Entomopathogenic Nematodes Induce Metabolic Reallocation in Maize Roots Without Altering the Performance of Two Root Herbivores, Diabrotica virgifera and Diabrotica balteata.

Entomopathogenic nematodes (EPNs) are key biological control agents in agriculture, but their direct effects on plant metabolism and resistance to herbivory remain underexplored. By combining transcriptomic, metabolomic, and herbivore assays, this study aimed at providing a holistic description of maize root responses to EPNs and to assess their potential relevance for plant-herbivore interactions. EPNs triggered a dynamic shift in root metabolism, suggesting a reallocation of primary resources towards chemical defences.

Synthetic communities of maize root bacteria interact and redirect benzoxazinoid metabolization.

Plant roots are colonized by diverse microbial communities. These communities are shaped by root exudates, including plant-specialized metabolites. Benzoxazinoids are such secreted compounds of maize.

Effects of Native or Exogenous Benzoxazinoids on In Vitro Ruminal Fermentation and Degradability of Either Fresh or Ensiled Whole-Crop Maize-Based Diets in Cattle.

Benzoxazinoids (BXs) are secondary plant compounds and an important part of the plant's defence system against herbivore attacks and microbial pathogens in maize. Whole-crop maize represents a common feed for ruminant livestock and is most commonly fed as silage, a conservation process that promotes the conversion of BXs into the potent downstream metabolite 6-Methoxy-benzoxazolin-2(3H)-one (MBOA). Possibly, the antimicrobial impact of BXs may not be restricted to plant pathogens but could as well affect the rumen ecosystem, which, however, has not yet been investigated.

The glutamate receptor-like GLR2.7 modulates insect egg-induced defense responses in Arabidopsis.

Upon perception of insect eggs, Arabidopsis thaliana activates a generic immune response that culminates in cell death (hypersensitive-like response (HR-like)). While this response can subsequently impact egg survival, the molecular mechanisms are poorly understood. Through a genome-wide association study (GWAS), we identified the amino acid-gated calcium channel GLUTAMATE-LIKE RECEPTOR2.

Herbivory-induced green leaf volatiles increase plant performance through jasmonate-dependent plant-soil feedbacks.

Plants influence each other chemically by releasing leaf volatiles and root exudates, but whether and how these two phenomena interact remains unknown. Here we demonstrate that volatiles that are released by herbivore-attacked leaves trigger plant-soil feedbacks, resulting in increased performance of different plant species. We show that this phenomenon is due to green leaf volatiles that induce jasmonate-dependent systemic defence signalling in receiver plants, which results in the accumulation of beneficial soil bacteria in the rhizosphere.

Description of Heterorhabditis americana n. sp. (Rhabditida, Heterorhabditidae), a new entomopathogenic nematode species isolated in North America.

Background: Heterorhabditis are important biological control agents in agriculture. Two Heterorhabditis populations, S8 and S10, were isolated from agricultural soils in the United States of America. Molecular analyses, based on mitochondrial and nuclear genes, showed that these populations are conspecific and represent a novel species of the "Bacteriophora" clade.

Environmental and Biological Drivers of Root Exudation.

Root exudation is the process by which plants release organic and inorganic metabolites from their roots into the surrounding soil. Root exudation is a dynamic process and shapes plant-environment interactions at the root-soil interface. Little is known about the biological and environmental factors that shape the exuded metabolome, hereafter referred to as the exudome, despite its importance in structuring soil processes.

Root Exudation: An In-Depth Experimental Guide.

Plants exude a wide variety of compounds into the rhizosphere, modulating soil functioning and diversity. The number of studies investigating exudation has exponentially increased over the past decades. Yet, the high inter-study variability of the results is slowing down our understanding of root-soil interactions.

The polyvalent sequestration ability of an economically important beetle.

Many specialized herbivorous insects sequester single classes of toxic secondary metabolites from their host plants as protection against natural enemies. If and how herbivores can use multiple classes of plant toxins across the large chemical diversity of plants for self-protection is unknown. We show that the polyphagous adults of the beetle Diabrotica virgifera are capable of selectively accumulating benzoxazinoids, cucurbitacins, and glucosinolates but not cyanogenic glycosides.

Maternal consumption of yoghurt activating the aryl hydrocarbon receptor increases group 3 innate lymphoid cells in murine offspring.

Unlabelled: Indole derivatives are microbial metabolites of the tryptophan pathway involved in gut immune homeostasis. They bind to the aryl hydrocarbon receptor (AhR), thereby modulating development of intestinal group 3 innate lymphoid cells (ILC3) and subsequent interleukin-22 production. In mice, indole derivatives of the maternal microbiota can reach the milk and drive early postnatal ILC3 development.

Stress-regulated Arabidopsis GAT2 is a low affinity γ-aminobutyric acid transporter.

The four-carbon non-proteinogenic amino acid γ-aminobutyric acid (GABA) accumulates to high levels in plants in response to various abiotic and biotic stress stimuli, and plays a role in C:N balance, signaling, and as a transport regulator. Expression in Xenopus oocytes and voltage-clamping allowed the characterization of Arabidopsis GAT2 (At5g41800) as a low affinity GABA transporter with a K0.5GABA ~8 mM.

Far-red light increases maize volatile emissions in response to volatile cues from neighbouring plants.

Plants perceive the presence and defence status of their neighbours through light and volatile cues, but how plants integrate both stimuli is poorly understood. We investigated if and how low Red to Far red light (R:FR) ratios, indicative of shading or canopy closure, affect maize (Zea mays) responses to herbivore-induced plant volatiles (HIPVs), including the green leaf volatile (Z)-3-hexenyl acetate. We modulated light signalling and perception by using FR supplementation and a phyB1phyB2 mutant, and we determined volatile release as a response readout.

Root-exuded specialized metabolites reduce arsenic toxicity in maize.

By releasing specialized metabolites, plants modify their environment. Whether and how specialized metabolites protect plants against toxic levels of trace elements is not well understood. We evaluated whether benzoxazinoids, which are released into the soil by major cereals, can confer protection against arsenic toxicity.

Volatile-mediated oviposition preference for healthy over root-infested plants by the European corn borer.

The selection of oviposition sites by female moths is crucial in shaping their progeny performance and survival, and consequently in determining insect fitness. Selecting suitable plants that promote the performance of the progeny is referred to as the Preference-Performance hypothesis (or 'mother-knows-best'). While root infestation generally reduces the performance of leaf herbivores, little is known about its impact on female oviposition.

Isolation and Structure Determination of Drought-Induced Multihexose Benzoxazinoids from Maize ().

Benzoxazinoids (BXDs) are plant specialized metabolites exerting a pivotal role in plant nutrition, allelopathy, and defenses. Multihexose benzoxazinoids were previously observed in cereal-based food products such as whole-grain bread. However, their production in plants and exact structure have not been fully elucidated.

The Chemical Ecology of Benzoxazinoids.

Benzoxazinoids are specialized metabolites that modulate plant physiology and plant interactions with their environment. In this review, we synthesize their multiple functions and ecological relevance. We first provide an overview of benzoxazinoid biosynthesis and highlight known regulatory elements involved in modulating their production.

Trade-offs between the accumulation of cuticular wax and jasmonic acid-mediated herbivory resistance in maize.

Plants have evolved complex physical and chemical defense systems that allow them to withstand herbivory infestation. Composed of a complex mixture of very-long-chain fatty acids (VLCFAs) and their derivatives, cuticular wax constitutes the first physical line of defense against herbivores. Here, we report the function of Glossy 8 (ZmGL8), which encodes a 3-ketoacyl reductase belonging to the fatty acid elongase complex, in orchestrating wax production and jasmonic acid (JA)-mediated defenses against herbivores in maize (Zea mays).

Bacterial tolerance to host-exuded specialized metabolites structures the maize root microbiome.

Plants exude specialized metabolites from their roots, and these compounds are known to structure the root microbiome. However, the underlying mechanisms are poorly understood. We established a representative collection of maize root bacteria and tested their tolerance against benzoxazinoids (BXs), the dominant specialized and bioactive metabolites in the root exudates of maize plants.

Plant secondary metabolite-dependent plant-soil feedbacks can improve crop yield in the field.

Plant secondary metabolites that are released into the rhizosphere alter biotic and abiotic soil properties, which in turn affect the performance of other plants. How this type of plant-soil feedback affects agricultural productivity and food quality in the field in the context of crop rotations is unknown. Here, we assessed the performance, yield and food quality of three winter wheat varieties growing in field plots whose soils had been conditioned by either wild type or benzoxazinoid-deficient maize mutant plants.

Stress tolerance in entomopathogenic nematodes: Engineering superior nematodes for precision agriculture.

Entomopathogenic nematodes (EPNs) are soil-dwelling parasitic roundworms commonly used as biocontrol agents of insect pests in agriculture. EPN dauer juveniles locate and infect a host in which they will grow and multiply until resource depletion. During their free-living stage, EPNs face a series of internal and environmental stresses.

Turnover of Benzoxazinoids during the Aerobic Deterioration of Maize Silage ().

While plant-specialized metabolites can affect mammal health, their fate during the aerobic deterioration of crop silage remains poorly understood. In this study, we investigated the metabolization of benzoxazinoids (BXs) in silages of two maize genotypes (W22 wild type and mutant line) during aerobic deterioration. In W22 plants, concentrations of the aglucone BXs DIMBOA and HMBOA in silage decreased over time upon air exposure, while concentrations of MBOA and BOA increased.

Metabolization and sequestration of plant specialized metabolites in insect herbivores: Current and emerging approaches.

Herbivorous insects encounter diverse plant specialized metabolites (PSMs) in their diet, that have deterrent, anti-nutritional, or toxic properties. Understanding how they cope with PSMs is crucial to understand their biology, population dynamics, and evolution. This review summarizes current and emerging cutting-edge methods that can be used to characterize the metabolic fate of PSMs, from ingestion to excretion or sequestration.

Soil chemistry determines whether defensive plant secondary metabolites promote or suppress herbivore growth.

Plant secondary (or specialized) metabolites mediate important interactions in both the rhizosphere and the phyllosphere. If and how such compartmentalized functions interact to determine plant-environment interactions is not well understood. Here, we investigated how the dual role of maize benzoxazinoids as leaf defenses and root siderophores shapes the interaction between maize and a major global insect pest, the fall armyworm.

Climate Change Modulates Multitrophic Interactions Between Maize, A Root Herbivore, and Its Enemies.

How climate change will modify belowground tritrophic interactions is poorly understood, despite their importance for agricultural productivity. Here, we manipulated the three major abiotic factors associated with climate change (atmospheric CO, temperature, and soil moisture) and investigated their individual and joint effects on the interaction between maize, the banded cucumber beetle (Diabrotica balteata), and the entomopathogenic nematode (EPN) Heterorhabditis bacteriophora. Changes in individual abiotic parameters had a strong influence on plant biomass, leaf wilting, sugar concentrations, protein levels, and benzoxazinoid contents.