Showing papers in "Symbiosis in 2021"
TL;DR: In this article, an intimate relationship between plant roots and arbuscular mycorrhizae fungi (AMF) is observed, which shows a major concern over plant nutrition by providing access to the soil-derived nutrients.
Abstract: Arbuscular mycorrhizae fungi (AMF) are a big player of the ecosystem which shows a major concern over plant nutrition by providing access to the soil-derived nutrients. Naturally, an intimate association between plant roots and AMF is observed. AMF are involved in improvement on the soil water regime and nutrient uptake both in the biotic and abiotic stress situations such as drought, temperature extreme, heavy metals, salinity, pathogen and metal pollution. This kind of symbiotic relationship between plant roots and fungal hyphae is observed to be 80% of the terrestrial plant species worldwide. In plant AMF association fungal hyphae are benefitted by obtaining sugar from the host plants root and host plants root are ameliorated by improved uptake of water and nutrients from soil surface. AMF have a dual role to manage the Zn nutrition in soil. For example below a critical Zn concentration, Zn uptake is enhanced by AMF application and above the critical level, Zn translocation to plant shoots is restricted. Synergistic association between Zn and AMF is important for sustainable yield and quality. It is observed that grain Zn content in the field is increased with applying AMF. AMF help in the plant growth, development and reproduction, as the Zn is essential for pollen tube formation. By AMF application there is an increment in the content of lycopene, vitamin C, vitamin A and antioxidant activities than non AMF plants in tomato. In traditional driven agriculture, inherent soil fertility is the major source of P with an occasional supply of manure for the crops. But after modernization in agriculture results in overexploitation of the P and results in low crop yield and farm income. Rock phosphate is the major source of the phosphatic fertilizer and is non-renewable which could be exhausted in the next 50–100 years. Moreover, the stimulation of secondary metabolites synthesis results in the improvement of crop quality by sustainable use of phosphatic fertilizers. So P application techniques which can also ameliorate AMF are widely promising. This is how AMF play a pivotal role in developing present era farming practices towards sustainable agriculture. Phytoremediation of heavy metals from different soil types has potential benefit of using AMF in soil. Mycorrhizae disrupt the uptake of the different heavy metals from the rhizosphere and movement from the root to the aerial parts. The major role of AMF in plant growth and development during stressful environments is to translocate important immovable nutrients like Cu, Zn and P and reducing metal toxicity in the host plant.
170 citations
TL;DR: This review tries to compile all the works carried out in the last decades on endophytic fungi use as plant growth promoters with great potential in agriculture.
Abstract: Current rates of population growth require the development of new agricultural strategies to feed the world human and livestock. The massive use of agricultural chemicals causes serious damage to the environment, and to human and animal health. For this reason, the use of endophytic fungi represents a biological alternative in increasing agricultural productivity in a sustainable way. This group of microorganisms, which inhabit plant tissues and organs without causing symptoms of damage, includes a great diversity of filamentous fungi and yeasts that are capable of increasing agricultural productivity. Some of the mechanisms involved in promoting plant growth by means of endophytic fungi include the increasing access to nutrients (nitrogen, phosphorus, potassium, zinc, iron, etc.), production of plant hormones, the ethylene amount reduction, or increase in water acquisition rate. This review tries to compile all the works carried out in the last decades on endophytic fungi use as plant growth promoters with great potential in agriculture.
109 citations
TL;DR: In this article, a review describes how inorganic/organic N-fertilization induces shifts in bacterial communities in soils and plants, making plants dependent on applied mineral nutrients, susceptible to disease and less resistant to abiotic stress resulting in lower crop yields.
Abstract: Global demand for agricultural crops is increasing, and global food production is already dependent on intensive management. Despite efforts to improve production through genetically modified crop varieties and fertilization and pesticide management strategies, yields are stagnant or in declinining. Fertilization is a common farming practice in which organic and inorganic fertilizers are used primarily to improve plant nutrition and crop productivity. However, long-term nitrogen (N) fertilization alters the community and diversity of soil microorganisms and plant endophytes. Nitrogen inputs inhibits or excludes services provided by microbial symbionts making plants dependent on applied mineral nutrients, susceptible to disease and less resistant to abiotic stress resulting in lower crop yields. Stress in plants also triggers changes in plants that affect microbes in soils and in plants. This review describes how inorganic/organic N-fertilization induces shifts in bacterial communities in soils and plants.
36 citations
TL;DR: A review of the AD microbial pathways so far known was done, followed by an introduction of the metagenomics coupled with metabolomics approach for a more intricate understanding of the biological processes that happen in AD systems.
Abstract: The anaerobic digestion process used for methane production has been studied for decades but most studies focused on the optimisation of physico-chemical operating parameters. A holistic understanding of the role played by different microbial communities and their symbiotic associations in facilitating the breakdown of the organic substrates to form methane gas is very key and yet it has only received little attention. This review discusses the AD process and various traditional approaches that have been used to improve its efficiency. The major limitation of these approaches in failing to elucidate the actual roles played by the myriads of microorganisms within their communities and symbiotic associations, as a fundamental starting point for AD process control and optimisation was highlighted. A review of the AD microbial pathways so far known was done, followed by an introduction of the metagenomics coupled with metabolomics approach for a more intricate understanding of the biological processes that happen in AD systems. Progress in the application of this approach during the digestion of various organic substrates including animal manures was also reviewed and finally, prospects for the future use of multi-omics (metagenomics, transcriptomics and metabolomics) approach, were highlighted.
35 citations
TL;DR: In this article, the authors discuss the successful evidence of the use of arbuscular mycorrhizal symbiosis in phytoextraction and phytostabilization of polluted areas.
Abstract: Agricultural and industrial activity generates high concentrations of organic and inorganic pollutants, many of which are incorporated into the trophic chain, affecting ecosystems. There are several strategies for the remediation of polluted areas; we discuss one of them in the present review that shows the successful evidence of the use of arbuscular mycorrhizal symbiosis in phytoextraction (the removal of contaminants from soil and water sources with mycorrhizal plants), and in the process of phytostabilization (the reduction of the mobility of heavy metals in soil by mycorrhizal roots, absorption onto roots, or precipitation within the root zone). Mechanisms of action of arbuscular mycorrhizal fungi (AMF) including, altered uptake and distribution of heavy metals, improvement in the mineral nutrition and water availability, protection against oxidative stress and increment in the physical stability of the soil by producing glomalin has been discussed with reference to heavy metals (HMs) and persistent oxidative pollutants (POPs). We report plant species associated with species of mycorrhizal fungi as strategy for phytostabilizing heavy metals and reducing biotranslocation to the aerial parts of plants.
34 citations
TL;DR: In this paper, the effects of Si on salt stress tolerance were investigated in alfalfa (Medicago sativa L.)-rhizobia symbioses, and the results showed that salt-stressed alalfa increased malonyldialdehyde (MDA), hydrogen peroxide (H2O2) and electrolyte leakage (EL), while Si incorporation in the cultured media reduced oxidative damages under salt-stress particularly in NS-Med variety by 26, 70% and 70% for MDA, H2O 2 and EL respectively.
Abstract: Silicon (Si) application to crops is a promising way for the deployment of sustainable agriculture. Here, the effects of Si on salt stress tolerance were investigated in alfalfa (Medicago sativa L.)-rhizobia symbioses. Two Moroccan, Ouad-Lmaleh (OL) and Demnate-201 (Dm), and one European, NS-Mediana-ZMS-V (NS-Med), alfalfa varieties were associated to Ensifer meliloti Rm41 rhizobial strain. One-month-old alfalfa plants were exposed to 120 mM NaCl for five weeks with or without 3 mM of Si. The plants subjected to salt stress showed reduced biomass, chlorophyll (Chl) contents and relative water content (RWC) in comparison to the controls. The alfalfa-rhizobia symbiosis was also impaired under stress as reflected by less root nodulation and lower nitrogen (N) content and nitrogen content index (NCI). Added Si significantly increased plant biomass, nodules number, N content, NCI, Chl contents and RWC under salt stress. Results showed that salt-stressed alfalfa increased malonyldialdehyde (MDA), hydrogen peroxide (H2O2) and electrolyte leakage (EL). However, Si incorporation in the cultured media reduced oxidative damages under salt-stress particularly in NS-Med variety by 26%, 70% and 70% for MDA, H2O2 and EL respectively. The lower amount of MDA, H2O2 and EL in the Si-treated plants seems to be related to its capacity to modulate superoxide dismutase and polyphenol oxidase activities and increase total polyphenol, flavonoid and carotenoid contents. Besides, compatible osmolytes, such as proline, glycine betaine and soluble sugars were found increased particularly in Si-treated OL plants by 46%, 33% and 26% respectively in comparison to Si-untreated plants. Alfalfa varieties reacted differently to Si treatment. Sodium concentration in alfalfa plants increased under salinity and reduced by Si treatment with an increase in the potassium content. Our findings showed that exogenous Si application could be a promising way to mitigate the toxic effect of salt and could improve alfalfa growth and its rhizobial symbiosis when grown in salt-affected soils.
32 citations
TL;DR: Investigation of the diversity and community composition of AMF in relation to the change in crop and soil management practices, and how the adapted AMF communities may perform in maintaining the ecosystem resilience of these agroecosystems under climate change conditions found that AMF-plant symbiosis can be effectively integrated into global climate change models.
Abstract: The changing global climate affects the agroecosystem making it challenging to achieve the world’s sustainable development goals. Among the facets of belowground microbial communities, the arbuscular mycorrhizal fungi (AMF) hold an important place. They represent the most common symbiont phylum colonizing more than 80% of the plant families and are likely to be affected by global climate change. These fungi facilitate plant’s mineral acquisition, improving growth and protecting them from biotic and abiotic stresses. The elevated carbon dioxide (eCO2) level, temperature, increased nitrogen and phosphorus deposition influences the plant phenology and AMF functioning through changes in diversity and community composition of AMF. The interaction effects of soil management practices due to climate change affect the system productivity and perturb mineral cycling. Understanding the carbon and nitrogen cycling of an agro-ecosystem and its associated AMF communities concerning ecosystem productivity is the need of the hour. Plant-fungal associations require a more environment resilient approach to ameliorate the effect of anthropogenic changes in carbon and nitrogen cycles. Since AMF communities alter due to local environmental conditions and land-use changes, the most adapted community may help in predicting the mycorrhizal responses to chemical fertilizers, eCO2, temperature and drought. In this review, we aimed at investigating (i) the diversity and community composition of AMF in relation to the change in crop and soil management practices, and (ii) how the adapted AMF communities may perform in maintaining the ecosystem resilience of these agroecosystems under climate change conditions. Hence, AMF-plant symbiosis can be effectively integrated into global climate change models. Eventually, the ecosystem resilience will be better understood to exploit the resident AMF communities to offset some of the detrimental effects of anthropogenic environmental change.
28 citations
TL;DR: Evidence is raised that sustains the ‘Symbiodiniaceae phycosphere’ as a relevant portion of the coral holobiont, where essential roles in the holobIONt’s fitness, acclimatization, adaptability and survival are presented, both in homeostatic and adverse conditions.
Abstract: Phycosphere is the region where algal exudates influence microbial communities. Since the term was coined, research has been focused on understanding free-living-phytoplankton and bacteria interactions. Coral-Symbiodiniaceae symbiosis and its associated microbiomes have also been widely studied due to the increasing number of global and local threats endangering coral reefs worldwide. Nevertheless, little is known about the specific interactions between Symbiodiniaceae and bacterial communities within a coral host. In this review, we focus on Symbiodiniaceae-bacteria relationships, occurring in a zone we call here ‘Symbiodiniaceae phycosphere’, within the coral holobiont, in view of 1) identifying and outlining Symbiodiniaceae-bacteria interactions; 2) highlighting interkingdom signaling among phycosphere partners and 3) characterizing microbiome diversity and its relevance to ‘Symbiodiniaceae phycosphere’ as an adaptability generator. Since free-living Symbiodiniaceae are associated with a diverse, structured and dynamic microbial community that are attracted by chemotaxis to the microalgae exudates’ gradient, the maintenance of this gradient and its effect on the microbiota inside the coral host is a must. Here, we raise evidence that sustains the ‘Symbiodiniaceae phycosphere’ as a relevant portion of the coral holobiont, where essential roles in the holobiont’s fitness, acclimatization, adaptability and survival are presented, both in homeostatic and adverse conditions.
26 citations
TL;DR: This review attempts to summarize the current understanding of the hybrid plant-associated microbiome with respect to its parental lines and wild progenitors and highlights some research gaps in the field.
Abstract: In this era of dwindling natural resources and climate change, the target of increasing crop production for feeding 10 billion people by the year 2050 has mounted huge pressure on the scientific community. The cultivation of hybrid varieties has contributed immensely towards food security and made it possible to meet the requirements of the rapidly increasing human population. A typical plant breeding approach involves hybridization i.e. crossing two genetically different individuals, to create genetic variation. At the genetic level, the genomes of two individuals combine to form a hybrid, but what happens to the associated microbiota is largely unknown. Endophytes are one such class of plant-associated microbiota that have been reported to inhabit the internal tissues of plants, without causing any disease symptoms. With the advent of the holobiome concept, the importance of microbiome in plant health and productivity is being increasingly realized. In this perspective, understanding the nature of plant-endophyte association in hybrids and transmission/colonization of endophytes upon hybridization (i.e. from parents to progenies) is a pre-requisite for laying the foundation of plant holobiont breeding. This emerging discipline aims to integrate the best of both worlds (hybrid plant genome and microbiome) for realizing the untapped potential of the plant microbiota (and hence, the holobiont) to adverse environmental conditions. This review attempts to summarize our current understanding of the hybrid plant-associated microbiome with respect to its parental lines and wild progenitors. Further, the review highlights some research gaps in the field and beckons the attention of scientific community towards understanding and applying this knowledge for further boosting the crop productivity, the need of the hour.
25 citations
TL;DR: There was a significant difference among camelina lines in terms of seed yield and quality in response to drought, and it strongly suggested that PGPB application can be a positive strategy to mitigate drought stress and increase crop yield.
Abstract: The effects of drought on growth and seed quality of oilseed crops are of crucial importance in edible oil production due to its pivotal role in sustainable agriculture. Plant growth-promoting bacteria (PGPB) can improve crop yield by promoting plant growth under various environmental conditions. In the present study, the physiological responses, growth, and seed quality of three camelina doubled haploid lines (DH51, DH69, and DH104) were assessed upon their exposure to two irrigation regimes at the presence of Micrococcus yunnanensis during their reproductive phase. The results showed that the investigated parameters of camelina were affected by genotype, irrigation regimes, and PGPB. Drought decreased crop yield as measured by silique length, silique, and seed number and 1000-weight seed. PGPB significantly decreased the adverse effects of stress consistent by increasing the branches per plant and root length. Drought also caused a significant enhancement in the hydrogen peroxide and malondialdehyde contents, but the PGPB-inoculated plants showed lower contents of both compounds. Relative water content significantly reduced in plant grown under stress but inoculation enhanced the potential of water retaining in plants under stress and non-stress conditions. Drought stress and PGPB elevated proline and total soluble carbohydrate content in genotypes. Drought stress had no significant effect on photosynthetic pigments content of genotypes while inoculation apparently moderated negative impact of drought with enhancement of pigments content. The obtained results were responsible for metabolic changes occurring in response to stress. PGPB improved the plant drought-tolerance by enhancing its physiological traits. The fatty acid profile showed some variations among camelina genotypes under drought stress and PGPB inoculation. Upon symbiosis association, an increase was observed in major constituents of polyunsaturated acids, linoleic and linolenic acids, and a significant increase in oleic acid as a main monounsaturated acid. They also altered another major constituent, gadeolic acid, under water deficit stress and/ or with PGPB. Both drought stress and PGPB decreased the poly unsaturated fatty acids/mono unsaturated fatty acids ratio. In general, there was a significant difference among camelina lines in terms of seed yield and quality in response to drought. Also, it strongly suggested that PGPB application can be a positive strategy to mitigate drought stress and increase crop yield.
25 citations
TL;DR: In this article, the authors analyzed fitness-related traits in isofemale lines from the unique natural population from Uman (Central Ukraine), in which they observed preservation of the rare wMelCS genotype despite the fluctuations of infection rates between years.
Abstract: Wolbachia is an intracellular symbiont that infects a large number of arthropod species, ensuring its success in populations by influencing host reproduction. The wMel strain in Drosophila melanogaster does not cause any strong modifications of sexual reproduction. Consequently, it is not clear how the high infection rates of the bacterium in populations of this species are maintained. The wMel strain is classified into two groups of genotypes - wMel and wMelCS. The wMel genotype is ubiquitous in populations, while wMelCS is rare. In this study, we analyzed fitness-related traits in isofemale lines from the unique natural population from Uman (Central Ukraine), in which we observed preservation of the rare wMelCS genotype despite the fluctuations of infection rates between years. We analyzed these effects of Wolbachia genotype and host genetic background on important fitness parameters such as sensitivity to cold and oxidative stress, female fecundity and lifespan. We found that, in the studied population, Wolbachia had an impact on fitness traits only in certain Drosophila genotypes. Positive effects were manifested in the alterations of fecundity, but at the cost of reduced lifespan and resistance to stress. Based on these findings, we conclude that the effect of bacteria on fitness and stress related traits is context-dependent and is modified by the host genotype, at least in the lines established from the Uman population.
TL;DR: The current review briefly summarized different species of wetland plants forming AM structures, the population of AM fungi inhabiting the rhizosphere of dryland plant, AM fungi-colonization of wetlands plants, and the effect ofAM fungi on physiological functions of wet land plants to neutralize the negative impact of waterlogging in addition to outlook of researchable issues.
Abstract: Presence and functional roles of arbuscular mycorrhizal (AM) fungi in wetland environment have gained a global importance in recent past. Wetlands build a low-oxygen atmosphere, forming a completely different ecological environment for AM fungi, known more to occur in terrestrial environment. Nevertheless, as many 101 of AM fungi species, belonging to 19 genera and 9 families have been observed in the rhizosphere of wetland plants. In order to obtain oxygen, AM fungi expand the aeration system of wetland plants, store oxygen through their own vesicles, or change the structure of AM to survive. Human activities negatively affect the wetland environment, thus, reducing the population of AM fungi, while certain AM fungi species still improved the survival and development of wetland plants. AM fungi regulate different physiological activities of wetland plants in response to waterlogging stress, including an enhancement of antioxidant defense system, increased proline accumulation, improved plant growth and root morphology, responses of nutrients and aquaporins, and suppression in ethanol accumulation. The current review briefly summarized different species of wetland plants forming AM structures, the population of AM fungi inhabiting the rhizosphere of wetland plant, AM fungi-colonization of wetland plants, and the effect of AM fungi on physiological functions of wetland plants to neutralize the negative impact of waterlogging in addition to outlook of researchable issues. This review also highlighted human impacts on AM fungi of wetland plants and the impact of AM fungi on wetland environments and wetland plants.
TL;DR: This work focuses on the functions of signaling molecules and secreted proteins released from mycorrhizal fungi at the early stage ofMycorrhiza formation, which helps host plants acquire more nutrients and water, thereby improving host plant resistance to abiotic and biotic stresses.
Abstract: Mycorrhizal symbiosis has been evolved to be ubiquitous in natural and agricultural ecosystems. Mycorrhiza formation helps host plants acquire more nutrients and water, thereby improving host plant resistance to abiotic and biotic stresses. Molecular crosstalk begins between symbiotic partners before the establishment of mycorrhizal symbiosis. Signaling molecules and small secreted proteins are then released from the two symbionts. Signaling molecules released from the fungi include Myc factors, indole 3-acetic acid, and hypaphorine, etc. Meanwhile, they secrete some carbohydrate active enzymes (e.g., proteases and lipases), and proteins with conserved LysM and CFEM motifs. These secreted signaling molecules and proteins function outside the host cell wall and improve the establishment efficiency of mycorrhizal symbiosis. Here we focus on the functions of these signaling molecules and secreted proteins released from mycorrhizal fungi at the early stage of mycorrhiza formation. Since global advances are much slower than those involved in pathogenic fungi, we hope the research in this field promotes deservedly.
TL;DR: The results suggest that the association with multiple fungal species with various carbon assimilation abilities may help the larvae of E. flabellicornis to achieve efficient nutrient intake in space-limited tunnels within nutrient-poor wood.
Abstract: Ship timber beetles (Coleoptera: Lymexylidae) grow symbiotic fungi of the genus Alloascoidea in wood. The female adults possess fungus-carrying organs (mycetangia) and deposit the symbiont onto wood during oviposition. The larvae acquire the symbiont, excavate a tunnel into wood, and feed on the symbiont growing on the tunnel walls. As lymexylids use wood as a larval habitat, it is possible that the fungal symbionts can utilize indigestible wood-associated sugars. However, their abilities to assimilate wood-associated carbon sources remain unknown. In addition, no lymexylid-associated fungal communities have been reported except for Elateroides dermestoides. Here, I report that the ship timber beetle E. flabellicornis originating from Japan harbored five fungal species. When microbial isolation was conducted from mycetangia of a female adult of E. flabellicornis, colonies of filamentous fungi and yeasts were recovered. DNA analyses revealed that they were Alloascoidea sp., Ambrosiozyma llanquihuensis, Ambrosiozyma sp., Cyberlindnera sp., and Saccharomycopsis sp. When wood-associated carbon assimilation abilities of four of the five fungal species: Alloascoidea sp., Am. llanquihuensis, Cyberlindnera sp., and Saccharomycopsis sp., were tested, the abilities were variable among them. Only Saccharomycopsis sp. assimilated galactose and galacturonic acid. Alloascoidea sp. and Cyberlindnera sp. strongly assimilated xylan from corn. Saccharomycopsis sp. and Cyberlindnera sp. assimilated cellobiose. All of the fungi assimilated glucose, mannose, and xylose. These results suggest that the association with multiple fungal species with various carbon assimilation abilities may help the larvae of E. flabellicornis to achieve efficient nutrient intake in space-limited tunnels within nutrient-poor wood.
TL;DR: The phylogenetic relationships between the strains studied in the present work and previously published Wolbachia strains distributed globally among taxonomically unrelated insects corroborate the notion of bacterial horizontal transmission in insects, including A. bipunctata.
Abstract: Wolbachia is a maternally inherited bacterium that causes male-killing in the aphidophagous two-spot ladybird Adalia bipunctata. Limited data on the prevalence or diversity of Wolbachia in this species are available. Wolbachia in A. bipunctata in the Moscow collection was first discovered in 1997, and the purpose of this study was to confirm the stability of symbiosis in the same locality over time. Wolbachia multilocus sequence typing was performed by sequencing six bacterial genes to explore the diversity of the Wolbachia strains. Based on the sequence analyses, Wolbachia in A. bipunctata appears to belong to two supergroups, A and B, giving rise to three distinct evolutionary lineages, which we have designated as wAbi-1, wAbi-2, and wAbi-3. One Wolbachia strain, wAbi-1, has probably been in existence – and caused male-killing in A. bipunctata – for at least 23 years. For the first time, we found Wolbachia strain wAbi-2, which do not cause male-killing in A. bipunctata. No association was found between bacterial strains and host mitochondrial haplotypes. Moreover, the phylogenetic relationships between the strains studied in the present work and previously published Wolbachia strains distributed globally among taxonomically unrelated insects corroborate the notion of bacterial horizontal transmission in insects, including A. bipunctata.
TL;DR: In this paper, a typology of anthropogenic change (AC) and a conceptual framework for how AC might mechanistically impact symbioses with select case examples to highlight the perspective.
Abstract: Recent human activity has profoundly transformed Earth biomes on a scale and at rates that are unprecedented. Given the central role of symbioses in ecosystem processes, functions, and services throughout the Earth biosphere, the impacts of human-driven change on symbioses are critical to understand. Symbioses are not merely collections of organisms, but co-evolved partners that arise from the synergistic combination and action of different genetic programs. They function with varying degrees of permanence and selection as emergent units with substantial potential for combinatorial and evolutionary innovation in both structure and function. Following an articulation of operational definitions of symbiosis and related concepts and characteristics of the Anthropocene, we outline a basic typology of anthropogenic change (AC) and a conceptual framework for how AC might mechanistically impact symbioses with select case examples to highlight our perspective. We discuss surprising connections between symbiosis and the Anthropocene, suggesting ways in which new symbioses could arise due to AC, how symbioses could be agents of ecosystem change, and how symbioses, broadly defined, of humans and “farmed” organisms may have launched the Anthropocene. We conclude with reflections on the robustness of symbioses to AC and our perspective on the importance of symbioses as ecosystem keystones and the need to tackle anthropogenic challenges as wise and humble stewards embedded within the system.
TL;DR: There is a clear need for further integrative studies on this unusual group of symbiotic crustaceans found only on octocorals in the channels of mesoglea and gall-like proliferations of the host tissues.
Abstract: This paper reviews all currently known records of copepod crustaceans of the family Lamippidae (Cyclopoida). The lamippids are highly modified endosymbionts found only on octocorals in the channels of mesoglea and gall-like proliferations of the host tissues. 54 species and 11 genera of copepods have been reported associated with 42 species, 33 genera and 18 families of the octocoral orders Alcyonacea and Pennatulacea. The highest numbers of records of lamippids living on octocorals have been reported among the diverse and common octocoral families Alcyoniidae, Gorgoniidae, Nephtheidae, Pennatulidae, and Plexauridae. Lamippids are better studied on more common octocorals from shallow depths and still comparatively poorly studied on octocorals from bathyal and abyssal depths. Lamippids have been recorded from 62 sites in 12 realms of the World Ocean and are comparatively better studied in the Northern Atlantic, Central Indo-Pacific and Tropic Atlantic; no lamippids have been reported so far from the Tropical Eastern Pacific, Temperate South America, South Africa, or Australasia. The data show that only approximately 1% of potential octocoral hosts have been explored thus far, showing a clear need for further integrative studies on this unusual group of symbiotic crustaceans.
TL;DR: The results showed that the PCEA genotype produced a higher amount of biomass and total N than the PMN hybrid when inoculated with strain Sp245 on seeds and strain LP343 sprayed on leaves, and may be responsible for the higher increase in the total N accumulated in the plant superior to N fertilization.
Abstract: Elephant grass (Pennisetum purpureum) is a perennial C4-plant with outstanding sustainable potential for bioenergy, grazing and silage, It is able to fix nitrogen in association with diazotrophic bacteria and is a high biomass producer, even in low fertility soils. This study aimed to investigate the response of two elephant grass genotypes (PCEA and PMN hybrid) to inoculation, via seed coat and leaf spray, with Azospirillum baldaniorum (Sp245) and Gluconacetobacter diazotrophicus (LP343), grown in the field. In addition, in situ colonization of field PCEA minisets with labeled mCherry strain LP343 and gfp strain Sp245 was analyzed. The results showed that the PCEA genotype produced a higher amount of biomass and total N than the PMN hybrid when inoculated with strain Sp245 on seeds and strain LP343 sprayed on leaves. The quantification of the 15N abundance (δ15N) showed no biological nitrogen fixation (BNF) contribution by either of the inoculated strains and mode of application in leaves of PCEA genotype. The microscopy confocal analysis showed internal tissue colonization of sprouted PCEA minisets by strain LP343 while detection of Sp245 was reduced during the assays. In contrast, leaf surface spot inoculation showed no internal tissue colonization by either strain although the LP343 strain remained longer on the leaf surface. The heavy miniset plant tissue colonization by LP343 (roots and leaves) could be related to its host specificity as compared to Sp245 and may therefore be responsible for the higher increase in the total N accumulated in the plant superior to N fertilization. This effect could, however, involve mechanisms other than the BNF process.
TL;DR: Overall, climate change is expected to affect ECM fungi through an alteration of plant metabolism and spatial distribution of trees, although industrial pollutants and pesticides effects remains less clear at large scale, N-deposition and/or fertilization could induce ECM shifts and alter nutrient cycling.
Abstract: The association between ectomycorrhizal (ECM) fungi and trees is at the heart of forest ecosystems. Nowadays, this association is increasingly facing pressures resulting from anthropogenic activities, impacting the structure, biodiversity and functions of ECM fungal communities and their hosts. Here, we review some of the most common anthropogenic activities (i.e. enrichment of atmospheric carbon dioxide, increase of global temperature, atmospheric pollution, nitrogen deposition, use of pesticides, land use management, introduction of invasive species and biodiversity loss) affecting ECM fungi (i.e. species richness, abundance, taxonomy, production of spores and carpophores, and enzymatic activities) and their tree hosts. The review was conducted at different scales, from species to populations and ecosystems and whenever possible, example including boreal, temperate and tropical forests were reported. To conclude, we discussed about the present challenges hindering a better holistic understanding of our future forest ecosystems hosting ECM fungi. Overall, climate change is expected to affect ECM fungi through an alteration of plant metabolism and spatial distribution of trees. Although industrial pollutants and pesticides effects remains less clear at large scale, N-deposition and/or fertilization could induce ECM shifts and alter nutrient cycling. Regarding other anthropogenic parameters (e.g. land use, invasive species), they may affect ECM fungal communities by impacting their diversity, abundance and richness.
TL;DR: This investigation is the first evidence of endophytic Rhizobia able to promote the rice growth of a Cuban cultivar subjected to intensive monoculture, without rotation with legume plants and without a previous history of rhizobia inoculation.
Abstract: Bacteria from the rhizobia group have been previously identified as grass-endophytes in grassland with cropping history of legumes. In this paper we aimed to demonstrate that strains of the Rhizobium genus, isolated from the rhizosphere of a rice Cuban cultivar subjected to intensive monoculture management, behave as endophytes and promote its growth. Eleven bacteria previously isolated from the rhizosphere of rice plants, were screened for their plant growth promoting traits. We found that some of them were able to solubilize inorganic phosphate compounds, produce siderophores and biofilm, have exocellulase and protease activity and were able to inhibit the phytopathogen Pyricularia oryzae growth. The phylogenetic analysis using partial sequences of 16S rRNA gene showed that bacteria isolated from rice plant of cultivar INCA LP-5 belonged to Rhizobium, Agrobacterium and Pseudomonas genera. Two strains analyzed, Rhizobium sp. Rpr2 and Rdp16, increased the height and biomass of rice plants, 70 days post-inoculation in greenhouse conditions. According to the quantification of Rhizobium sp. strain Rpd16 in surface-disinfected tissues of root and sheath, together with the analysis of confocal microscopy images, we can conclude that the Rdp16 strain is a rice endophyte of the cultivar INCA LP-5. This investigation is the first evidence of endophytic rhizobia able to promote the rice growth of a Cuban cultivar subjected to intensive monoculture, without rotation with legume plants and without a previous history of rhizobia inoculation.
TL;DR: In this paper, the authors review the process of endosymbiosis, its levels, requirements and mechanisms, and assess the potential barriers to the possibility of human-to-human hybridization.
Abstract: Endosymbiosis or symbiogenesis is a process where a cell hosts another cell that is acquired through phagocytosis or natural entry of the cell within its cytoplasm. Endosymbiosis has a profound effect on the survival of the host cell by conferring nutritional and/or biosynthetic advantage. Therefore, attempts of artificial endosymbiosis have become one of the most challenging projects in synthetic biology. In this paper, we review the process of endosymbiosis, its levels, requirements and mechanisms. We then review the unique cases of ‘natural endosymbiosis’. Furthermore, we describe and evaluate the recent cases of attempted artificial endosymbiosis. Subsequently, we assess the potential barriers to the possibility of endosymbiosis of highly evolved cell types such as mammalian cells that are known for their high inflexibility towards hosting potentially even the most ‘benign endosymbionts’. The paper concludes with possibilities and methodologies that may have not been evaluated or tried in the past, but may be used to increase the chance of artificial endosymbiosis of host cells such as those from mammalian origin that are not permissive to even benign endosymbionts. Artificial endosymbiosis is worth revisiting in this post-genomic, synthetic biology era because the tools and techniques currently available at our disposal have significantly advanced to make this grand challenge a possibility.
TL;DR: The distribution and diversity of the ectomycorrhizospheric yeast species suggest a different community to that of the bulk-soil and rhizosphere of previously reported Nothofagus native forests, which could be related to exudation and nutrient availability, as well as environmental features.
Abstract: Many surveys have studied soil yeasts and ectomycorrhizal fungi independently and reported their association with water availability and soil nutrients. Nevertheless, the importance of yeasts associated with ectomycorrhizal fungi and different exploration types is little understood. The aim of the present study is to describe the diversity of yeasts inhabiting the ectomycorrhizosphere, and their association with the ectomycorrhizal fungal community, in four Nothofagus forests in northwestern Patagonia. Most ectomycorrhizal fungi sequences were assigned to eight ectomycorrhizal lineages, a high percentage of which were related to /cortinarius lineage. Less than 25% of these sequences were associated with /non-ectomycorrhizal lineages reported as endophytic fungi. A large proportion of the sequences (81%) corresponded to the phylum Basidiomycota, and included the cosmopolitan genera Cortinarius, Inocybe and Tomentella. Three exploratory types were present in all forest sites, but with different distributions. The results showed that the ectomycorrhizal yeast communities were very diverse in the four forest sites studied. Ectomycorrhizospheric yeasts were also dominated by the phylum Basidiomycota, including the genera Naganishia, Solicoccozyma, Saitozyma and Piskurozyma. The species Apiotrichum porossum, Solicoccozyma podzolica, Solicoccozyma terricola, Solicoccozyma sp. and Humicolopsis cephalosporioides were frequently associated with EcM fungal species. The distribution and diversity of the ectomycorrhizospheric yeast species suggest a different community to that of the bulk-soil and rhizosphere of previously reported Nothofagus native forests, which could be related to exudation and nutrient availability, as well as environmental features. The data reported here are relevant for disturbance (natural and human-related) and management studies on Nothofagus forests.
TL;DR: The present review discusses on the effect of salinity on Azolla and its cyanobiont with an emphasis on the physiological, biochemical and molecular mechanisms ofSalinity tolerance.
Abstract: Salinity is one of the major constraints for agricultural productivity and the problem of salinity is likely to increase further. The aquatic fern Azolla is employed as an important bio-inoculant for the cultivation of rice paddy. In addition to this it is also used as feed supplement for cattle and poultry. However, increasing soil salinity is a serious threat for its wider exploitation. Stressors such as salinity leads to drastic changes in the metabolic activities especially the photosynthesis and nitrogen fixation. The potential of plants to tolerate salinity is determined by efficient mechanisms operating at cellular and sub-cellular levels. Several adaptation strategies are required to cope with salinity stress. Complicated interactions between the host plant Azolla and its symbiont should be considered if this organism is employed as bio-inoculant. Therefore, in the present review we discuss on the effect of salinity on Azolla and its cyanobiont with an emphasis on the physiological, biochemical and molecular mechanisms of salinity tolerance.
TL;DR: The potential of D. pallida to shift the prevalence of its symbiont communities within a population in response to bleaching is conveyed, which may reflect symbionT shuffling and/or differential mortality and partly explain the predominance of Dipsastraea corals in the Persian Gulf and Gulf of Oman.
Abstract: Reef-building corals are in obligate symbiosis with dinoflagellates of the family Symbiodiniaceae. The partnership, however, is prone to breakdown as a result of thermal stress, which leads to coral bleaching. According to the Adaptive Bleaching Hypothesis, corals’ recovery from bleaching is profoundly influenced by forming stable associations with thermotolerant algal strains during bleaching. Consequently, the knowledge of the diversity of host-symbiont associations during this period is substantial. Since the extent of symbiont shuffling varies among different host taxa, we investigated the diversity of dominant Symbiodiniaceae in association with the scleractinian coral Dipsastraea pallida before and after massive bleaching events of 2017 in the Persian Gulf and 2018 in the Gulf of Oman. We observed a flexible association between D. pallida and five lineages of Symbiodiniaceae (i.e., ITS2-types A1.4, C3, C39, D1a, D5) with a clear regional pattern. However, the pattern of these associations was changed following bleaching events, with the complete replacement of Cladocopium-C39 by Durusdinium-D1a in the Gulf of Oman, and increased proportion of Durusdinium-D1a and disappearance of Symbiodinium-A1.4 in the northeastern Persian Gulf. In the westernmost Persian Gulf, on the other hand, a stable D. pallida-Cladocopium-C3 partnership was observed. These findings convey the potential of D. pallida to shift the prevalence of its symbiont communities within a population in response to bleaching, which may reflect symbiont shuffling and/or differential mortality and partly explain the predominance of Dipsastraea corals in the Persian Gulf and Gulf of Oman.
TL;DR: The results concur that the positive interaction of non-rhizobial endophytic yeast with rhizobIAL strain may emerge as a novel bio-inoculant for sustainable pulse productivity.
Abstract: Non-rhizobial endophytes (NRE) from root nodule niche are well known for their plant growth-promoting (PGP) traits, unique metabolites, and assisting rhizobial nodulation. A co- inoculant developed with NRE yeast strain Candida tropicalis VYW1 and Rhizobium sp. VRE1 obtained from mungbean nodules significantly influenced nodulation behavior, plant growth, and soil health by exhibiting increased nodules plant−1, nodule biomass (141.71 mg), and N uptake (1.13 kg ha−1). Besides, root and shoot length, total biomass also increased significantly in co-inoculated plants registering 23.9 cm, 22.5 cm, and 0.51 g, respectively. Similarly, soil nutrient status, including soil pH, EC, organic carbon, available N, P, K, and Zn, also enhanced due to co-inoculation. The stimulatory effects by co-inoculation are presumably affirmed due to unique metabolites such as indole, tryptophan, leucine, benzaldehyde, octadecanoic acid, α-D-galactopyranoside, and L- Proline as evidenced through metabolite profiling using GC-MS. Our results concur that the positive interaction of non-rhizobial endophytic yeast with rhizobial strain may emerge as a novel bio-inoculant for sustainable pulse productivity.
TL;DR: In the ostracod microbiome, a significant proportion of all reads belonged to the sequences of the genus Rickettsia related to intracellular parasites, which are likely facultative and consumed by ostracods together with detritus.
Abstract: We studied the microbial communities associated with the Baikal ostracods, Candona sp. (Candonidae). Bacterial biofilms were identified on the shell valves of the ostracods localized near epibiotic ciliates of the genus Lagenophrys (Ciliophora: Lagenoprydae). In situ hybridization confirmed the presence of eubacterial cells in different parts of the ostracod’s body. Bacteria of two morphotypes were detected in bacterial biofilms, including filamentous bacteria. Next-generation sequencing of 16S rRNA bacterial gene fragment allowed us to identify representatives of five bacterial phyla. Members of the phyla Proteobacteria and Bacteroidetes typical of non-marine epibiotic associations of ostracods were dominant taxa in the ostracod microbiomes. Members of other taxa (Actinobacteria, Gracilibacteria and Cyanobacteria) are likely facultative and consumed by ostracods together with detritus. In the ostracod microbiome, a significant proportion (20% of all reads) belonged to the sequences of the genus Rickettsia related to intracellular parasites.
TL;DR: Evaluating the effect of the deterioration of the reef on the cryptofauna in Culebra Bay, Costa Rica, finds changes in live coral cover favored an increase in the diversity of organisms, but this enhanced diversity may be temporary as bioerosion reduces dead colonies to skeleton rubble.
Abstract: The cryptofauna are the small cryptic organisms that inhabit the interstices of coral colonies and have a great contribution to the biodiversity of the reef. Some of these species are vulnerable to environmental deterioration due to their dependency on living coral. In the 1990s, Culebra Bay, located in the North Pacific of Costa Rica, was considered one of the most important reef areas in the country, with a mean live coral cover over 40%. However, in the last two decades there was a drastic decrease in live coral cover to 5%, due to El Nino events and recurrent harmful phytoplankton blooms. To evaluate the effect of the deterioration of the reef on the cryptofauna, we compare two time periods: before (2003–2004) and after (2013–2014) coral decline. Pocillopora spp. colonies (~20 cm high by ~20 cm wide) were collected and all associated invertebrates removed. Twenty colonies were sampled each period. During the first period, sampled colonies were alive and healthy, whereas a decade later, exposed skeletons of dead colonies were sampled. A total of 3482 invertebrate individuals were found, belonging to 133 species, 72 families, and nine classes. While abundance and diversity were greater during the 2013–2014 period, we hypothesize that this is due to disturbance intensity being intermediate to high. If these conditions are persistent or intensify over time, however, we expect that once all substrate and reef structure is lost, an abrupt decline in cryptofauna abundance and diversity will take place. Reefs with dead corals therefore have a remarkably different composition of the cryptofauna. Obligate commensal fauna were replaced by boring, opportunistic, and facultative species in these habitats. These changes in live coral cover favored an increase in the diversity of organisms, but this enhanced diversity may be temporary as bioerosion reduces dead colonies to skeleton rubble. This change in the cryptofauna community can affect the recovery and sustainability of the reef ecosystem over time.
TL;DR: The plant-secreted genistein functions as a chemical signal in the communications between soybean plants and Delftia sp.
Abstract: The effect of plant-produced flavonoids in rhizobial cells is well-known, and flavonoids are considered the first signals in the rhizobia-plant communication. We previously reported that Delftia strains increase the performance (nodulation and nitrogen fixation) of leguminous plants in co-inoculation experiments, as compared with the single rhizobial inoculation. By using an approach based on quantitative shotgun proteomics, we explored the response of Delftia sp. JD2 cells to the presence of the flavonoid genistein (nod gene-inducer of Bradyrhizobium cells). We found that genistein up-regulates the production of regulatory proteins associated with the epiphytic habit (TetR and diguanylate cyclase), proteins involved in the formation of flagella, iron acquisition, resistance to several drugs, the rhizoplane colonization (biofilm establishment), and the rearrangement of the peptidoglycan structure and membrane proteins. These results indicate that genistein induces chemotaxis, mobility and prepares JD2 strain for an epiphytic lifestyle. We also analyzed the effect of the co-inoculation on the proteome of symbiosome-enriched fractions from soybean nodules. The fractions from co-inoculated plants showed an up-regulation of proteins involved in stress endurance (“stem 31 kDa glycoprotein”, “Kunitz trypsin protease inhibitor”, proteasome subunits) and ferritin (involved in iron storage and homeostasis), suggesting that co-inoculation with JD2 prepares the soybean plants to deal with unfriendly environmental conditions. In summary, the plant-secreted genistein functions as a chemical signal in the communications between soybean plants and Delftia sp. JD2, while the presence of JD2 would prepare the plant to cope with abiotic stresses in co-inoculation experiments.