50 research outputs found
Rhizobia-legume Symbiosis mediates direct and indirect interactions between plants, herbivores and their parasitoids
Microorganisms associated with plant roots significantly impact the quality and quantity of plant defences. However, the bottom-up effects of soil microbes on the aboveground multitrophic interactions remain largely under studied. To address this gap, we investigated the chemically- mediated effects of nitrogen-fixing rhizobia on legume-herbivore-parasitoid multitrophic interactions. To address this, we initially examined the cascading effects of the rhizobia bean association on herbivore caterpillars, their parasitoids, and subsequently investigated how rhizobia influence on plant volatiles and extrafloral nectar. Our goal was to understand how these plant- mediated effects can affect parasitoids. Lima bean plants (Phaseoulus lunatus) inoculated with rhizobia exhibited better growth, and the number of root nodules positively correlated with defensive cyanogenic compounds. Despite increase of these chemical defences, Spodoptera latifascia caterpillars preferred to feed and grew faster on rhizobia-inoculated plants. Moreover, the emission of plant volatiles after leaf damage showed distinct patterns between inoculation treatments, with inoculated plants producing more sesquiterpenes and benzyl nitrile than non- inoculated plants. Despite these differences, Euplectrus platyhypenae parasitoid wasps were similarly attracted to rhizobia- or no rhizobia-treated plants. Yet, the oviposition and offspring development of E. platyhypenae was better on caterpillars fed with rhizobia-inoculated plants. We additionally show that rhizobia-inoculated common bean plants (Phaseolus vulgaris) produced more extrafloral nectar, with higher hydrocarbon concentration, than non-inoculated plants. Consequently, parasitoids performed better when fed with extrafloral nectar from rhizobia- inoculated plants. While the overall effects of bean-rhizobia symbiosis on caterpillars were positive, rhizobia also indirectly benefited parasitoids through the caterpillar host, and directly through the improved production of high quality extrafloral nectar. This study underscores the importance of exploring diverse facets and chemical mechanisms that influence the dynamics between herbivores and predators. This knowledge is crucial for gaining a comprehensive understanding of the ecological implications of rhizobia symbiosis on these interactions
Effects of prolonged drought on plant-soil feedbacks and implications for plant community dynamics
Plant-soil feedback (PSFs) refers to the ability of a given plant to alter soil physicochemical properties in ways that modify the growth of a plant subsequently grown in the same soil. It is well established that PSFs influence plant community structure and dynamics, plant succession and invasion process. There is also evidence that change in climate will affect PSFs impacting plant community dynamics and, through this, ecosystem functioning and stability. However, our knowledge about the effects of climate change, specifically prolonged drought, on PSFs and its role in shaping plant community dynamics under natural conditions is limited. Therefore, in this thesis, I (i) experimentally assessed shifts in PSFs in response to prolonged drought legacies across plant species, functional types, and community level under laboratory condition; (ii) investigated drought induced shifts in plant-soil feedbacks under field conditions utilizing an experimental rainfall manipulation in a mesic grassland; (iii) assessed the effects of a foliar herbivore on PSFs in monocultures and mixtures in soils with prolonged drought legacies; (iv) investigated the role of long-term drought soil legacies on the performance of two globally recognized notorious foliar herbivores, and their influence on PSFs; (v) assessed the contribution of potential belowground mechanisms, specifically changes in litter decomposition, belowground carbon allocation and competition for nitrogen, to shifts in the strength and direction of PSFs under prolonged drought using stable isotope (13C and 15N) labelling; and (vi) conducted a literature review quantifying shifts of PSFs in response to drought and warming using a meta-analytical approach and identify key future knowledge gaps. I conclude that drought effects on PSFs are context-dependent and may differ within and among plant functional types. Belowground biota, such as plant-parasitic nematodes, arbuscular mycorrhizal fungi (AMF) and bacteria, contribute to shifts in PSFs between ambient rainfall and drought. Aboveground biota, such as foliar herbivores, are likely to be key drivers involved in altering PSFs under prolonged drought through affecting plant foliar N and CN ratio and herbivore-induced shifts in plant-soil biotic interactions, including beneficial relationships with rhizobia. Belowground mechanisms, such as litter decomposition, significantly contributed to shifts in PSFs in drought. Moreover, changes in relative belowground carbon allocation and competition for nutrients are also likely to contribute to contrasting outcomes under drought conditions; additional analyses of archived samples will provide further insight into the role of these mechanisms
Comparing induced responses of medicago truncatula to biotic challenges: common themes, varying patterns
In der vorliegenden Arbeit wurden die Antworten von Medicago truncatula Gaertner (gestutzter Schneckenklee, Fabaceae) auf verschiedene biotische Reize verglichen. Dabei wurden Reaktionen auf verschiedene Fraßfeinde und mikrobielle Oligosaccharide analysiert. Des Weiteren wurden der Einfluß von Mykorrhizierung auf herbivorieinduzierte Duftstoffemission und die Reaktionen auf verschiedene abiotische und biotische Elicitoren untersucht. Besonderes Augenmerk wurde auf die Emission von Duftstoffen als Strategie der indirekten Verteidigung gerichtet, die von M. truncatula in hoher Vielfalt freigesetzt werden. Die nach unterschiedlicher Induktion emittierten Duftmuster wiesen deutliche Charakteristika auf und konnten mit Hilfe multivariater statistischer Methoden diskriminiert werden. Als mögliche Komponenten der Signaltransduktion wurden die Phytohormone Jasmonsäure und Salicylsäure, die Überproduktion reaktiver Sauerstoffspezies und Stickoxid untersucht, sowie die Akkumulierung phenolischer Substanzen als Bestandteil der direkten Verteidigung analysiert. Während viele Reaktionen hinsichtlich der qualitativen Merkmale ähnlich waren, zeigten der quantitative Aspekt sowie der zeitliche Verlauf starke Unterschiede abhängig vom induzierenden Reiz. Durch unterschiedliche Kombination ähnlicher Komponenten ergaben sich charakteristische Antwortmuster auf die getesteten biotischen Stimuli
Rhizobacterial modification of plant defenses against insect herbivores: from molecular mechanisms to tritrophic interactions
SUMMARY Plants as primary producers in terrestrial ecosystems are under constant threat from a multitude of attackers, which include insect herbivores. In addition to interactions with detrimental organisms, plants host a diversity of beneficial organisms, which include microbes in the rhizosphere. Furthermore, the interactions between plants and several groups of root-associated microbes such as mycorrhizae, plant growth promoting rhizobacteria (PGPR) and plant growth promoting fungi (PGPF) can affect plant interactions with foliar insect herbivores. The beneficial root-associated microbes are able to modify plant physiology by promoting plant growth and induced systemic resistance (ISR), in which the balance between both effects will determine the final impact on the insect herbivores. Using Arabidopsis thaliana Col-0, this thesis explores the molecular mechanisms on how plants integrate responses when simultaneously interacting with the rhizobacterium Pseudomonas fluorescens and the generalist and the specialist leaf-chewing insects Mamestra brassicae and Pieris brassicae respectively. A literature review on the state-of-the-art in the field of microbe-plant-insect interactions (Chapter 2) explores how root-associated microbes and insect folivores can influence each other via a shared host plant. For more than a decade, both ecological and mechanistic studies mostly focused on exploring these belowground and aboveground interactions using single microbe and single herbivore species. The importance of increasing the complexity of the study system in order to understand the interactions in more natural situations is being emphasized. Furthermore, this review discusses the role of plant hormones in regulating plant growth and defense against folivores, while simultaneously being involved in associations with root-associated microbes. Experimental evidence has shown patterns on the effects of mycorrhizal colonization on plant interactions with insect herbivores, and raises the question whether plant colonization by different groups of root-associated microbes has similar effects on particular categories of insect herbivores. In Chapter 3, plant-mediated effects of a non-pathogenic rhizobacterium on the performance of leaf-chewing insects, and the underlying mechanisms modulating the interactions, have been examined. Colonization of A. thaliana Col-0 roots by the bacterium P. fluorescens strain WCS417r resulted in decreased larval weight of the generalist leaf-chewing M. brassicae, and had no effect on larval weight of the specialist leaf-chewing P. brassicae. The crucial role of jasmonic acid (JA) in regulating rhizobacteria-mediated induced systemic resistance (ISR) against M. brassicae is confirmed by including plant mutants in the study. Interestingly, I also observed that rhizobacteria can induce systemic susceptibility to M. brassicae caterpillars. Comparison of M. brassicae performance and gene transcription in A. thaliana plants, grown in potting soil or a mixture of potting soil and sand in a 1:1 ratio, shows that in a mixture of potting soil and sand, rhizobacterial treatment had a consistently negative effect on M. brassicae, whereas the effect is more variable in potting soil. Rhizobacterial treatment primed plants grown in potting soil and sand for stronger expression of JA- and ethylene-regulated genes PDF1.2 and HEL, supporting stronger resistance to M. brassicae. Taken together, the results show that soil composition can be one of the factors modulating the outcome of microbe-plant-insect interactions. Chapter 4 further addresses the mechanisms underlying rhizobacteria-mediated ISR against the generalist leaf-chewing M. brassicae by integrating plant gene transcription, chemistry and performance of M. brassicae in wild type A. thaliana Col-0 plants and mutants defective in the JA-pathway, i.e. dde2-2 and myc2, in the ET pathway, i.e. ein2-1, and in the JA-/ET-pathway, i.e. ora59. Results of this study show that rhizobacterial colonization alone or in combination with herbivore infestation induced the expression of the defense-associated genes ORA59 and PDF1.2 at higher levels than activation by herbivore feeding alone, and the expression of both genes is suppressed in the knock-out mutant ora59. Interestingly, the colonization of plant roots by rhizobacteria alters the levels of plant defense compounds, i.e. camalexin and glucosinolates (GLS), by enhancing the synthesis of constitutive and induced levels of camalexin and aliphatic GLS while suppressing the induced levels of indole GLS. The changes are associated with modulation of the JA-/ET-signaling pathways as shown by investigating mutants. Furthermore, the herbivore performance results show that functional JA- and ET-signaling pathways are required for rhizobacteria-mediated ISR against leaf-chewing insects as observed in the knock-out mutants dde2-2 and ein2-1. The results indicate that colonization of plant roots by rhizobacteria modulates plant-insect interactions by prioritizing the ORA59-branch over the MYC2-branch, although the transcription factor ORA59 is not the only one responsible for the observed effects of rhizobacteria-mediated ISR against leaf-chewing insects. Taking a step further in increasing the complexity of the study system, Chapter 5 investigates how co-cultivation of P. fluorescens strains WCS417r and SS101 affects direct plant defense to the caterpillar M. brassicae. Inoculation of either P. fluorescens WCS417r or SS101 singly at root tips or simultaneously at two different positions along the roots resulted in a similar level of rhizobacterial colonization by each strain, whereas co-cultivation of both strains at either the root tips or at two different positions along the roots resulted in a higher colonization level of strain WCS417r compared to colonization by SS101. The results suggest that the site of inoculation influences the direct interactions between the two strains in the rhizosphere, as also confirmed by in vitro antagonism assays in the absence of plants. Both upon single inoculation and co-cultivation of both strains at the same or different sites along the roots, the two rhizobacterial strains induced the same strength of ISR against the caterpillar M. brassicae and the same degree of plant growth promotion. In the roots, colonization by the two strains as single or mixed culture resulted in a similar gene expression pattern of up-regulation of MYC2, down-regulation of WRKY70 and no effect on NPR1 expression, genes representing JA-signaling, SA-signaling and the node of crosstalk between the two pathways, respectively. We hypothesize that both rhizobacterial strains use negative crosstalk between JA- and SA-pathways as mechanism to suppress plant immunity and establish colonization. This study shows that competitive interactions between rhizobacterial strains known to induce plant defense in systemic tissue via different signaling pathways, may interfere with synergistic effects on ISR and plant growth promotion. While the effect of root-associated microbes on direct plant defense against insect herbivores has been studied previously, the effect of these microbes on indirect plant defense to herbivores is much less known. Chapter 6 explores how colonization by the rhizobacterium P. fluorescens strain WCS417r affects indirect plant defense against the generalist herbivore M. brassicae by combining behavioral, chemical and gene transcriptional approaches. The results show that rhizobacterial colonization of A. thaliana roots results in an increased attraction of the parasitoid Microplitis mediator to caterpillar-infested plants. Volatile analysis revealed that rhizobacterial colonization suppressed emission of the terpene (E)-α-bergamotene, and the aromatics methyl salicylate and lilial in response to caterpillar feeding. Rhizobacterial colonization decreased the caterpillar-induced transcription of the terpene synthase genes TPS03 and TPS04. Rhizobacteria enhanced both growth and indirect defense of plants under caterpillar attack. This study shows that rhizobacteria have a high potential to enhance the biocontrol of leaf-chewing herbivores based on enhanced attraction of parasitoids. Taken together, the research presented in this thesis has shown how single or combined applications of rhizobacteria affect interactions of plants with leaf-chewing insects in terms of direct and indirect resistance. Furthermore, results presented in this thesis have revealed some of the molecular mechanisms underlying plant-mediated interactions between rhizobacteria and leaf-chewing insects that can be used in developing practical approaches by applying beneficial root-associated microbes for improving plant resistance. </p
THE ROLE OF GIBBERELLIC ACID IN APHID-PLANT-ARBUSCULAR MYCORRHIZAL FUNGUS INTERACTIONS
Arbuscular mycorrhizal (AM) fungi form beneficial associations with the roots of most terrestrial plants, which is mostly characterized by increased plant nutrient acquisition (phosphate and nitrogen) by the fungi in exchange for carbon and lipids from the plants. These associations can also enhance plant coping mechanisms to abiotic and biotic stresses. However, insect herbivores, such as aphids, can benefit from AM fungi-plant symbioses by altering plant defenses that are driven mainly by the phytohormones jasmonic acid (JA) and salicylic acid (SA). Nevertheless, other phytohormones can modulate plant defenses by altering the balance of the JA and SA signaling pathways, such as the growth promoting phytohormone gibberellic acid (GA). Although GA signaling plays an important role in modulating plant defenses during plant-pathogen interactions, its role in insect-plant and insect-plant-beneficial microbe interactions remains largely unknown. Therefore, the current study set out to investigate the following two objectives: 1) examine the role of exogenous GA application in regulating plant defenses during aphid-plant-AM fungus interactions, and 2) evaluate the role of GA signaling in modulating plant defenses during aphid-plant interactions. In objective 1, we found that exogenous GA negatively affected aphid fitness on GA-treated mycorrhizal plants 7-days post pea aphid feeding. Exogenous GA had a synergistic effect on JA-related plant gene expression in shoots, and increased JA and SA levels in leaves and petioles after 36 hours of aphid feeding. Pea aphid feeding for 36 hours induced SA-related defense gene expression and increased SA levels in leaves and petioles. In addition, root colonization by the AM fungus resulted in induced JA- and SA-related plant defense gene expression in shoots and roots, but decreased SA levels in leaves and petioles after 36 hours of aphid feeding. In objective 2, we found that GA signaling had an antagonistic effect on JA-related defense signaling after 36 hours of aphid feeding. In summary, this study serves as a foundation for future studies examining the role of GA in regulating plant defenses during insect-plant and insect-plant-AM fungus interactions
The Microbe-Free Plant: Fact or Artifact?
Plant–microbe interactions are ubiquitous. Plants are threatened by pathogens, but they are even more commonly engaged in neutral or mutualistic interactions with microbes: belowground microbial plant associates are mycorrhizal fungi, Rhizobia, and plant-growth promoting rhizosphere bacteria, aboveground plant parts are colonized by internally living bacteria and fungi (endophytes) and by microbes in the phyllosphere (epiphytes). We emphasize here that a completely microbe-free plant is an exotic exception rather than the biologically relevant rule. The complex interplay of such microbial communities with the host–plant affects multiple vital parameters such as plant nutrition, growth rate, resistance to biotic and abiotic stressors, and plant survival and distribution. The mechanisms involved reach from direct ones such as nutrient acquisition, the production of plant hormones, or direct antibiosis, to indirect ones that are mediated by effects on host resistance genes or via interactions at higher trophic levels. Plant-associated microbes are heterotrophic and cause costs to their host plant, whereas the benefits depend on the current environment. Thus, the outcome of the interaction for the plant host is highly context dependent. We argue that considering the microbe-free plant as the “normal” or control stage significantly impairs research into important phenomena such as (1) phenotypic and epigenetic plasticity, (2) the “normal” ecological outcome of a given interaction, and (3) the evolution of plants. For the future, we suggest cultivation-independent screening methods using direct PCR from plant tissue of more than one fungal and bacterial gene to collect data on the true microbial diversity in wild plants. The patterns found could be correlated to host species and environmental conditions, in order to formulate testable hypotheses on the biological roles of plant endophytes in nature. Experimental approaches should compare different host–endophyte combinations under various relevant environmental conditions and study at the genetic, epigenetic, transcriptional, and physiological level the parameters that cause the interaction to shift along the mutualism–parasitism continuum
Effets des inoculants de champignon mycorhizien arbusculaire et de rhizobactéries sur les insectes du soja
L’utilisation d’inoculants de champignon mycorhizien arbusculaire (CMA) et de bactéries promotrices de la croissance de la plante (PGPR) comme biofertilisants pour améliorer la croissance de la plante et augmenter les rendements des cultures connait de plus en plus un intérêt remarquable. Ces inoculants peuvent influencer les relations trophiques à travers les changements induits au niveau de la plante. Cependant, en contexte agroécologique, il est difficile de prédire les effets de leur application sur les niveaux trophiques supérieurs, notamment sur les insectes phytophages et leurs ennemis naturels. Ainsi, l’objectif de ce projet de thèse était d’évaluer les effets des inoculants de champignon mycorhizien et bactériens sur les insectes du soja. Spécifiquement il est question : 1) d’évaluer l’influence sur le puceron du soja Aphis glycines (2e niveau trophique), de la symbiose tripartite entre un CMA Rhizophagus irregularis, une bactérie rhizobium Bradyrhizobium japonicum et le soja Glycine max ; 2) de déterminer l’impact des inoculants de R. irregularis et de B. japonicum associés au soja sur les ennemis naturels du puceron de soja, la coccinelle Coleomegilla maculata et le parasitoïde Aphelinus certus (3e niveau trophique) ; 3) d’évaluer les effets de la co-inoculation des inoculants de R. irregularis, B. japonicum et de Bacillus pumilus sur les insectes phytophages et leurs ennemis naturels associés au soja au champ.
Les expériences en chambre de croissance (objectifs 1 et 2) ont montré une altération des traits de performance des plantes en présence des inoculants comparées aux plantes témoins. Les différences de colonisation mycorhizienne et de nodulation, observées entre les traitements sont une preuve du fonctionnement de l’inoculation. Avec le double inoculant, j’ai observé une augmentation de la biomasse de la plante, des concentrations en azote et carbone, et une diminution de la concentration en phosphore. Avec le rhizobium seul, j’ai obtenu les mêmes effets, sauf pour la biomasse racinaire qui n’a pas été affectée. Avec le CMA seul, une augmentation de la concentration en phosphore a été observée, mais aucun des autres paramètres de la plante n'a été affecté. Au deuxième niveau trophique sur le puceron du soja, le soja inoculé avec le double inoculant CMA+rhizobium, suivi du rhizobium seul, ont augmenté significativement la densité de la population de pucerons, alors qu’aucun des inoculants n’a eu un effet sur le fitness du puceron. En revanche, aucun des traits de performance du puceron (fécondité et taille des individus) n’a été affecté par la présence de l’inoculant CMA seul. D’autre part, j’ai noté une corrélation positive entre la concentration en azote et le taux de reproduction des pucerons, alors qu’avec la concentration en phosphore, la corrélation avec la colonie des pucerons est négative. Quant au troisième niveau trophique, une réduction significative du taux de parasitisme chez A. certus a été observée en présence du rhizobium seul, mais aucun autre paramètre n’a été affecté comparativement aux autres traitements : contrôle, CMA et double inoculant (CMA+rhizobium). Avec le prédateur C. maculata, aucun paramètre mesuré n’a été affecté par les effets indirects des inoculants.
Il ressort de l’évaluation que j’ai faite au champ (objectif 3), une augmentation de l'abondance des insectes piqueurs-suceurs avec le triple inoculant (CMA+rhizobium+Bacillus), mais aucune différence entre les traitements pour les autres groupes d'insectes (broyeurs, et ennemis naturels des pucerons). Aucun groupe fonctionnel n’a été affecté en présence du double inoculant CMA+rhizobium sauf le puceron du soja, A. glycines, qui a vu sa population décroître mais seulement dans les parcelles fertilisées en potassium. J’ai également montré que les abondances des insectes piqueurs-suceurs et des insectes broyeurs, et la diversité alpha des insectes phytophages étaient toutes corrélées négativement avec la colonisation mycorhizienne globale.
Ces résultats confirment que la co-inoculation de deux symbiotes peut non seulement améliorer les performances des plantes mais aussi celles des insectes phytophages au-delà de ce que chaque symbiote peut apporter seul. Au moins dans notre système d'étude en chambre de croissance, il semble que les avantages que les symbioses microbe-plante confèrent au deuxième niveau trophique avec une augmentation de la population de pucerons sont peu transférés au troisième niveau sur les ennemis naturels du puceron. Dans un système agricole où les agriculteurs veulent bénéficier des retombées de ces inoculants, notamment dans la gestion des insectes associés aux cultures, les CMA semblent favorables s’ils sont utilisés seuls et du fait de leur potentiel à réduire les insectes ravageurs.The use of arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPR) inoculants, as biofertilizers to boost plant growth and increase crop yields, is gaining interest. These inoculants can also influence trophic relationships through changes on plant. However, in an agroecological context, it is difficult to predict the effects of their application on higher trophic levels, namely phytophagous insects, and their natural enemies. The objective of this thesis research is to evaluate the effects of mycorrhizal fungi and bacterial inoculants on soybean-associated insects. Specifically, it is to: 1) evaluate the influence on the soybean aphid, Aphis glycines (2nd trophic level), of the tripartite symbiosis between an AMF, Rhizophagus irregularis, a rhizobium bacterium, Bradyrhizobium japonicum, and the soybean, Glycine max; 2) determinate the impact of R. irregularis and B. japonicum inoculants associated with soybean on the natural enemies of soybean aphid, the ladybug Coleomegilla maculata and the parasitoid wasp Aphelinus certus (3rd trophic level); 3) evaluate the effects of co-inoculation of R. irregularis, B. japonicum and Bacillus pumilus inoculants on soybean-associated phytophagous insects and their natural enemies in an agricultural field conditions.
The walk-in growth room experiments (objectives 1 and 2) showed an alteration of the performance traits of the plants in the presence of the inoculants compared to control plants. The differences in mycorrhizal colonization and nodulation, observed between treatments, are evidence that the inoculation works. With the double inoculant, I observed an increase in plant biomass, nitrogen and carbon concentrations, and a decrease in phosphorus concentration. With rhizobium inoculation alone, without AMF, I obtained the same effects, except the root biomass that was not affected. With AMF alone, an increase in phosphorus concentration was observed, but none of the other plant parameters were affected. At second trophic level, inoculation of soybeans with the dual inoculant AMF-rhizobium, followed by rhizobium alone, significantly increased aphid population density, while none of inoculant influenced the fitness of the aphid. However, AMF alone did not affect any parameter traits (reproduction and fitness) of the aphid. I noted a positive correlation between nitrogen concentration and aphid reproductive rate, whereas the correlation between phosphorus concentration and aphid colony growth was negative. At the third trophic level, a significant reduction in the rate of parasitism of A. certus was observed in the presence of rhizobium inoculant alone, but no other parameters were affected with any other treatments, namely the control, the AMF inoculant, or the double inoculant (AMF+rhizobium). With the predator C. maculata, no measured parameters were affected by the indirect effects of any of the inoculant treatments.
During my field assessment (objective 3), I observed an increase in the abundance of piercing-sucking insects with the triple inoculant (AMF+rhizobium+Bacillus), but no differences between treatments for other insect groups (chewing insects, or natural enemies of aphids). No functional group was affected by the presence of the double inoculant, CMA+rhizobium except the soybean aphid, A. glycines, which saw its population decrease in potassium-fertilized plots. I also showed that the abundance of piercing-sucking insects, chewing insects, and the alpha diversity of phytophagous insects were all negatively correlated with mycorrhizal colonization.
The results of my studies confirm that co-inoculation of two symbionts can not only improve plant performance but also that of phytophagous insects beyond what each symbiont can provide alone. At least in our growth chamber study system, it appears that the benefits that microbe-plant symbioses confer to the second trophic level, with an increase in aphid population, are little transferred to the third level on the natural enemies of the soybean aphid. In agricultural system where farmers seek the benefits of these inoculants, especially in the management of insects associated with crops, AMF seem favorable when they are used alone and because of their potential to reduce insect pests
Manipulating Wild and Tamed Phytobiomes: Challenges and Opportunities
This white paper presents a series of perspectives on current and future phytobiome management, discussed at the Wild and Tamed Phytobiomes Symposium in University Park, PA, USA, in June 2018. To enhance plant productivity and health, and to translate lab- and greenhouse-based phytobiome research to field applications, the academic community and end-users need to address a variety of scientific, practical, and social challenges. Prior discussion of phytobiomes has focused heavily on plant-associated bacterial and fungal assemblages, but the phytobiomes concept covers all factors that influence plant function. Here we discuss various management considerations, including abiotic conditions (e.g. soil, nutrient applications), microorganisms (e.g. bacterial and fungal assemblages, bacterial and fungal inoculants, viruses), macroorganisms (e.g. arthropods, plant genetics), and societal factors (e.g. communication approaches, technology diffusion). An important near-term goal for this field should be to estimate the potential relative contribution of different components of the phytobiome to plant health, as well as the potential and risk of modifying each in the near-future
More than a meat- or synthetic nitrogen fertiliser-substitute:a review of legume phytochemicals as drivers of 'One Health' via their influence on the functional diversity of soil- and gut-microbes
Legumes are essential to healthy agroecosystems, with a rich phytochemical content that impacts overall human and animal well-being and environmental sustainability. While these phytochemicals can have both positive and negative effects, legumes have traditionally been bred to produce genotypes with lower levels of certain plant phytochemicals, specifically those commonly termed as 'antifeedants' including phenolic compounds, saponins, alkaloids, tannins, and raffinose family oligosaccharides (RFOs). However, when incorporated into a balanced diet, such legume phytochemicals can offer health benefits for both humans and animals. They can positively influence the human gut microbiome by promoting the growth of beneficial bacteria, contributing to gut health, and demonstrating anti-inflammatory and antioxidant properties. Beyond their nutritional value, legume phytochemicals also play a vital role in soil health. The phytochemical containing residues from their shoots and roots usually remain in-field to positively affect soil nutrient status and microbiome diversity, so enhancing soil functions and benefiting performance and yield of following crops. This review explores the role of legume phytochemicals from a 'one health' perspective, examining their on soil- and gut-microbial ecology, bridging the gap between human nutrition and agroecological science.</p