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Soil contamination by crude oil is a common occurrence during accidental spills, transportation, or refining processes. Bioremediation as an environmentally friendly and cost-effective approach is interesting for treating hydrocarbon-contaminated sites via natural microorganisms to break down or transform the hydrocarbons into less toxic substances. However, the bioremediation process is time-consuming due to the low accessibility of cells to hydrocarbon contaminants in soil. Applying hydrocarbon degraders with the capability to produce biosurfactants during the hydrocarbon degradation pathways could significantly handle the problem. In this study, a bacterial consortium consists Roseomonas aestuarii , Pseudomonas oryzihabitans , Pantoea agglomerans , and Arthrobacter sp. was evaluated for crude oil removal from the aqueous environment and soil microcosm. To examine the effect of supplementary biosurfactants in the bioremediation process, surfactin and rhamnolipid (ratio 1:1) were used at a concentration of 1000 ppm. Our findings indicate the consortium has high potential in removing saturated hydrocarbons from aqueous (removal yield = 96.16% after 9 days) and soil (removal yield = 64.65% after 120 days) environments. The consortium had a significantly higher removal efficiency than the single-cell treatments, possibly due to the species’ synergistic effect. The GC-MS analysis confirmed a uniform removal of different molecular weight hydrocarbons by the consortium from soil. However, adding supplementary biosurfactants showed a slight modification in the consortium’s performance after 120 days in soil microcosms (removal yield for saturated hydrocarbons was 65.97%). This study showed the potential application of this in-situ producing biosurfactant consortium for bioremediation purposes.

Plants emit a plethora of volatile organic compounds in response to biotic and abiotic stresses. These compounds act as infochemicals for ecological communication in the phytobiome. This study reviews the role of microbe-induced plant volatiles (MIPVs) in plant–microbe interactions. MIPVs are affected by the taxonomic position of the microbe, the identity of the plant and the type of interaction. Plants also emit exclusive blends of volatiles in response to nonhost and host interactions, as well as to beneficial microbes and necrotrophic/biotrophic pathogens. These MIPVs directly inhibit pathogen growth and indirectly promote resistance/susceptibility to subsequent plant pathogen attack. Viruses and phloem-limiting bacteria modify plant volatiles to attract insect vectors. Susceptible plants can respond to MIPVs from resistant plants and become resistant. Recent advances in our understanding of the molecular mechanisms of MIPV synthesis in plants and how plant pathogen effectors manipulate their biosynthesis are discussed. This knowledge will help broaden our understanding of plant–microbe interactions and should facilitate the development of new emerging techniques for sustainable plant disease management.

In plants, the regulation of plasma membrane (PM) dynamics through endocytosis plays a crucial role in responding to external environmental cues and defending against pathogens. The Arabidopsis plant elicitor peptides (Peps), originating from precursor proteins called PROPEPs, have been implicated in various aspects of plant immunity. This study delves into the signaling pathway of Peps, particularly Pep1, and its effect on PM protein internalization. Using PIN2 and BRI1 as PM markers, we demonstrated that Pep1 stimulates the endocytosis of these PM-localized proteins through clathrin-mediated endocytosis (CME). CLC2 and CLC3, two light chains of clathrin, are vital for Pep1-induced PIN2-GFP and BRI1-GFP internalization.The internalized PIN2 and BRI1 are subsequently transported to the vacuole via the trans-Golgi network/early endosome (TGN/EE) and prevacuolar compartment (PVC) pathways. Intriguingly, salicylic acid (SA) negatively regulates the effect of Pep1 on PM endocytosis. This study sheds light on a previously unknown signaling pathway by which danger peptides like Pep1 influence PM dynamics, contributing to a deeper understanding of the function of plant elicitor peptide.

Plant Elicitor Peptides (Peps) induce plant immune responses and inhibit root growth through their receptors PEPR1 and PEPR2, two receptor-like kinases. In our study, we found a previously unknown function of Peps that enhance root hair growth in a PEPRs-independent manner. When we characterized the expression patterns of PROPEP genes, we found several gene promoters of PROPEP gene family were particularly active in root hairs. Furthermore, we observed that PROPEP2 is vital for root hair development, as disruption of PROPEP2 gene led to a significant reduction in root hair density and length. We also discovered that PROPEP2 regulates root hair formation via the modulation of CPC and GL2 expression, thereby influencing the cell-fate determination of root hairs. Additionally, calcium signaling appeared to be involved in PROPEP2/Pep2-induced root hair growth. These findings shed light on the function of Peps in root hair development.

Abstract Background Bacterial volatile compounds (BVCs) are important mediators of beneficial plant–bacteria interactions. BVCs promote above-ground plant growth by stimulating photosynthesis and sugar accumulation and by modulating phytohormone signalling. These compounds also improve below-ground mineral uptake and modify root system architecture. Scope We review advances in our understanding of the mode of action and practical applications of BVCs since the discovery of BVC-mediated plant growth promotion in 2003. We also discuss unanswered questions about the identity of plant receptors, the effectiveness of combination of two or more BVCs on plant growth, and the potential side effects of these compounds for human and animal health. Conclusion BVCs have good potential for use as biostimulants and protectants to improve plant health. Further advances in the development of suitable technologies and preparing standards and guidelines will help in the application of BVCs in crop protection and health.

Bacterial volatiles protect plants either by directly inhibiting a pathogenic fungus or by improving the defense capabilities of plants. The effect of bacterial volatiles on fungal growth was dose-dependent. A low dosage did not have a noticeable effect on Botrytis cinerea growth and development, but was sufficient to elicit induced resistance in Arabidopsis thaliana. Bacterial volatiles displayed negative effects on biofilm formation on a polystyrene surface and in in planta leaf colonization of B. cinerea. However, bacterial volatile-mediated induced resistance was the major mechanism mediating protection of plants from B. cinerea. It was responsible for more than 90% of plant protection in comparison with direct fungal inhibition. Our results broaden our knowledge of the role of bacterial volatiles in plant protection.

In this study, the effect of six commercial biocontrol strains, Bacillus pumilus INR7, B. megaterium P2, B. subtilis GB03, B. subtilis S, B. subtilis AS and B. subtilis BS and four indigenous strains Achromobacter sp. B124, Pseudomonas geniculate B19, Serratia marcescens B29 and B. simplex B21 and two plant defense inducers, methyl salicylate (Me-SA) and methyl jasmonate (Me-JA) were assessed on suppression of wheat take-all disease. Treatments were applied either as soil drench or sprayed on shoots. In the soil drench method, the highest disease suppression was achieved in treatment with strains INR7, GB03, B19 and AS along with two chemical inducers. Bacillus subtilis S, as the worst treatment, suppressed take-all severity up to 56%. Both chemical inducers and bacterial strains AS and P2 exhibited the highest effect on suppression of take-all disease in the shoot spray method. Bacillus subtilis S suppressed the disease severity up to 49% and was again the worst strain. The efficacy of strains GB03 and B19 decreased significantly in the shoot spray method compared to the soil drench application method. Our results showed that most treatments had the same effect on take-all disease when they were applied as soil drench or sprayed on aerial parts. This means that induction of plant defense was the main mechanism in suppressing take-all disease by the given rhizobacteria. It also revealed that plant growth was reduced when it was treated with chemical inducers. In contrast, rhizobacteria not only suppressed the disease, but also increased plant growth.

Hydrocarbons are considered as one of the most common and harmful environmental pollutants affecting human health and the environment. Bioremediation as an environmentally friendly, highly efficient, and cost-effective method in remediating oil-contaminated environments has been interesting in recent decades. In this study, hydrocarbon degrader bacterial strains were isolated from the highly petroleum-contaminated soils in the Dehloran oil field in the west of Iran. Out of 37 isolates, 15 can grow on M9 agar medium that contains 1.5 g L−1 of crude oil as the sole carbon source. The morphological, biochemical, and 16SrRNA sequencing analyses were performed for the isolates. The choosing of the isolates as the hydrocarbon degrader was examined by evaluating the efficacy of their crude oil removal at a concentration of 10 g L−1 in an aqueous medium. The results showed that five isolates belonging to Pseudomonas sp., Pseudomonas oryzihabitans, Roseomonas aestuarii, Pantoea agglomerans, and Arthrobacter sp. had a hyper hydrocarbon-degrading activity and they could remove more than 85% of the total petroleum hydrocarbon (TPH) after 96 h. The highest TPH removal of about 95.75% and biodegradation rate of 0.0997 g L−1 h−1 was observed for P. agglomerans. The gas chromatography–mass spectroscopy (GC–MS) analysis was performed during the biodegradation process by P. agglomerans to detect the degradation intermediates and final products. The results confirmed the presence of intermediates such as alcohols and fatty acids in the terminal oxidation pathway of alkanes in this biodegradation process. A promising P. agglomerans NB391 strain can remove aliphatic and aromatic hydrocarbons simultaneously.

Introduction:Fluorescent pseudomonads produced a variety of siderophores in which the pyoverdine type siderophore is the main one. These bacteria employ siderophores to increase availability of Iron for their own and plants consumption. Siderophores have a special role in the biological control activity of these bacteria against plant pathogens. Materials and methods: Siderophore production was checked in 21 indigenous Pseudomonads strains, two reference strains and one Bacillus sp. strain by qualitative CAS-Agar, semi-quantitative CAS-AD and quantitative spectrophotometric methods. Results: Colony growth in some of isolates such as UTPF93 has been inhibited in CAS-Agar method because of the detergent compound HDTMA. So, siderophore production was low in these strains. All strains produced siderophore by the CAS-AD method. The highest and the lowest siderophore production were recorded in UTPF76 and UTPF45 with 1.005 and 0.0026 mM of defroxamin equivalent, respectively. The Pyoverdine mutant strain MPFM1 and the Bacillussp. strain also produce low amounts of siderophore in two recent methods. So, these methods are non-selective to the type of siderophore. In quantitative method only Pyoverdine type siderophore was detectable and the strains MPFM1 and Bacillus sp. did not produce this type of siderophore. The highest amount of pyoverdine was recorded in non-indigenous strain 7NSK2 with 625.29 mM/L followed by UTPF65, UTPF81 and UTPF87. Discussion and conclusion: CAS-AD was the best method for total siderophore measurement and spectrophotometric was the accurate and efficient method for detection of pyoverdine type siderophore in fluorescent pseudomonads.