Defense Enzymes Research Articles

Induced Systemic Resistance-Mediated Defense Against Alternaria Blight Disease in Lentil by Pesticide Degrading Plant Growth-Promoting Rhizobacteria.

Enzymatic and antioxidative responses are key defense mechanisms in plants following pathogen invasion, collectively known as induced systemic resistance (ISR). Alternaria sp., a well-known soil-borne pathogen, causes blight diseases in various crops. This study investigates the defence response in lentil plants through the treatment-induced application of two multipotent pesticide degrading plant growth-promoting rhizobacteria (PGPR), Bacillus cereus and Bacillus safensis, to mitigate the destructive effects of Alternaria. Both bacterial strains were applied in different carrier-based bioformulations via soil drenching. We assessed the modulation of defense-related enzymes by various combinational treatments with the Alternaria pathogen. The in vitro production of antimicrobial compounds was analyzed using GC-MS to confirm their pathogen-suppressive capabilities. Field trials showed a positive correlation between treatments and improvements in yield and growth index (GI). The highest (180%) enzymatic induction of phenylalanine ammonia lyase (PAL) followed by catalase (CAT)(100%) and polyphenol oxidase (PPO) (54%), was observed in treatments with B. cereus alone or in combination with B. safensis, in presence of Alternaria, in respect to the control. In vitro analysis revealed the production of antimicrobial compounds, including benzoic acid derivatives, cyclotetrasiloxanes, hexacosane, chlorpyrifos, and phthalates, which may contribute to pathogen suppression. Our findings demonstrate that these biocontrol agents (BCAs) not only stimulate the plant's enzymatic defense system but also enhance growth, seed yield and produce several antimicrobial compounds in vitro. Thus, pesticide-tolerant PGPR, used in this study, exhibit both disease control and plant growth-promoting properties, offering promising applications in sustainable agriculture.

AM fungus plant colonization rather than an Epichloë endophyte attracts fall armyworm feeding.

Most cold-season grasses can be colonized by belowground arbuscular mycorrhizal (AM) fungi and foliar grass endophytes (Epichloë) simultaneously while also be attacked by insect herbivores. The colonization of AM fungi or the presence of grass endophytes is associated with increased resistance by the host plant. However, studies on how these two symbionts affect host plants and mitigate insect pest attack are currently lacking. In a glasshouse study we investigated the effects of an AM fungus (Acaulospora delicata), a foliar grass endophyte (Epichloë), and the insect pest Spodoptera frugiperda (fall armyworm, FAW) on plant growth, defense enzyme activity, and hormone concentrations of the important pasture grass Lolium perenne. Additionally, we assessed the selective behavior of FAW larvae in response to these interactions using olfactometer tests. Our results showed that the AM fungus and its co-colonization with Epichloë endophytes increased aboveground biomass, while Epichloë endophytes alone had no significant impact on ryegrass aboveground biomass. In contrast, FAW reduced aboveground biomass. The Epichloë endophytes and FAW significantly decreased the mycorrhizal colonization rate by 21.67% and 30.16%, respectively. Interestingly, compared to non-mycorrhizal plants, AM fungus colonized plants were more attractive to FAW larvae feeding, and the defense enzyme activity was not discernibly affected by any experimental treatments. The interactions of the AM fungus and Epichloë endophyte increased the jasmonic acid concentrations by 24.29% and decreased trasylol activity by 11.75% in the host plants under FAW attack. Neither the AM fungus nor Epichloë endophyte influenced the relative growth rate (RGR) of FAW. Overall, the AM fungus had a greater positive effect on plant growth than the Epichloë endophyte, regardless of FAW larvae infestation.

Versatility of Caenorhabditis elegans as a Model Organism for Evaluating Foodborne Neurotoxins and Food Bioactive Compounds in Nutritional Neuroscience.

Epidemiological evidence has shown that the regular ingestion of vegetables and fruits is associated with reduced risk of developing chronic diseases. The introduction of the 3Rs (replacement, reduction, and refinement) principle into animal experiments has led to the use of valid, cost-effective, and efficient alternative and complementary invertebrate animal models which are simpler and lower in the phylogenetic hierarchy. Caenorhabditis elegans (C. elegans), a nematode with a much simpler anatomy and physiology compared to mammals, share similarities with humans at the cellular and molecular levels, thus making it a valid model organism in neurotoxicology. This review explores the versatility of C. elegans in elucidating the neuroprotective mechanisms elicited by food bioactive compounds against neurotoxic effects of food- and environmental-related contaminants. Several signaling pathways linked to the molecular basis of neuroprotection exerted by bioactive compounds in chemically induced or transgenic C. elegans models of neurodegenerative diseases are also discussed. Specifically, the modulatory effects of bioactive compounds on the DAF-16/FoxO and SKN-1/Nrf2 signaling pathways, stress resistance- and autophagy-related genes, and antioxidant defense enzyme activities were highlighted. Altogether, C. elegans represent a valuable model in nutritional neuroscience for the identification of promising neuroprotective agents and neurotherapeutic targets which could help in overcoming the limitations of current therapeutic agents for neurotoxicity and neurodegenerative diseases.

Blood Catalase, Superoxide Dismutase, and Glutathione Peroxidase Activities in Alcohol- and Opioid-Addicted Patients

Background and Objectives: Multiple evaluations of oxidative stress in individuals with substance use disorder show elevated levels compared to non-substance-abusing individuals. Information concerning antioxidant defense mechanisms in relation to alcohol and opioid dependence is variable and sometimes contradictory. The objective of the present investigation was to identify and compare several antioxidants in plasma during distinct phases of alcohol and opioid dependency (intoxication and withdrawal). Materials and Methods: This case study focuses on individuals with opioid and alcohol addiction. We recruited 80 participants (males aged 40 ± 10 years) and equally divided them into two categories: those with alcohol addiction and those with opioid addiction. A control group consisted of 20 healthy adults (males aged 35 ± 10 years). The spectrophotometric methods were used to quantify catalase, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activity in plasma. Antioxidant values were analyzed between groups using pairwise Mann–Whitney tests. Results: During withdrawal from alcohol and opioids, catalase activity tends to decrease compared to intoxication. The overall activity of superoxide dismutase exhibited an increase during alcohol intoxication and withdrawal and a reduction during opioid withdrawal compared to the intoxication phase. Both alcohol and opioids reduced plasma GPx activity in withdrawal cases, although the extent of this decrease varied considerably. Conclusions: The study confirms the valuable impact of addiction on the organism’s oxidative stress and reveals various behaviors of antioxidant defense enzymes during intoxication and withdrawal phases.

Impact of Ultraviolet Radiation on Growth, Development and Antioxidant Enzymes of Tuta absoluta (Meyrick)

Ultraviolet radiation serves as a significant abiotic stressor for numerous organisms, particularly impacting insects in various ways. Tuta absoluta, a highly destructive pest infesting of the Solanaceae species, was investigated to elucidate its growth, development, and enzymatic defense mechanisms of insects in response to UV exposure. This study investigates the effects of three types of UV radiation on the lifespan, egg laying behavior, and antioxidant enzyme activities of T. absoluta. Our study revealed a significant reduction in the lifespan of T. absoluta upon exposure to both UV-A and UV-B radiation, whereas extended exposure to UV-C radiation for 120 min and 180 min resulted in a decline in its egg laying capacity. Exposure to all three types of radiation (UV-A, UV-B, and UV-C) led to an irreversible decrease in catalase (CAT) enzyme activity. Upon exposure to UV-A, there was a gradual increase in peroxidase (POD) enzyme activity; however, at 120 min post-exposure, a subsequent decrease was observed. A notable elevation in superoxide dismutase (SOD) activity was observed following exposures of both 60 min and 120 min durations under the rays of UV-A. These findings provide valuable insights into understanding the effects of UV exposure on T. absoluta as well as its potential application as a control measure, warranting further investigation.

The unique structure of the highly conserved PPLP region in HIV-1 Vif is critical for the formation of APOBEC3 recognition interfaces.

The human cellular cytidine deaminases APOBEC3s (A3s) inhibit virion infectivity factor (Vif)-deficient HIV-1 replication. However, virus-encoded Vifs abolish this defense system by specifically recruiting A3s to an E3 ubiquitin ligase complex to induce their degradation. The highly conserved Vif PPLP motif is critical for the Vif-mediated antagonism of A3s and is believed to be important for Vif multimerization. However, how the PPLP motif dictates the functions of Vif remains unclear. Here, we aimed to elucidate this mechanism using biochemical and structural biology approaches. First, we found that no stable Vif multimer complexes formed in our tandem coimmunoprecipitation assays. Next, a series of Vif truncation mutants were constructed, and the short α-helix α6 just downstream of PPLP was found to be the smallest fragment essential for efficient A3G degradation in cells. In silico structural analysis suggested that PPLP-α6 adopts a stable L-shaped conformation when complexed in Vif/CBF-β and contributes to the structural integrity of Vif. In vitro ubiquitination assays with recombinant proteins confirmed that PPLP-α6 is necessary to form the functional complex of the E3 ligase adaptor of Vif/CBF-β/elongin B/elongin C. Additionally, mutations of the highly conserved PPLP-α6 hydrophobic residues severely disrupted Vif function. In the Vif structure, PPLP-α6 is positioned behind α1-α2 that constitutes the A3-binding Vif interfaces. Therefore, both the PPLP motif and α6 play critical allosteric roles in maintaining the integrity of the A3 interaction interfaces. Our findings will also provide important data for the design of novel anti-HIV-1 compounds that disrupt the A3-binding Vif interfaces.IMPORTANCEThe APOBEC3 (A3) family enzymes potently block the replication of retroviruses, such as HIV-1. However, HIV-1 expresses Vif, a small multifaceted protein that binds and specifically eliminates A3s in infected cells via ubiquitination-proteasome degradation. Thus, A3-Vif interactions are attractive targets for anti-HIV-1 drug development. The Vif PPLP motif that is distal from these interfaces is necessary for A3 degradation; however, the mechanism by which PPLP participates in A3 degradation is unknown. In this study, we performed biochemical and structural biology analyses to elucidate the underlying mechanisms involved. We found that the PPLP motif, in addition to the short downstream fragment α6, forms a stable L-shaped conformation and acts as a scaffold for the A3 recognition interfaces. Importantly, mutations in α6 abolished Vif function to antagonize multiple A3 family enzymes. These findings provide important data for the development of novel HIV-1 inhibitors that utilize A3s as cellular defense enzymes.

Nutrient Formulation—A Sustainable Approach to Combat PRSV and Enhance Productivity in Papaya

Papaya (Carica papaya L.) is a highly nutritious fruit crop cultivated commercially in the tropical and subtropical regions of the world. Being a shallow rooted fruit crop, it requires frequent application of nutrients. Papaya is highly remunerative due to its high productivity and responds positively to nutrient application. Papaya Ring Spot Virus (PRSV) is a major threat to papaya production, which causes severe yield loss and reduces fruit quality. To combat PRSV and enhance productivity, a nutrient formulation was developed by combining organic, inorganic nutrient sources with biocontrol agents to improve the health and vigor of the plants. Experiments were conducted to standardize the application time and evaluate the efficacy of nutrient formulation in enhancing yield, and to combat papaya ring spot virus (PRSV) incidence in papaya from January 2021 to December 2023 at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. The results revealed that foliar application of nutrient formulation at monthly intervals from the 3rd to the 7th month after planting (MAP) along with regular application of recommended dose of fertilizers (RDF) at bimonthly intervals from the 3rd MAP significantly increased the yield (37.79% and 30.57% in TNAU Papaya CO 8 and Red Lady, respectively) and reduced PRSV disease incidence (22.49% in TNAU Papaya CO 8 and 16.53% in Red Lady). Metabolomics study indicates that foliar spray of nutrient formulation enhanced the activators and precursors of defense enzymes, viz., peroxidase (PO), polyphenol oxidase (PPO), phenyl ammonia lyase (PAL), catalase (CAT) and nitrate reductase (NRase) in the sprayed plants over unsprayed control. Therefore, the sprayed plants exhibited tolerance to PRSV incidence by maintaining vigor and induced systemic resistance by the defense enzymes.

Combined application of methyl jasmonate and Bacillus subtilis LLCG89 suppresses blue and green mold of lemon (Citrus limon L.).

Bacillus species produce antimicrobial lipopeptides (LPs) and methyl jasmonate (MeJA) induces resistance in harvested fruits against postharvest pathogens. However, there is limited evidence of the combined efficacy of Bacillus LPs and MeJA to suppress postharvest diseases. This study presents the combined effect of Bacillus LPs and MeJA to suppress P. digitatum and P. italicum associated with green and blue mold of lemon. Eight Bacillus strains were screened in a direct antagonism plate assay, where Bacillus subtilis LLCG89 and B. atrophaeus HFZ23 exhibited the highest inhibition of both molds. Subsequently, in an in vitro assay, LPs extracted from LLCG89 demonstrated the highest antifungal activity against both pathogens compared to HFZ23. When combined with MeJA, LLCG89 LPs reduced the lesion diameter and disease incidence of blue and green mold on lemon fruit. Co-application of MeJA and LLCG89 LPs decreased the levels of MDA, H2O2, and electrolyte leakage compared to single treatments and controls. Furthermore, treatment with MeJA and LLCG89 LPs increased the activities of defense enzymes including SOD, CAT, POD, PPO, CHI, GLU, APX, and PAL with peak activity between 48 to 72 h. The co-application of MeJA and LLCG89 LPs showed the highest enzyme activity compared to the control. Postharvest quality analysis indicated that co-application of LLCG89 LPs and MeJA showed little impact on fruit quality. The findings of our study highlight the potential of Bacillus-derived LPs and MeJA as effective tools for managing the Penicillium decay of lemons by maintaining fruit quality. © 2025 Society of Chemical Industry.

Analysis of the Control Effect of Bacillus amyloliquefaciens C4 Wettable Powder on Potato Bacterial Wilt Caused by Ralstonia solanacearum

Potatoes are one of the most important food crops worldwide, but their growth and development are often seriously threatened by potato bacterial wilt. The wettable powder produced by Bacillus amyloliquefaciens C4 under optimized fermentation conditions effectively inhibits potato bacterial wilt. In this study, lipopeptide antibiotics were identified via PCR and MALDI-TOF-MS, and their antibacterial activity was determined. The optimal formulation of C4 wettable powder was optimized via a single-factor experiment combined with a response surface. The effect of C4 wettable powder on potato bacterial wilt was evaluated. In the antibacterial activity test, surfactin showed better inhibition ability. After determining the optimal liquid fermentation conditions and wettable powder formula, the surfactin activity increased to 540.15 mg/L, and the C4 wettable powder activity reached 69.67 × 108 cfu/g. The results of the pot experiment showed that the best cost-effectiveness was achieved under 500 times dilution and spraying, with a control effect of 79.05 ± 24.79%. The physiological and biochemical results showed that C4 wettable powder could induce rapid defense enzyme responses in leaves and enhance plant resistance to pathogenic bacteria. The results showed that C4 wettable powder effectively controlled potato bacterial wilt, and its application method was determined.

Titanium dioxide-induced fibrotic liver model and the therapeutic effect of resveratrol by modulation of α-SMA and 8-oHdG expressions, oxidative stress, and inflammation.

The research sought to assess the therapeutic impact of resveratrol by biochemical, immunohistochemical, and histopathological analyses in a TiO2-induced liver fibrosis model. Titanium dioxide (100 mg/kg body weight) was delivered for 15 days to induce liver fibrosis, either alone or in conjunction with resveratrol (30 mg/kg body weight) therapy for the same duration. Resveratrol has been identified as a crucial therapeutic drug that provides an alternative treatment method for TiO2-induced liver fibrosis by mitigating inflammation, oxidative stress, and the expressions of α-SMA and 8-OHdG. Resveratrol treatment mitigated TiO2-induced liver fibrosis by repairing hepatocellular injury and decreasing plasma AST, ALT, and ALP levels. Resveratrol improves the activity of superoxide dismutase (SOD) and catalase (CAT), crucial enzymes for antioxidant defense, and elevates glutathione peroxidase (GSH-Px) levels, so augmenting antioxidant function. Furthermore, resveratrol decreased hepatic inflammation (IL-6 and IL-1β) and oxidative stress markers. Furthermore, histological alterations and immunohistochemistry expression of α-SMA and 8-OhdG were reinstated after resveratrol administration in the TiO2-induced liver fibrosis model. Our research indicates that resveratrol administration effectively protects against liver fibrosis produced by TiO2.

Physiological and transcriptome analysis of sex-specific responses to cadmium stress in poplars.

Soil cadmium (Cd) pollution is a serious ecological problem worldwide. Understanding Cd-detoxification mechanisms in woody plants will help to evaluate their tolerance ability and phytoremediation potential to Cd-polluted soils. This study investigated the growth, physiochemistry, Cd distribution, and transcriptome sequencing of male and female poplars under three Cd levels (0, 50, and 100 mg·kg-1). The results showed that Cd stress significantly inhibited the growth of aboveground parts. Over 70 % of the Cd was distributed in the cell wall fraction of roots, stems, and leaves, with the majority accumulating in the roots. Poplars can conjugate Cd with phytochelatins to reduce Cd damage, which is more evident in males than females. The antioxidant defense system of females is more effective than that of males at reducing the damage from Cd. Females demonstrated a stronger Cd-regulation ability than males under the 100 mg·kg-1 Cd treatment. Sex-specific responses to Cd were associated with differential gene expression. Under Cd stress, the genes related to oxidation-reduction processes, antioxidant enzyme activity and defense mechanisms, cell wall synthesis, and glutathione metabolism were mainly enriched and upregulated in females, whereas in males, genes related to photosynthesis and photosynthetic pigment biosynthesis were mainly enriched and downregulated, indicating greater damage to the photosynthetic system than in females. Our study provides novel insights into the mechanisms responding to Cd tolerance in poplars. Further studies should be carried out to assess the impact of soil Cd pollution on the wood quality of poplars.

Modulatory responses of physiological and biochemical status are related to drought tolerance levels in peanut cultivars.

Peanut (Arachis hypogaea L.) is the fourth most cultivated oilseed in the world, but its cultivation is subject to fluctuations in water demand. Current studies of tolerance between cultivars and physiological mechanisms involved in plant recovery after drought are insufficient for selection of tolerant cultivars. We evaluated tolerance of different peanut cultivars to water deficit and subsequent rehydration, based on physiological and biochemical status. Gas exchange, photosynthetic pigments, Fv/Fm, MDA, H2O2 and antioxidant enzyme activity were analysed. Drought stress and rehydration triggered distinct changes in pigments, Fv/Fm, gas exchange, and H2O2 across genotypes, with increased MDA in all cultivars under stress. Based on multivariate analysis, 'IAC Sempre Verde' was identified as most drought sensitive, while 'IAC OL3', 'IAC 503', and 'IAC OL6' exhibited variations in physiological responses and antioxidant activity correlated to their respective tolerance levels. Notably, 'IAC OL3' had higher WUE and enhanced enzymatic defence and was classified as the most drought tolerant in this context. The above findings suggest that antioxidant metabolism is a important factor for plant recovery post-rehydration. Our study provides insights into antioxidant and physiological responses of peanut cultivars, which can support breeding programs for selection of drought-tolerant genotypes. Future field studies should be conducted for a better understanding of tolerance of these cultivars, particularly through correlation of these data with crop yield impact.

Bacillus endophytes for sustainable management of tomato spotted wilt virus and yield production.

Tomato-spotted wilt virus (TSWV) from the Tospovirus genus affects over 1000 plant species, including key crops, and traditional control methods often prove inadequate. This study investigates the effectiveness of Bacillus amyloliquefaciens and Bacillus subtilis in reducing TSWV infection, enhancing plant growth, and strengthening defense in Nicotiana benthamiana. The aim is to assess Bacillus as a sustainable biocontrol alternative, offering an eco-friendly solution for managing TSWV disease in agriculture. Here, we report the efficacy of five Bacillus isolates (out of 15 tested) - B. amyloliquefaciens (DJB5, YN48, YN28, Mg6) and B. subtilis L1-21 - significantly reducing TSWV copies per gram in N. benthamiana leaves, using a half-leaf assay. In glasshouse trials, isolates DJB5, YN48, and Mg6 decreased TSWV copies per gram by 75.7%, 83.6%, and 88.2%, with biocontrol efficacy rates of 91.2%, 94.1%, and 95.7% respectively. All the isolates consistently mitigated the symptoms of TSWV, reduced the disease severity, and area under the disease progress curve (AUDPC) at 21 days post-inoculation. Additionally, these isolates enhanced plant growth parameters, including shoot and root length, leaf number, area, and biomass. The application of endophytes in the infected plants activated antioxidant defense enzymes by elevating the activities of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), and chitinase. However, defense-related enzymes, such as malondialdehyde (MDA), catalase (CAT), phenylalanine ammonia-lyase (PAL), total phenol, and β-1,3-glucanase decreased as TSWV infection reduced in the leaves. Our findings indicate that B. amyloliquefaciens isolates, DJB5, YN48, and Mg6, effectively manage TSWV by activating plant defense, reducing virus load, reducing TSWV symptoms, and promoting plant growth. © 2024 Society of Chemical Industry.

Achilles tenocytes from diabetic and non diabetic donors exposed to hyperglycemia respond differentially to inflammatory stimuli and stretch.

Diabetes mellitus type 2 (DMT2) promotes Achilles tendon (AS) degeneration and exercise could modulate features of DMT2. Hence, this study investigated whether tenocytes of non DMT2 and DMT2 rats respond differently to normo- (NG) and hyperglycemic (HG) conditions in the presence of tumor necrosis factor (TNF)α or cyclic stretch. AS tenocytes, isolated from DMT2 (fa/fa) or non DMT2 (lean, fa/+) adult Zucker Diabetic Fatty (ZDF) rats, were treated with 10 ng/mL TNFα either under NG or HG conditions (1 g/L vs. 4.5 g/L glucose) and were exposed to cyclic stretch (14%, 0.3 Hz, 48 h). Tenocyte survival, metabolic activity, gene and/or protein expression of tendon extracellular matrix component collagen type 1, alpha smooth muscle actin (αSMA, Acta2), the stress defense enzyme heme oxygenase-1 (Hmox1) as well as suppressors of cytokine signaling (Socs)1 and Socs3 were analyzed. Tenocyte vitality remained high, but metabolic activity was slightly impaired by HG conditions irrespectively of cell origin. Collagen type 1 alpha protein and gene expression was suppressed by TNFα, but only in cells of non DMT2 animals in NG culture medium. Higher amounts of αSMA were visualized in tendons/tenocytes of diabetic rats or those exposed to TNFα. Cyclic stretch caused cell alignment in zero stretch direction. In addition, it led to a significant reduction of cell perimeters, particularly in cells of DMT2 donor rats under HG conditions. Hmox1, Socs1 and Socs3 were induced by HG, but only in tenocytes of diabetic rats (4 h). Stretch induced significantly Hmox1 transcriptional activity under NG conditions and Socs3 under HG conditions especially in tenocytes of DMT2 rats. The response of tenocytes to TNFα and cyclic stretch depends on glucose supply and origin suggesting their irreversible impairment by DMT2.

Exploring the potentiality of botanicals and phyllosphere microbiome for the management of anthracnose disease in Black gram (Vigna mungo L. Hepper)

Black gram (Vigna mungo L. Hepper) is the third most important pulse crop, and its yield is reduced due to many diseases. Among them, anthracnose is one of the devasting global fungal diseases which cause severe damage. Use of fungicide is highly effective in controlling this disease, but continuous use of fungicides is unsafe for environment, and it causes fungicidal resistance. To overcome these problems, effect of plant extracts viz., Anisomeles malabarica, Azadirachta indica leaf extracts, phyllosphere antagonist Bacillus amyloliquifaciens, and essential oils viz., peppermint oil and lemon grass oil were evaluated against black gram anthracnose disease caused by Colletotrichum lindimuthianum under pot culture. Among the different treatments tested, plants sprayed with standard chemical viz., Carbendazim @ 0.2 percent recorded the least percent disease index (PDI) of 13.39 followed by A. malabarica leaf extract (10%) treatments, which recorded a PDI of 16.62, whereas plants treated with B. amyloliquifaciens, lemongrass oil and peppermint oil recorded a PDI of 20.91, 21.23 and 24.0, respectively, compared to the inoculated control (77.33 PDI). The induction of defense enzymes viz., phenol, peroxidase (PO), polyphenol oxidase (PPO) was recorded more (21.25 µg of catechol/g of leaf tissue, 3.82 changes in absorbance/min/g leaf tissue, 3.32 changes in absorbance/min/g leaf tissue, respectively) in the plants sprayed with A. malabarica. GC-MS analysis of hexane and ethanol extract of A. malabarica showed the presence of 26 phytocompounds. Among them, phenol 2,4- bis (1,1- dimethylethyl) phosphite from ethanol extract was a predominant compound (100%). Formulation and standardization of dosage for phenol 2,4- bis (1,1- dimethylethyl) phosphite compound will be useful for managing the disease effectively.

Biological management of rhizome rot in ginger (Zingiber officinale ) plants and stored ginger seeds

Two endospore-forming endophytic bacteria (EEB1 A8 and EEB2 B13) were isolated from ginger rhizome collected from the fields of College of Agriculture, Vellayani and identified as Bacillus spp. Their antagonistic potential against Pythium myriotylum , the soft rot pathogen of ginger, was analyzed in vitro by dual culture plate assay and the agar well diffusion method. They tested positive for biocontrol traits such as the production of hydrogen cyanide, siderophore and volatile organic compounds. The bacterial isolates were applied to ginger plants to test biocontrol efficiency against P. myriotylum , individually and in combination with Piriformospora indica , a fungal root endophyte capable of promoting plant growth and enhancing plant defense. A lesser percent disease index (PDI) was observed in plants where the combination of EEB1 A8 and P. indica was applied. The activity of enzymes pertinent to protective mechanisms against pathogens, like peroxidase, phenylalanine ammonia-lyase, super oxide dismutase (SOD) and polyphenol oxidase (PPO) in the plants were analyzed before challenging, 1st, 3rd and 5th day after challenging with pathogen. The values followed the same trend in all treatments as it increased after inoculation up to 3rd day and then decreased for peroxidase (PO) and SOD. The plants treated with EEB1 A8 and combination of EEB1 A8 and P. indica showed the highest values for the level of defense enzyme production. In a storage study, when ginger seed rhizomes were treated with individual bacterial isolates and as a consortium of both, followed by inoculation with the pathogen P. myriotylum , rhizomes treated with consortium were more tolerant to rhizome rot. Applying endospore-forming bacteria with biocontrol properties is a propitious method for controlling rhizome rot in ginger, in the field and during seed storage.

Investigation of the anti-Huanglongbing effects using antimicrobial lipopeptide and phytohormone complex powder prepared from Bacillus amyloliquefaciens MG-2 fermentation

Global citrus production has been severely affected by citrus Huanglongbing (HLB) disease, caused by Candidatus Liberibacter asiaticus (Clas), and the development of effective control methods are crucial. This study employed antimicrobial lipopeptide and phytohormone complex powder (L1) prepared from the fermentation broth of the endophytic plant growth promoting bacterium (PGPB) of Bacillus amyloliquefaciens strain MG-2 to treat Candidatus Liberibacter asiaticus (CLas)-infected ‘Citrus reticulata ‘Chun Jian’ plants. Real-time fluorescence quantitative polymerase chain reaction (qPCR) and PCR were employed for disease detection. The results revealed that after 15 spray-drench treatments with L1 solution, the HLB infection rate decreased from 100 to 50%, the bacterial titer decreased by 51.9% compared with a 27.9% decrease in the control group. L1 treatment triggered the production of reactive oxygen species, increased lignin content, and increased defense enzyme activities (p < 0.05). Defense-related gene expression significantly increased within 12 h of treatment. In addition, L1 application also promoted plant growth, as evidenced by higher transpiration rates and net photosynthetic rates as well as increased leave or root density. Root flora analysis revealed that the abundances of Burkholderia_thailandensis, unclassified_g_Burkholderia-Caballeronia-Paraburkholderia, unclassified_g__Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, and Pseudomonas_mosselii were 1.64, 1.46, 5.84, and 6.93 times greater, respectively, than those in the control group. The levels of phenylpropanoids, polyketides, lipids, lipid-like molecules, organic acids, and derivatives, significantly increased following L1 treatment (FC > 2, p < 0.05). Additionally, salicylic acid, dihydrojasmonic acid, and isopentenyl adenosine levels in leaves markedly increased. High-performance liquid chromatography (HPLC) confirmed that L1 contained surfactin, iturin and fengycin cyclic-lipopeptides (CLPs) as well as indole-3-acetic acid (IAA), 3-indolebutyric acid (IBA), indole-3-carboxylic acid and indole-3-carboxaldehyde auxins, N6-entopentenyladenine and t-zeatin-riboside cytokinins, abscisic acid, 1-aminocyclicpanecarboxylic acid, salicylic acid, and gibberellin A1, A3 and A4 phytohormones. These findings provide insight into multiple mechanisms by which endophytic Bacillus PGPB L1 is able to combat HLB disease, to promote citrus plant growth, and to optimize the root flora for soil health which offering an innovative strategy for sustainable management of this severe disease and improving citrus plant growth and productivity

Metabolite profiling of PGPR Bacillus subtilis BGKMR1: A potential strategy for managing Fusarium equiseti causing wilt in bitter gourd (Momordica charantia L.)

Wilt caused by Fusarium equiseti is one of the most destructive diseases that leads to substantial yield loss in bitter gourd. The F. equiseti strain CBEFE1((PQ111513.1) which was identified morphologically with falcate shaped three septate macroconidia and oval shaped microconidia and molecularly confirmed through amplification of the ITS region at 560bp was used for this study. Plant growth promoting rhizobacteria (PGPR) act as a sustainable biocontrol agent against major plant pathogens through multiple mode of actions. PGPR were isolated from native rhizopshere region in bitter gourd. The isolated PGPR Bacillus subtilis BGKMR 1 shows maximum mycelial inhibition of 68.73 % against F. equiseti in dual plate assay. The presence of metabolites produced by B. subtilis and F. equiseti along with its interaction were identified through the GCMS profiling. Primarily, pathogenic compound squalene (8.88 %) was identified in F. equiseti and antifungal compound 1,4-benzenedicarboxylic acid (6.1 %) was identified in B. subtilis. Further, B. subtilis BGKMR 1 during its interaction shows propanoic acid (14.69 %) which was found to have effectiveness against F. equiseti. KEGG analysis revealed pyrimidine metabolism in F. equiseti and nitrogen, alanine, aspartate and glutamate metabolism in B. subtilis and propanoate metabolism pathways were detected during its interaction. B. subtilis BGKMR 1 promote the seed germination rate upto 96 % and vigor index to 1919.04 when compared to control. The seed treatment with soil application of B. subtilis BGKMR1 reduced disease incidence upto 25.95 % under glass house condition. Moreover, B. subtilis BGKMR1 treated plants shows enhanced defense enzymes activity such as peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase indicating induction of systemic resistance. Therefore, B. subtilis BGKMR 1 contains novel antifungal metabolites which were identified via GC-MS and induced defense enzyme activity highlights its practical application as a sustainable and eco-friendly solution for managing wilt disease in bitter gourd.

Trichoderma longibrachiatum (T6) Peptaibols Inhibiting the Monilia yunnanensis Growth and Inducing Pear Fruit Resistance in Its Infection.

Pear fruit brown rot, caused by Monilia yunnanensis, affects pear fruit yields and quality. The present study determined Trichoderma longibrachiatum T6 (T6) peptaibols as a biological control alternative to synthetic fungicides and assessed its efficacy against M. yunnanensis through dual plate culture and surface spraying at different concentrations. T6 peptaibols effectively inhibited M. yunnanensis growth, achieving an 85.99% inhibitory rate at 1250 µg/mL after inoculation on PDA medium for 5 days, and 84.57% control efficacy on pear fruit with the same concentration at 6 days. Treatment with T6 peptaibols significantly decreased the average contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), as well as electrolyte leakage, by 31.99%, 27.93%, and 21.00% from days 1 to 9 post-inoculation, respectively, in comparison to the negative control. Additionally, the average antioxidant enzyme activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and polyphenol oxidase (PPO) increased by 86.27%, 56.76%, 25.94%, and 47.88%, respectively; the average defense enzyme activities of phenylalanine ammonia-lyase (PAL), lipoxygenase (LOX), chitinase (CHI), and β-1,3-glucanase (β-Glu) increased by 63.00%, 55.70%, 26.19%, and 16.34%, respectively. Moreover, the expression levels of the antioxidant and defense-related genes (CAT, SOD, POD, PPO, CHI, LOX, PAL, β-Glu) were significantly upregulated by 2.80, 2.81, 3.03, 2.79, 3.37, 2.49, 2.73, and 1.83-folds at 3 days after inoculation compared to the negative control. Thus, T6 peptaibols effectively reduced the pathogen infection through growth inhibition and antioxidant defenses, thereby boosting fruit immunity.

Managing tomato bacterial wilt through pathogen suppression and host resistance augmentation using microbial peptide.

The increasing health and environmental risks associated with synthetic chemical pesticides necessitate the exploration of safer, sustainable alternatives for plant protection. This study investigates a novel biosynthesized antimicrobial peptide (AMP) from Lactiplantibacillus argentoratensis strain IT, identified as the amino acid chain PRKGSVAKDVLPDPVYNSKLVTRLINHLMIDGKRG, for its efficacy in controlling bacterial wilt (BW) disease in tomato (Solanum lycopersicum) caused by Ralstonia solanacearum. Our research demonstrates that foliar application of this AMP at a concentration of 200 ppm significantly reduces disease incidence by 49.3% and disease severity by 45.8%. Scanning electron microscopy revealed severe morphological disruptions in the bacterial cells upon exposure to the AMP. Additionally, the AMP enhanced host resistance by elevating defense enzyme activities, leading to notable improvements in plant morphology, including a 95.5% increase in plant length, a 20.1% increase in biomass, and a 96.69% increase in root length. This bifunctional AMP provides dual protection by exerting direct antimicrobial activity against the pathogen and eliciting plant defense mechanisms. These findings underscore the potential of this biologically sourced AMP as a natural agent for combating plant diseases and promoting growth in tomato crops. To the best of our knowledge, this is the first study to demonstrate the use of a foliar spray application of a biosynthesized microbial peptide as biocontrol agent against R. solanacearum. This interaction not only highlights its biocontrol efficacy but also its role in promoting the growth of Solanum lycopersicum thereby increasing overall agricultural yield.