Cherry blossom crown gall has caused serious damage to plant growth, and is highly contagious and extremely difficult to control. The antagonism of pathogens by rhizosphere bacteria has attracted widespread attention. However, there is still limited research on the cherry blossom crown gall. In this study, we explored the control effect of rhizosphere bacteria Pseudomonas aurantiaca ST-TJ4 on cherry blossom crown gall. We also investigated the long-term survival status of ST-TJ4 in the cherry blossom roots and the induction of plant defense resistance. The results showed that ST-TJ4 had obvious inhibition effect on the population of Agrobacterium tumefaciens, which could reduce the number of A. tumefaciens by 70% to 90%, and its population kept the advantage in the rhizosphere soil and cherry blossom roots. The incidence of crown gall in the therapy group and the prevention group was reduced by 37.5% and 50%, respectively, and the disease index was reduced from 80 to 20 and 10, respectively. At the 150th day, ST-TJ4 could still be isolated from the rhizosphere soil and root surface, indicating that ST-TJ4 could survive in soil for a long time and had long-term performance. Compared with the control group, the therapy group and prevention group could reduce the levels of H2O2, malondialdehyde (MDA) and the oxidative damage, and up-regulated the expression of active oxygen-related genes DHAR1, SOD1, GR1 and CAT to activate defense response. On the other hand, it could up-regulate the expression of SA1, SA2 and JA1 genes related to the induction of salicylic acid (SA) and jasmonic acid (JA), and lead to the increase of SA hormone level. Collectively, P. aurantiaca ST-TJ4 had the potential to be applied for biocontrol of cherry blossom crown gall by reducing root pathogen colonization and inducing plant resistance.

Pesticide contamination has become a major environmental concern with organophosphates such as chlorpyrifos emerging as major pollutants posing significant risks to both ecosystems and human health. Chlorpyrifos is widely used in agriculture to control pests, however due to its persistence, its accumulation in soils can lead to long-term environmental damage. The objective of this study was to isolate and characterize chlorpyrifos-degrading bacteria from a tobacco field exposed to intensive pesticide use in T & uuml;rkiye. To achieve this, a selective enrichment strategy was employed to promote the growth of chlorpyrifos-degrading microorganisms. Two distinct experimental setups were established to target both normally growing and slower-growing bacteria: the first involved a 4-week incubation with weekly subculturing as described in the literature, while the second applied an 8-week incubation with biweekly subculturing. At the end of the enrichment period, bacterial loads were compared between the two groups. Four of the nine bacterial isolates were obtained from the newly tested long-term setup. Among all isolates, members of the genus Pseudomonas exhibited the best adaptation to the prolonged enrichment conditions. Additionally, isolates belonging to the genera Klebsiella, Sphingobacterium, and Peribacillus were isolated from the normally growing group. Two isolates (AB4 & AB15), identified as Sphingobacterium thalpophilum, were determined to be novel chlorpyrifos degraders. This is the first reported study from T & uuml;rkiye focusing on the biodegradation of chlorpyrifos by native soil bacteria. The findings revealed that various ecological areas, constitute potential sources for new microbial metabolic processes and these bacterial strains can be used in bioremediation studies.

A polyphasic taxonomic approach was conducted to characterize the bacterial strain B22T isolated from the rhizospheric soil of the halophyte Salicornia hispanica. This strain is aerobic, Gram-negative, rod-shaped, catalase and oxidase positive, motile, reduces nitrates and chemoheterotrophic. It is halotolerant, exhibiting optimal growth at 28 degrees C and pH 7.0 in the presence of 0.5-2.5% (w/v) of NaCl. The B22T genome size is 5.7 Mbp, with a G+C content of 60.5 mol%. This strain has the capacity to promote tomato growth by producing siderophores, indole-3-acetic acid and enzymes such as phytase and acid phosphatase. Additionally, strain B22T produces a quorum quenching (QQ) enzyme capable of degrading synthetic N-acylhomoserine lactones (AHLs) as well as those produced by phytopathogens. The interference of plant pathogen communication reduced virulence in tomato fruits and plants. Phylogenetic analysis revealed that the closest relatives of strain B22T was Pseudomonas tehranensis SWRI 196T. The average nucleotide identity values between strain B22T and P. tehranensis SWRI 196T was 95.1% while digital DNA-DNA hybridization values was 64.5% The main cellular fatty acids of strain B22T were C16:0, summed feature 3 (C16:1 omega 7c/C16:1 omega 6c) and summed feature 8 (C18:1 omega 7c/C18:1 omega 6c). The major polar lipids identified were diphosphatidylglycerol and phosphatidylethanolamine, while the predominant respiratory quinone was ubiquinone (Q-9). Based on genomic, phylogenetic and chemotaxonomic data, strain B22T (=CECT 31209; =LMG33902) represents a novel species within the genus Pseudomonas. The name Pseudomonas halotolerans sp. nov. is proposed. Additionally, this study highlights the potential of P. halotolerans as a sustainable biocontrol agent due to its plant growth-promoting activity in tomato plants and its ability to reduce phytopathogen virulence factors, mitigating damage to fruits and plants.

Herein, we synthesized 34 novel tryptanthrin derivatives, among which T7NHCO-series compounds showed great antibacterial activity againstXanthomonas axonopodis pv. citri,Pseudomonas syringae pv. actinidiae, andRalstonia solanacearum with EC50 values ranging from 0.26 to 0.56 mu g/mL. Meanwhile, these compounds exhibited low cytotoxicity against HEK-293. Additionally, compound T7NHCO can inhibit biofilm formation, damage bacterial morphology, downregulate the expression of bacterial chemotaxis-related proteins, cause bacterial necrosis, and effectively control citrus and kiwifruit canker (the curative and protective efficiency is 79.35 and 88.31%, respectively) diseases. However, compound T7NHCO exhibited a significant phytotoxicity to tobacco. Subsequently, based on the characteristic of tobacco wilt disease being prone to outbreak in weakly acidic soil conditions, we introduced the pH-responsive ZIF-8 drug delivery system. Fortunately, T7NHCO@ZIF-8 nanoparticles exhibited low phytotoxicity and noticeable activity against tobacco wilt disease. Above all, T7NHCO@ZIF-8 nanoparticles may be a promising green lead agent against plant bacterial diseases.

Polycyclic aromatic hydrocarbons (PAHs), one of the major environmental pollutants, produced from incomplete combustion of materials like coal, oil, gas, wood, and charbroiled meat, that contaminate the air, soil, and water, necessitating urgent remediation. Understanding the metabolic pathways for PAHs degradation is crucial to preventing environmental damage and health issues. Biological methods are gaining increasing interest due to their cost-effectiveness and environmental friendliness. These methods are particularly suitable for remediating PAHs contamination and mitigating associated risks. The paper also outlines the processes for biodegrading PAHs, emphasizing the function of Pseudomonas spp., a kind of bacterium recognized for its capacity to degrade PAHs. To eliminate PAHs from the environment and reduce threats to human health and the environment, Pseudomonas spp. is essential. Understanding the mechanism of PAH breakdown by means of microbes could lead to effective clean-up strategies. The review highlights the enzymatic capabilities, adaptability, and genetic versatility of the genes like nah and phn of Pseudomonas spp., which are involved in PAHs degradation pathways. Scientific evidence supports using Pseudomonas spp. as biocatalysts for PAHs clean-up, offering cost-effective and eco-friendly solutions.

The extensive agricultural use of the fungicide difenoconazole (DIF) and its associated toxicity increasingly damage ecosystems and human health. Thus, an urgent need is to develop environmentally friendly technological approaches capable of effectively removing DIF residues. In this study, strain Pseudomonas putida A-3 was isolated for the first time which can degrade DIF efficiently. After optimization of the degradation conditions, the degradation rate reached 75.98%. Moreover, a new DIF degradation pathway, including hydroxylation, hydrolysis, dechlorination, and ether bond breaking. The acute and chronic toxicity of DIF degradation products assessed using ECOSAR software showed lower toxicity than the parent compound. Furthermore, strain A-3 remarkably accelerated the degradation of DIF in contaminated water-sediment systems. We successfully predicted six potential key enzymes for DIF degradation based on the results of whole genome sequencing, RT-qPCR, and molecular docking. Overall, the results revealed novel pathways for DIF biodegradation and provide a strong candidate for bioremediation of DIF residue-polluted environments.

In past few years, salinity has become one of the important abiotic stresses in the agricultural fields due to anthropogenic activities. Salinity is leading towards yield losses due to soil infertility and increasing vulnerability of crops to diseases. Fluorescent pseudomonads are a diverse group of soil microorganisms known for promoting plant growth by involving various traits including protecting crops from infection by the phytopathogens. In this investigation, salt tolerant plant growth promoting bacterium Pseudomonas hunanensis SPT26 was selected as an antagonist against Fusarium oxysporum, causal organism of fusarium wilt in tomato. P. hunanensis SPT26 was found capable to produce various antifungal metabolites. Characterization of purified metabolites using Fourier transform infrared spectroscopy (FT-IR) and liquid chromatography-electron spray ionization-mass spectrometry (LC-ESI/MS) showed the production of various antifungal compounds viz., pyrolnitrin, pyochelin and hyroxyphenazine by P. hunanensis SPT26. In the preliminary examination, biocontrol activity of purified antifungal metabolites was checked by dual culture method and results showed 68%, 52% and 65% growth inhibition by pyrolnitrin, 1- hydroxyphenazine and the bacterium (P. hunanensis SPT26) respectively. Images from scanning electron microscopy (SEM) revealed the damage to the mycelia of fungal phytopathogen due to production of antifungal compounds secreted by P. hunanensis SPT26. Application of bioinoculant of P. hunanensis SPT26 and purified metabolites significantly decreased the disease incidence in tomato and increased the plant growth parameters (root and shoot length, antioxidant activity, number of fruits per plant, etc.) under saline conditions. The study reports a novel bioinoculant formulation with the ability to promote plant growth parameters in tomato in presence of phytopathogens even under saline conditions.

Background Plants have evolved various defense mechanisms against insect herbivores, including the formation of physical barriers, the synthesis of toxic metabolites, and the activation of phytohormone responses. Although plant-associated microbiota influence plant growth and health, whether they play a role in plant defense against insect pests in natural ecosystems is unknown. Results Here, we show that leaves of beetle-damaged weeping willow (Salix babylonica) trees are more resistant to the leaf beetle Plagiodera versicolora (Coleoptera) than those of undamaged leaves. Bacterial community transplantation experiments demonstrated that plant-associated microbiota from the beetle-damaged willow contribute to the resistance of the beetle-damaged willow to P. versicolora. Analysis of the composition and abundance of the microbiome revealed that Pseudomonas spp. is significantly enriched in the phyllosphere, roots, and rhizosphere soil of beetle-damaged willows relative to undamaged willows. From a total of 49 Pseudomonas strains isolated from willows and rhizosphere soil, we identified seven novel Pseudomonas strains that are toxic to P. versicolora. Moreover, re-inoculation of a synthetic microbial community (SynCom) with these Pseudomonas strains enhances willow resistance to P. versicolora. Conclusions Collectively, our data reveal that willows can exploit specific entomopathogenic bacteria to enhance defense against P. versicolora, suggesting that there is a complex interplay among plants, insects, and plant-associated microbiota in natural ecosystems.

Plant growth-promoting rhizobacteria (PGPR) have been reported to suppress various diseases as potential bioagents. It can inhibit disease occurrence through various means such as directly killing pathogens and inducing systemic plant resistance. In this study, a bacterium isolated from soil showed significant inhibition of Valsa mali. Morphological observations and phylogenetic analysis identified the strain as Pseudomonas thivervalensis, named K321. Plate confrontation assays demonstrated that K321 treatment severely damaged V. mali growth, with scanning electron microscopy (SEM) observations showing severe distortion of hyphae due to K321 treatment. In vitro twigs inoculation experiments indicated that K321 had good preventive and therapeutic effects against apple Valsa canker (AVC). Applying K321 on apples significantly enhanced the apple inducing systemic resistance (ISR), including induced expression of apple ISR-related genes and increased ISR-related enzyme activity. Additionally, applying K321 on apples can activate apple MAPK by enhancing the phosphorylation of MPK3 and MPK6. In addition, K321 can promote plant growth by solubilizing phosphate, producing siderophores, and producing 3-indole-acetic acid (IAA). Application of 0.2% K321 increased tomato plant height by 53.71%, while 0.1% K321 increased tomato fresh weight by 59.55%. Transcriptome analysis revealed that K321 can inhibit the growth of V. mali by disrupting the integrity of its cell membrane through inhibiting the metabolism of essential membrane components (fatty acids) and disrupting carbohydrate metabolism. In addition, transcriptome analysis also showed that K321 can enhance plant resistance to AVC by inducing ISR-related hormones and MAPK signaling, and application of K321 significantly induced the transcription of plant growthrelated genes. In summary, an excellent biocontrol strain has been discovered that can prevent AVC by inducing apple ISR and directly killing V. mali. This study indicated the great potential of P. thivervalensis K321 for use as a biological agent for the control of AVC.

Abiotic stress, such as high temperatures, droughts and soil salinity, as well as biotic stress, such as pythopathogenic bacteria, are causing serious damage to crops and they result in significant economic losses. In addition, excessive application of agrochemicals has deteriorated productive agricultural land, contributed to spreading antimicrobial resistance genes among pathogenic microorganisms and caused damage to human health. Developing alternative strategies to the use of chemicals is an ongoing challenge for achieving a sustainable agriculture. In this context, biological products, including bacteriocins, enhance crop growth and health without harming the environment. Bacteriocins are proteinaceous compounds that exhibit high specificity and kill competitors closely related to the producing bacteria. They are secreted by both Gram-negative bacteria and Gram-positive bacteria, and they have been used to treat bacterial infections in humans and animals, and to preserve food. In recent years, studies that projected the use of bacteriocins in agriculture have increased due to their high biotechnological potential. These bacteriocins have been explored as plant biostimulants or as biocontrol agents, and provide an innovative solution to the problems in agriculture. In particular, tailocins have a great potential as antimicrobials because they are very stable, extremely specific, and efficient as killers; in fact, a single particle is enough to kill a susceptible cell.In this review, we examine the bacteriocins produced by rhizobacteria and their application for a sustainable agriculture, a topic that has not been addressed extensively yet. In addition, we discuss bacteriocin expression in plants and the study of bacteriocins through omics.