RESUMEN
Saline soils pose significant challenges to global agricultural productivity, hindering crop growth and efficiency. Despite various mitigation strategies, the issue persists, underscoring the need for innovative and sustainable solutions. One promising approach involves leveraging microorganisms and their plant interactions to reclaim saline soils and bolster crop yields. This review highlights pioneering and recent advancements in utilizing multi-traits Trichoderma and Bacillus species as potent promoters of plant growth and health. It examines the multifaceted impacts of saline stress on plants and microbes, elucidating their physiological and molecular responses. Additionally, it delves into the role of ACC deaminase in mitigating plant ethylene levels by Trichoderma and Bacillus species. Although there are several studies on Trichoderma-Bacillus, much remains to be understood about their synergistic relationships and their potential as auxiliaries in the phytoremediation of saline soils, which is why this work addresses these challenges.
RESUMEN
Beauveria bassiana is an entomopathogenic fungus that parasitizes and kills insects. The role of volatile organic compounds (VOCs) emitted by B. bassiana acting as semiochemicals during its interaction with lepidopterans is poorly explored. Here, we studied the effect of VOCs from B. bassiana and 3-methylbutanol (as a single compound) on the feeding behavior of L2 larvae of Spodoptera frugiperda in sorghum plants. Additionally, we assessed whether fungal VOCs induce chemical modifications in the plants that affect larval food preferences. Metabolomic profiling of plant tissues was performed by mass spectrometry and bioassays in a dual-choice olfactometer. The results showed that the larval feeding behavior was affected by the B. bassiana strain AI2, showing that the insect response is strain-specific. Furthermore, 80 µg of 3-methylbutanol affected the number of bites. The larval feeding choice was dependent on the background context. Fragment spectra and a matching precursor ion mass of 165.882 m/z enabled the putative identification of 4-coumaric acid in sorghum leaves exposed to fungal VOCs, which may be associated with larval deterrent responses. These results provide valuable insights into the bipartite interaction of B. bassiana with lepidopterans through VOC emission, with the plant as a mediator of the interaction.
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Beauveria bassiana is a dimorphic and entomopathogenic fungus with different ecological roles in nature. In pathogenic fungi, yeast-to-mycelial conversion, which is controlled by environmental factors, is required for virulence. Here, we studied the effects of different stimuli on the morphology of two B. bassiana strains and compared the toxicities of culture filtrates. In addition, we explored the role of volatiles as quorum sensing-like signals during dimorphic transition. The killing assays in Caenorhabditis elegans (Nematoda: Rhabditidae) showed that strain AI2 isolated from a mycosed insect cadaver had higher toxicity than strain AS5 isolated from soil. Furthermore, AI2 showed earlier yeast-to-mycelial switching than AS5. However, an increase in inoculum size induced faster yeast-to-mycelium conversion in AS5 cells, suggesting a cell-density-dependent phenomenon. Gas chromatography-mass spectrometry (GC-MS) analyses showed that the fingerprint of the volatiles was strain-specific; however, during the morphological switching, an inverse relationship between the abundance of total terpenes and 3-methylbutanol was observed in both strains. Fungal exposure to 3-methylbutanol retarded the yeast-to-mycelium transition. Hence, this study provides evidence that volatile compounds are associated with critical events in the life cycle of B. bassiana.
RESUMEN
Microbial volatile organic compounds may act as semiochemicals, inciting different behavioral responses in insects. Beauveria bassiana is an entomopathogenic fungus, and physiological and environmental factors are positively related to fungal virulence. In this study, we examined the volatile profiles produced by eight B. bassiana strains, isolated from soil plots and mycosed insect cadavers, with different speeds of kill and determined if these compounds induce oviposition behavior in Spodoptera frugiperda. Fungal volatilome analysis revealed differences between the isolates. Isolates from mycosed insects showed higher virulence, larger egg mass area and length, and a higher number of eggs by mass, than those obtained from soil. Furthermore, a dilution of the fungal odoriferous compounds increased the insect response, suggesting that S. frugiperda is highly susceptible to the fungal compound's fingerprint. Otherwise, the insect response to the natural blend of volatiles released by the fungus was different from that obtained with 3-methylbutanol, which was the most abundant compound in all isolates. The ability of an entomopathogen to produce volatiles that can induce olfactory stimulation of egg-laying behavior could represent an ecological adaptive advantage in which the entomopathogen stimulates the insect population growth.
Asunto(s)
Beauveria , Mariposas Nocturnas , Compuestos Orgánicos Volátiles , Animales , Femenino , Insectos , Oviposición , Pentanoles , Feromonas/farmacología , Suelo , Spodoptera , Compuestos Orgánicos Volátiles/farmacologíaRESUMEN
BACKGROUND: Trichoderma spp. are soil fungi that interact with plant roots and associated biota such as other microorganisms and soil fauna. However, information about their interactions with root-feeding insects is limited. Here, interactions between Trichoderma harzianum and the root-feeding insect Phyllophaga vetula, a common insect pest in maize agroecosystems, were examined. RESULTS: Applications of T. harzianum and P. vetula to the root system increased and decreased maize growth, respectively. Induced tolerance against herbivore attack was provided by T. harzianum maintaining a robust and functional root system as evidenced by the increased uptake of Cu, Ca, Mg, Na and K. Herbivore tolerance also coincided with changes in the emission of root volatile terpenes known to induce indirect defense responses and attract natural enemies of the herbivore. More importantly, T. harzianum induced de novo emission of several sesquiterpenes such as ß-caryophyllene and δ-cadinene. In addition, single and combined applications of T. harzianum and P. vetula altered the sucrose content of the roots. Finally, T. harzianum produced 6-pentyl-2H-pyran-2-one (6-PP) a volatile compound that may act as an antifeedant-signaling compound mitigating root herbivory by P. vetula. CONCLUSION: Our results provide novel information about belowground multitrophic plant-microbe-arthropod interactions between T. harzianum and P. vetula in the maize rhizosphere resulting in alterations in maize phenotypic plant responses, inducing root herbivore tolerance.
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Herbivoria , Trichoderma , Animales , Hypocreales , Raíces de Plantas , Zea maysRESUMEN
Plants host a diverse microbiome and differentially react to the fungal species living as endophytes or around their roots through emission of volatiles. Here, using divided Petri plates for Arabidopsis-T. atroviride co-cultivation, we show that fungal volatiles increase endogenous sugar levels in shoots, roots and root exudates, which improve Arabidopsis root growth and branching and strengthen the symbiosis. Tissue-specific expression of three sucrose phosphate synthase-encoding genes (AtSPS1F, AtSPS2F and AtSPS3F), and AtSUC2 and SWEET transporters revealed that the gene expression signatures differ from those of the fungal pathogens Fusarium oxysporum and Alternaria alternata and that AtSUC2 is largely repressed either by increasing carbon availability or by perception of the fungal volatile 6-pentyl-2H-pyran-2-one. Our data point to Trichoderma volatiles as chemical signatures for sugar biosynthesis and exudation and unveil specific modulation of a critical, long-distance sucrose transporter in the plant.
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Arabidopsis/crecimiento & desarrollo , Hypocreales/química , Sacarosa/metabolismo , Compuestos Orgánicos Volátiles/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Transporte Biológico , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Glucosa/metabolismo , Glucosiltransferasas/genética , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Exudados de Plantas/metabolismo , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Plantas Modificadas Genéticamente , Pironas/farmacología , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Sacarosa/farmacologíaRESUMEN
Trichoderma spp. are universal saprotrophic fungi in terrestrial ecosystems, and as rhizosphere inhabitants, they mediate interactions with other soil microorganisms, plants, and arthropods at multiple trophic levels. In the rhizosphere, Trichoderma can reduce the abundance of phytopathogenic microorganisms, which involves the action of potent inhibitory molecules, such as gliovirin and siderophores, whereas endophytic associations between Trichoderma and the seeds and roots of host plants can result in enhanced plant growth and crop productivity, as well as the alleviation of abiotic stress. Such beneficial effects are mediated via the activation of endogenous mechanisms controlled by phytohormones such as auxins and abscisic acid, as well as by alterations in host plant metabolism. During either root colonization or in the absence of physical contact, Trichoderma can trigger early defense responses mediated by Ca2+ and reactive oxygen species, and subsequently stimulate plant immunity by enhancing resistance mechanisms regulated by the phytohormones salicylic acid, jasmonic acid, and ethylene. In addition, Trichoderma release volatile organic compounds and nitrogen or oxygen heterocyclic compounds that serve as signaling molecules, which have effects on plant growth, phytopathogen levels, herbivorous insects, and at the third trophic level, play roles in attracting the natural enemies (predators and parasitoids) of herbivores. In this paper, we review some of the most recent advances in our understanding of the environmental influences of Trichoderma spp., with particular emphasis on their multiple interactions at different trophic levels.
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Interacciones Microbianas/fisiología , Plantas/microbiología , Trichoderma/fisiología , Animales , Artrópodos/microbiología , Agentes de Control Biológico , Ciclopentanos , Ecosistema , Etilenos , Herbivoria , Ácidos Indolacéticos/metabolismo , Oxilipinas , Desarrollo de la Planta , Enfermedades de las Plantas , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas/inmunología , Plantas/parasitología , Rizosfera , Ácido Salicílico/metabolismo , Metabolismo Secundario , Estrés FisiológicoRESUMEN
Biofertilizer production and application for sustainable agriculture is already a reality. The methods for biofertilizers delivery in crop fields are diverse. Although foliar spray is gaining wide acceptance, little is known about the influence that the biochemical features of leaves have on the microbial colonization. Arthrobacter agilis UMCV2 is a rhizospheric and endophytic bacteria that promotes plant growth and health. In this study, we determined the capacity of the UMCV2 strain to colonize different leaves from Medicago truncatula in a foliar inoculation system. By using two powerful analytical methods based on mass spectrometry, we determined the chemical profile of the leaves in 15-d old plants. The metabolic signatures between the unifoliate leaf (m1) and the metameric units developing above (m2 and m3) were different, and interestingly, the highest colony forming units (CFU) was found in m1. The occurrence of the endophyte strongly affects the sugar composition in m1 and m2 leaves. Our results suggest that A. agilis UMCV2 colonize the leaves under a foliar inoculation system independently of the phenological age of the leaf and it is capable of modulating the carbohydrate metabolism without affecting the rest of the metabolome.
Asunto(s)
Arthrobacter/metabolismo , Endófitos/metabolismo , Medicago truncatula/metabolismo , Medicago truncatula/microbiología , Hojas de la Planta/microbiología , Metabolismo de los Hidratos de Carbono/fisiología , Fertilizantes/microbiología , Medicago truncatula/crecimiento & desarrollo , Hojas de la Planta/química , Simbiosis/fisiologíaRESUMEN
Iron is an essential plant micronutrient. It is a component of numerous proteins and participates in cell redox reactions; iron deficiency results in a reduction in nutritional quality and crop yields. Volatiles from the rhizobacterium Arthrobacter agilis UMCV2 induce iron acquisition mechanisms in plants. However, it is not known whether microbial volatiles modulate other metabolic plant stress responses to reduce the negative effect of iron deficiency. Mass spectrometry has great potential to analyze metabolite alterations in plants exposed to biotic and abiotic factors. Direct liquid introduction-electrospray-mass spectrometry was used to study the metabolite profile in Medicago truncatula due to iron deficiency, and in response to microbial volatiles. The putatively identified compounds belonged to different classes, including pigments, terpenes, flavonoids, and brassinosteroids, which have been associated with defense responses against abiotic stress. Notably, the levels of these compounds increased in the presence of the rhizobacterium. In particular, the analysis of brassinolide by gas chromatography in tandem with mass spectrometry showed that the phytohormone increased ten times in plants grown under iron-deficient growth conditions and exposed to microbial volatiles. In this mass spectrometry-based study, we provide new evidence on the role of A. agilis UMCV2 in the modulation of certain compounds involved in stress tolerance in M. truncatula.
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Arthrobacter/metabolismo , Brasinoesteroides/metabolismo , Hierro/metabolismo , Medicago truncatula/metabolismo , Espectrometría de Masa por Ionización de Electrospray/métodos , Compuestos Orgánicos Volátiles/farmacología , Inoculantes Agrícolas , Brasinoesteroides/análisis , Análisis por Conglomerados , Medicago truncatula/efectos de los fármacos , Medicago truncatula/crecimiento & desarrollo , Modelos Biológicos , Plantones/efectos de los fármacos , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Estrés FisiológicoRESUMEN
Several species of Trichoderma promote plant growth and help in defense against root pathogens. The role of root-exuded carbohydrates as chemo-attractive stimuli for Trichoderma colonization is attracting considerable interest. In this project, we studied the interaction between Trichoderma atroviride and tomato (Lycopersicon esculentum L. cv. Río Grande) plants in two different stages, before and during root colonization. In addition, the biocontrol capacity of T. atroviride against the phytopathogen Phytophthora cinnamomi in a tripartite interaction system was examined. We found that the beneficial effects of T. atroviride on plant growth were fine-tuned depending on the progress of interaction. Interestingly, the composition of the carbohydrate exudate from plants interacting with T. atroviride was different from that produced by other treatments and probably provided a nutritional source for the fungus. Particularly, sucrose was found only during root colonization by the fungus. Our data show that root-derived sugars enabled a higher Trichoderma growth rate, and that, in the tripartite interaction system with P. cinnamomi, the fungus competes for space and available soil nutrients more efficiently than P. cinnamomi, thereby antagonizing the growth of the phytopathogen.
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Agentes de Control Biológico/metabolismo , Carbohidratos/aislamiento & purificación , Phytophthora/crecimiento & desarrollo , Enfermedades de las Plantas/prevención & control , Enfermedades de las Plantas/parasitología , Raíces de Plantas/metabolismo , Solanum lycopersicum/microbiología , Solanum lycopersicum/parasitología , Trichoderma/crecimiento & desarrollo , Solanum lycopersicum/metabolismo , Desarrollo de la Planta , Raíces de Plantas/microbiología , Raíces de Plantas/parasitología , Sacarosa/metabolismo , Trichoderma/metabolismoRESUMEN
KEY MESSAGE: Our results show that Sorghum bicolor is able to recognize bacteria through its volatile compounds and differentially respond to beneficial or pathogens via eliciting nutritional or defense adaptive traits. Plants establish beneficial, harmful, or neutral relationships with bacteria. Plant growth promoting rhizobacteria (PGPR) emit volatile compounds (VCs), which may act as molecular cues influencing plant development, nutrition, and/or defense. In this study, we compared the effects of VCs produced by bacteria with different lifestyles, including Arthrobacter agilis UMCV2, Bacillus methylotrophicus M4-96, Sinorhizobium meliloti 1021, the plant pathogen Pseudomonas aeruginosa PAO1, and the commensal rhizobacterium Bacillus sp. L2-64, on S. bicolor. We show that VCs from all tested bacteria, except Bacillus sp. L2-64, increased biomass and chlorophyll content, and improved root architecture, but notheworthy A. agilis induced the release of attractant molecules, whereas P. aeruginosa activated the exudation of growth inhibitory compounds by roots. An analysis of the expression of iron-transporters SbIRT1, SbIRT2, SbYS1, and SbYS2 and genes related to plant defense pathways COI1 and PR-1 indicated that beneficial, pathogenic, and commensal bacteria could up-regulate iron transporters, whereas only beneficial and pathogenic species could induce a defense response. These results show how S. bicolor could recognize bacteria through their volatiles profiles and highlight that PGPR or pathogens can elicit nutritional or defensive traits in plants.
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Fenómenos Fisiológicos Bacterianos , Proteínas de Transporte de Catión/genética , Inmunidad Innata/genética , Exudados de Plantas/metabolismo , Raíces de Plantas/metabolismo , Sorghum/metabolismo , Compuestos Orgánicos Volátiles/farmacología , Bacterias/genética , Bacterias/inmunología , Regulación de la Expresión Génica de las Plantas , Transporte Iónico , Hierro/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/microbiología , Rizosfera , Transducción de Señal/efectos de los fármacos , Sorghum/efectos de los fármacos , Sorghum/genética , Sorghum/microbiologíaRESUMEN
Plant growth-promoting rhizobacteria stimulate plant growth and development via different mechanisms. In this study, we characterized the effect of volatiles from Bacillus methylotrophicus M4-96 isolated from the maize rhizosphere on root and shoot development, and auxin homeostasis in Arabidopsis thaliana. Phytostimulation occurred after 4 days of interaction between M4-96 and Arabidopsis grown on opposite sides of divided Petri plates, as revealed by enhanced primary root growth, root branching, leaf formation, and shoot biomass accumulation. Analysis of indole-3-acetic acid content revealed two- and threefold higher accumulation in the shoot and root of bacterized seedlings, respectively, compared to uninoculated plants, which was correlated with increased expression of the auxin response marker DR5::GUS. The auxin transport inhibitor 1-naphthylphthalamic acid inhibited primary root growth and lateral root formation in axenically grown seedlings and antagonized the plant growth-promoting effects of M4-96. Analysis of bacterial volatile compounds revealed the presence of four classes of compounds, including ten ketones, eight alcohols, one aldehyde, and two hydrocarbons. However, the abundance of ketones and alcohols represented 88.73 and 8.05%, respectively, of all airborne signals detected, with acetoin being the main compound produced. Application of acetoin had a different effect from application of volatiles, suggesting that either the entire pool or acetoin acting in concert with another unidentified compound underlies the strong phytostimulatory response. Taken together, our results show that B. methylotrophicus M4-96 generates bioactive volatiles that increase the active auxin pool of plants, stimulate the growth and formation of new organs, and reprogram root morphogenesis.
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Arabidopsis/crecimiento & desarrollo , Bacillus/fisiología , Zea mays/microbiología , Arabidopsis/metabolismo , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Bacillus/aislamiento & purificación , Expresión Génica , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos/metabolismo , Rizoma/crecimiento & desarrollo , Rizoma/metabolismo , Rizoma/microbiología , Compuestos Orgánicos Volátiles/metabolismoRESUMEN
Trichodermaspp. are common soil and root inhabitants that have been widely studied due to their capacity to produce antibiotics, parasitize other fungi and compete with deleterious plant microorganisms. These fungi produce a number of secondary metabolites such as non-ribosomal peptides, terpenoids, pyrones and indolic-derived compounds. In the rhizosphere, the exchange and recognition of signaling molecules byTrichodermaand plants may alter physiological and biochemical aspects in both. For example, severalTrichodermastrains induce root branching and increase shoot biomass as a consequence of cell division, expansion and differentiation by the presence of fungal auxin-like compounds. Furthermore,Trichoderma, in association with plant roots, can trigger systemic resistance and improve plant nutrient uptake. The present review describes the most recent advances in understanding the ecological functions ofTrichodermaspp. in the rhizosphere at biochemical and molecular levels with special emphasis on their associations with plants. Finally, through a synthesis of the current body of work, we present potential future research directions on studies related toTrichodermaspp. and their secondary metabolites in agroecosystems.
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Raíces de Plantas/microbiología , Rizosfera , Trichoderma/fisiología , Biomasa , Ecología , Ácidos Indolacéticos/metabolismo , Enfermedades de las Plantas/prevención & control , Plantas/microbiología , Microbiología del SueloRESUMEN
Plants interact with root microbes via chemical signaling, which modulates competence or symbiosis. Although several volatile organic compounds (VOCs) from fungi may affect plant growth and development, the signal transduction pathways mediating VOC sensing are not fully understood. 6-pentyl-2H-pyran-2-one (6-PP) is a major VOC biosynthesized by Trichoderma spp. which is probably involved in plant-fungus cross-kingdom signaling. Using microscopy and confocal imaging, the effects of 6-PP on root morphogenesis were found to be correlated with DR5:GFP, DR5:VENUS, H2B::GFP, PIN1::PIN1::GFP, PIN2::PIN2::GFP, PIN3::PIN3::GFP and PIN7::PIN7::GFP gene expression. A genetic screen for primary root growth resistance to 6-PP in wild-type seedlings and auxin- and ethylene-related mutants allowed identification of genes controlling root architectural responses to this metabolite. Trichoderma atroviride produced 6-PP, which promoted plant growth and regulated root architecture, inhibiting primary root growth and inducing lateral root formation. 6-PP modulated expression of PIN auxin-transport proteins in a specific and dose-dependent manner in primary roots. TIR1, AFB2 and AFB3 auxin receptors and ARF7 and ARF19 transcription factors influenced the lateral root response to 6-PP, whereas EIN2 modulated 6-PP sensing in primary roots. These results indicate that root responses to 6-PP involve components of auxin transport and signaling and the ethylene-response modulator EIN2.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Morfogénesis/efectos de los fármacos , Raíces de Plantas/crecimiento & desarrollo , Receptores de Superficie Celular/metabolismo , Trichoderma/química , Compuestos Orgánicos Volátiles/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Transporte Biológico/efectos de los fármacos , Biomasa , Oscuridad , Etilenos/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Raíces de Plantas/efectos de los fármacos , Pironas/química , Pironas/farmacología , Plantones/efectos de los fármacos , Plantones/metabolismo , Transducción de Señal/efectos de los fármacos , Compuestos Orgánicos Volátiles/químicaRESUMEN
Trichoderma atroviride is a symbiotic fungus that interacts with roots and stimulates plant growth and defense. Here, we show that Arabidopsis seedlings cocultivated with T. atroviride have an altered root architecture and greater biomass compared with axenically grown seedlings. These effects correlate with increased activity of mitogen-activated protein kinase 6 (MPK6). The primary roots of mpk6 mutants showed an enhanced growth inhibition by T. atroviride when compared with wild-type (WT) plants, while T. atroviride increases MPK6 activity in WT roots. It was also found that T. atroviride produces ethylene (ET), which increases with l-methionine supply to the fungal growth medium. Analysis of growth and development of WT seedlings and etr1, ein2, and ein3 ET-related Arabidopsis mutants indicates a role for ET in root responses to the fungus, since etr1 and ein2 mutants show defective root-hair induction and enhanced primary-root growth inhibition when cocultivated with T. atroviride. Increased MPK6 activity was evidenced in roots of ctr1 mutants, which correlated with repression of primary root growth, thus connecting MPK6 signaling with an ET response pathway. Auxin-inducible gene expression analysis using the DR5:uidA reporter construct further revealed that ET affects auxin signaling through the central regulator CTR1 and that fungal-derived compounds, such as indole-3-acetic acid and indole-3-acetaldehyde, induce MPK6 activity. Our results suggest that T. atroviride likely alters root-system architecture modulating MPK6 activity and ET and auxin action.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Enfermedades de las Plantas/microbiología , Reguladores del Crecimiento de las Plantas/metabolismo , Transducción de Señal , Trichoderma/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Biomasa , Etilenos/metabolismo , Regulación de la Expresión Génica de las Plantas , Genes Reporteros , Ácidos Indolacéticos/metabolismo , Indoles/metabolismo , Metionina/metabolismo , Proteínas Quinasas Activadas por Mitógenos/genética , Modelos Biológicos , Mutación , Raíces de Plantas/enzimología , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Proteínas Quinasas , Plantones/enzimología , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/microbiologíaRESUMEN
Salt stress is an important constraint to world agriculture. Here, we report on the potential of Trichoderma virens and T. atroviride to induce tolerance to salt in Arabidopsis seedlings. We first characterized the effect of several salt concentrations on shoot biomass production and root architecture of Arabidopsis seedlings. We found that salt repressed plant growth and root development in a dose-dependent manner by blocking auxin signaling. Analysis of the wild type and eir1, aux1-7, arf7arf19, and tir1abf2abf19 auxin-related mutants revealed a key role for indole-3-acetic acid (IAA) signaling in mediating salt tolerance. We also found that T. virens (Tv29.8) and T. atroviride (IMI 206040) promoted plant growth in both normal and saline conditions, which was related to the induction of lateral roots and root hairs through auxin signaling. Arabidopsis seedlings grown under saline conditions inoculated with Trichoderma spp. showed increased levels of abscissic acid, L-proline, and ascorbic acid, and enhanced elimination of Na⺠through root exudates. Our data show the critical role of auxin signaling and root architecture to salt tolerance in Arabidopsis and suggest that these fungi may enhance the plant IAA level as well as the antioxidant and osmoprotective status of plants under salt stress.
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Arabidopsis , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Raíces de Plantas , Trichoderma/fisiología , Antioxidantes/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/microbiología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Biomasa , Carbohidratos , Caseínas/metabolismo , Lípidos , Mutación , Exudados de Plantas/metabolismo , Proteínas de Vegetales Comestibles/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/genética , Brotes de la Planta/crecimiento & desarrollo , Brotes de la Planta/microbiología , Tolerancia a la Sal , Plantones/efectos de los fármacos , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/microbiología , Transducción de Señal , Cloruro de Sodio/metabolismo , Cloruro de Sodio/farmacología , Estrés FisiológicoRESUMEN
Plant diseases caused by fungal pathogens such as Botrytis cinerea and the oomycete Phytophthora cinnamomi affect agricultural production worldwide. Control of these pests can be done by the use of fungicides such as captan, which may have deleterious effects on human health. This study demonstrates that the rhizobacterium Arthrobacter agilis UMCV2 produces volatile organic compounds that inhibit the growth of B. cinerea in vitro. A single compound from the volatile blends, namely dimethylhexadecylamine (DMHDA), could inhibit the growth of both B. cinerea and P. cinnamomi when supplied to the growth medium in low concentrations. DMHDA also inhibited the growth of beneficial fungi Trichoderma virens and Trichoderma atroviride but at much higher concentrations. DMHDA-related aminolipids containing 4, 8, 10, 12, and 14 carbons in the alkyl chain were tested for their inhibitory effect on the growth of the pathogens. The results show that the most active compound from those tested was dimethyldodecylamine. This effect correlates with a decrease in the number of membrane lipids present in the mycelium of the pathogen including eicosanoic acid, (Z)-9-hexadecenoic acid, methyl ester, and (Z)-9-octadecenoic acid, methyl ester. Strawberry leaflets treated with DMHDA were not injured by the compound. These data indicate that DMHDA and related compounds, which can be produced by microorganisms may effectively inhibit the proliferation of certain plant pathogens.
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Aminas/farmacología , Arthrobacter/química , Fragaria/microbiología , Hongos/efectos de los fármacos , Hongos/crecimiento & desarrollo , Hidrocarburos/farmacología , Metilaminas/farmacología , Aminas/química , Antifúngicos/farmacología , Botrytis/efectos de los fármacos , Botrytis/crecimiento & desarrollo , Medios de Cultivo/farmacología , Humanos , Hidrocarburos/química , Metilaminas/química , Fosfolípidos/metabolismo , Phytophthora/efectos de los fármacos , Phytophthora/crecimiento & desarrollo , Trichoderma/efectos de los fármacos , Trichoderma/crecimiento & desarrolloRESUMEN
Medicago truncatula represents a model plant species for understanding legume-bacteria interactions. M. truncatula roots form a specific root-nodule symbiosis with the nitrogen-fixing bacterium Sinorhizobium meliloti. Symbiotic nitrogen fixation generates high iron (Fe) demands for bacterial nitrogenase holoenzyme and plant leghemoglobin proteins. Leguminous plants acquire Fe via "Strategy I," which includes mechanisms such as rhizosphere acidification and enhanced ferric reductase activity. In the present work, we analyzed the effect of S. meliloti volatile organic compounds (VOCs) on the Fe-uptake mechanisms of M. truncatula seedlings under Fe-deficient and Fe-rich conditions. Axenic cultures showed that both plant and bacterium modified VOC synthesis in the presence of the respective symbiotic partner. Importantly, in both Fe-rich and -deficient experiments, bacterial VOCs increased the generation of plant biomass, rhizosphere acidification, ferric reductase activity, and chlorophyll content in plants. On the basis of our results, we propose that M. truncatula perceives its symbiont through VOC emissions, and in response, increases Fe-uptake mechanisms to facilitate symbiosis.
Asunto(s)
Hierro/metabolismo , Medicago truncatula/metabolismo , Medicago truncatula/microbiología , Sinorhizobium meliloti/metabolismo , Compuestos Orgánicos Volátiles/metabolismo , Biomasa , Clorofila/análisis , FMN Reductasa/metabolismo , Concentración de Iones de Hidrógeno , Medicago truncatula/química , Medicago truncatula/crecimiento & desarrollo , Nódulos de las Raíces de las Plantas/microbiología , Suelo/químicaRESUMEN
In tequila production, fermentation is an important step. Fermentation determines the ethanol productivity and organoleptic properties of the beverage. In this study, a yeast isolated from native residual agave must was identified as Kluyveromyces marxianus UMPe-1 by 26S rRNA sequencing. This yeast was compared with the baker's yeast Saccharomyces cerevisiae Pan1. Our findings demonstrate that the UMPe-1 yeast was able to support the sugar content of agave must and glucose up to 22% (w/v) and tolerated 10% (v/v) ethanol concentration in the medium with 50% cells survival. Pilot and industrial fermentation of agave must tests showed that the K. marxianus UMPe-1 yeast produced ethanol with yields of 94% and 96% with respect to fermentable sugar content (glucose and fructose, constituting 98%). The S. cerevisiae Pan1 baker's yeast, however, which is commonly used in some tequila factories, showed 76% and 70% yield. At the industrial level, UMPe-1 yeast shows a maximum velocity of fermentable sugar consumption of 2.27g·L(-1)·h(-1) and ethanol production of 1.38g·L(-1)·h(-1), providing 58.78g ethanol·L(-1) at 72h fermentation, which corresponds to 96% yield. In addition, the major and minor volatile compounds in the tequila beverage obtained from UMPe-1 yeast were increased. Importantly, 29 volatile compounds were identified, while the beverage obtained from Pan1-yeast contained fewer compounds and in lower concentrations. The results suggest that the K. marxianus UMPe-1 is a suitable yeast for agave must fermentation, showing high ethanol productivity and increased volatile compound content comparing with a S. cerevisiae baker's yeast used in tequila production.
Asunto(s)
Agave/metabolismo , Bebidas Alcohólicas/microbiología , Etanol/metabolismo , Fermentación , Microbiología de Alimentos , Kluyveromyces/metabolismo , Saccharomyces cerevisiae/metabolismo , Agave/química , Agave/microbiología , Metabolismo de los Hidratos de Carbono , Etanol/análisis , Kluyveromyces/genética , Kluyveromyces/aislamiento & purificación , ARN Ribosómico/genéticaRESUMEN
Filamentous fungi belonging to the genus Trichoderma have long been recognized as agents for the biocontrol of plant diseases. In this work, we investigated the mechanisms involved in the defense responses of Arabidopsis thaliana seedlings elicited by co-culture with Trichoderma virens and Trichoderma atroviride. Interaction of plant roots with fungal mycelium induced growth and defense responses, indicating that both processes are not inherently antagonist. Expression studies of the pathogenesis-related reporter markers pPr1a:uidA and pLox2:uidA in response to T. virens or T. atroviride provided evidence that the defense signaling pathway activated by these fungi involves salicylic acid (SA) and/or jasmonic acid (JA) depending on the amount of conidia inoculated. Moreover, we found that Arabidopsis seedlings colonized by Trichoderma accumulated hydrogen peroxide and camalexin in leaves. When grown under axenic conditions, T. virens produced indole-3-carboxaldehyde (ICAld) a tryptophan-derived compound with activity in plant development. In Arabidopsis seedlings whose roots are in contact with T. virens or T. atroviride, and challenged with Botrytis cinerea in leaves, disease severity was significantly reduced compared to axenically grown seedlings. Our results indicate that the defense responses elicited by Trichoderma in Arabidopsis are complex and involve the canonical defense hormones SA and JA as well as camalexin, which may be important factors in boosting plant immunity.