Displaying publications 1 - 20 of 55 in total

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  1. Alhusayni S, Roswanjaya YP, Rutten L, Huisman R, Bertram S, Sharma T, et al.
    BMC Plant Biol, 2023 Nov 24;23(1):587.
    PMID: 37996841 DOI: 10.1186/s12870-023-04594-0
    BACKGROUND: Nitrogen-fixing nodules occur in ten related taxonomic lineages interspersed with lineages of non-nodulating plant species. Nodules result from an endosymbiosis between plants and diazotrophic bacteria; rhizobia in the case of legumes and Parasponia and Frankia in the case of actinorhizal species. Nodulating plants share a conserved set of symbiosis genes, whereas related non-nodulating sister species show pseudogenization of several key nodulation-specific genes. Signalling and cellular mechanisms critical for nodulation have been co-opted from the more ancient plant-fungal arbuscular endomycorrhizal symbiosis. Studies in legumes and actinorhizal plants uncovered a key component in symbiotic signalling, the LRR-type SYMBIOSIS RECEPTOR KINASE (SYMRK). SYMRK is essential for nodulation and arbuscular endomycorrhizal symbiosis. To our surprise, however, despite its arbuscular endomycorrhizal symbiosis capacities, we observed a seemingly critical mutation in a donor splice site in the SYMRK gene of Trema orientalis, the non-nodulating sister species of Parasponia. This led us to investigate the symbiotic functioning of SYMRK in the Trema-Parasponia lineage and to address the question of to what extent a single nucleotide polymorphism in a donor splice site affects the symbiotic functioning of SYMRK.

    RESULTS: We show that SYMRK is essential for nodulation and endomycorrhization in Parasponia andersonii. Subsequently, it is revealed that the 5'-intron donor splice site of SYMRK intron 12 is variable and, in most dicotyledon species, doesn't contain the canonical dinucleotide 'GT' signature but the much less common motif 'GC'. Strikingly, in T. orientalis, this motif is converted into a rare non-canonical 5'-intron donor splice site 'GA'. This SYMRK allele, however, is fully functional and spreads in the T. orientalis population of Malaysian Borneo. A further investigation into the occurrence of the non-canonical GA-AG splice sites confirmed that these are extremely rare.

    CONCLUSION: SYMRK functioning is highly conserved in legumes, actinorhizal plants, and Parasponia. The gene possesses a non-common 5'-intron GC donor splice site in intron 12, which is converted into a GA in T. orientalis accessions of Malaysian Borneo. The discovery of this functional GA-AG splice site in SYMRK highlights a gap in our understanding of splice donor sites.

    Matched MeSH terms: Symbiosis/genetics
  2. Delavaux CS, LaManna JA, Myers JA, Phillips RP, Aguilar S, Allen D, et al.
    Commun Biol, 2023 Oct 19;6(1):1066.
    PMID: 37857800 DOI: 10.1038/s42003-023-05410-z
    One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fungi, which may counteract these effects. Across 43 large-scale forest plots worldwide, we tested whether ectomycorrhizal tree species exhibit weaker negative CDD than arbuscular mycorrhizal tree species. We further tested for conmycorrhizal density dependence (CMDD) to test for benefit from shared mutualists. We found that the strength of CDD varies systematically with mycorrhizal type, with ectomycorrhizal tree species exhibiting higher sapling densities with increasing adult densities than arbuscular mycorrhizal tree species. Moreover, we found evidence of positive CMDD for tree species of both mycorrhizal types. Collectively, these findings indicate that mycorrhizal interactions likely play a foundational role in global forest diversity patterns and structure.
    Matched MeSH terms: Symbiosis
  3. Tong CY, Honda K, Derek CJC
    Environ Res, 2023 Jul 01;228:115872.
    PMID: 37054838 DOI: 10.1016/j.envres.2023.115872
    Mass microalgal-bacterial co-cultures have come to the fore of applied physiological research, in particularly for the optimization of high-value metabolite from microalgae. These co-cultures rely on the existence of a phycosphere which harbors unique cross-kingdom associations that are a prerequisite for the cooperative interactions. However, detailed mechanisms underpinning the beneficial bacterial effects onto microalgal growth and metabolic production are rather limited at the moment. Hence, the main purpose of this review is to shed light on how bacteria fuels microalgal metabolism or vice versa during mutualistic interactions, building upon the phycosphere which is a hotspot for chemical exchange. Nutrients exchange and signal transduction between two not only increase the algal productivity, but also facilitate in the degradation of bio-products and elevate the host defense ability. Main chemical mediators such as photosynthetic oxygen, N-acyl-homoserine lactone, siderophore and vitamin B12 were identified to elucidate beneficial cascading effects from the bacteria towards microalgal metabolites. In terms of applications, the enhancement of soluble microalgal metabolites is often associated with bacteria-mediated cell autolysis while bacterial bio-flocculants can aid in microalgal biomass harvesting. In addition, this review goes in depth into the discussion on enzyme-based communication via metabolic engineering such as gene modification, cellular metabolic pathway fine-tuning, over expression of target enzymes, and diversion of flux toward key metabolites. Furthermore, possible challenges and recommendations aimed at stimulating microalgal metabolite production are outlined. As more evidence emerges regarding the multifaceted role of beneficial bacteria, it will be crucial to incorporate these findings into the development of algal biotechnology.
    Matched MeSH terms: Symbiosis
  4. Doni F, Suhaimi NSM, Mispan MS, Fathurrahman F, Marzuki BM, Kusmoro J, et al.
    Int J Mol Sci, 2022 Jan 10;23(2).
    PMID: 35054923 DOI: 10.3390/ijms23020737
    Rice, the main staple food for about half of the world's population, has had the growth of its production stagnate in the last two decades. One of the ways to further improve rice production is to enhance the associations between rice plants and the microbiome that exists around, on, and inside the plant. This article reviews recent developments in understanding how microorganisms exert positive influences on plant growth, production, and health, focusing particularly on rice. A variety of microbial species and taxa reside in the rhizosphere and the phyllosphere of plants and also have multiple roles as symbiotic endophytes while living within plant tissues and even cells. They alter the morphology of host plants, enhance their growth, health, and yield, and reduce their vulnerability to biotic and abiotic stresses. The findings of both agronomic and molecular analysis show ways in which microorganisms regulate the growth, physiological traits, and molecular signaling within rice plants. However, many significant scientific questions remain to be resolved. Advancements in high-throughput multi-omics technologies can be used to elucidate mechanisms involved in microbial-rice plant associations. Prospectively, the use of microbial inoculants and associated approaches offers some new, cost-effective, and more eco-friendly practices for increasing rice production.
    Matched MeSH terms: Symbiosis*
  5. Rosland NA, Ikhsan N, Min CC, Yusoff FM, Karim M
    Curr Microbiol, 2021 Nov;78(11):3901-3912.
    PMID: 34522979 DOI: 10.1007/s00284-021-02642-2
    The emerging aquaculture industry is in need of non-antibiotic-based disease control approaches to minimize the risk of antibiotic-resistant bacteria. Bacterial infections mainly caused by Vibrio spp. have caused mass mortalities of fish especially during the larval stages. The objectives of this study were to verify the potential of symbiotic probiont strains, isolated from microalgae (Amphora, Chlorella, and Spirulina) for suppressing the growth of Vibrio spp. and at the same time ascertain their abilities to enhance microalgal biomass by mutualistic interactions through microalgae-bacteria symbiosis. In addition, in vivo studies on Artemia bioencapsulated with probiont strains (single strain and mix strains) and microalgae were evaluated. The selected potential probionts were identified as Lysinibacillus fusiformis strain A-1 (LFA-1), Bacillus sp. strain A-2 (BA-2), Lysinibacillus fusiformis strain Cl-3 (LFCl-3), and Bacillus pocheonensis strain S-2 (BPS-2) using 16s rRNA. The cell densities of Amphora culture supplemented with BA-2 and Chlorella culture supplemented with LFCl-3 were higher than those of the controls. Artemia bioencapsulated with mix strains (LFA-1 + BA-2 + LFCl-3 + BPS-2) and Amphora demonstrated the highest survival rate compared to the controls, after being challenged with V. harveyi (60 ± 4%) and V. parahaemolyticus (78 ± 2%). Our study postulated that BA-2 and LFCl-3 were found to be good promoting bacteria for microalgal growth and microalgae serve as a vector to transport probiotic into Artemia. Moreover, mixture of potential probionts is beneficial for Artemia supplementation in conferring protection to Artemia nauplii against pathogenic Vibrios.
    Matched MeSH terms: Symbiosis
  6. Teoh MC, Furusawa G, Veera Singham G
    Arch Microbiol, 2021 Jul;203(5):1891-1915.
    PMID: 33634321 DOI: 10.1007/s00203-021-02230-9
    Insects and bacteria are the most widespread groups of organisms found in nearly all habitats on earth, establishing diverse interactions that encompass the entire range of possible symbiotic associations from strict parasitism to obligate mutualism. The complexity of their interactions is instrumental in shaping the roles of insects in the environment, meanwhile ensuring the survival and persistence of the associated bacteria. This review aims to provide detailed insight on the multifaceted symbiosis between one of the most versatile bacterial genera, Pseudomonas (Gammaproteobacteria: Pseudomonadaceae) and a diverse group of insect species. The Pseudomonas engages with varied interactions with insects, being either a pathogen or beneficial endosymbiont, as well as using insects as vectors. In addition, this review also provides updates on existing and potential applications of Pseudomonas and their numerous insecticidal metabolites as biocontrol agents against pest insects for the improvement of integrated pest management strategies. Here, we have summarized several known modes of action and the virulence factors of entomopathogenic Pseudomonas strains essential for their pathogenicity against insects. Meanwhile, the beneficial interactions between pseudomonads and insects are currently limited to a few known insect taxa, despite numerous studies reporting identification of pseudomonads in the guts and haemocoel of various insect species. The vector-symbiont association between pseudomonads and insects can be diverse from strict phoresy to a role switch from commensalism to parasitism following a dose-dependent response. Overall, the pseudomonads appeared to have evolved independently to be either exclusively pathogenic or beneficial towards insects.
    Matched MeSH terms: Symbiosis
  7. Akhtar N, Ilyas N, Yasmin H, Sayyed RZ, Hasnain Z, A Elsayed E, et al.
    Molecules, 2021 Mar 12;26(6).
    PMID: 33809305 DOI: 10.3390/molecules26061569
    Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr+3) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr+3) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.
    Matched MeSH terms: Symbiosis
  8. Cai L, Arnold BJ, Xi Z, Khost DE, Patel N, Hartmann CB, et al.
    Curr Biol, 2021 03 08;31(5):1002-1011.e9.
    PMID: 33485466 DOI: 10.1016/j.cub.2020.12.045
    Despite more than 2,000-fold variation in genome size, key features of genome architecture are largely conserved across angiosperms. Parasitic plants have elucidated the many ways in which genomes can be modified, yet we still lack comprehensive genome data for species that represent the most extreme form of parasitism. Here, we present the highly modified genome of the iconic endophytic parasite Sapria himalayana Griff. (Rafflesiaceae), which lacks a typical plant body. First, 44% of the genes conserved in eurosids are lost in Sapria, dwarfing previously reported levels of gene loss in vascular plants. These losses demonstrate remarkable functional convergence with other parasitic plants, suggesting a common genetic roadmap underlying the evolution of plant parasitism. Second, we identified extreme disparity in intron size among retained genes. This includes a category of genes with introns longer than any so far observed in angiosperms, nearing 100 kb in some cases, and a second category of genes with exceptionally short or absent introns. Finally, at least 1.2% of the Sapria genome, including both genic and intergenic content, is inferred to be derived from host-to-parasite horizontal gene transfers (HGTs) and includes genes potentially adaptive for parasitism. Focused phylogenomic reconstruction of HGTs reveals a hidden history of former host-parasite associations involving close relatives of Sapria's modern hosts in the grapevine family. Our findings offer a unique perspective into how deeply angiosperm genomes can be altered to fit an extreme form of plant parasitism and demonstrate the value of HGTs as DNA fossils to investigate extinct symbioses.
    Matched MeSH terms: Symbiosis/genetics*
  9. Herrera M, Klein SG, Campana S, Chen JE, Prasanna A, Duarte CM, et al.
    ISME J, 2021 01;15(1):141-153.
    PMID: 32934356 DOI: 10.1038/s41396-020-00768-y
    Coral reef research has predominantly focused on the effect of temperature on the breakdown of coral-dinoflagellate symbioses. However, less is known about how increasing temperature affects the establishment of new coral-dinoflagellate associations. Inter-partner specificity and environment-dependent colonization are two constraints proposed to limit the acquisition of more heat tolerant symbionts. Here, we investigated the symbiotic dynamics of various photosymbionts in different host genotypes under "optimal" and elevated temperature conditions. To do this, we inoculated symbiont-free polyps of the sea anemone Exaiptasia pallida originating from Hawaii (H2), North Carolina (CC7), and the Red Sea (RS) with the same mixture of native symbiont strains (Breviolum minutum, Symbiodinium linucheae, S. microadriaticum, and a Breviolum type from the Red Sea) at 25 and 32 °C, and assessed their ITS2 composition, colonization rates, and PSII photochemical efficiency (Fv/Fm). Symbiont communities across thermal conditions differed significantly for all hosts, suggesting that temperature rather than partner specificity had a stronger effect on symbiosis establishment. Overall, we detected higher abundances of more heat resistant Symbiodiniaceae types in the 32 °C treatments. Our data further showed that PSII photophysiology under elevated temperature improved with thermal pre-exposure (i.e., higher Fv/Fm), yet, this effect depended on host genotype and was influenced by active feeding as photochemical efficiency dropped in response to food deprivation. These findings highlight the role of temperature and partner fidelity in the establishment and performance of symbiosis and demonstrate the importance of heterotrophy for symbiotic cnidarians to endure and recover from stress.
    Matched MeSH terms: Symbiosis
  10. Chua KO, See-Too WS, Tan JY, Song SL, Yong HS, Yin WF, et al.
    J Microbiol, 2020 Dec;58(12):988-997.
    PMID: 33095388 DOI: 10.1007/s12275-020-0325-8
    In this study, bacterial strains Ha5T, Ta1, and Jb2 were isolated from different colonies of weaver ant Oecophylla smaragdina. They were identified as bacterial symbionts of the ant belonging to family Acetobacteraceae and were distinguished as different strains based on distinctive random-amplified polymorphic DNA (RAPD) fingerprints. Cells of these bacterial strains were Gram-negative, rod-shaped, aerobic, non-motile, catalase-positive and oxidase-negative. They were able to grow at 15-37°C (optimum, 28-30°C) and in the presence of 0-1.5% (w/v) NaCl (optimum 0%). Their predominant cellular fatty acids were C18:1ω7c, C16:0, C19:0ω8c cyclo, C14:0, and C16:0 2-OH. Strains Ha5T, Ta1, and Jb2 shared highest 16S rRNA gene sequence similarity (94.56-94.63%) with Neokomagataea tanensis NBRC106556T of family Acetobacteraceae. Both 16S rRNA gene sequence-based phylogenetic analysis and core gene-based phylogenomic analysis placed them in a distinct lineage in family Acetobacteraceae. These bacterial strains shared higher than species level thresholds in multiple overall genome-relatedness indices which indicated that they belonged to the same species. In addition, they did not belong to any of the current taxa of Acetobacteraceae as they had low pairwise average nucleotide identity (< 71%), in silico DNA-DNA hybridization (< 38%) and average amino acid identity (< 67%) values with all the type members of the family. Based on these results, bacterial strains Ha5T, Ta1, and Jb2 represent a novel species of a novel genus in family Acetobacteaceae, for which we propose the name Oecophyllibacter saccharovorans gen. nov. sp. nov., and strain Ha5T as the type strain.
    Matched MeSH terms: Symbiosis/physiology*
  11. Louis YD, Bhagooli R, Seveso D, Maggioni D, Galli P, Vai M, et al.
    Mol Ecol, 2020 11;29(22):4382-4394.
    PMID: 32967057 DOI: 10.1111/mec.15642
    Corals show spatial acclimatisation to local environment conditions. However, the various cellular mechanisms involved in local acclimatisation and variable bleaching patterns in corals remain to be thoroughly understood. In this study, the modulation of a protein implicated in cellular heat stress tolerance, the heat shock protein 70, was compared at both gene (hsp70) and protein (Hsp70) expression level in bleaching tolerant near-coast Acropora muricata colonies and bleaching susceptible reef colonies, in the lagoon of Belle Mare (Mauritius). The relative Hsp70 levels varied significantly between colonies from the two different locations, colonies having different health conditions and the year of collection. Before the bleaching event of 2016, near-coast colonies had higher basal levels of both Hsp70 gene and protein compared to reef colonies. During the bleaching event, the near-coast colonies did not bleach and had significantly higher relative levels of both Hsp70 gene and protein compared to bleached reef colonies. No significant genetic differentiation between the two studied coral populations was observed and all the colonies analysed were associated with Symbiodiniaceae of the genus Symbiodinium (Clade A) irrespective of location and sampling period. These findings provide further evidence of the involvement of Hsp70 in conferring bleaching tolerance to corals. Moreover, the consistent expression differences of Hsp70 gene and protein between the near-coast and reef coral populations in a natural setting indicate that the modulation of this Hsp is involved in local acclimatisation of corals to their environments.
    Matched MeSH terms: Symbiosis
  12. Allman MJ, Fraser JE, Ritchie SA, Joubert DA, Simmons CP, Flores HA
    Insects, 2020 Oct 27;11(11).
    PMID: 33120915 DOI: 10.3390/insects11110735
    The artificial introduction of the endosymbiotic bacterium, Wolbachia pipientis, into Aedes (Ae.) aegypti mosquitoes reduces the ability of mosquitoes to transmit human pathogenic viruses and is now being developed as a biocontrol tool. Successful introgression of Wolbachia-carrying Ae. aegypti into native mosquito populations at field sites in Australia, Indonesia and Malaysia has been associated with reduced disease prevalence in the treated community. In separate field programs, Wolbachia is also being used as a mosquito population suppression tool, where the release of male only Wolbachia-infected Ae. aegypti prevents the native mosquito population from producing viable eggs, subsequently suppressing the wild population. While these technologies show great promise, they require mass rearing of mosquitoes for implementation on a scale that has not previously been done. In addition, Wolbachia induces some negative fitness effects on Ae. aegypti. While these fitness effects differ depending on the Wolbachia strain present, one of the most consistent and significant impacts is the shortened longevity and viability of eggs. This review examines the body of evidence behind Wolbachia's negative effect on eggs, assesses nutritional parasitism as a key cause and considers how these impacts could be overcome to achieve efficient large-scale rearing of these mosquitoes.
    Matched MeSH terms: Symbiosis
  13. El-Sadawy HA, Ramadan MY, Abdel Megeed KN, Ali HH, El Sattar SA, Elakabawy LM
    Trop Biomed, 2020 Jun 01;37(2):288-302.
    PMID: 33612799
    The sand fly Phlebotomus papatasi is an important disease-bearing vector. Five entomopathogenic nematodes (EPNs) - Steinernema carpocapsae DD136, Steinernema sp. (SII), S. carpocapsae all, S. abbasi, and Heterorhabditis bacteriophora HP88 - were applied as biocontrol agents against the late third instar larvae of P. papatasi. In addition, the effect of toxin complexes (TCs) of Xenorhabdus nematophila and Photorhabdus luminescens laumondii bacteria was evaluated. Results revealed that S. carpocapsae DD136 was the most virulent species followed by Steinernema sp. (SII) and S. carpocapsae all where LC50 were 472, 565, 962 IJs/ml, respectively. Also, the crude TCs were slightly more active and toxic than their fractionated protein. Histopathological examination of infected larvae with H. bacteriophora HP88 showed negative effect on their midgut cells. In conclusion, EPNs with their symbiotic bacteria are more effective as biocontrol agents than the crude or fractionated TCs against sand fly larvae.
    Matched MeSH terms: Symbiosis
  14. Uni S, Mat Udin AS, Agatsuma T, Junker K, Saijuntha W, Bunchom N, et al.
    Parasit Vectors, 2020 Feb 06;13(1):50.
    PMID: 32028994 DOI: 10.1186/s13071-020-3907-8
    BACKGROUND: The genus Onchocerca Diesing, 1841 includes species of medical importance, such as O. volvulus (Leuckart, 1893), which causes river blindness in the tropics. Recently, zoonotic onchocercosis has been reported in humans worldwide. In Japan, O. dewittei japonica Uni, Bain & Takaoka, 2001 from wild boars is a causative agent for this zoonosis. Many filarioid nematodes are infected with Wolbachia endosymbionts which exhibit various evolutionary relationships with their hosts. While investigating the filarial fauna of Borneo, we discovered an undescribed Onchocerca species in the bearded pig Sus barbatus Müller (Cetartiodactyla: Suidae).

    METHODS: We isolated Onchocerca specimens from bearded pigs and examined their morphology. For comparative material, we collected fresh specimens of O. d. dewittei Bain, Ramachandran, Petter & Mak, 1977 from banded pigs (S. scrofa vittatus Boie) in Peninsular Malaysia. Partial sequences of three different genes (two mitochondrial genes, cox1 and 12S rRNA, and one nuclear ITS region) of these filarioids were analysed. By multi-locus sequence analyses based on six genes (16S rDNA, ftsZ, dnaA, coxA, fbpA and gatB) of Wolbachia, we determined the supergroups in the specimens from bearded pigs and those of O. d. dewittei.

    RESULTS: Onchocerca borneensis Uni, Mat Udin & Takaoka n. sp. is described on the basis of morphological characteristics and its genetic divergence from congeners. Molecular characteristics of the new species revealed its close evolutionary relationship with O. d. dewittei. Calculated p-distance for the cox1 gene sequences between O. borneensis n. sp. and O. d. dewittei was 5.9%, while that between O. d. dewittei and O. d. japonica was 7.6%. No intraspecific genetic variation was found for the new species. Wolbachia strains identified in the new species and O. d. dewittei belonged to supergroup C and are closely related.

    CONCLUSIONS: Our molecular analyses of filarioids from Asian suids indicate that the new species is sister to O. d. dewittei. On the basis of its morphological and molecular characteristics, we propose to elevate O. d. japonica to species level as O. japonica Uni, Bain & Takaoka, 2001. Coevolutionary relationships exist between the Wolbachia strains and their filarial hosts in Borneo and Peninsular Malaysia.

    Matched MeSH terms: Symbiosis
  15. Harman G, Khadka R, Doni F, Uphoff N
    Front Plant Sci, 2020;11:610065.
    PMID: 33912198 DOI: 10.3389/fpls.2020.610065
    Plants exist in close association with uncountable numbers of microorganisms around, on, and within them. Some of these endophytically colonize plant roots. The colonization of roots by certain symbiotic strains of plant-associated bacteria and fungi results in these plants performing better than plants whose roots are colonized by only the wild populations of microbes. We consider here crop plants whose roots are inhabited by introduced organisms, referring to them as Enhanced Plant Holobionts (EPHs). EPHs frequently exhibit resistance to specific plant diseases and pests (biotic stresses); resistance to abiotic stresses such as drought, cold, salinity, and flooding; enhanced nutrient acquisition and nutrient use efficiency; increased photosynthetic capability; and enhanced ability to maintain efficient internal cellular functioning. The microbes described here generate effects in part through their production of Symbiont-Associated Molecular Patterns (SAMPs) that interact with receptors in plant cell membranes. Such interaction results in the transduction of systemic signals that cause plant-wide changes in the plants' gene expression and physiology. EPH effects arise not only from plant-microbe interactions, but also from microbe-microbe interactions like competition, mycoparasitism, and antibiotic production. When root and shoot growth are enhanced as a consequence of these root endophytes, this increases the yield from EPH plants. An additional benefit from growing larger root systems and having greater photosynthetic capability is greater sequestration of atmospheric CO2. This is transferred to roots where sequestered C, through exudation or root decomposition, becomes part of the total soil carbon, which reduces global warming potential in the atmosphere. Forming EPHs requires selection and introduction of appropriate strains of microorganisms, with EPH performance affected also by the delivery and management practices.
    Matched MeSH terms: Symbiosis
  16. Doni F, Mispan MS, Suhaimi NSM, Ishak N, Uphoff N
    Appl Microbiol Biotechnol, 2019 Jul;103(13):5131-5142.
    PMID: 31101941 DOI: 10.1007/s00253-019-09879-9
    The system of rice intensification (SRI) is an agroecological approach to rice cultivation that seeks to create optimal conditions for healthy plant growth by minimizing inter-plant competition, transplanting widely spaced young single seedlings, and optimizing favorable soil conditions with organic amendments, increased soil aeration by weeding, and controlled water management. These practices improve rice plant growth with yields up to three times more than with conventional cultivation methods, and increase crop resilience under biotic and abiotic stresses. This review discusses the roles of beneficial microbes in improving rice plant growth, yield, and resilience when SRI practices are used, and how these modifications in plant, soil, water, and nutrient management affect the populations and diversity of soil microorganisms. Mechanisms whereby symbiotic microbes support rice plants' growth and performance are also discussed.
    Matched MeSH terms: Symbiosis
  17. Chang Y, Liu H, Liu M, Liao X, Sahu SK, Fu Y, et al.
    Gigascience, 2019 03 01;8(3).
    PMID: 30535374 DOI: 10.1093/gigascience/giy152
    BACKGROUND: The expanding world population is expected to double the worldwide demand for food by 2050. Eighty-eight percent of countries currently face a serious burden of malnutrition, especially in Africa and south and southeast Asia. About 95% of the food energy needs of humans are fulfilled by just 30 species, of which wheat, maize, and rice provide the majority of calories. Therefore, to diversify and stabilize the global food supply, enhance agricultural productivity, and tackle malnutrition, greater use of neglected or underutilized local plants (so-called orphan crops, but also including a few plants of special significance to agriculture, agroforestry, and nutrition) could be a partial solution.

    RESULTS: Here, we present draft genome information for five agriculturally, biologically, medicinally, and economically important underutilized plants native to Africa: Vigna subterranea, Lablab purpureus, Faidherbia albida, Sclerocarya birrea, and Moringa oleifera. Assembled genomes range in size from 217 to 654 Mb. In V. subterranea, L. purpureus, F. albida, S. birrea, and M. oleifera, we have predicted 31,707, 20,946, 28,979, 18,937, and 18,451 protein-coding genes, respectively. By further analyzing the expansion and contraction of selected gene families, we have characterized root nodule symbiosis genes, transcription factors, and starch biosynthesis-related genes in these genomes.

    CONCLUSIONS: These genome data will be useful to identify and characterize agronomically important genes and understand their modes of action, enabling genomics-based, evolutionary studies, and breeding strategies to design faster, more focused, and predictable crop improvement programs.

    Matched MeSH terms: Symbiosis/genetics
  18. Chong PP, Chin VK, Wong WF, Madhavan P, Yong VC, Looi CY
    Genes (Basel), 2018 Nov 07;9(11).
    PMID: 30405082 DOI: 10.3390/genes9110540
    Candida albicans is an opportunistic fungal pathogen, which causes a plethora of superficial, as well as invasive, infections in humans. The ability of this fungus in switching from commensalism to active infection is attributed to its many virulence traits. Biofilm formation is a key process, which allows the fungus to adhere to and proliferate on medically implanted devices as well as host tissue and cause serious life-threatening infections. Biofilms are complex communities of filamentous and yeast cells surrounded by an extracellular matrix that confers an enhanced degree of resistance to antifungal drugs. Moreover, the extensive plasticity of the C. albicans genome has given this versatile fungus the added advantage of microevolution and adaptation to thrive within the unique environmental niches within the host. To combat these challenges in dealing with C. albicans infections, it is imperative that we target specifically the molecular pathways involved in biofilm formation as well as drug resistance. With the advent of the -omics era and whole genome sequencing platforms, novel pathways and genes involved in the pathogenesis of the fungus have been unraveled. Researchers have used a myriad of strategies including transcriptome analysis for C. albicans cells grown in different environments, whole genome sequencing of different strains, functional genomics approaches to identify critical regulatory genes, as well as comparative genomics analysis between C. albicans and its closely related, much less virulent relative, C. dubliniensis, in the quest to increase our understanding of the mechanisms underlying the success of C. albicans as a major fungal pathogen. This review attempts to summarize the most recent advancements in the field of biofilm and antifungal resistance research and offers suggestions for future directions in therapeutics development.
    Matched MeSH terms: Symbiosis
  19. Séne S, Selosse MA, Forget M, Lambourdière J, Cissé K, Diédhiou AG, et al.
    ISME J, 2018 06;12(7):1806-1816.
    PMID: 29535364 DOI: 10.1038/s41396-018-0088-y
    Global trade increases plant introductions, but joint introduction of associated microbes is overlooked. We analyzed the ectomycorrhizal fungi of a Caribbean beach tree, seagrape (Coccoloba uvifera, Polygonacaeae), introduced pantropically to stabilize coastal soils and produce edible fruits. Seagrape displays a limited symbiont diversity in the Caribbean. In five regions of introduction (Brazil, Japan, Malaysia, Réunion and Senegal), molecular barcoding showed that seagrape mostly or exclusively associates with Scleroderma species (Basidiomycota) that were hitherto only known from Caribbean seagrape stands. An unknown Scleroderma species dominates in Brazil, Japan and Malaysia, while Scleroderma bermudense exclusively occurs in Réunion and Senegal. Population genetics analysis of S. bermudense did not detect any demographic bottleneck associated with a possible founder effect, but fungal populations from regions where seagrape is introduced are little differentiated from the Caribbean ones, separated by thousands of kilometers, consistently with relatively recent introduction. Moreover, dry seagrape fruits carry Scleroderma spores, probably because, when drying on beach sand, they aggregate spores from the spore bank accumulated by semi-hypogeous Scleroderma sporocarps. Aggregated spores inoculate seedlings, and their abundance may limit the founder effect after seagrape introduction. This rare pseudo-vertical transmission of mycorrhizal fungi likely contributed to efficient and repeated seagrape/Scleroderma co-introductions.
    Matched MeSH terms: Symbiosis*
  20. van Velzen R, Holmer R, Bu F, Rutten L, van Zeijl A, Liu W, et al.
    Proc Natl Acad Sci U S A, 2018 May 15;115(20):E4700-E4709.
    PMID: 29717040 DOI: 10.1073/pnas.1721395115
    Nodules harboring nitrogen-fixing rhizobia are a well-known trait of legumes, but nodules also occur in other plant lineages, with rhizobia or the actinomycete Frankia as microsymbiont. It is generally assumed that nodulation evolved independently multiple times. However, molecular-genetic support for this hypothesis is lacking, as the genetic changes underlying nodule evolution remain elusive. We conducted genetic and comparative genomics studies by using Parasponia species (Cannabaceae), the only nonlegumes that can establish nitrogen-fixing nodules with rhizobium. Intergeneric crosses between Parasponia andersonii and its nonnodulating relative Trema tomentosa demonstrated that nodule organogenesis, but not intracellular infection, is a dominant genetic trait. Comparative transcriptomics of P. andersonii and the legume Medicago truncatula revealed utilization of at least 290 orthologous symbiosis genes in nodules. Among these are key genes that, in legumes, are essential for nodulation, including NODULE INCEPTION (NIN) and RHIZOBIUM-DIRECTED POLAR GROWTH (RPG). Comparative analysis of genomes from three Parasponia species and related nonnodulating plant species show evidence of parallel loss in nonnodulating species of putative orthologs of NIN, RPG, and NOD FACTOR PERCEPTION Parallel loss of these symbiosis genes indicates that these nonnodulating lineages lost the potential to nodulate. Taken together, our results challenge the view that nodulation evolved in parallel and raises the possibility that nodulation originated ∼100 Mya in a common ancestor of all nodulating plant species, but was subsequently lost in many descendant lineages. This will have profound implications for translational approaches aimed at engineering nitrogen-fixing nodules in crop plants.
    Matched MeSH terms: Symbiosis*
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