RESUMEN
Tanshinones are bioactive ingredients derived from the herbal plant Salvia miltiorrhiza and are used for treating diseases of the heart and brain, thus ensuring quality of S. miltiorrhiza is paramount. Applying the endophytic fungus Trichoderma atroviride D16 can significantly increase the content of tanshinones in S. miltiorrhiza, but the potential mechanism remains unknown. In the present study, the colonization of D16 effectively enhanced the levels of Ca2+ and H2O2 in the roots of S. miltiorrhiza, which is positively correlated with increased tanshinones accumulation. Further experiments found that the treatment of plantlets with Ca2+ channel blocker (LaCl3) or H2O2 scavenger (DMTU) blocked D16-promoted tanshinones production. LaCl3 suppressed not only the D16-induced tanshinones accumulation but also the induced Ca2+ and H2O2 generation; nevertheless, DMTU did not significantly inhibit the induced Ca2+ biosynthesis, implying that Ca2+ acted upstream in H2O2 production. These results were confirmed by observations that S. miltiorrhiza treated with D16, CaCl2, and D16+LaCl3 exhibit H2O2 accumulation and influx in the roots. Moreover, H2O2 as a downstream signal of Ca2+ is involved in D16 enhanced tanshinones synthesis by inducing the expression of genes related to the biosynthesis of tanshinones, such as DXR, HMGR, GGPPS, CPS, KSL and CYP76AH1 genes. Transcriptomic analysis further supported that D16 activated the transcriptional responses related to Ca2+ and H2O2 production and tanshinones synthesis in S. miltiorrhiza seedlings. This is the first report that Ca2+ and H2O2 play important roles in regulating fungal-plant interactions thus improving the quality in the D16-S. miltiorrhiza system.
Asunto(s)
Abietanos , Calcio , Endófitos , Peróxido de Hidrógeno , Raíces de Plantas , Salvia miltiorrhiza , Salvia miltiorrhiza/metabolismo , Salvia miltiorrhiza/microbiología , Peróxido de Hidrógeno/metabolismo , Abietanos/biosíntesis , Abietanos/metabolismo , Endófitos/metabolismo , Endófitos/genética , Raíces de Plantas/microbiología , Raíces de Plantas/metabolismo , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Lantano/farmacología , Lantano/metabolismo , Regulación de la Expresión Génica de las Plantas , Hypocreales/metabolismo , Hypocreales/genéticaRESUMEN
Biological nitrogen fixation by free-living bacteria and rhizobial symbiosis with legumes plays a key role in sustainable crop production. Here, we study how different crop combinations influence the interaction between peanut plants and their rhizosphere microbiota via metabolite deposition and functional responses of free-living and symbiotic nitrogen-fixing bacteria. Based on a long-term (8 year) diversified cropping field experiment, we find that peanut co-cultured with maize and oilseed rape lead to specific changes in peanut rhizosphere metabolite profiles and bacterial functions and nodulation. Flavonoids and coumarins accumulate due to the activation of phenylpropanoid biosynthesis pathways in peanuts. These changes enhance the growth and nitrogen fixation activity of free-living bacterial isolates, and root nodulation by symbiotic Bradyrhizobium isolates. Peanut plant root metabolites interact with Bradyrhizobium isolates contributing to initiate nodulation. Our findings demonstrate that tailored intercropping could be used to improve soil nitrogen availability through changes in the rhizosphere microbiome and its functions.
Asunto(s)
Fabaceae , Fijación del Nitrógeno , Fabaceae/microbiología , Nodulación de la Raíz de la Planta , Suelo , Microbiología del Suelo , Simbiosis , Arachis , Verduras , Nitrógeno , Nódulos de las Raíces de las Plantas/microbiologíaRESUMEN
Endophytic fungi play important roles in regulating plant growth and development and usually used as a promising strategy to enhance the biosynthesis of host valuable secondary metabolite, but the underlying growth-promoting mechanisms are only partly understood. In this study, the wild-type Arabidopsis thaliana seedlings co-cultured with fungal endophyte Epichloë bromicola showed auxin (IAA)-stimulated phenotypes, and the growth-promoting effects caused by E. bromicola were further verified by the experiments of spatially separated co-culture and fungal extract treatment. IAA was detected and identified in the extract of E. bromicola culture by LC-HRMS/MS, whereas 2,3-butanediol was confirmed to be the predominant volatile active compound in the diethyl ether and ethyl acetate extracts by GC-MS. Further study observed that IAA-related genes including synthesis key enzyme genes (CYP79B2, CYP79B3, NIT1, TAA1 and YUCCA1) and controlling polar transport genes (AUX1, BIG, EIR1, AXR3 and ARF1), were highly expressed at different periods after E. bromicola inoculation. More importantly, the introduction of fungal endophyte E. bromicola could effectively promote the growth and accumulation of coixol in Coix under soil conditions. Our study showed that endophytic fungus E. bromicola might be considered as a potential inoculant for improving medicinal plant growth.
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Coix , Epichloe , Coix/microbiología , Epichloe/genéticaRESUMEN
Using endophytic fungal elicitors to increase the accumulation of valuable secondary metabolites in plant tissue culture is an effective biotechnology strategy. In this study, a collection of 56 strains of endophytic fungi were isolated from different organs of cultivated Panax ginseng, of which seven strains can be symbiotically co-cultured with the hairy roots of P. ginseng. Further experiments observed that strain 3R-2, identified as endophytic fungus Schizophyllum commune, can not only infect hairy roots but also promote the accumulation of specific ginsenosides. This was further verified because S. commune colonization significantly affected the overall metabolic profile of ginseng hairy roots. By comparing the effects of S. commune mycelia and its mycelia extract (EM) on ginsenoside production in P. ginseng hairy roots, the EM was confirmed to be a relatively better stimulus elicitor. Additionally, the introduction of EM elicitor can significantly enhance the expressions of key enzyme genes of pgHMGR, pgSS, pgSE, and pgSD involved in the biosynthetic pathway of ginsenosides, which was deemed the most relevant factor for promoting ginsenosides production during the elicitation period. In conclusion, this study is the first to show that the EM of endophytic fungus S. commune can be considered as an effective endophytic fungal elicitor for increasing the biosynthesis of ginsenosides in hairy root cultures of P. ginseng.
Asunto(s)
Ginsenósidos , Panax , Schizophyllum , Ginsenósidos/metabolismo , Ginsenósidos/farmacología , Panax/genética , Panax/metabolismo , Panax/microbiología , Schizophyllum/genética , Schizophyllum/metabolismo , Técnicas de Cocultivo , Raíces de PlantasRESUMEN
Endophytic fungi exist widely in plants and play an important role in the growth and adaptation of plants. They could be used in phytoremediation techniques against heavy metal contaminated soil since beneficial microbial symbionts can endow plants with resistance to external heavy metal stresses. This review summarized the regulation mechanism of plant response to heavy metal stress mediated by endophytic fungi. Potential endophytic fungi in enhancing plant's adaption to heavy metal stresses include arbuscular mycorrhizal fungi, dark septate endophytic fungi, plant growth promoting endophytic fungi. The mechanisms involve coevolution strategy, immune regulation and detoxification transport to improve the ability of plants to adapt to heavy metal stress. They can increase the synthesis of host hormones and maintaining the balance of endogenous hormones, strengthen osmotic regulation, regulate carbon and nitrogen metabolism, and increase immune activity, antioxidant enzyme and glutathione activity. They also help to improve the detoxification transport and heavy metal emission capacity of the host by significantly producing iron carrier, metallothionein and 1-aminocyclopropane-1-carboxylic acid deaminase. The combination of endophytic fungi and hyperaccumulation plants provides a promising technology for the ecological restoration of heavy metal contaminated soil. Endophytic fungi reserves further development on enhancing host plant's adaptability to heavy metal stresses.
Phytoremediation is an effective method for ecological remediation of heavy metal contaminated soil. Endophytic fungi such as arbuscular mycorrhizal fungi, dark septate endophytic fungi, plant growth promoting endophytic fungi can synergistically improve the adaptability to heavy metal stress. This review comprehensively summarizes the regulation mechanism of plant response to heavy metal stress mediated by endophytic fungi for the first time, and provides new insights and proposals for exploring novel hyperaccumulator for phytoremediation more effectively. HIGHLIGHTSEndophytic fungi combined with phytoremediation could enhance plant's adaptition to heavy metal stress and ecological restoration efficiency.Promising endophytic fungi in improving phytoremediation for heavy metal contaminated soil are presented.The regulation mechanism of plant response to heavy metal stress mediated by endophytic fungi is firstly summarized.
Asunto(s)
Metales Pesados , Micorrizas , Contaminantes del Suelo , Biodegradación Ambiental , Contaminantes del Suelo/metabolismo , Metales Pesados/análisis , Plantas/metabolismo , SueloRESUMEN
The complex environments of plants force them to prioritize their immune responses to stimuli occurring simultaneously, including colonization by microbes or nutrient availability. Little is known about how the interplay between endophytes and nutrient status affects the immune responses of both plants and fungi. We primarily monitored immune responses in rice following inoculation with the endophytic fungus Phomopsis liquidambaris under different nitrogen (N) conditions. Ph. liquidambaris promoted plant growth under low N (LN) conditions, concomitant with higher root colonization. Plant production of oxidative signals, including hydrogen peroxide and nitric oxide, was activated by Ph. liquidambaris colonization under LN conditions, while salicylic acid (SA) was maintained at high levels and was involved in controlling rice-fungal interactions. High N (HN) conditions enhanced the ability of Ph. liquidambaris in suppressing plant cell death and the ability of roots to degrade Ph. liquidambaris cell walls. Furthermore, under both LN and HN conditions, the activity of plant defence-associated enzymes and fungal antioxidases was not affected in the interactive association. Our data reveal the alteration of plant immunity, including oxidative signalling and plant cell death, by fungal colonization in response to external N conditions and identify SA signalling as a potential controller for rice-Ph. liquidambaris interaction.
Asunto(s)
Ascomicetos , Oryza , Ascomicetos/metabolismo , Endófitos/metabolismo , Peróxido de Hidrógeno/metabolismo , Óxido Nítrico/metabolismo , Nitrógeno/metabolismo , Inmunidad de la Planta , Raíces de Plantas/microbiología , Plantas/metabolismo , Ácido Salicílico/metabolismoRESUMEN
Salvia miltiorrhiza Bunge. is commonly used to treat vascular diseases because of its activity ingredients, phenolic acids, and tanshinones. Polysaccharide fraction (PSF) extracted from Trichoderma atroviride D16 could promote tanshinone accumulation in S. miltiorrhiza hairy roots. Transcriptome sequencing was conducted to describe the global gene expression of PSF-treatment hairy roots, and data analyses showed enzymes of tanshinone biosynthetic pathways were up-regulated, and genes associated to signal molecules and transcription factors were responsive. Endogenous H2O2, abscisic acid, and nitric oxide contents were measured after PSF treatment, while tanshinone accumulations were measured with treatment of exogenous H2O2 or H2O2 inhibitor on PSF-treatment S. miltiorrhiza hairy roots. The results showed H2O2 was important in tanshinone biosynthesis caused by PSF and nitric oxide might be the downstream molecules of H2O2. Taken together, the study indicates that D16 PSF enhances the accumulation of tanshinones through enzymes of tanshinone biosynthetic pathways, signal molecules, and transcription factors.
Asunto(s)
Salvia miltiorrhiza , Abietanos , Regulación de la Expresión Génica de las Plantas , Peróxido de Hidrógeno/metabolismo , Hypocreales , Óxido Nítrico/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Polisacáridos/metabolismo , Salvia miltiorrhiza/genética , Salvia miltiorrhiza/metabolismo , Transducción de Señal , Factores de Transcripción/metabolismo , TranscriptomaRESUMEN
In agroecosystems, drought stress severely threatens crops development. Although potassium (K) is required in amounts by crops under drought stress, the mobilization and availablity of K are limited by the soil water status. Arbuscular mycorrhizal (AM) fungi can form mutualistic associations with most crops and play direct or indirect roles in the host drought resistance. Considering that the glomalin generated by living AM fungal hyphae can sequester multiple minerals, however, the function of mineral-sequestering glomalin in the crop drought resistance remains unclear. In this study, peanuts cultivated in the sterilized soil with a history of AM fungi inoculation showed significantly enhanced leaf K accumulation, drought resistance and pod yield under drought stress. Through the collection of different types of mineral-sequestering glomalin from living AM fungal hyphae, the peanut drought resistance was improved only when K-sequestering glomalin was added. Moreover, we found that peanut root exudates could prime the dissociation of glomalin-bound K and further satisfy the K requirement of crops. Our study is the first report that K-sequestering glomalin could improve drought performance and peanut pod yield, and it helps us to understand the ecological importance of improving AM symbiosis to face agricultural challenges.
Asunto(s)
Arachis/microbiología , Arachis/fisiología , Proteínas Fúngicas/metabolismo , Hongos/metabolismo , Glicoproteínas/metabolismo , Micorrizas/metabolismo , Potasio/metabolismo , Arachis/crecimiento & desarrollo , Productos Agrícolas/crecimiento & desarrollo , Productos Agrícolas/fisiología , Sequías , Hifa/metabolismo , Hojas de la Planta/metabolismo , Potasio/farmacología , Microbiología del Suelo , Estrés Fisiológico , SimbiosisRESUMEN
Plants establish symbioses with mutualistic fungi, such as arbuscular mycorrhizal (AM) fungi, and bacteria, such as rhizobia, to exchange key nutrients and thrive. Plants and symbionts have coevolved and represent vital components of terrestrial ecosystems. Plants employ an ancestral AM signaling pathway to establish intracellular symbioses, including the legume-rhizobia symbiosis, in their roots. Nevertheless, the relationship between the AM and rhizobial symbioses in native soil is poorly understood. Here, we examined how these distinct symbioses affect root-associated bacterial communities in Medicago truncatula by performing quantitative microbiota profiling (QMP) of 16S rRNA genes. We found that M. truncatula mutants that cannot establish AM or rhizobia symbiosis have an altered microbial load (quantitative abundance) in the rhizosphere and roots, and in particular that AM symbiosis is required to assemble a normal quantitative root-associated microbiota in native soil. Moreover, quantitative microbial co-abundance network analyses revealed that AM symbiosis affects Rhizobiales hubs among plant microbiota and benefits the plant holobiont. Through QMP of rhizobial rpoB and AM fungal SSU rRNA genes, we revealed a new layer of interaction whereby AM symbiosis promotes rhizobia accumulation in the rhizosphere of M. truncatula. We further showed that AM symbiosis-conditioned microbial communities within the M. truncatula rhizosphere could promote nodulation in different legume plants in native soil. Given that the AM and rhizobial symbioses are critical for crop growth, our findings might inform strategies to improve agricultural management. Moreover, our work sheds light on the co-evolution of these intracellular symbioses during plant adaptation to native soil conditions.
Asunto(s)
Micorrizas/fisiología , Microbiota/fisiología , ARN Ribosómico 16S/genética , Rhizobium/fisiología , Rizosfera , Simbiosis/genética , Simbiosis/fisiologíaRESUMEN
Endophytic fungi can profoundly affect host productivity, but the underlying mechanisms of these effects are only partly understood. As the most important regulators of plant-soil feedback, root exudates can easily cause soil sickness in continuous monoculture systems by reducing certain microbes in the rhizosphere. In this study, exudates from roots colonized by the endophytic fungus Phomopsis liquidambaris significantly increased rhizosphere bacterial abundance, soil respiration, microbial biomass and enzyme activities in a long-term continuously cropped peanut soil. Further analysis revealed that P. liquidambaris-colonized root exudates clearly altered the carbon metabolism and rhizosphere bacterial diversity, which were closely correlated with changes in soil chemical properties caused by the exudates from the colonized roots. Finally, a synthetic root exudate experiment further confirmed that the root exudates derived from P. liquidambaris colonization can indeed play an important role in promoting peanut growth. Therefore, these results show that this endophytic fungus could improve the carbon metabolism and rhizosphere bacterial community in long-term monoculture soils via exudates from colonized roots, which contribute to the alleviation of soil sickness.
Asunto(s)
Rizosfera , Suelo , Arachis , Carbono , Hongos , Raíces de Plantas , Microbiología del SueloRESUMEN
The mechanisms underlying nitrogen (N)-regulated plant-fungi interactions are not well understood. N application modulates plant carbohydrate (C) sinks and is involved in the overall plant-fungal association. We hypothesized that N regulates plant-fungi interactions by influencing the carbohydrate metabolism. The mutualistic fungus Phomopsis liquidambaris was found to prioritize host hexose resources through in vitro culture assays and in planta inoculation. Rice-Ph. liquidambaris systems were exposed to N gradients ranging from N-deficient to N-abundant conditions to study whether and how the sugar composition was involved in the dynamics of N-mediated fungal colonization. We found that root soluble acid invertases were activated, resulting in increased hexose fluxes in inoculated roots. These fluxes positively influenced fungal colonization, especially under N-deficient conditions. Further experiments manipulating the carbohydrate composition and root invertase activity through sugar feeding, chemical treatments and the use of different soil types revealed that the external disturbance of root invertase could reduce endophytic colonization and eliminate endophyte-induced host benefits under N-deficient conditions. Collectively, these results suggest that the activation of root invertase is related to N deficiency-enhanced endophytic colonization via increased hexose generation. Certain combinations of farmland ecosystems with suitable N inputs could be implemented to maximize the benefits of plant-fungi associations.
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Nitrógeno , beta-Fructofuranosidasa , Ecosistema , Fertilizantes , Hongos , Hexosas , Raíces de Plantas , SimbiosisRESUMEN
Watermelon Fusarium wilt is a common soil-borne disease that has significantly affected its yield. In this study, fusaric acid-deficient mutant designated as ΔFUBT (mutated from Fusarium oxysporum f. sp. niveum, FON) was obtained. The ΔFUBT mutant showed significant decrease in fusaric acid production but maintained wild-type characteristics, such as in vitro colony morphology, size, and conidiation. A field pot experiment demonstrated that ΔFUBT could successfully colonize the rhizosphere and the roots of watermelon, leading to significant reduction in FON colonization in the watermelon plant. In addition, ΔFUBT inoculation significantly improved the rhizosphere microenvironment and effectively increased the resistance in watermelon. This study demonstrated that a nonpathogenic Fusarium mutant (ΔFUBT) could be developed as an effective microbial control agent to alleviate Fusarium wilt disease in watermelon and increase its yield.
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Citrullus/microbiología , Fusarium/genética , Micotoxinas/genética , Enfermedades de las Plantas/microbiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Ácido Fusárico/metabolismo , Fusarium/crecimiento & desarrollo , Fusarium/fisiología , Mutación , Micotoxinas/metabolismo , Raíces de Plantas/microbiología , RizosferaRESUMEN
Endophytic fungi play important roles in the modification of ecosystem productivity; however, the underlying mechanisms are only partly understood. A 2-year field plot experiment verified that the endophytic fungus Phomopsis liquidambaris increased peanut (Arachis hypogaea L.) yields and significantly increased nodulation and N2 fixation regardless of whether N fertilizers were added. Root exudates collected from P. liquidambaris-colonized plants significantly improved nodulation and N2 fixation. Rhizosphere stimulation experiments further showed that colonized root exudates had significantly decreased soil nitrate (NO3-) concentrations, with decreased abundance and diversity of ammonia oxidizing archaea (AOA). In contrast, the abundance and diversity of diazotrophs significantly increased, and most diazotrophs identified were peanut nodulation-related strains (Bradyrhizobium sp.). P. liquidambaris symbiosis increased the expression of phenolic and flavonoid synthesis-related genes, and the derived phenolics and flavonoids could effectively increase the chemotaxis, biofilm formation, and nodC gene expression (nodulation-related biological processes) of the Bradyrhizobium strain. Metabolic pattern analysis showed that phenolics and flavonoids are more likely to accumulate to higher levels in the rhizosphere soil of peanuts colonized with P. liquidambaris Finally, a synthetic root exudate experiment further confirmed the underlying mechanisms for the P. liquidambaris-induced improvement in nodulation and N2 fixation, i.e., that the specific root exudates derived from P. liquidambaris colonization decrease nitrate concentration and increase the population and biological activities of peanut nodulation-related Bradyrhizobium species, which beneficially enhance peanut-Bradyrhizobium interactions. Therefore, this study is the ï¬rst to provide new insight into a positive relationship between an exotic endophytic fungus, crop nodulation, and N2 fixation increase.IMPORTANCE Endophytic fungi play an important role in balancing the ecosystem and boosting host growth; however, the underpinning mechanisms remain poorly understood. Here, we found that endophytic fungal colonization with P. liquidambaris significantly increased the productivity, nodulation, and N2 fixation of peanuts through the secretion of specific root exudates. We provide a reasonable mechanism explaining how P. liquidambaris promotes peanut nodulation and N2 fixation, whereby the specific root exudates produced by P. liquidambaris colonization decrease rhizosphere soil nitrate (NO3-) and increase the population and biological activities of peanut-nodulating-related Bradyrhizobium strains, which is beneficial to enhancing the peanut-Bradyrhizobium symbiotic interaction. Our study provides reliable empirical evidence to show the mechanism of how an exotic endophytic fungus drives an increase in nodulation and N2 fixation, which will be helpful in erecting a resource-efficient and sustainable agricultural system.
Asunto(s)
Endófitos/fisiología , Hongos/fisiología , Fijación del Nitrógeno , Nodulación de la Raíz de la Planta , Raíces de Plantas/metabolismo , Raíces de Plantas/microbiología , Arachis/fisiología , Flavonoides/metabolismo , Regulación de la Expresión Génica de las Plantas , Modelos Biológicos , Fenoles/metabolismo , Raíces de Plantas/genética , Rizosfera , Microbiología del Suelo , SimbiosisRESUMEN
BACKGROUND: The continuous cropping of peanuts is a primary cause of yield and quality loss. Solutions to this problem should be therefore developed to ensure the sustainability of peanut production. RESULTS: In this study, colonization by the endophytic fungus Phomopsis liquidambari was detected, which led to significantly improved rhizosphere soil microenvironment, enhanced N, P and K assimilation and suppressed incidence of peanut disease. Statistical analysis demonstrated that the yield enhancement was significantly correlated with improvement of the rhizosphere soil microenvironment and the peanut's physiological status by P. liquidambari colonization. In addition, P. liquidambari colonization also significantly improved peanut quality. CONCLUSION: Our results indicate that the practical application of the endophytic fungus P. liquidambari has a strong potential to alleviate the obstacles associated with continuous peanut cropping under field conditions. © 2018 Society of Chemical Industry.
Asunto(s)
Arachis/microbiología , Ascomicetos/crecimiento & desarrollo , Endófitos/crecimiento & desarrollo , Enfermedades de las Plantas/prevención & control , Arachis/química , Arachis/crecimiento & desarrollo , Arachis/metabolismo , Nitrógeno/análisis , Nitrógeno/metabolismo , Nutrientes/análisis , Nutrientes/metabolismo , Enfermedades de las Plantas/microbiología , Potasio/análisis , Potasio/metabolismo , Rizosfera , Microbiología del SueloRESUMEN
The continuous cropping obstacles in monoculture fields are a major production constraint for peanuts. Application of the endophytic fungus Phomopsis liquidambari has increased peanut yields, and nodulation and N2 fixation increases have been considered as important factors for P. liquidambari infection-improved peanut yield. However, the mechanisms involved in this process remain unknown. This work showed that compared with only Bradyrhizobium inoculation, co-inoculation with P. liquidambari significantly elevated endogenous H2O2 and NO levels in peanut roots. Pre-treatment of seedlings with specific scavengers of H2O2 (CAT) and NO (cPTIO) blocked P. liquidambari-induced nodulation and N2 fixation. CAT not only suppressed the P. liquidambari-induced nodulation and N2 fixation, but also suppressed the enhanced H2O2 and NO generation. Nevertheless, the cPTIO did not significantly inhibit the induced H2O2 biosynthesis, implying that H2O2 acted upstream of NO production. These results were confirmed by observations that exogenous H2O2 and sodium nitroprusside (SNP) reversed the inhibition of P. liquidambari-increased nodulation and N2 fixation by the specific scavengers. The transcriptional activities of the symbiosis-related genes SymRK and CCaMK of peanut-Bradyrhizobium interactions also increased significantly in response to P. liquidambari, H2O2 and SNP treatments. The pot experiment further confirmed that the P. liquidambari infection-enhanced H2O2 and NO signalling pathways were significantly related to the increase in peanut nodulation and N2 fixation. This is the first report that endophytic fungus P. liquidambari can increase peanut-Bradyrhizobium interactions via enhanced H2O2/NO-dependent signalling crosstalk, which is conducive to the alleviation of continuous cropping obstacles via an increase in nodulation and N2 fixation.
Asunto(s)
Arachis/microbiología , Ascomicetos/fisiología , Fijación del Nitrógeno , Nodulación de la Raíz de la Planta , Endófitos/fisiología , Peróxido de Hidrógeno/metabolismo , Óxido Nítrico/metabolismo , SimbiosisRESUMEN
The biodegradation potential of sinapic acid, one of the most representative methoxy phenolic pollutants presented in industrial wastewater, was first studied using an endophytic fungus called Phomopsis liquidambari. This strain can effectively degrade sinapic acid in flasks and in soil and the possible biodegradation pathway was first systematically proposed on the basis of the metabolite production patterns and the identification of the metabolites by GC-MS and HPLC-MS. Sinapic acid was first transformed to 2,6-dimethoxy-4-vinylphenol that was further degraded via 4-hydroxy-3,5-dimethoxybenzaldehyde, syringic acid, gallic acid, and citric acid which involved in the continuous catalysis by phenolic acid decarboxylase, laccase, and gallic acid dioxygenase. Moreover, their activities and gene expression levels exhibited a 'cascade induction' response with the changes in metabolic product concentrations and the generation of fungal laccase significantly improved the degradation process. This study is the first report of an endophytic fungus that has great potential to degrade xenobiotic sinapic acid, and also provide a basis for practical application of endophytic fungus in the bioremediation of sinapic acid-contaminated industrial wastewater and soils.
Asunto(s)
Ascomicetos/metabolismo , Ácidos Cumáricos/metabolismo , Endófitos/metabolismo , Contaminantes Ambientales/metabolismo , Biotransformación , Cromatografía Líquida de Alta Presión , Cromatografía de Gases y Espectrometría de Masas , Espectrometría de Masas , Redes y Vías MetabólicasRESUMEN
In peanut continuous cropping soil, the application of fungal endophyte Phomopsis liquidambari B3 showed peanut pod yield promotion and root nodule number increase. P. liquidambari improved soil environment by degrading allelochemicals and thus promoted peanut pod yield. Furthermore, peanut yield promotion is in part due to the root nodule increase since nodular nitrogen fixation provides the largest source of nitrogen for peanut. However, it is unknown whether this nodule number increase is induced by fungal endophyte. We therefore conducted several pot experiments using vermiculite to investigate the effects of P. liquidambari on peanut-bradyrhizobium nodulation. Our results showed that P. liquidambari co-inoculated with bradyrhizobium increased root nodule number and shoot accumulated nitrogen by 28.25% and 29.71%, respectively. Nodulation dynamics analysis showed that P. liquidambari accelerated nodule initiation and subsequent nodule development. Meanwhile, P. liquidambari was able to colonize the peanut root as an endophyte. The dynamics of P. liquidambari and bradyrhizobial root colonization analysis showed that P. liquidambari inoculation significantly increased the rate of bradyrhizobial colonization. Furthermore, P. liquidambari inoculation significantly increased flavonoids synthesis-related enzymes activities, two common types of flavonoid (luteolin and quercetin-peanut rhizobial nod gene inducer) secretion and lateral root (peanut rhizobial infection site) formation, indicating that P. liquidambari altered the peanut nodulation-related physiological and metabolic activities. These obtained results confirmed the direct contribution of P. liquidambari in enhancing peanut-bradyrhizobium interaction, nodulation and yield.
Asunto(s)
Arachis/crecimiento & desarrollo , Ascomicetos/fisiología , Bradyrhizobium/fisiología , Nodulación de la Raíz de la Planta , Simbiosis , Arachis/microbiología , Endófitos , Flavonoides/metabolismo , Nitrógeno/metabolismo , Fijación del Nitrógeno , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Microbiología del SueloRESUMEN
Biodegradation of ferulic acid, by an endophytic fungus called Phomopsis liquidambari was investigated in this study. This strain can use ferulic acid as the sole carbon for growth. Both in mineral salt medium and in soil, more than 97% of added ferulic acid was degraded within 48 h. The metabolites were identified and quantified using GC-MS and HPLC-MS. Ferulic acid was first decarboxylated to 4-vinyl guaiacol and then oxidized to vanillin and vanillic acid, followed by demethylation to protocatechuic acid, which was further degraded through the ß-ketoadipate pathway. During degradation, ferulic acid decarboxylase, laccase and protocatechuate 3,4-dioxygenase activities and their gene transcription levels were significantly affected by the variation of substrate and product concentrations. Moreover, ferulic acid degradation was determined to some extent by P. liquidambari laccase. This study is the first report of an endophytic fungus that has a great potential for practical application in ferulic acid-contaminated environments.