Going back to the Roots: Impact of the microbiome on plant health and growth

Conferencia científicaPlant roots are colonized by an astounding number of microorganisms that can reach cell densities much greater than the number of plant cells. Various studies have shown that members of the plant microbiome contribute to plant tolerance to abiotic (e.g. drought) and biotic (e.g. diseases) stress factors, but also to plant nutrition, growth and development. For the vast majority of plant-associated microorganisms, however, there is limited knowledge on their support functions and the mechanisms involved. Novel ‘omics technologies have provided more in-depth knowledge of the diversity and functioning of the plant microbiome and significant advances are being made to uncover mechanisms, genes and metabolites involved in the multi-trophic interactions in the plant microbiome. To better understand this intriguing complexity, both reductionists’ and systems approaches are needed to identify the biotic and abiotic factors involved in microbiome assembly and activity. Here, new results are presented on the role of rhizosphere and endosphere bacteria in protection of plants against soil-borne pathogens. For the rhizosphere bacteria, we showed that representatives of the Proteobacteria protect plants from pathogen infection by the production of chlorinated peptides and alter root architecture and plant growth via modulation of sulfur assimilation. In-depth metagenomic sequencing of the endosphere allowed de novo assembly of high quality bacterial genomes and revealed various yet unknown biosynthetic genes and pathways with new potential for plant protection and antibiotic discovery. An overview will be given on the wealth of genes and functions of the plant microbiome.Máster y Programa de Doctroado "Biología Celular y Molecular", y el Departamento de Microbiología, Univesidad de Málaga . Campus de Excelencia Internacional Andalucía Tech

El biocontrol de Pseudomonas chlororaphis PCL1606 es debido al compuesto antifúngico producido por los genes dar

XXIV Congreso de Microbiología SEMPseudomonas chlororaphis PCL1606 es una rizobacteria con capacidad de biocontrol frente a Rosellinia necatrix, agente causal de la podredumbre radicular blanca y Fusarium oxysporum f. sp. radicis-lycorpersici, que causa la podredumbre de cuello y raices de las plantas de tomate. Esta bacteria se caracteriza por la producción del antibiótico antifúngico 2-hexil, 5-propil resorcinol (HPR). Para determinar las bases genéticas de la producción de HPR en P. chlororaphis PCL1606, se rastreó una genoteca genómica de PCL1606 empleando como sonda los genes dar decritos previamente como responsables de la producción de HPR en P. aurantica BL915. Tras el análisis, se aisló el plásmido pCGNOV-1, que contenía un clon genómico con la presencia de cinco genes homólogos a los genes dar. Para determinar el papel de cada uno de los genes homólogos a los genes dar en la producción de HPR y su capacidad de biocontrol, se llevó a cabo la construcción de una colección de mutantes dirigidos en la producción de HPR por inserción. Además se obtuvieron los correspondientes complementantes de los mutantes defectivos. Sobre estos mutantes y sus respectivos complementates, se realizó una caracterización fenótipica de las propiedades relacionadas con el biocontrol, entre ellas la capacidad de antagonismo frente a Rosellina necatrix y Fusarium oxysporum, la producción de antibióticos y ensayos de control biológico en los sistemas experimentales aguacate-Rosellinia y tomate-Fusarium. Los resultados obtenidos muestran que los genes darA, darB pierden la capacidad de producir HPR. Esta propiedad queda restaurada al complementar cada uno de los mutantes con sus respectivos genes. Estos genes darA y darB junto con el gen darR, estan involucrados en la capacidad de biocontrol de la cepa silvestre P. fluorescens PCL1606. En conclusión, la capacidad de biocontrol de la cepa P. chlororaphis PCL1606 depende de la producción de HPR, llevada a cabo por los genes dar. Esta investigación ha sido apoyada por el Proyecto GL2011-30345-C02-01 (MICINN, España). CE Calderón recibió el apoyo de una beca de FPI, MICINN, España

Characterisation of the mgo operon in Pseudomonas syringae pv. syringae UMAF0158 that is required for mangotoxin production

<p>Abstract</p> <p>Background</p> <p>Mangotoxin is an antimetabolite toxin that is produced by strains of <it>Pseudomonas syringae </it>pv. <it>syringae</it>; mangotoxin-producing strains are primarily isolated from mango tissues with symptoms of bacterial apical necrosis. The toxin is an oligopeptide that inhibits ornithine N-acetyl transferase (OAT), a key enzyme in the biosynthetic pathway of the essential amino acids ornithine and arginine. The involvement of a putative nonribosomal peptide synthetase gene (<it>mgo</it>A) in mangotoxin production and virulence has been reported.</p> <p>Results</p> <p>In the present study, we performed a RT-PCR analysis, insertional inactivation mutagenesis, a promoter expression analysis and terminator localisation to study the gene cluster containing the <it>mgo</it>A gene. Additionally, we evaluated the importance of <it>mgo</it>C, <it>mgo</it>A and <it>mgo</it>D in mangotoxin production. A sequence analysis revealed an operon-like organisation. A promoter sequence was located upstream of the <it>mgo</it>B gene and was found to drive <it>lac</it>Z transcription. Two terminators were located downstream of the <it>mgo</it>D gene. RT-PCR experiments indicated that the four genes (<it>mgo</it>BCAD) constitute a transcriptional unit. This operon is similar in genetic organisation to those in the three other <it>P. syringae </it>pathovars for which complete genomes are available (<it>P. syringae </it>pv. <it>syringae </it>B728a, <it>P. syringae </it>pv. <it>tomato </it>DC3000 and <it>P. syringae </it>pv. <it>phaseolicola </it>1448A). Interestingly, none of these three reference strains is capable of producing mangotoxin. Additionally, extract complementation resulted in a recovery of mangotoxin production when the defective mutant was complemented with wild-type extracts.</p> <p>Conclusions</p> <p>The results of this study confirm that <it>mgo</it>B, <it>mgo</it>C, <it>mgo</it>A and <it>mgo</it>D function as a transcriptional unit and operon. While this operon is composed of four genes, only the last three are directly involved in mangotoxin production.</p

Astronomical radio-reception techniques for emission spectroscopy of molecular and short lived species in cold plasmas

Santiago de Compostela, Facultade de Química,17-21 julio 2017. -- http://www.bienalrsef2017.com/bienalrsef17/This work has received funding from the European Research Council under the Program (FP/2007- 2013) / ERC-SyG-2013 Grant Agreement n. 610256 NANOCOSMOS and from Spanish MINECO under the Consolider-Ingenio Program CSD2009-00038 (ASTROMOL) and the grants FIS2013- 48087-C2-1-P, FIS2016-77726-C3-1-P.Peer Reviewe

A decade of GRB follow-up by BOOTES in Spain (2003-2013)

This article covers ten years of GRB follow-ups by the Spanish BOOTES stations: 71 follow-ups providing 23 detections. Follow-ups by BOOTES-1B from 2005 to 2008 were given in the previous article, and are here reviewed, updated, and include additional detection data points as the former article merely stated their existence. The all-sky cameras CASSANDRA have not yet detected any GRB optical afterglows, but limits are reported where available

Crop rotation and native microbiome inoculation restore soil capacity to suppress a root disease

14 páginas.- 5 figuras.- 58 referencias.- Supplementary information The online version contains supplementary material available at https://doi.org/10.1038/s41467-023-43926-4.It is widely known that some soils have strong levels of disease suppression and prevent the establishment of pathogens in the rhizosphere of plants. However, what soils are better suppressing disease, and how management can help us to boost disease suppression remain unclear. Here, we used field, greenhouse and laboratory experiments to investigate the effect of management (monocropping and rotation) on the capacity of rhizosphere microbiomes in suppressing peanut root rot disease. Compared with crop rotations, monocropping resulted in microbial assemblies that were less effective in suppressing root rot diseases. Further, the depletion of key rhizosphere taxa in monocropping, which were at a disadvantage in the competition for limited exudates resources, reduced capacity to protect plants against pathogen invasion. However, the supplementation of depleted strains restored rhizosphere resistance to pathogen. Taken together, our findings highlight the role of native soil microbes in fighting disease and supporting plant health, and indicate the potential of using microbial inocula to regenerate the natural capacity of soil to fight disease. © 2023, The Author(s).This research was supported by the National Key Research and Development Program of China 2022YFD2201900 (Xi.L.), the National Natural Science Foundation of China 32122056, 42011045 (Xi.L.), and the earmarked fund for CARS-13 (X.W.). M.D-B. acknowledges support from TED2021-130908B-C41/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/PRTR and from the Spanish Ministry of Science and Innovation for the I + D + i project PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033.Peer reviewe

Mitigation of Pseudomonas syringae virulence by signal inactivation

Pseudomonas syringae is an important plant pathogen of many valuable crops worldwide, with more than 60 identified pathovars. The phytotoxins produced by these organisms were related to the severity of the damage caused to the plant. An emerging strategy to treat bacterial infections relies on interference with their signaling systems. In this study, we investigated P. syringae pv. syringae, which produces the virulence factor mangotoxin that causes bacterial apical necrosis on mango leaves. A previously unknown signaling molecule named leudiazen was identified, determined to be unstable and volatile, and responsible for mangotoxin production. A strategy using potassium permanganate, compatible with organic farming, was developed to degrade leudiazen and thus to attenuate the pathogenicity of P. syringae pv. syringae.Plant science

Pathogen-induced activation of disease-suppressive functions in the endophytic root microbiome

Microorganisms living inside plants can promote plant growth and health, but their genomic and functional diversity remain largely elusive. Here, metagenomics and network inference show that fungal infection of plant roots enriched for Chitinophagaceae and Flavobacteriaceae in the root endosphere and for chitinase genes and various unknown biosynthetic gene clusters encoding the production of nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). After strain-level genome reconstruction, a consortium of Chitinophaga and Flavobacterium was designed that consistently suppressed fungal root disease. Site-directed mutagenesis then revealed that a previously unidentified NRPS-PKS gene cluster from Flavobacterium was essential for disease suppression by the endophytic consortium. Our results highlight that endophytic root microbiomes harbor a wealth of as yet unknown functional traits that, in concert, can protect the plant inside out.</p

The mbo Operon Is Specific and Essential for Biosynthesis of Mangotoxin in Pseudomonas syringae

Mangotoxin is an antimetabolite toxin produced by certain Pseudomonas syringae pv. syringae strains. This toxin is an oligopeptide that inhibits ornithine N-acetyl transferase, a key enzyme in the biosynthesis of ornithine and arginine. Previous studies have reported the involvement of the putative nonribosomal peptide synthetase MgoA in virulence and mangotoxin production. In this study, we analyse a new chromosomal region of P. syringae pv. syringae UMAF0158, which contains six coding sequences arranged as an operon (mbo operon). The mbo operon was detected in only mangotoxin-producing strains, and it was shown to be essential for the biosynthesis of this toxin. Mutants in each of the six ORFs of the mbo operon were partially or completely impaired in the production of the toxin. In addition, Pseudomonas spp. mangotoxin non-producer strains transformed with the mbo operon gained the ability to produce mangotoxin, indicating that this operon contains all the genetic information necessary for mangotoxin biosynthesis. The generation of a single transcript for the mbo operon was confirmed and supported by the allocation of a unique promoter and Rho-independent terminator. The phylogenetic analysis of the P. syringae strains harbouring the mbo operon revealed that these strains clustered together