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1.
Mycorrhiza ; 30(1): 23-49, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32130512

RESUMEN

An accurate understanding of the diversity and distribution of fungal symbioses in land plants is essential for mycorrhizal research. Here we update the seminal work of Wang and Qiu (Mycorrhiza 16:299-363, 2006) with a long-overdue focus on early-diverging land plant lineages, which were considerably under-represented in their survey, by examining the published literature to compile data on the status of fungal symbioses in liverworts, hornworts and lycophytes. Our survey combines data from 84 publications, including recent, post-2006, reports of Mucoromycotina associations in these lineages, to produce a list of at least 591 species with known fungal symbiosis status, 180 of which were included in Wang and Qiu (Mycorrhiza 16:299-363, 2006). Using this up-to-date compilation, we estimate that fewer than 30% of liverwort species engage in symbiosis with fungi belonging to all three mycorrhizal phyla, Mucoromycota, Basidiomycota and Ascomycota, with the last being the most widespread (17%). Fungal symbioses in hornworts (78%) and lycophytes (up to 100%) appear to be more common but involve only members of the two Mucoromycota subphyla Mucoromycotina and Glomeromycotina, with Glomeromycotina prevailing in both plant groups. Our fungal symbiosis occurrence estimates are considerably more conservative than those published previously, but they too may represent overestimates due to currently unavoidable assumptions.


Asunto(s)
Embryophyta , Glomeromycota , Micorrizas , Hongos , Filogenia , Simbiosis
2.
World J Microbiol Biotechnol ; 36(3): 47, 2020 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-32144505

RESUMEN

Beauveria bassiana (Bals.) Vuillemin (B. bassiana) is an entomopathogenic fungus that establishes endophytic symbiosis with plants. In the present study, the effects of B. bassiana strains colonization in growing Zea mays L. (Z. mays), crop production, and drought tolerance were evaluated. Z. mays seeds were inoculated with B. bassiana strains (GHA, PTG4, and PTG6), using 1 × 106 blastospores/mL and methyl cellulose (MC) or cornstarch (CS) as adherents. Colonization was determined by B. bassiana recovery from plant tissues plated on PDA medium. Plant height, fresh and dry weight, and flowering time were analyzed to assess plant performance. Drought tolerance was evaluated by stopping watering for 10 days, watering again, and determining vigor recovery after 24 h. Results showed 100% endophytic roots colonization, regardless of adherent type or strain tested. Colonization was variable in shoots and leaves, but GHA strain achieved the highest inoculation rates, including 88% in stems and 50% in leaves, which did not depend on adherent type used; for PTG4 strain, adherent type had an important effect (MC = 100% stems and leaves; CS = 63% stems and 25% leaves). For PTG6 strain, the best adherent type was CS (71% stems and 75% leaves), whereas MC showed variable inoculation percentage (25% stems and 75% leaves). Interestingly, only MCPTG4 treatment showed consistent positive effects on germination percentage (day 5 = 46 ± 2%; day 14 = 87 ± 7%) compared with controls (CC = 63 ± 4%, CMC = 50 ± 3%, CCS = 47 ± 0%). In addition, the other treatments showed low germination percentages at day 5 (7 ± 7% to 46 ± 2%), which recovered at day 14 (53 ± 0% to 73 ± 8%), except for MCPTG6 treatment with 23 ± 10% germination. About plant performance, not significant effects on plant height and fresh/dry weight in all the treatments were observed. However, B. bassiana-treated plants, using either GHA, PTG4 or PTG6 strains, and MC as adherent, showed tolerance to drought and flowered one to two weeks earlier, providing evidence supporting further applications of these seed treatments in agricultural systems, for abiotic stress sustainable management practices.


Asunto(s)
Beauveria/fisiología , Sequías , Endófitos/fisiología , Flores/crecimiento & desarrollo , Estrés Fisiológico , Zea mays/crecimiento & desarrollo , Germinación , Desarrollo de la Planta , Hojas de la Planta/microbiología , Semillas/crecimiento & desarrollo , Semillas/microbiología , Simbiosis , Zea mays/microbiología
3.
Cell Host Microbe ; 27(3): 312-314, 2020 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-32164840

RESUMEN

How gut cells distinguish between beneficial symbionts and deleterious pathobionts is a central question. In this issue of Cell Host & Microbe, Kim et al. (2020) demonstrate that the nucleoside catabolism pathway controlling bacterial uracil and ribose production is an essential trigger of the commensal to pathogen transition.


Asunto(s)
Infecciones por Alphavirus , Simbiosis , Sitios de Unión , Evolución Biológica , Humanos , Uracilo , Uridina
4.
Int J Syst Evol Microbiol ; 70(2): 1421-1430, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-32122457

RESUMEN

For many smallholder farmers of Sub-Saharan Africa, pigeonpea (Cajanus cajan) is an important crop to make ends meet. To ascertain the taxonomic status of pigeonpea isolates of Côte d'Ivoire previously identified as bradyrhizobia, a polyphasic approach was applied to strains CI-1BT, CI-14A, CI-19D and CI-41S. Phylogeny of 16S ribosomal RNA (rRNA) genes placed these nodule isolates in a separate lineage from current species of the B. elkanii super clade. In phylogenetic analyses of single and concatenated partial dnaK, glnII, gyrB, recA and rpoB sequences, the C. cajan isolates again formed a separate lineage, with strain CI-1BT sharing the highest sequence similarity (95.2 %) with B. tropiciagri SEMIA 6148T. Comparative genomic analyses corroborated the novel species status, with 86 % ANIb and 89 % ANIm as the highest average nucleotide identity (ANI) values with B. elkanii USDA 76T. Although CI-1BT, CI-14A, CI-19D and CI-41S shared similar phenotypic and metabolic properties, growth of CI-41S was slower in/on various media. Symbiotic efficacy varied significantly between isolates, with CI-1BT and CI-41S scoring on the C. cajan 'Light-Brown' landrace as the most and least proficient bacteria, respectively. Also proficient on Vigna radiata (mung bean), Vigna unguiculata (cowpea, niébé) and additional C. cajan cultivars, CI-1BT represents a potential bioinoculant adapted to local soil conditions and capable of fostering the growth of diverse legume crops in Côte d'Ivoire. Given the data presented here, we propose the 19 C. cajan isolates to belong to a novel species called Bradyrhizobium ivorense sp. nov., with CI-1BT (=CCOS 1862T=CCMM B1296T) as a type strain.


Asunto(s)
Bradyrhizobium/clasificación , Cajanus/microbiología , Filogenia , Nódulos de las Raíces de las Plantas/microbiología , Técnicas de Tipificación Bacteriana , Composición de Base , Bradyrhizobium/aislamiento & purificación , Costa de Marfil , ADN Bacteriano/genética , Fabaceae/microbiología , Genes Bacterianos , Fijación del Nitrógeno , Hibridación de Ácido Nucleico , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Simbiosis
5.
Cell Host Microbe ; 27(3): 376-388.e8, 2020 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-32075741

RESUMEN

During short-lived perturbations, such as inflammation, the gut microbiota exhibits resilience and reverts to its original configuration. Although microbial access to the micronutrient iron is decreased during colitis, pathogens can scavenge iron by using siderophores. How commensal bacteria acquire iron during gut inflammation is incompletely understood. Curiously, the human commensal Bacteroides thetaiotaomicron does not produce siderophores but grows under iron-limiting conditions using enterobacterial siderophores. Using RNA-seq, we identify B. thetaiotaomicron genes that were upregulated during Salmonella-induced gut inflammation and were predicted to be involved in iron uptake. Mutants in the xusABC locus (BT2063-2065) were defective for xenosiderophore-mediated iron uptake in vitro. In the normal mouse gut, the XusABC system was dispensable, while a xusA mutant colonized poorly during colitis. This work identifies xenosiderophore utilization as a critical mechanism for B. thetaiotaomicron to sustain colonization during inflammation and suggests a mechanism of how interphylum iron metabolism contributes to gut microbiota resilience.


Asunto(s)
Bacteroides thetaiotaomicron/metabolismo , Colitis/microbiología , Enterobacteriaceae/genética , Microbioma Gastrointestinal , Hierro/metabolismo , Sideróforos/genética , Animales , Bacteroides thetaiotaomicron/genética , Femenino , Genes Bacterianos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Simbiosis
6.
Cell Host Microbe ; 27(3): 345-357.e6, 2020 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-32078802

RESUMEN

Although the gut microbiome is generally symbiotic or commensal, some microbiome members become pathogenic under certain circumstances. However, the factors driving this pathogenic switch are largely unknown. Pathogenic bacteria can generate uracil that triggers host dual oxidase (DUOX) to produce antimicrobial reactive oxygen species (ROS). We show that pathogens generate uracil and ribose upon nucleoside catabolism of gut luminal uridine, which triggers not only host defenses but also inter-bacterial communication and pathogenesis in Drosophila. Uridine-derived uracil triggers DUOX-dependent ROS generation, whereas ribose induces bacterial quorum sensing (QS) and virulence gene expression. Genes implicated in nucleotide metabolism are found in pathogens but not commensal bacteria, and their genetic ablation blocks QS and the commensal-to-pathogen transition in vivo. Furthermore, commensal bacteria lack functional nucleoside catabolism, which is required to achieve gut-microbe symbiosis, but can become pathogenic by enabling nucleotide catabolism. These findings reveal molecular mechanisms governing the commensal-to-pathogen transition in different contexts of host-microbe interactions.


Asunto(s)
Bacterias/metabolismo , Bacterias/patogenicidad , Drosophila/microbiología , Percepción de Quorum , Uracilo/metabolismo , Virulencia , Animales , Proteínas Bacterianas/metabolismo , Oxidasas Duales/metabolismo , N-Glicosil Hidrolasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Ribosa/metabolismo , Simbiosis , Uridina/metabolismo
7.
Cell Host Microbe ; 27(3): 358-375.e7, 2020 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-32101704

RESUMEN

Despite the recognized capacity of the gut microbiota to regulate intestinal lipid metabolism, the role of specific commensal species remains undefined. Here, we aimed to understand the bacterial effectors and molecular mechanisms by which Lactobacillus paracasei and Escherichia coli regulate lipid metabolism in enterocytes. We show that L-lactate produced by L. paracasei inhibits chylomicron secretion from enterocytes and promotes lipid storage by a mechanism involving L-lactate absorption by enterocytes, its conversion to malonyl-CoA, and the subsequent inhibition of lipid beta-oxidation. In contrast, acetate produced by E. coli also inhibits chylomicron secretion by enterocytes but promotes lipid oxidation by a mechanism involving acetate absorption by enterocytes, its metabolism to acetyl-CoA and AMP, and the subsequent upregulation of the AMPK/PGC-1α/PPARα pathway. Our study opens perspectives for developing specific bacteria- and metabolite-based therapeutic interventions against obesity, atherosclerosis, and malnutrition by targeting lipid metabolism in enterocytes.


Asunto(s)
Enterocitos/metabolismo , Escherichia coli/metabolismo , Fermentación , Lactobacillus paracasei/metabolismo , Metabolismo de los Lípidos , Simbiosis , Animales , Línea Celular , Quilomicrones , Enterocitos/microbiología , Femenino , Intestinos/microbiología , Ratones Endogámicos C57BL
8.
Mycorrhiza ; 30(1): 63-77, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32062707

RESUMEN

Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with many plant species, transferring significant amounts of soil nutrients such as phosphorus to plants and receiving photosynthetically fixed carbon in return. Functioning of AM symbiosis is thus based on interaction between two living partners. The importance of dead AM fungal biomass (necromass) in ecosystem processes remains unclear. Here, we applied either living biomass or necromass (0.0004 potting substrate weight percent) of monoxenically produced AM fungus (Rhizophagus irregularis) into previously sterilized potting substrate planted with Andropogon gerardii. Plant biomass production significantly improved in both treatments as compared to non-amended controls. Living AM fungus, in contrast to the necromass, specifically improved plant acquisition of nutrients normally supplied to the plants by AM fungal networks, such as phosphorus and zinc. There was, however, no difference between the two amendment treatments with respect to plant uptake of other nutrients such as nitrogen and/or magnesium, indicating that the effect on plants of the AM fungal necromass was not primarily nutritional. Plant growth stimulation by the necromass could thus be either due to AM fungal metabolites directly affecting the plants, indirectly due to changes in soil/root microbiomes or due to physicochemical modifications of the potting substrate. In the necromass, we identified several potentially bioactive molecules. We also provide experimental evidence for significant differences in underground microbiomes depending on the amendment with living or dead AM fungal biomass. This research thus provides the first glimpse into possible mechanisms responsible for observed plant growth stimulation by the AM fungal necromass.


Asunto(s)
Andropogon , Glomeromycota , Micorrizas , Biomasa , Raíces de Plantas , Simbiosis
9.
Syst Appl Microbiol ; 43(2): 126067, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32005490

RESUMEN

Forty rhizobial strains were isolated from Lotus creticus, L. pusillus and Bituminaria bituminosa endemic to Tunisia, and they belonged to the Mesorhizobium and Ensifer genera based on 16S rDNA sequence phylogeny. According to the concatenated recA and glnII sequence-based phylogeny, four Bituminaria isolates Pb5, Pb12, Pb8 and Pb17 formed a monophyletic group with Mesorhizobium chacoense ICMP14587T, whereas four other strains Pb1, Pb6, Pb13 and Pb15 formed two separate lineages within the Ensifer genus. Among the L. pusillus strains, Lpus9 and Lpus10 showed a 96% identical nucleotide with Ensifer meliloti CCBAU83493T; whereas six other strains could belong to previously undescribed Mesorhizobium and Ensifer species. For L. creticus strains, Lcus37, Lcus39 and Lcus44 showed 98% sequence identity with Ensifer aridi JNVU TP6, and Lcus42 shared a 96% identical nucleotide with Ensifer meliloti CCBAU83493T; whereas another four strains were divergent from all the described Ensifer and Mesorhizobium species. The analysis of the nodC gene-based phylogeny identified four symbiovar groups; Mesorhizobium sp. sv. anthyllidis (Lpus3 and Lpus11 from L. pusillus, Lcus43 from L. creticus), Ensifer medicae sv. meliloti (four strains from L. creticus and two strains from L. pusillus), E. meliloti sv. meliloti (four from L. creticus, four from L. pusillus and four from B. bituminosa). In addition, four B. bituminosa strains (Pb5, Pb8, Pb12, and Pb17) displayed a distinctive nodC sequence distant from those of other symbiovars described to date. According to their symbiotic gene sequences and host range, the B. bituminosa symbionts (Pb5, Pb8, Pb12 and Pb17) would represent a new symbiovar of M. chacoense for which sv. psoraleae is proposed.


Asunto(s)
Productos Agrícolas/microbiología , Fabaceae/microbiología , Mesorhizobium/fisiología , Nódulos de las Raíces de las Plantas/microbiología , Sinorhizobium/fisiología , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Fabaceae/clasificación , Genes Esenciales/genética , Variación Genética , Genoma Bacteriano/genética , Mesorhizobium/clasificación , Mesorhizobium/genética , Mesorhizobium/aislamiento & purificación , Hibridación de Ácido Nucleico , Filogenia , Nodulación de la Raíz de la Planta , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Sinorhizobium/clasificación , Sinorhizobium/genética , Sinorhizobium/aislamiento & purificación , Microbiología del Suelo , Simbiosis/genética , Túnez
10.
Microbes Environ ; 35(1)2020.
Artículo en Inglés | MEDLINE | ID: mdl-32074548

RESUMEN

Bradyrhizobium elkanii, a rhizobium with a relatively wide host range, possesses a functional type III secretion system (T3SS) that is involved in symbiotic incompatibility against Rj4-genotype soybean (Glycine max) and some accessions of mung bean (Vigna radiata). To expand our knowledge on the T3SS-mediated partner selection mechanism in the symbiotic legume-rhizobia association, we inoculated three Lotus experimental accessions with wild-type and T3SS-mutant strains of B. elkanii USDA61. Different responses were induced by T3SS in a host genotype-dependent manner. Lotus japonicus Gifu inhibited infection; L. burttii allowed infection, but inhibited nodule maturation at the post-infection stage; and L. burttii and L. japonicus MG-20 both displayed a nodule early senescence-like response. By conducting inoculation tests with mutants of previously reported and newly identified effector protein genes of B. elkanii USDA61, we identified NopF as the effector protein triggering the inhibition of infection, and NopM as the effector protein triggering the nodule early senescence-like response. Consistent with these results, the B. elkanii USDA61 gene for NopF introduced into the Lotus symbiont Mesorhizobium japonicum induced infection inhibition in L. japonicus Gifu, but did not induce any response in L. burttii or L. japonicus MG-20. These results suggest that Lotus accessions possess at least three checkpoints to eliminate unfavorable symbionts, including the post-infection stage, by recognizing different T3SS effector proteins at each checkpoint.


Asunto(s)
Bradyrhizobium/fisiología , Lotus/microbiología , Simbiosis/genética , Sistemas de Secreción Tipo III/genética , Proteínas Bacterianas/genética , Bradyrhizobium/genética , Bradyrhizobium/metabolismo , Genotipo , Especificidad del Huésped/genética , Lotus/genética , Nodulación de la Raíz de la Planta/genética
11.
Ecol Lett ; 23(2): 409-411, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31898406

RESUMEN

Whether natural selection favours 'cheating' in mutualisms is hotly debated. Gano-Cohen et al. (2019a) report a negative correlation between fitness and mutualist quality in rhizobia, suggesting that rhizobia evolve to cheat. However, reanalysis of their data shows that the correlation is an artefact of unequal sampling across populations.


Asunto(s)
Fabaceae , Rhizobium , Selección Genética , Simbiosis
12.
Arch Insect Biochem Physiol ; 103(4): e21655, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31953886

RESUMEN

Some studies have highlighted benefits for Lobesia botrana by adding Botrytis cinerea mycelium to an artificial larval diet and have suggested a mutualistic relationship between the two organisms on grapevine, hypothesizing that fungal sterols were the nutritional factor involved. Because the nutritional quality of an artificial diet should be similar to grapes to allow extrapolation of the results to the field conditions, in the current study L. botrana larval performance was compared when larvae were fed on grapes (berries) or two artificial diets either with or without enrichment with B. cinerea. Based on sterol analysis, the two artificial diets had high cholesterol content, but relative to berries showed comparable and low phytosterol contents, respectively (high- and low-phytosterol, HPh, and LPh). While larval fitness on the HPh diet was similar to berries, the LPh diet led to higher mortality and worse larval performance. The addition of the fungus compensated for the shortage in the LPh diet but did not improve the HPh diet. Supplementing the LPh diet with linoleic acid, which is supplied also from B. cinerea, partially improved larval performance. In a field experiment, females did not show any egg-laying preferences towards naturally botrytized bunches. The positive effect of B. cinerea on the moth's next generation that is reported in the literature could be a consequence of fungus developed inside berry tunnels bored by larvae. Therefore, based on our data and previous reports the existence of a mutualistic relationship between L. botrana and B. cinerea is not well-founded.


Asunto(s)
Botrytis/fisiología , Mariposas Nocturnas/microbiología , Mariposas Nocturnas/fisiología , Simbiosis , Alimentación Animal/análisis , Animales , Dieta , Larva/crecimiento & desarrollo , Larva/microbiología , Larva/fisiología , Mariposas Nocturnas/crecimiento & desarrollo , Oviposición , Vitis
13.
Biol Lett ; 16(1): 20190702, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31910734

RESUMEN

Bacterial endosymbionts evolve under strong host-driven selection. Factors influencing host evolution might affect symbionts in similar ways, potentially leading to correlations between the molecular evolutionary rates of hosts and symbionts. Although there is evidence of rate correlations between mitochondrial and nuclear genes, similar investigations of hosts and symbionts are lacking. Here, we demonstrate a correlation in molecular rates between the genomes of an endosymbiont (Blattabacterium cuenoti) and the mitochondrial genomes of their hosts (cockroaches). We used partial genome data for multiple strains of B. cuenoti to compare phylogenetic relationships and evolutionary rates for 55 cockroach/symbiont pairs. The phylogenies inferred for B. cuenoti and the mitochondrial genomes of their hosts were largely congruent, as expected from their identical maternal and cytoplasmic mode of inheritance. We found a correlation between evolutionary rates of the two genomes, based on comparisons of root-to-tip distances and on comparisons of the branch lengths of phylogenetically independent species pairs. Our results underscore the profound effects that long-term symbiosis can have on the biology of each symbiotic partner.


Asunto(s)
Cucarachas , Genoma Mitocondrial , Animales , Evolución Molecular , Genoma Bacteriano , Filogenia , Simbiosis
14.
Mycorrhiza ; 30(1): 51-61, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31965295

RESUMEN

Some mixotrophic plants from temperate forests use the mycorrhizal fungi colonizing their roots as a carbon source to supplement their photosynthesis. These fungi are also mycorrhizal on surrounding trees, from which they transfer carbon to mixotrophic plants. These plants are thus reputed difficult to transplant, even when their protection requires it. Here, we take profit of a successful ex situ pot cultivation over 1 to 3 years of the mixotrophic orchid Epipacis helleborine to investigate its mycorrhizal and nutrition status. Firstly, compared with surrounding autotrophic plants, it did not display the higher N content and higher isotopic (13C and 15N) abundance that normally feature mixotrophic orchids because they incorporate N-, 13C-, and 15N-rich fungal biomass. Second, fungal barcoding by next-generation sequencing revealed that the proportion of ectomycorrhizal fungi (expressed as percentage of the total number of either reads or operational taxonomic units) was unusually low compared with E. helleborine growing in situ: instead, we found a high percentage of rhizoctonias, the usual mycorrhizal partners of autotrophic orchids. Altogether, this supports autotrophic survival. Added to the recently published evidence that plastid genomes of mixotrophic orchids have intact photosynthetic genes, this suggests that at least some of them have abilities for autotrophy. This adds to the ecological plasticity of mixotrophic plants, and may allow some reversion to autotrophy in their evolution.


Asunto(s)
Micorrizas , Orchidaceae , Procesos Autotróficos , Fotosíntesis , Raíces de Plantas , Simbiosis
15.
Mycorrhiza ; 30(1): 5-22, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31982950

RESUMEN

Orchids are associated with diverse fungal taxa, including nonmycorrhizal endophytic fungi as well as mycorrhizal fungi. The orchid mycorrhizal (OM) symbiosis is an excellent model for investigating the biological interactions between plants and fungi due to their high dependency on these symbionts for growth and survival. To capture the complexity of OM interactions, significant genomic, numerous transcriptomic, and proteomic studies have been performed, unraveling partly the role of each partner. On the other hand, several papers studied the bioactive metabolites from each partner but rarely interpreted their significance in this symbiotic relationship. In this review, we focus from a biochemical viewpoint on the OM dynamics and its molecular interactions. The ecological functions of OM in plant development and stress resistance are described first, summarizing recent literature. Secondly, because only few studies have specifically looked on OM molecular interactions, the signaling pathways and compounds allowing the establishment/maintenance of mycorrhizal association involved in arbuscular mycorrhiza (AM) are discussed in parallel with OM. Based on mechanistic similarities between OM and AM, and recent findings on orchids' endophytes, a putative model representing the different molecular strategies that OM fungi might employ to establish this association is proposed. It is hypothesized here that (i) orchids would excrete plant molecule signals such as strigolactones and flavonoids but also other secondary metabolites; (ii) in response, OM fungi would secrete mycorrhizal factors (Myc factors) or similar compounds to activate the common symbiosis genes (CSGs); (iii) overcome the defense mechanism by evasion of the pathogen-associated molecular patterns (PAMPs)-triggered immunity and by secretion of effectors such as small inhibitor proteins; and (iv) finally, secrete phytohormones to help the colonization or disrupt the crosstalk of plant defense phytohormones. To challenge this putative model, targeted and untargeted metabolomics studies with special attention to each partner's contribution are finally encouraged and some technical approaches are proposed.


Asunto(s)
Micorrizas , Orchidaceae , Endófitos , Hongos , Proteómica , Simbiosis
16.
Trends Plant Sci ; 25(4): 395-405, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31948791

RESUMEN

Strigolactones (SLs) are a class of plant hormones involved in several biological processes that are of great agricultural concern. While initiating plant-fungal symbiosis, SLs also trigger germination of parasitic plants that pose a major threat to farming. In vascular plants, SLs control shoot branching, which is linked to crop yield. SL research has been a fascinating field that has produced a variety of different signaling models, reflecting a complex picture of hormone perception. Here, we review recent developments in the SL field and the crystal structures that gave rise to various models of receptor activation. We also highlight the increasing number of discovered SL molecules, reflecting the existence of cross-kingdom SL communication.


Asunto(s)
Lactonas , Reguladores del Crecimiento de las Plantas , Germinación , Transducción de Señal , Simbiosis
17.
Syst Appl Microbiol ; 43(2): 126053, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31937424

RESUMEN

Bradyrhizobium are N2-fixing microsymbionts of legumes with relevant applications in agricultural sustainability, and we investigated the phylogenetic relationships of conserved and symbiotic genes of 21 bradyrhizobial strains. The study included strains from Western Australia (WA), isolated from nodules of Glycine spp. the country is one genetic center for the genus and from nodules of other indigenous legumes grown in WA, and strains isolated from forage Glycine sp. grown in South Africa. The 16S rRNA phylogeny divided the strains in two superclades, of B. japonicum and B. elkanii, but with low discrimination among the species. The multilocus sequence analysis (MLSA) with four protein-coding housekeeping genes (dnaK, glnII, gyrB and recA) pointed out seven groups as putative new species, two within the B. japonicum, and five within the B. elkanii superclades. The remaining eleven strains showed higher similarity with six species, B. lupini, B. liaoningense, B. yuanmingense, B. subterraneum, B. brasilense and B. retamae. Phylogenetic analysis of the nodC symbiotic gene clustered 13 strains in three different symbiovars (sv. vignae, sv. genistearum and sv. retamae), while seven others might compose new symbiovars. The genetic profiles of the strains evaluated by BOX-PCR revealed high intra- and interspecific diversity. The results point out the high level of diversity still to be explored within the Bradyrhizobium genus, and further studies might confirm new species and symbiovars.


Asunto(s)
Bradyrhizobium/clasificación , Bradyrhizobium/genética , Filogenia , Proteínas Bacterianas/genética , Bradyrhizobium/aislamiento & purificación , ADN Bacteriano/genética , Fabaceae/microbiología , Genes Esenciales/genética , Variación Genética , Genoma Bacteriano/genética , ARN Ribosómico 16S/genética , Nódulos de las Raíces de las Plantas/microbiología , Análisis de Secuencia de ADN , Sudáfrica , Simbiosis/genética , Australia Occidental
18.
Syst Appl Microbiol ; 43(2): 126056, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31987702

RESUMEN

In this study, the diversity and the phylogenetic relationships of bacteria isolated from root nodules of Chamaecytisus ruthenicus growing in Poland were investigated using ERIC-PCR fingerprinting and by multilocus sequence analysis (MLSA). Two major clusters comprising 13 and 3 isolates were detected which 16S rRNA gene sequencing identified as Bradyrhizobium and Phyllobacterium. The results of phylogenetic analysis of individual and concatenated atpD, gyrB and recA gene sequences showed that the studied strains may represent novel species in the genera Bradyrhizobium and Phyllobacterium. In the phylogenetic tree based on the atpD-gyrB-recA concatemers, Bradyrhizobium isolates were split into two groups closely related to Bradyrhizobium algeriense STM89T and Bradyrhizobium valentinum LmjM3T. The genus Phyllobacterium isolates formed a separate cluster close to Phyllobacterium ifriqiyense LMG27887T in the atpD-gyrB-recA phylogram. Analysis of symbiotic gene sequences (nodC, nodZ, nifD, and nifH) showed that the Bradyrhizobium isolates were most closely related to Bradyrhizobium algeriense STM89T, Bradyrhizobium valentinum LmjM3T and Bradyrhizobium retamae Ro19T belonging to symbiovar retamae. This is the first report on the occurrence of members of symbiovar retamae from outside the Mediterranean region. No symbiosis related genes were amplified from Phyllobacterium strains, which were also unable to induce nodules on C. ruthenicus roots. Based on these findings Phyllobacterium isolates can be regarded as endophytic bacteria inhabitating root nodules of C. ruthenicus.


Asunto(s)
Bradyrhizobium/clasificación , Fabaceae/microbiología , Phyllobacteriaceae/clasificación , Filogenia , Proteínas Bacterianas/genética , Bradyrhizobium/genética , Bradyrhizobium/aislamiento & purificación , ADN Bacteriano/genética , Genes Esenciales/genética , Variación Genética , Fijación del Nitrógeno/genética , Phyllobacteriaceae/genética , Phyllobacteriaceae/aislamiento & purificación , Nodulación de la Raíz de la Planta/genética , Polonia , ARN Ribosómico 16S/genética , Nódulos de las Raíces de las Plantas/microbiología , Análisis de Secuencia de ADN , Simbiosis/genética
19.
Microbes Environ ; 35(1)2020.
Artículo en Inglés | MEDLINE | ID: mdl-31996499

RESUMEN

In central Europe, soybean cultivation is gaining increasing importance to reduce protein imports from overseas and make cropping systems more sustainable. In the field, despite the inoculation of soybean with commercial rhizobia, its nodulation is low. In many parts of Europe, limited information is currently available on the genetic diversity of rhizobia and, thus, biological resources for selecting high nitrogen-fixing rhizobia are inadequate. These resources are urgently needed to improve soybean production in central Europe. The objective of the present study was to identify strains that have the potential to increase nitrogen fixation by and the yield of soybean in German soils. We isolated and characterized 77 soybean rhizobia from 18 different sampling sites. Based on a multilocus sequence analysis (MLSA), 71% of isolates were identified as Bradyrhizobium and 29% as Rhizobium. A comparative analysis of the nodD and nifH genes showed no significant differences, which indicated that the soybean rhizobia symbiotic genes in the present study belong to only one type. One isolate, GMF14 which was tolerant of a low temperature (4°C), exhibited higher nitrogen fixation in root nodules and a greater plant biomass than USDA 110 under cold conditions. These results strongly suggest that some indigenous rhizobia enhance biological nitrogen fixation and soybean yield due to their adaption to local conditions.


Asunto(s)
Bradyrhizobium/fisiología , Rhizobium/fisiología , Microbiología del Suelo , Soja/crecimiento & desarrollo , Soja/microbiología , Agricultura , Proteínas Bacterianas/genética , Bradyrhizobium/clasificación , Bradyrhizobium/genética , Bradyrhizobium/metabolismo , Frío , Alemania , Tipificación de Secuencias Multilocus , Fijación del Nitrógeno/genética , Oxidorreductasas/genética , Filogenia , Rhizobium/clasificación , Rhizobium/genética , Rhizobium/metabolismo , Nódulos de las Raíces de las Plantas/microbiología , Estrés Fisiológico , Simbiosis/genética
20.
J Agric Food Chem ; 68(5): 1169-1185, 2020 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-31922733

RESUMEN

Epichloë endophytes in forage grasses have attracted widespread attention and interest of chemistry researchers as a result of the various unique chemical structures and interesting biological activities of their secondary metabolites. This review describes the diversity of unique chemical structures of taxa from Epichloë endophytes and grass infected with Epichloë endophytes and demonstrates their reported biological activities. Until now, nearly 160 secondary metabolites (alkaloids, peptides, indole derivatives, pyrimidines, sesquiterpenoids, flavonoids, phenol and phenolic acid derivatives, aliphatic metabolites, sterols, amines and amides, and others) have been reported from Epichloë endophytes and grass infected with Epichloë endophytes. Among these, non-alkaloids account for half of the population of total metabolites, indicating that they also play an important role in Epichloë endophytes and grass infected with Epichloë endophytes. Also, a diverse array of secondary metabolites isolated from Epichloë endophytes and symbionts is a rich source for developing new pesticides and drugs. Bioassays disclose that, in addition to toxic alkaloids, the other metabolites isolated from Epichloë endophytes and symbionts have notable biological activities, such as antifungal, anti-insect, and phytotoxic activities. Accordingly, the biological functions of non-alkaloids should not be neglected in the future investigation of Epichloë endophytes and symbionts.


Asunto(s)
Alcaloides/metabolismo , Endófitos/química , Epichloe/química , Poaceae/microbiología , Simbiosis , Alcaloides/química , Alcaloides/toxicidad , Animales , Endófitos/fisiología , Epichloe/metabolismo , Insectos/efectos de los fármacos , Ganado/metabolismo , Poaceae/fisiología
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