RESUMO
Co-evolution of plant beneficial microbes in contaminated environments enhances plant growth and mitigates abiotic stress. However, few studies on heavy metal (HM) tolerant plant growth-promoting bacteria (PGPB) promoting crop growth in Morocco's farming areas affected by drought and salinity are available. Plant associated bacteria tolerant to HM and able to produce indole acetic acid and siderophores, display ACC-deaminase activity and solubilize phosphate, were isolated from long-term metal exposed environments. Tolerance to HM and biofilms formation in the absence or presence of HM were assessed. A consortium including two Ensifer meliloti strains (RhOL6 and RhOL8), one Pseudomonas sp. strain (DSP17), and one Proteus sp. strain (DSP1), was used to inoculate alfalfa (Medicago sativa) seedlings under various conditions, namely, salt stress (85 mM) and water stress (30% water holding capacity). Shoot and root dry weights of alfalfa were measured 60 days after sowing. In the presence of HM, DSP17 showed the greatest auxin production, whereas RhOL8 had the highest ACC-deaminase activity and DSP17 formed the densest biofilm. Root dry weight increased 138% and 195% in salt and water stressed plants, respectively, regarding non-inoculated controls. Our results confirm the improvement of alfalfa growth and mitigation of salt and drought stress upon inoculation.
Assuntos
Medicago sativa , Metais Pesados , Medicago sativa/microbiologia , Medicago sativa/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Ácidos Indolacéticos/metabolismo , Microbiologia do Solo , Estresse Salino , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Marrocos , Secas , Poluentes do Solo , Biofilmes/crescimento & desenvolvimento , Estresse Fisiológico , Carbono-Carbono Liases/metabolismoRESUMO
Plant-associated streptomycetes play important roles in plant growth and development. However, knowledge of volatile-mediated crosstalk between Streptomyces spp. and plants remains limited. In this study, we investigated the impact of volatiles from nine endophytic Streptomyces strains on the growth and development of plants. One versatile strain, Streptomyces setonii WY228, was found to significantly promote the growth of Arabidopsis thaliana and tomato seedlings, confer salt tolerance, and induce early flowering and increased fruit yield following volatile treatment. Analysis of plant growth-promoting traits revealed that S. setonii WY228 could produce indole-3-acetic acid, siderophores, ACC deaminase, fix nitrogen, and solubilize inorganic phosphate. These capabilities were further confirmed through genome sequencing and analysis. Volatilome analysis indicated that the volatile organic compounds emitted from ISP-2 medium predominantly comprised sesquiterpenes and 2-ethyl-5-methylpyrazine. Further investigations showed that 2-ethyl-5-methylpyrazine and sesquiterpenoid volatiles were the primary regulators promoting growth, as confirmed by experiments using the terpene synthesis inhibitor phosphomycin, pure compounds, and comparisons of volatile components. Transcriptome analysis, combined with mutant and inhibitor studies, demonstrated that WY228 volatiles promoted root growth by activating Arabidopsis auxin signaling and polar transport, and enhanced root hair development through ethylene signaling activation. Additionally, it was confirmed that volatiles can stimulate plant abscisic acid signaling and activate the MYB75 transcription factor, thereby promoting anthocyanin synthesis and enhancing plant salt stress tolerance. Our findings suggest that aerial signaling-mediated plant growth promotion and abiotic stress tolerance represent potentially overlooked mechanisms of Streptomyces-plant interactions. This study also provides an exciting strategy for the regulation of plant growth and the improvement of horticultural crop yields within sustainable agricultural practices.
Assuntos
Arabidopsis , Ácidos Indolacéticos , Tolerância ao Sal , Streptomyces , Compostos Orgânicos Voláteis , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Streptomyces/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Ácidos Indolacéticos/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Desenvolvimento Vegetal/efeitos dos fármacos , Estresse Salino , Transdução de Sinais , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Plântula/metabolismo , Regulação da Expressão Gênica de Plantas , Carbono-Carbono Liases/metabolismo , Fosfatos/metabolismoRESUMO
Drought is a major stressor that poses significant challenges for agricultural practices. It becomes difficult to meet the global demand for food crops and fodder. Plant physiology, physico-chemistry and morphology changes in plants like decreased photosynthesis and transpiration rate, overproduction of reactive oxygen species, repressed shoot and root shoot growth and modified stress signalling pathways by drought, lead to detrimental impacts on plant development and output. Coping with drought stress requires a variety of adaptations and mitigation techniques. Crop yields could be effectively increased by employing plant growth-promoting rhizobacteria (PGPR), which operate through many mechanisms. These vital microbes colonise the rhizosphere of crops and promote drought resistance by producing exopolysaccharides (EPS), 1-aminocyclopropane-1-carboxylate (ACC) deaminase and phytohormones including volatile compounds. The upregulation or downregulation of stress-responsive genes causes changes in root architecture due to acquiring drought resistance. Further, PGPR induces osmolyte and antioxidant accumulation. Another key feature of microbial communities associated with crops includes induced systemic tolerance and the production of free radical-scavenging enzymes. This review is focused on detailing the role of PGPR in assisting plants to adapt to drought stress.
Assuntos
Agricultura , Produtos Agrícolas , Secas , Desenvolvimento Vegetal , Reguladores de Crescimento de Plantas , Raízes de Plantas , Rizosfera , Microbiologia do Solo , Estresse Fisiológico , Produtos Agrícolas/microbiologia , Produtos Agrícolas/crescimento & desenvolvimento , Agricultura/métodos , Reguladores de Crescimento de Plantas/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Bactérias/genética , Bactérias/metabolismo , Carbono-Carbono Liases/metabolismo , Carbono-Carbono Liases/genéticaRESUMO
An essential aromatic plant, Pelargonium graveolens, does not grow well in areas where chromium contamination is a problem. Because of oxidative stress and the collapse of the photosynthetic system, crops frequently sustain severe damage. The production of excess ethylene, known as stress ethylene, which is detrimental to plant growth, the formation of roots, and early senescence, is also increased by heavy metal exposure. The effectiveness of the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase gene in transgenic Pelargonium graveolens under the control of CaMV 35S promoter was investigated to lessen the stress ethylene during chromium stress. Chromium was administered as potassium dichromate (K2Cr2O7) at four distinct concentrations (100 µM, 200 µM, 300 µM, and 500 µM) to transgenic and wild-type P. graveolens and stress-induced physiological changes were monitored. Transgenic P. graveolens demonstrated greater tolerance to chromium stress than wild-type P. graveolens, as evidenced by higher leaf-relative water content, chlorophyll content, CO2 absorption, transpiration rate, stomatal conductance, proline buildup, and antioxidant activity. The L1, L5, and L7, ACC deaminase-expressing transgenic lines also show a drop in ACC content during chromium stress, which subsequently lowered ethylene synthesis. Therefore, the reported transgenic P. graveolens lines having the ACC deaminase gene could be useful resources for growing in chromium-prone regions.
Assuntos
Carbono-Carbono Liases , Pelargonium , Plantas Geneticamente Modificadas , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Pelargonium/genética , Pelargonium/crescimento & desenvolvimento , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Estresse Fisiológico/genética , Cromo/toxicidade , Cromo/metabolismo , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fotossíntese/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Oxidativo , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/efeitos dos fármacos , Clorofila/metabolismoRESUMO
Complications of diabetes are often attributed to glucose and reactive dicarbonyl metabolites derived from glycolysis or gluconeogenesis, such as methylglyoxal. However, in the CNS, neurons and endothelial cells use lactate as energy source in addition to glucose, which does not lead to the formation of methylglyoxal and has previously been considered a safer route of energy consumption than glycolysis. Nevertheless, neurons and endothelial cells are hotspots for the cellular pathology underlying neurological complications in diabetes, suggesting a cause that is distinct from other diabetes complications and independent of methylglyoxal. Here, we show that in clinical and experimental diabetes plasma concentrations of dimethylglyoxal are increased. In a mouse model of diabetes, ilvb acetolactate-synthase-like (ILVBL, HACL2) is the enzyme involved in formation of increased amounts of dimethylglyoxal from lactate-derived pyruvate. Dimethylglyoxal reacts with lysine residues, forms Nε-3-hydroxy-2-butanonelysine (HBL) as an adduct, induces oxidative stress more strongly than other dicarbonyls, causes blood-brain barrier disruption, and can mimic mild cognitive impairment in experimental diabetes. These data suggest dimethylglyoxal formation as a pathway leading to neurological complications in diabetes that is distinct from other complications. Importantly, dimethylglyoxal formation can be reduced using genetic, pharmacological and dietary interventions, offering new strategies for preventing CNS dysfunction in diabetes.
Assuntos
Neuropatias Diabéticas , Glioxal , Ácido Pirúvico , Complicações do Diabetes/metabolismo , Complicações do Diabetes/patologia , Animais , Camundongos , Glioxal/análogos & derivados , Neuropatias Diabéticas/metabolismo , Neuropatias Diabéticas/patologia , Glucose/metabolismo , Ácido Pirúvico/metabolismo , Acetolactato Sintase/metabolismo , Encéfalo/metabolismo , Carbono-Carbono Liases/metabolismo , Humanos , Camundongos Endogâmicos C57BLRESUMO
The reaction of benzylsuccinate synthase, the radical-based addition of toluene to a fumarate cosubstrate, is initiated by hydrogen transfer from a conserved cysteine to the nearby glycyl radical in the active center of the enzyme. In this study, we analyze this step by comprehensive computer modeling, predicting (i) the influence of bound substrates or products, (ii) the energy profiles of forward- and backward hydrogen-transfer reactions, (iii) their kinetic constants and potential mechanisms, (iv) enantiospecificity differences, and (v) kinetic isotope effects. Moreover, we support several of the computational predictions experimentally, providing evidence for the predicted H/D-exchange reactions into the product and at the glycyl radical site. Our data indicate that the hydrogen transfer reactions between the active site glycyl and cysteine are principally reversible, but their rates differ strongly depending on their stereochemical orientation, transfer of protium or deuterium, and the presence or absence of substrates or products in the active site. This is particularly evident for the isotope exchange of the remaining protium atom of the glycyl radical to deuterium, which appears dependent on substrate or product binding, explaining why the exchange is observed in some, but not all, glycyl-radical enzymes.
Assuntos
Biocatálise , Cinética , Liases de Carbono-Enxofre/química , Liases de Carbono-Enxofre/metabolismo , Domínio Catalítico , Modelos Moleculares , Cisteína/química , Cisteína/metabolismo , Hidrogênio/química , Radicais Livres/química , Radicais Livres/metabolismo , Carbono-Carbono LiasesRESUMO
Magnesium ions (Mg2+) are crucial in class II terpene cyclases that utilize substrates with diphosphate groups. Interestingly, these enzymes catalyze reactions without cleaving the diphosphate group, instead initiating the reaction through protonation. In our recent research, we discovered a novel class II sesquiterpene cyclase in Streptomyces showdoensis. Notably, we determined its crystal structure and identified Mg2+ within its active site. This finding has shed light on the previously elusive question of Mg2+ binding in class II terpene cyclases. In this chapter, we outline our methods for discovering this novel enzyme, including steps for its purification, crystallization, and kinetic analysis.
Assuntos
Magnésio , Sesquiterpenos , Streptomyces , Magnésio/metabolismo , Magnésio/química , Sesquiterpenos/metabolismo , Sesquiterpenos/química , Streptomyces/enzimologia , Sítios de Ligação , Cinética , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Cristalografia por Raios X/métodos , Relação Estrutura-Atividade , Cristalização/métodos , Carbono-Carbono LiasesRESUMO
Soil salinity is a major environmental stressor impacting global food production. Staple crops like wheat experience significant yield losses in saline environments. Bioprospecting for beneficial microbes associated with stress-resistant plants offers a promising strategy for sustainable agriculture. We isolated two novel endophytic bacteria, Bacillus cereus (ADJ1) and Priestia aryabhattai (ADJ6), from Agave desmettiana Jacobi. Both strains displayed potent plant growth-promoting (PGP) traits, such as producing high amounts of indole-3-acetic acid (9.46, 10.00 µgml-1), ammonia (64.67, 108.97 µmol ml-1), zinc solubilization (Index of 3.33, 4.22, respectively), ACC deaminase production and biofilm formation. ADJ6 additionally showed inorganic phosphate solubilization (PSI of 2.77), atmospheric nitrogen fixation, and hydrogen cyanide production. Wheat seeds primed with these endophytes exhibited enhanced germination, improved growth profiles, and significantly increased yields in field trials. Notably, both ADJ1 and ADJ6 tolerated high salinity (up to 1.03 M) and significantly improved wheat germination and seedling growth under saline stress, acting both independently and synergistically. This study reveals promising stress-tolerance traits within endophytic bacteria from A. desmettiana. Exploiting such under-explored plant microbiomes offers a sustainable approach to developing salt-tolerant crops, mitigating the impact of climate change-induced salinization on global food security.
Assuntos
Produtos Agrícolas , Tolerância ao Sal , Triticum , Triticum/microbiologia , Triticum/crescimento & desenvolvimento , Produtos Agrícolas/microbiologia , Produtos Agrícolas/crescimento & desenvolvimento , Bacillus/isolamento & purificação , Bacillus/fisiologia , Bacillus/metabolismo , Endófitos/fisiologia , Salinidade , Ácidos Indolacéticos/metabolismo , Microbiologia do Solo , Fixação de Nitrogênio , Germinação , Bacillus cereus/fisiologia , Bacillus cereus/crescimento & desenvolvimento , Bacillus cereus/isolamento & purificação , Plântula/microbiologia , Plântula/crescimento & desenvolvimento , Carbono-Carbono Liases/metabolismoRESUMO
The WRKY transcription factor (TF) genes form a large family in higher plants, with 72 members in Arabidopsis (Arabidopsis thaliana). The gaseous phytohormone ethylene (ET) regulates multiple physiological processes in plants. It is known that 1-aminocyclopropane-1-carboxylic acid (ACC) synthases (ACSs, EC 4.4.1.14) limit the enzymatic reaction rate of ethylene synthesis. However, whether WRKY TFs regulate the expression of ACSs and/or ACC oxidases (ACOs, EC 1.14.17.4) remains largely elusive. Here, we demonstrated that Arabidopsis WRKY22 positively regulated the expression of a few ACS and ACO genes, thus promoting ethylene production. Inducible overexpression of WRKY22 caused shorter hypocotyls without ACC treatment. A qRT-PCR screening demonstrated that overexpression of WRKY22 activates the expression of several ACS and ACO genes. The promoter regions of ACS5, ACS11, and ACO5 were also activated by WRKY22, which was revealed by a dual luciferase reporter assay. A follow-up chromatin immunoprecipitation coupled with quantitative PCR (ChIP-qPCR) and electrophoretic mobility shift assay (EMSA) showed that the promoter regions of ACS5 and ACO5 could be bound by WRKY22 directly. Moreover, wrky22 mutants had longer primary roots and more lateral roots than wild type, while WRKY22-overexpressing lines showed the opposite phenotype. In conclusion, this study revealed that WRKY22 acts as a novel TF activating, at least, the expression of ACS5 and ACO5 to increase ethylene synthesis and modulate root development.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Etilenos , Regulação da Expressão Gênica de Plantas , Liases , Raízes de Plantas , Fatores de Transcrição , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Etilenos/metabolismo , Etilenos/biossíntese , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Liases/genética , Liases/metabolismo , Aminoácido Oxirredutases/genética , Aminoácido Oxirredutases/metabolismo , Regiões Promotoras Genéticas/genética , Carbono-Carbono Liases/metabolismo , Carbono-Carbono Liases/genética , Ativação Transcricional/genéticaRESUMO
Petunia hybrida, widely grown as a bedding plant, has reduced growth and flower quality at temperatures above 30 °C (heat stress), primarily due to heat stress-induced ethylene (ET) production. The gene acdS encodes the 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCD) enzyme, which is known for its role in reducing ET production by breaking down the ET precursor, ACC, in plant tissues. This study investigated the impact of heat stress on both 'Mirage Rose' WT petunia and its acdS-overexpressing transgenic lines. Heat stress-induced growth inhibition was observed in WT plants but not in transgenic plants. The increased stress tolerance of transgenic plants over WT plants was associated with lower ET production, ROS accumulation, higher SPAD values, water content, and relative water content. Furthermore, higher sensitivity of the WT to heat stress than the transgenic plants was confirmed by analysing ET signalling genes, heat shock transcription factor genes, and antioxidant- and proline-related genes, more strongly induced in WT than in transgenic plants. Overall, this study suggests the potential application of acdS overexpression in other floriculture plants as a viable strategy for developing heat stress-tolerant varieties. This approach holds promise for advancing the floricultural industry by overcoming challenges related to heat-induced growth inhibition and loss of flower quality.
Assuntos
Etilenos , Resposta ao Choque Térmico , Petunia , Plantas Geneticamente Modificadas , Petunia/genética , Petunia/fisiologia , Petunia/metabolismo , Etilenos/metabolismo , Resposta ao Choque Térmico/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Carbono-Carbono Liases/metabolismo , Carbono-Carbono Liases/genética , Espécies Reativas de Oxigênio/metabolismo , Termotolerância/genética , Termotolerância/fisiologia , Temperatura AltaRESUMO
In the present study, ten (10) selected bacteria isolated from chasmophytic wild Chenopodium were evaluated for alleviation of drought stress in chickpea. All the bacterial cultures were potential P, K and Zn solubilizer. About 50% of the bacteria could produce Indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. The bacteria showed wide range of tolerance towards pH, salinity, temperature and osmotic stress. Bacillus paralicheniformis L38, Pseudomonas sp. LN75, Enterobacter hormachei subsp. xiangfengensis LJ89, B. paramycoides L17 and Micrococcus luteus LA9 significantly improved growth and nutrient (N, P, K, Fe and Zn) content in chickpea under water stress during a green house experiment conducted following a completely randomized design (CRD). Application of Microbacterium imperiale LJ10, B. stercoris LN74, Pseudomonas sp. LN75, B. paralicheniformis L38 and E. hormachei subsp. xiangfengensis LJ89 reduced the antioxidant enzymes under water stress. During field experiments conducted following randomized block design (RBD), all the bacterial inoculations improved chickpea yield under water stress. Highest yield (1363 kg ha-1) was obtained in plants inoculated with Pseudomonas sp. LN75. Pseudomonas sp. LN75, B. paralicheniformis L38 and E. hormachei subsp. xiangfengensis LJ89 have potential as microbial stimulants to alleviate the water stress in chickpea. To the best of our knowledge this is the first report of using chasmophyte associated bacteria for alleviation of water stress in a crop plant.
Assuntos
Cicer , Secas , Estresse Fisiológico , Cicer/microbiologia , Cicer/fisiologia , Cicer/crescimento & desenvolvimento , Bactérias/metabolismo , Ácidos Indolacéticos/metabolismo , Nutrientes/metabolismo , Carbono-Carbono Liases/metabolismo , Enterobacter/fisiologia , Enterobacter/metabolismo , Pseudomonas/fisiologia , Antioxidantes/metabolismoRESUMO
This study aimed to (i) investigate the potential for enhanced phytoremediation to remove contaminants from soil historically co-contaminated with petroleum hydrocarbons (PHs) and heavy metals (HMs) and (ii) analyze the expression of crucial bacterial genes and whole metatranscriptomics profiles for better understanding of soil processes during applied treatment. Phytoremediation was performed using Zea mays and supported by the Pseudomonas qingdaonensis ZCR6 strain and a natural biofertilizer: meat and bone meal (MBM). In previous investigations, mechanisms supporting plant growth and PH degradation were described in the ZCR6 strain. Here, ZCR6 survived in the soil throughout the experiment, but the efficacy of PH removal from all soils fertilized with MBM reached 32â¯% regardless of the bacterial inoculation. All experimental groups contained 2â¯% (w/w) MBM. The toxic effect of this amendment on plants was detected 30 days after germination, irrespective of ZCR6 inoculation. Among the 17 genes tested using the qPCR method, only expression of the acdS gene, encoding 1-aminocyclopropane-1-carboxylic acid deaminase, and the CYP153 gene, encoding cytochrome P450-type alkane hydroxylase, was detected in soils. Metatranscriptomic analysis of soils indicated increased expression of methane particulated ammonia monooxygenase subunit A (pmoA-amoA) by Nitrosomonadales bacteria in all soils enriched with MBM compared to the non-fertilized control. We suggest that the addition of 2â¯% (w/w) MBM caused the toxic effect on plants via the rapid release of ammonia, and this led to high pmoA-amoA expression. In parallel, due to its wide substrate specificity, enhanced bacterial hydrocarbon removal in MBM-treated soils was observed. The metatranscriptomic results indicate that MBM application should be considered to improve bioremediation of soils polluted with PHs rather than phytoremediation. However, lower concentrations of MBM could be considered for phytoremediation enhancement. From a broader perspective, these results indicated the superior capability of metatranscriptomics to investigate the microbial mechanisms driving various bioremediation techniques.
Assuntos
Biodegradação Ambiental , Pseudomonas , Microbiologia do Solo , Poluentes do Solo , Zea mays , Poluentes do Solo/metabolismo , Zea mays/metabolismo , Zea mays/microbiologia , Pseudomonas/genética , Pseudomonas/metabolismo , Pseudomonas/isolamento & purificação , Metais Pesados/metabolismo , Petróleo/metabolismo , Solo/química , Hidrocarbonetos/metabolismo , Perfilação da Expressão Gênica , Carbono-Carbono Liases/metabolismo , Carbono-Carbono Liases/genética , TranscriptomaRESUMO
Plant growth-promoting endophytes (PGPE) can effectively regulate plant growth and metabolism. The regulation is modulated by metabolic signals, and the resulting metabolites can have considerable effects on the plant yield and quality. Here, tissue culture Houttuynia cordata Thunb., was inoculated with Rhizobium sp. (BH46) to determine the effect of BH46 on H. cordata growth and metabolism, and elucidate associated regulatory mechanisms. The results revealed that BH46 metabolized indole-3-acetic acid and induced 1-aminocyclopropane-1-carboxylate deaminase to decrease ethylene metabolism. Host peroxidase synthesis MPK3/MPK6 genes were significantly downregulated, whereas eight genes associated with auxins, cytokinins, abscisic acid, jasmonic acid, and antioxidant enzymes were significantly upregulated. Eight genes associated with flavonoid biosynthesis were significantly upregulated, with the CPY75B1 gene regulating the production of rutin and quercitrin and the HCT gene directly regulating the production of chlorogenic acid. Therefore, BH46 influences metabolic signals in H. cordata to modulate its growth and metabolism, in turn, enhancing yield and quality of H. cordata.
Assuntos
Endófitos , Houttuynia , Proteínas de Plantas , Houttuynia/microbiologia , Houttuynia/metabolismo , Houttuynia/genética , Endófitos/metabolismo , Endófitos/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Ácidos Indolacéticos/metabolismo , Rhizobium/genética , Rhizobium/metabolismo , Flavonoides/metabolismo , Ácido Abscísico/metabolismo , Etilenos/metabolismo , Carbono-Carbono Liases/metabolismo , Carbono-Carbono Liases/genéticaRESUMO
The genome sequencing of Botrytis cinerea supplies a general overview of the map of genes involved in secondary metabolite synthesis. B. cinerea genomic data reveals that this phytopathogenic fungus has seven sesquiterpene cyclase (Bcstc) genes that encode proteins involved in the farnesyl diphosphate cyclization. Three sesquiterpene cyclases (BcStc1, BcStc5 and BcStc7) are characterized, related to the biosynthesis of botrydial, abscisic acid and (+)-4-epi-eremophilenol, respectively. However, the role of the other four sesquiterpene cyclases (BcStc2, BcStc3, BcStc4 and BcStc6) remains unknown. BcStc3 is a well-conserved protein with homologues in many fungal species, and here, we undertake its functional characterization in the lifecycle of the fungus. A null mutant ΔBcstc3 and an overexpressed-Bcstc3 transformant (OvBcstc3) are generated, and both strains show the deregulation of those other sesquiterpene cyclase-encoding genes (Bcstc1, Bcstc5 and Bcstc7). These results suggest a co-regulation of the expression of the sesquiterpene cyclase gene family in B. cinerea. The phenotypic characterization of both transformants reveals that BcStc3 is involved in oxidative stress tolerance, the production of reactive oxygen species and virulence. The metabolomic analysis allows the isolation of characteristic polyketides and eremophilenols from the secondary metabolism of B. cinerea, although no sesquiterpenes different from those already described are identified.
Assuntos
Botrytis , Carbono-Carbono Liases , Botrytis/enzimologia , Botrytis/genética , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Estresse Oxidativo , Sesquiterpenos/metabolismoRESUMO
The 1-aminocyclopropane-1-carboxylate (ACC) deaminase is a crucial bacterial trait, yet it is not widely distributed among rhizobia. Hence, employing a co-inoculation approach that combines selected plant growth-promoting bacteria with compatible rhizobial strains, especially those lacking ACC deaminase, presents a practical solution to alleviate the negative effects of diverse abiotic stresses on legume nodulation. Our objective was to explore the efficacy of three non-rhizobial endophytes, Phyllobacterium salinisoli (PH), Starkeya sp. (ST) and Pseudomonas turukhanskensis (PS), isolated from native legumes grown in Tunisian arid regions, in improving the growth of cool-season legume and fostering symbiosis with an ACC deaminase-lacking rhizobial strain under heat stress. Various combinations of these endophytes (ST + PS, ST + PH, PS + PH, and ST + PS + PH) were co-inoculated with Rhizobium leguminosarum 128C53 or its ΔacdS mutant derivative on Pisum sativum plants exposed to a two-week heat stress period.Our findings revealed that the absence of ACC deaminase activity negatively impacted both pea growth and symbiosis under heat stress. Nevertheless, these detrimental effects were successfully mitigated in plants co-inoculated with ΔacdS mutant strain and specific non-rhizobial endophytes consortia. Our results indicated that heat stress significantly altered the phenolic content of pea root exudates. Despite this, there was no impact on IAA production. Interestingly, these changes positively influenced biofilm formation in consortia containing the mutant strain, indicating synergistic bacteria-bacteria interactions. Additionally, no positive effects were observed when these endophytic consortia were combined with the wild-type strain. This study highlights the potential of non-rhizobial endophytes to improve symbiotic performance of rhizobial strains lacking genetic mechanisms to mitigate stress effects on their legume host, holding promising potential to enhance the growth and yield of targeted legumes by boosting symbiosis.
Assuntos
Carbono-Carbono Liases , Fabaceae , Rhizobium , Simbiose , Rhizobium/genética , Pisum sativum , Bactérias , Endófitos/genética , Verduras , Resposta ao Choque TérmicoRESUMO
Climate change intensifies soil salinization and jeopardizes the development of crops worldwide. The accumulation of salts in plant tissue activates the defense system and triggers ethylene production thus restricting cell division. We hypothesize that the inoculation of plant growth-promoting bacteria (PGPB) producing ACC (1-aminocyclopropane-1-carboxylate) deaminase favors the development of arbuscular mycorrhizal fungi (AMF), promoting the growth of maize plants under saline stress. We investigated the efficacy of individual inoculation of PGPB, which produce ACC deaminase, as well as the co-inoculation of PGPB with Rhizophagus clarus on maize plant growth subjected to saline stress. The isolates were acquired from the bulk and rhizospheric soil of Mimosa bimucronata (DC.) Kuntze in a temporary pond located in Pernambuco State, Brazil. In the first greenhouse experiment, 10 halophilic PGPB were inoculated into maize at 0, 40 and 80â¯mM of NaCl, and in the second experiment, the PGPB that showed the best performance were co-inoculated with R. clarus in maize under the same conditions as in the first experiment. Individual PGPB inoculation benefited the number of leaves, stem diameter, root and shoot dry mass, and the photosynthetic pigments. Inoculation with PGPB 28-10 Pseudarthrobacter enclensis, 24-1â¯P. enclensis and 52â¯P. chlorophenolicus increased the chlorophyll a content by 138%, 171%, and 324% at 0, 40 and 80â¯mM NaCl, respectively, comparing to the non-inoculated control. We also highlight that the inoculation of PGPB 28-10, 28-7 Arthrobacter sp. and 52 increased the content of chlorophyll b by 72%, 98%, and 280% and carotenoids by 82%, 98%, and 290% at 0, 40 and 80â¯mM of NaCl, respectively. Co-inoculation with PGPB 28-7, 46-1 Leclercia tamurae, 70 Artrobacter sp., and 79-1 Micrococcus endophyticus significantly increased the rate of mycorrhizal colonization by roughly 50%. Furthermore, co-inoculation promoted a decrease in the accumulation of Na and K extracted from plant tissue, with an increase in salt concentration, from 40â¯mM to 80â¯mM, also favoring the establishment and development of R. clarus. In addition, co-inoculation of these PGPB with R. clarus promoted maize growth and increased plant biomass through osmoregulation and protection of the photosynthetic apparatus. The tripartite symbiosis (plant-fungus-bacterium) is likely to reprogram metabolic pathways that improve maize growth and crop yield, suggesting that the AMF-PGPB consortium can minimize damages caused by saline stress.
Assuntos
Bactérias , Carbono-Carbono Liases , Micorrizas , Raízes de Plantas , Microbiologia do Solo , Zea mays , Zea mays/microbiologia , Zea mays/crescimento & desenvolvimento , Micorrizas/fisiologia , Carbono-Carbono Liases/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/metabolismo , Bactérias/isolamento & purificação , Estresse Salino , Clorofila/metabolismo , Glomeromycota/fisiologia , Tolerância ao Sal , Fotossíntese , Rizosfera , Cloreto de Sódio/metabolismo , Folhas de Planta/microbiologia , Solo/químicaRESUMO
Codonopsis pilosula is a perennial herbaceous liana with medicinal value. It is critical to promote Codonopsis pilosula growth through effective and sustainable methods, and the use of plant growth-promoting bacteria (PGPB) is a promising candidate. In this study, we isolated a PGPB, Klebsiella michiganensis LDS17, that produced a highly active 1-aminocyclopropane-1-carboxylate deaminase from the Codonopsis pilosula rhizosphere. The strain exhibited multiple plant growth-promoting properties. The antagonistic activity of strain LDS17 against eight phytopathogenic fungi was investigated, and the results showed that strain LDS17 had obvious antagonistic effects on Rhizoctonia solani, Colletotrichum camelliae, Cytospora chrysosperma, and Phomopsis macrospore with growth inhibition rates of 54.22%, 49.41%, 48.89%, and 41.11%, respectively. Inoculation of strain LDS17 not only significantly increased the growth of Codonopsis pilosula seedlings but also increased the invertase and urease activities, the number of culturable bacteria, actinomycetes, and fungi, as well as the functional diversity of microbial communities in the rhizosphere soil of the seedlings. Heavy metal (HM) resistance tests showed that LDS17 is resistant to copper, zinc, and nickel. Whole-genome analysis of strain LDS17 revealed the genes involved in IAA production, siderophore synthesis, nitrogen fixation, P solubilization, and HM resistance. We further identified a gene (koyR) encoding a plant-responsive LuxR solo in the LDS17 genome. Klebsiella michiganensis LDS17 may therefore be useful in microbial fertilizers for Codonopsis pilosula. The identification of genes related to plant growth and HM resistance provides an important foundation for future analyses of the molecular mechanisms underlying the plant growth promotion and HM resistance of LDS17. IMPORTANCE: We comprehensively evaluated the plant growth-promoting characteristics and heavy metal (HM) resistance ability of the LDS17 strain, as well as the effects of strain LDS17 inoculation on the Codonopsis pilosula seedling growth and the soil qualities in the Codonopsis pilosula rhizosphere. We conducted whole-genome analysis and identified lots of genes and gene clusters contributing to plant-beneficial functions and HM resistance, which is critical for further elucidating the plant growth-promoting mechanism of strain LDS17 and expanding its application in the development of plant growth-promoting agents used in the environment under HM stress.
Assuntos
Codonopsis , Klebsiella , Rizosfera , Microbiologia do Solo , Klebsiella/genética , Klebsiella/enzimologia , Klebsiella/efeitos dos fármacos , Klebsiella/crescimento & desenvolvimento , Codonopsis/genética , Codonopsis/crescimento & desenvolvimento , Codonopsis/microbiologia , Desenvolvimento Vegetal , Rhizoctonia/crescimento & desenvolvimento , Rhizoctonia/genética , Rhizoctonia/efeitos dos fármacos , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Reguladores de Crescimento de Plantas/metabolismo , Doenças das Plantas/microbiologia , Solo/químicaRESUMO
The plant cuticle is composed of cuticular wax and cutin polymers and plays an essential role in plant tolerance to diverse abiotic and biotic stresses. Several stresses, including water deficit and salinity, regulate the synthesis of cuticular wax and cutin monomers. However, the effect of wounding on wax and cutin monomer production and the associated molecular mechanisms remain unclear. In this study, we determined that the accumulation of wax and cutin monomers in Arabidopsis leaves is positively regulated by wounding primarily through the jasmonic acid (JA) signaling pathway. Moreover, we observed that a wound- and JA-responsive gene (CYP96A4) encoding an ER-localized cytochrome P450 enzyme was highly expressed in leaves. Further analyses indicated that wound-induced wax and cutin monomer production was severely inhibited in the cyp96a4 mutant. Furthermore, CYP96A4 interacted with CER1 and CER3, the core enzymes in the alkane-forming pathway associated with wax biosynthesis, and modulated CER3 activity to influence aldehyde production in wax synthesis. In addition, transcripts of MYC2 and JAZ1, key genes in JA signaling pathway, were significantly reduced in cyp96a4 mutant. Collectively, these findings demonstrate that CYP96A4 functions as a cofactor of the alkane synthesis complex or participates in JA signaling pathway that contributes to cuticular wax biosynthesis and cutin monomer formation in response to wounding.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ciclopentanos , Sistema Enzimático do Citocromo P-450 , Regulação da Expressão Gênica de Plantas , Lipídeos de Membrana , Oxilipinas , Folhas de Planta , Ceras , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/enzimologia , Ceras/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Oxilipinas/metabolismo , Ciclopentanos/metabolismo , Lipídeos de Membrana/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/genética , Transdução de Sinais , Epiderme Vegetal/metabolismo , Epiderme Vegetal/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Carbono-Carbono Liases , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix BásicosRESUMO
The sesquiterpene cyclase epi-isozizaene synthase (EIZS) from Streptomyces coelicolor catalyzes the metal-dependent conversion of farnesyl diphosphate (FPP) into the complex tricyclic product epi-isozizaene. This remarkable transformation is governed by an active site contour that serves as a template for catalysis, directing the conformations of multiple carbocation intermediates leading to the final product. Mutagenesis of residues defining the active site contour remolds its three-dimensional shape and reprograms the cyclization cascade to generate alternative cyclization products. In some cases, mutagenesis enables alternative chemistry to quench carbocation intermediates, e.g., through hydroxylation. Here, we combine structural and biochemical data from previously characterized EIZS mutants to design and prepare F95S-F198S EIZS, which converts EIZS into an α-bisabolol synthase with moderate fidelity (65% at 18 °C, 74% at 4 °C). We report the complete biochemical characterization of this double mutant as well as the 1.47 Å resolution X-ray crystal structure of its complex with three Mg2+ ions, inorganic pyrophosphate, and the benzyltriethylammonium cation, which partially mimics a carbocation intermediate. Most notably, the two mutations together create an active site contour that stabilizes the bisabolyl carbocation intermediate and positions a water molecule for the hydroxylation reaction. Structural comparison with a naturally occurring α-bisabolol synthase reveals common active site features that direct α-bisabolol generation. In showing that EIZS can be redesigned to generate a sesquiterpene alcohol product instead of a sesquiterpene hydrocarbon product, we have expanded the potential of EIZS as a platform for the development of designer cyclases that could be utilized in synthetic biology applications.
Assuntos
Carbono-Carbono Liases , Sesquiterpenos , Sesquiterpenos/metabolismo , Sesquiterpenos MonocíclicosRESUMO
Water stress is a major limiting factor for agricultural production under current and projected climate change scenarios. As a sustainable strategy, plant growth-promoting bacterial consortia have been used to reduce plant water stress. However, few studies have examined the effects of stress on multi-trait efficiency and interactivity of bacterial species. In this study, we used several in-vitro experiments, plant assays and greenhouse trials to investigate the effects of stress and bacterial consortia on 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) activities, indole-3-acetic acid (IAA) production and plant growth-promoting traits (Phosphate-solubilization, starch hydrolysis, siderophores and ammonium production). We further assessed biofilm formation and the chemotactic behaviour in response to ACC. A total of fifteen ACCD rhizobacteria with multiple growth-promoting traits from the dominant plant species from the hyperseasonal Aripo Savannas were screened in this study. Five of the isolates were further analyzed based on their ACCD activities and were tested in single and dual consortium to assess their abilities in promoting growth under simulated drought stress (-0.35 MPa) and chemically induced ACC conditions (0.03 mM). Our findings showed that bacteria which produce high concentrations of IAA affected the isolates' ability to promote growth under stress, irrespective of microbial combination with ACCD activity above the minimal threshold of 20 nmol α-ketobutyrate mg-1 h-1. Biofilm production with co-culture interaction varied greatly across treatments, however, the general trend showed an increase in biofilm under stress induce conditions. The best performing co-culture, UWIGT-83 and UWIGT-120 (Burkholderia sp.) showed enhanced growth in germination assays and in greenhouse trials with Capsicum chinense (Moruga red hot peppers) under drought stress, when compared to non-inoculated treatments. The findings highlight the importance of testing interactivity of bacterial species with multiple growth promoting traits under stress conditions; and proposed the use of ACC growth media as a novel biofilm screening method for selecting potential stress plant growth-promoting bacteria. Better screening strategies for appropriate plant growth-promoting bacteria may narrow the inconsistency observed between laboratory and field trials.