These results suggest that entomopathogenic fungal infection triggers the defense response of hosts, which induces changes in nutrients and antioxidant enzymes in P. striolata adults. Our findings provide useful information for understanding the potential for using M. anisopliae Ma6 as a biocontrol agent.

Phenolic compounds suppress anthracnose decay by enhancing antifungal properties and biochemical defence responses in avocado fruit

Phenolic compounds suppress anthracnose decay by enhancing antifungal properties and biochemical defence responses in avocado fruit

Apolygus lucorum-induced resistance in Vitis vinifera L. elicits changes at the phenotypic, physiological, and biochemical levels

The infestation of the pest Apolygus lucorum (Meyer-Dür, 1843) induced changes in Vitis vinifera L. ‘Cabernet Sauvignon’ at the growth, physiological, and biochemical levels, which were recorded in this study. Continuous infestation by A. lucorum for > 4 d significantly affected plant height and leaf width, although there were no effects when infestation was for ≤ 4 d. Over the long term, A. lucorum mortality increased and their average survival time decreased. A. lucorum-based injury induced plant defense responses, and a spike in defense enzymes was observed. Additionally, infestation induced significant changes in protease inhibitor and secondary metabolite levels in the grape leaves. After A. lucorum infestation, total sugar, protein, and chlorophyll in the leaf decreased significantly. Puncture injury generally induced a milder response compared with A. lucorum infestation. In summary, A. lucorum infestation induced resistance in Cabernet Sauvignon by activating various physiological and biochemical defense responses. In addition to providing new insights into the coevolution of plants and insects, the results presented in this study may lead to the development of an effective, innovative, and environmentally friendly pest control method.

Biopriming with rhizosphere Trichoderma harzianum elicit protection against grapevine downy mildew disease by triggering histopathological and biochemical defense responses

The economic loss and the failure of the chemical control measures to impede downy mildew infection on the grapevine (Vitis vinifera L.) have led to the exploration of biocontrol agents that can effectively manage the invading disease by invoking defense responses of the host plant. Hence, the present study was aimed to explore the efficacy of the talc-based formulation of biocontrol agent Trichoderma harzianum to induce protection against oomycete pathogen, Plasmopara viticola (Berk et Curt.) Berl. et de Toni by triggering defense mechanisms in grapevine. The field study demonstrated that priming with T. harzianum led to the elicitation of defense responses in pathogen inoculated grapevines, with maximum disease protection up to 82.9% on the 4th-day. In addition, the microscopic observation of histochemicals revealed an increased accumulation of lignin, callose and hydrogen peroxide initiated at early 12 h and reached the highest at 24 h post-inoculation. Furthermore, the activities of the defense enzymes, namely, phenylalanine ammonia-lyase, peroxidase and 1,3-glucanase, were upregulated in the tripartite system between the course of tested time intervals. Overall, the findings from the present study highlighted the induced protection incited by T. harzianum in response to P. viticola infestation and witness the significant role of cellular and biochemical enzymes priming for defense in conferring protection against downy mildew disease in grapevine.

Detection of genetic divergence among some wheat (Triticum aestivum L.) genotypes using molecular and biochemical indicators under salinity stress.

Wheat has remarkable importance among cereals in Egypt. Salt stress affects plant growth, development, and crop productivity. Therefore, salinity tolerance is an essential trait that must be incorporated in crops. This research aimed to investigate molecular and biochemical indicators and defence responses in seedlings of 14 Egyptian wheat genotypes to distinguish the most contrasting salt-responsive genotypes. Analysis of ISSR and SCoT markers revealed high polymorphism and reproducible fingerprinting profiles for evaluating genetic variability within the studied genotypes. The HB-10 and SCoT 1 primers had the highest values for all the studied parameters. All the tested primers generated a set of 66 polymorphic bands among tolerant and sensitive genotypes. The transcript profiles of eight TaWRKY genes showed significant induction under the salinity treatments. Moreover, the expression of TaWRKY6 for genotypes Sids 14 and Sakha 93 sharply increased and recorded the highest expression, while the expression of TaWRKY20 for Misr 1 recorded the lowest expression. Under salt stress, the total sugar, proline, and phenolic contents increased significantly, while the chlorophyll content decreased significantly. Additionally, five peroxidase and polyphenol oxidase isoforms were observed in treated leaves and clustered into five different patterns. Some isoforms increased significantly as salinity levels increased. This increase was clearer in salt-tolerant than in salt-sensitive genotypes. Eighteen protein bands appeared, most of which were not affected by salinity compared with the control, and specific bands were rare. Generally, the Sids 14, Sakha 93, Sohag 4, and Gemmeiza 12 genotypes are considered salt tolerant in comparison to the other genotypes.

Zinc phosphate protects tomato plants against Pseudomonas syringae pv. tomato

The purpose of this study was to determine whether zinc phosphate treatments of tomato plants (Solanum lycopersicum L.) can attenuate bacterial speck disease severity through reduction of Pseudomonas syringae pv. tomato (Pst) growth in planta and induce morphological and biochemical plant defence responses. Tomato plants were treated with 10 ppm (25.90 µM) zinc phosphate and then spray inoculated with strain DAPP-PG 215, race 0 of Pst. Disease symptoms were recorded as chlorosis and/or necrosis per leaf (%) and as numbers of necrotic spots. Soil treatments with zinc phosphate protected susceptible tomato plants against Pst, with reductions in both disease severity and pathogen growth in planta. The reduction of Pst growth in planta combined with significantly higher zinc levels in zinc-phosphate-treated plants indicated direct antimicrobial toxicity of this microelement, as also confirmed by in vitro assays. Morphological (i.e. callose apposition) and biochemical (i.e., expression of salicylic-acid-dependent pathogenesis-related protein PR1b1 gene) defence responses were induced by the zinc phosphate treatment, as demonstrated by histochemical and qPCR analyses, respectively. In conclusion, soil treatments with zinc phosphate can protect tomato plants against Pst attacks through direct antimicrobial activity and induction of morphological and biochemical plant defence responses.

Biochemical responses of wheat to silicon application under salinity

AbstractBackground: Salinity is one of the main threats that can cause crop yield losses by limiting plant growth. Several important cultivated crops including wheat exhibit sensitivity to salt stress by severe yield reductions. Approaches to improve salt resistance are critical for improved food production in the future.Aims: Silicon (Si) is well known for its role as quasi‐essential element to enhance growth and development of monocot food crops, especially under a variety of abiotic and biotic stress conditions. However, the mechanism of Si‐induced stress resistance is still not fully understood. Here, we investigate the biochemical basis of Si‐induced salt resistance of wheat.Methods: Effect of Si treatment on wheat plants under salt stress was measured by biochemical studies of photosynthetic pigments, ions, oxidative stress indicators, enzymatic and non‐enzymatic antioxidant systems, phytohormones along with expression of two Si‐transport genes.Results: Our results suggest that Si‐induced salt resistance of wheat involves a signaling cascade that triggers the biochemical defense responses. Salinity induces production of the stress hormone abscisic acid that upregulates the expression of Si‐influx transporter gene TaLsi1 and Si‐efflux transporter gene TaLsi2, in the presence of soluble Si in cytosol, and this triggers jasmonate‐mediated activation of both enzymatic and non‐enzymatic antioxidant systems along with osmolyte production. Moreover, peculiar stoichiometric changes in photosynthetic pigments after Si application, as signatures of shaded condition, also lead us to the hypothesis that insoluble Si phytoliths in plants may aid a physical defense response by creating a “mechanically shielded leaf microenvironment” against a variety of abiotic and biotic stress conditions.Conclusion: This study demonstrates that Si activates biochemical defense responses against salt stress in wheat plants.

Silicon triggers sorghum root enzyme activities and inhibits the root cell colonization by Alternaria alternata.

Silicon inhibits the growth of Alternaria alternata into sorghum root cells by maintaining their integrity through stimulating biochemical defense reactions rather than by silica-based physical barrier creation. Although the ameliorating effect of silicon (Si) on plant resistance against fungal pathogens has been proven, the mechanism of its action needs to be better understood on a cellular level. The present study explores the effect of Si application in sorghum roots infected with fungus Alternaria alternata under controlled in vitro conditions. Detailed anatomical and cytological observations by both fluorescent and electron microscopy revealed that Si supplementation results in the inhibition of fungal hyphae growth into the protoplast of root cells. An approach of environmental scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy enabling spatial detection of Si even at low concentrations showed that there is no continual solid layer of silica in the root cell walls of the rhizodermis, mesodermis and exodermis physically blocking the fungal growth into the protoplasts. Additionally, biochemical evidence suggests that Si speeds up the onset of activities of phenylpropanoid pathway enzymes phenylalanine ammonia lyase, peroxidases and polyphenol oxidases involved in phenolic compounds production and deposition to plant cell walls. In conclusion, Si alleviates the negative impact of A. alternata infection by limiting hyphae penetration through sorghum root cell walls into protoplasts, thus maintaining their structural and functional integrity. This might occur by triggering plant biochemical defense responses rather than by creating compact Si layer deposits.

Biochemical defense responses of tolerant and susceptible lettuce accessions following infection by Sclerotinia sclerotiorum

Sclerotinia sclerotiorum is one of the most destructive lettuce diseases, restricting lettuce cultivation globally. Here, we measured the activity of three antioxidant enzymes in two contrastingly responding lettuce accessions (susceptible ML1 and tolerant Jah accessions) challenged by S. sclerotiorum. These enzymes included superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Moreover, we applied the 2,2-diphenylpicrylhydrazyl (DPPH) method and the malondialdehyde (MDA) assay. The activities of SOD and GPx were much pronounced in the tolerant accession than in the susceptible one. Our results indicate that MDA concentration increased significantly in the leaves of tolerant accession compared with that of the susceptible one at 1 dpi whereas MDA level was pronounced in the later time points in the susceptible accession compared with tolerant accession. Taken together, we observed that the examined biochemical markers differentially fluctuated in the applied accessions, shedding light to understand better resistance mechanisms involved in restricting this notorious fungal pathogen.

Delineating induced defense responses in wheat seedlings exposed to volatiles emitted by Puccinia triticina infected wheat

Volatile organic compounds (VOCs) can play an essential role in eliciting an induced defense response in exposed plants. Preceding research showed that Puccinia triticina (Pt) infected resistant wheat emitted VOCs that induced a defense response in uninfected exposed wheat (UR) plants. The current study aimed to determine the biochemical nature of this induced defense response in the UR plants. Seedlings exposed to infected resistant plant VOCs for 8 h were used for proteomic analysis. A total of 26 proteins were up-regulated and 55 proteins were down-regulated. Five up-regulated chaperones proteins (Hsp70, chaperonin 60 subunit beta 3, ClpC, ClpC1 and ClpC2), two elongation factor-Tu, four isoforms of glyceraldehyde-3-phosphate dehydrogenase and xyloglucan galactosyltransferase are generally associated with plant defense responses. The proteomic expression profiles were supported by gene transcript expression patterns showing down-regulated phosphoglycerate kinase, up-regulated ClpC2 chaperone and unchanged carbonic anhydrase encoding transcript levels. In addition, the mitochondrial Cu/Zn superoxide dismutase (Cu/Zn-SOD Mt) encoding gene transcripts and SOD enzymatic activity were significantly induced at 8, 24 and 48 h post volatile exposure (hpe) relative to control (0 hpe). Salicylic acid quantities were significantly induced in the UR plants at 8, 24 and 48 hpe. These findings suggested that induced salicylic acid could be involved in the signaling of biochemical changes in the UR plants upon the reception of the VOCs emitted by the Pt infected wheat plants. The current study thus contributed to improving our understanding of the nature of the biochemical induced defence responses during VOCs exposed uninfected plants in an interplant signaling event.

Early production of reactive oxygen species coupled with an efficient antioxidant system play a role in potato resistance to late blight

The association between reactive oxygen species (ROS) production and potato resistance to the hemibiotrophic pathogen Phytophthora infestans is poorly understood. In this study, the concentrations of hydrogen peroxide (H2O2), malondialdehyde (MDA), and soluble phenolics, as well as the activities of superoxide dismutase, catalase, and ascorbate peroxidase were measured during the early biotrophic and late necrotrophic stages of P. infestans infection on resistant and susceptible ‘Ovatio’ and ‘Bintje’ potato plants, respectively. Pathogen biomass was examined using semi-quantitative RT-PCR. Late blight (LB) severity was also evaluated. The LB severity in Ovatio was lower than that in Bintje, irrespective of the evaluation time. Moreover, in both cultivars, various biochemical defense responses occurred following pathogen infection. The susceptible cultivar activated defense responses at the later pathogen infection stages, resulting in higher concentrations of H2O2 and greater MDA content, with lower activity of antioxidant enzymes and phenolic content. These responses were accompanied by the necrotrophic phase, leading to extensive necrotic lesions on leaves. In contrast, fast hypersensitive-like lesions, an early peak in H2O2 concentration, low cell membrane integrity during the biotrophic phase, and a more efficient antioxidative system effectively restricted pathogen colonization before the transition to the necrotrophic phase in the resistant cultivar. These results suggest that LB resistance or susceptibility is regulated by a balance between the induction of ROS/antioxidants (intensity and timing) and the trophic phase of P. infestans.

Burkholderia phytofirmans PsJN and tree twigs derived biochar together retrieved Pb-induced growth, physiological and biochemical disturbances by minimizing its uptake and translocation in mung bean (Vigna radiata L.)

Anthropogenic activities like industrial mining, refining and smelting release substantial amounts of lead (Pb) into the soil causing potential ecological menaces to environment, soil productivity and food security. Present pot scale study was undertaken to investigate the effects of tree twigs-derived biochar and a bacterium Burkholderia phytofirmans PsJN on Pb accumulation, growth, physiological, biochemical and antioxidative defense responses of mung bean grown in Pb spiked soil. The original soil was spiked with Pb (600 mg kg−1) and amended with biochar (1% w/w). Upon screening in laboratory, B. phytofirmans PsJN exhibited high Pb tolerance and was able to grow at high Pb concentrations. Surface-disinfected seeds of mung bean were inoculated with B. phytofirmans PsJN and sown in pots along with un-inoculated seeds. Data were collected for various growth, physiological and biochemical parameters from fully matured harvested plants. Application of biochar and B. phytofirmans PsJN ameliorated Pb induced negative impacts in mung bean both individually and in combination, but better growth, physiological and seed quality responses were observed with their combined use. Compared with respective controls, their combined use increased the following parameters in normal and Pb spiked soils, respectively: plant height (69% and 159%), root dry weight (97% and 130%), shoot dry weight (42% and 104%), number of pods (70% and 210%), grains weight (58% and 194%) and number of root nodules (71% and 255%). Moreover, combined use increased chlorophyll contents (27% and 37%), photosynthetic rate (93% and 204%), transpiration rate (42% and 132%), stomatal conductance (70% and 218%), sub-stomatal conductance (93% and 148%) and water use efficiency (35% and 43%). In addition, combined application of biochar and B. phytofirmans PsJN retarded Pb-induced oxidative stress by intensifying antioxidant enzyme activities and reducing activities of reactive oxygen species. Similarly, considerable reduction in Pb uptake, translocation and bioaccumulation in mung bean was noticed in Pb spiked soil due to applied amendments. Furthermore, their combined use resulted in considerable increase in grain quality parameters (protein, fat, ash) both in normal and Pb-spiked soils. Therefore, it can be inferred that interactive use of biochar and B. phytofirmans PsJN provides an efficient innovative strategy to repossess Pb induced growth, physiological, biochemical and oxidative disturbances in mung bean.