Metabolism of plant-derived toxins from its insect host increases the success of the entomopathogenic fungus Beauveria bassiana

Multiple glutathione-S-transferases detoxify diverse glucosinolate-based defenses of Brassicales plants in a generalist lepidopteran herbivore (Spodoptera littoralis)

Brassicales plants defend themselves with glucosinolates that, upon herbivory, are hydrolyzed into toxic isothiocyanates (ITCs) and other derivatives. The side chain diversity of glucosinolates results in a range of structurally distinct products, but how this chemical variation affects herbivores and their detoxification responses remains incompletely understood. Here, we show the effects of ITC hydrolysis products with various side chains on Spodoptera littoralis larvae and their detoxification system. ITCs inhibit larval growth to varying degrees, depending on the chemical nature of their side chain. The larvae metabolize ITCs by conjugating them to glutathione in the mercapturic acid pathway and to lysine forming an amine conjugate. Over half of the 34 S. littoralis glutathione-S-transferases (GSTs), tested as His-tagged derivatives, actively conjugate ITCs, with most catalyzing reactions with multiple substrates. Larval performance on various ITC-containing diets correlates positively with GST activity, highlighting this detoxification system's role in supporting growth on glucosinolate-containing plants. The propensity of multiple GSTs to react with an individual ITC and the wide expression of GST-encoding genes across larval organs likely promote the ability of this generalist herbivore to thrive on glucosinolate-defended Brassicales plants. These findings provide insight into herbivore adaptation and may inform future research on plant-insect interactions.

Inhibition of Glucosinolate Sulfatases to Combat Plutella xylostella: Development of Novel Phenylcarboxamide Derivatives for Plant-Integrated Pest Management

Glucosinolates in cruciferous plants are hydrolyzed by myrosinase to produce toxic isothiocyanates (ITCs). However, Plutella xylostella (P. xylostella), one of the top 10 global agricultural pests, utilizes glucosinolate sulfatases (GSSs) in its gut to convert glucosinolates into nontoxic desulfo-glucosinolates, thereby effectively avoiding the toxicity of ITCs. This study investigates the potential of inhibiting GSSs. Among 16 synthesized phenylcarboxamide derivatives, compound 1n exhibited strong inhibitory activity against GSS1 (59.72%) and GSS2 (88.47%), key enzymes involved in glucosinolate desulfation in P. xylostella, leading to toxic ITC accumulation and disrupted detoxification. This resulted in an approximately 30% reduction in larval weight, at a concentration of 100 mg/L, the mortality rate reached 96%. Importantly, in the absence of glucosinolates, these inhibitors showed no direct toxicity to the insect, indicating that their action relies on interaction with the plant's chemical defense system. These findings provide strong evidence supporting the development of GSSs inhibitions as more specific and selective insecticide, offering a promising alternative to conventional chemical pesticides.

Plant-aphid interactions: recent trends in plant resistance to aphids

Aphids are highly destructive agricultural pests characterized by complex life cycles and phenotypic variability, facilitating their adaptation to diverse climates and host plants. Their feeding behavior leads to plant deformation, wilting, stunted growth, disease transmission, and significant yield losses. Given the economic risks aphids pose, regular updates on their seasonal behaviors, adaptive mechanisms, and destructive activities are critical for improving management strategies to mitigate crop losses. This review comprehensively synthesizes recent studies on aphids as plant pests, the extrinsic factors influencing their life cycles, and the intricate interactions between aphids and their hosts. It also highlights recent advancements in biological control measures, including natural enemies, antibiosis, and antixenosis. Additionally, we explore plant defense mechanisms against aphids, focusing on the roles of cell wall components such as lignin, pectin and callose deposition and the genetic regulations underlying these defenses. Aphids, however, can evolve specialized strategies to overcome general plant defenses, prompting the development of targeted mechanisms in plants, such as the use of resistance (R) genes against specific aphid species. Additionally, plant pattern recognition receptors (PRRs) recognize compounds in aphid saliva, which triggers enhanced phloem sealing and more focused immune responses. This work enhances understanding of aphid-plant interaction and plant resistance and identifies key research gaps for future studies.

Harnessing Fungal Bioagents Rich in Volatile Metabolites for Sustainable Crop Protection: A Critical Review

Pests and diseases have a significant impact on crop health and yields, posing a serious threat to global agriculture. Effective management strategies, such as integrated pest management (IPM), including crop rotation, use of synthetic pesticides, biological control, and resistant/tolerant crop varieties, are essential to mitigate these risks and ensure sustainable agricultural practices. Fungal bioagents play an important role in managing phytopathogens and insect pests by acting as biological agents. They promote healthy plant growth by enhancing the uptake of nutrients and combating systemic resistance in plants. Furthermore, fungal bioagents are environmentally friendly, reducing application of fungicides and insecticides and minimizing their negative impact on the crops and environment. Their use in IPM promotes sustainable agriculture and ensures high-quality crops while maintaining soil health and microbial biodiversity. These fungal bioagents are rich sources of volatile organic compounds (VOCs), which play an important role in biological communication during interaction with insect pests and phytopathogens. In pest management, VOC production by beneficial fungi is accountable for their efficacy against pests and pathogens. Thus, this review discusses the important fungal bioagents producing VOCs, extraction methods of VOC, and the use of VOC-producing fungi in pest and disease management, knowledge gaps, and future research areas.

Keystone root bacteria in Ambrosia artemisiifolia promote invasive growth by increasing the colonization rate of Funneliformis mosseae

Higher arbuscular mycorrhizal fungi (AMF) colonization rates in the roots of invasive plants than in those of native plants are associated with invasion success. Keystone plant-root bacteria (or root-associated bacteria) can influence plant growth by interacting with other members of the microbial community (eg.AMF). We aimed to investigate the effects of keystone taxa on AMF colonization and their interactions on invasive plant growth. Here, the common key root-associated species from the roots of Ambrosia artemisiifolia among four geographical populations in China were identified, and the strains were subsequently isolated. Plate and pot experiments were conducted to examine the impact of keystone species on the colonization of Funneliformis mosseae and elucidate the mechanisms that enhance plant growth. Sphingomonas was identified as a common keystone root-associated genus of A. artemisiifolia. Sphingomonas sanxanigenens was found to facilitate AMF colonization in the roots of A. artemisiifolia by promoting flavonoid biosynthesis. A synergistic effect on the growth of A. artemisiifolia was observed when the plant was co-inoculated with S. sanxanigenens and F. mosseae. This study provides new insights into the mechanisms whereby root-associated microbes facilitate AMF colonization in invasive plants. These findings confirm the pivotal role of keystone microbes in weed invasion and enhance our understanding that microbial synergistic interactions promote weed invasiveness.

A Comprehensive Review of the Diversity of Fungal Secondary Metabolites and Their Emerging Applications in Healthcare and Environment

Fungi and their natural products, like secondary metabolites, have gained a huge demand in the last decade due to their increasing applications in healthcare, environmental cleanup, and biotechnology-based industries. The fungi produce these secondary metabolites (SMs) during the different phases of their growth, which are categorized into terpenoids, alkaloids, polyketides, and non-ribosomal peptides. These SMs exhibit significant biological activity, which contributes to the formulation of novel pharmaceuticals, biopesticides, and environmental bioremediation agents. Nowadays, these fungal-derived SMs are widely used in food and beverages, for fermentation, preservatives, protein sources, and in dairy industries. In healthcare, it is being used as an antimicrobial, anticancer, anti-inflammatory, and immunosuppressive drug. The usage of modern tools of biotechnology can achieve an increase in demand for these SMs and large-scale production. The present review comprehensively analyses the diversity of fungal SMs along with their emerging applications in healthcare, agriculture, environmental sustainability, and nutraceuticals. Here, the authors have reviewed the recent advancements in genetic engineering, metabolic pathway manipulation, and synthetic biology to improve the production and yield of these SMs. Advancement in fermentation techniques, bioprocessing, and co-cultivation approaches for large-scale production of SMs. Investigators further highlighted the importance of omics technologies in understanding the regulation and biosynthesis of SMs, which offers an understanding of novel applications in drug discovery and sustainable agriculture. Finally, the authors have addressed the potential for genetic manipulation and biotechnological innovations for further exploitation of fungal SMs for commercial and environmental benefits.

Glucosinolate structural diversity shapes recruitment of a metabolic network of leaf-associated bacteria

Host defenses can have broader ecological roles, but how they shape natural microbiome recruitment is poorly understood. Aliphatic glucosinolates (GLSs) are secondary defense metabolites in Brassicaceae plant leaves. Their genetically defined structure shapes interactions with pests in Arabidopsis thaliana leaves, and here we find that it also shapes bacterial recruitment. In model genotype Col-0, GLSs (mostly 4-methylsulfinylbutyl-GLS) have no clear effect on natural leaf bacterial recruitment. In a genotype from a wild population, however, GLSs (mostly allyl-GLS) enrich specific taxa, mostly Comamonadaceae and Oxalobacteraceae. Consistently, Comamonadaceae are also enriched in wild A. thaliana, and Oxalobacteraceae are enriched from wild plants on allyl-GLS as carbon source, but not on 4-methylsulfinylbutyl-GLS. Recruitment differences between GLS structures most likely arise from bacterial myrosinase specificity. Community recruitment is then defined by metabolic cross-feeding among bacteria. The link of genetically defined metabolites to recruitment could lead to new strategies to shape plant microbiome balance.

Essentials in the acquisition, interpretation, and reporting of plant metabolite profiles

Plant metabolite profiling reveals the diversity of secondary or specialized metabolites in the plant kingdom with its hundreds of thousands of species. Specialized plant metabolites constitute a vast class of chemicals posing significant challenges in analytical chemistry. In order to be of maximum scientific relevance, reports dealing with these compounds and their source species must be transparent, make use of standards and reference materials, and be based on correctly and traceably identified plant material. Essential aspects in qualitative plant metabolite profiling include: (i) critical review of previous literature and a reasoned sampling strategy; (ii) transparent plant sampling with wild material documented by vouchers in public herbaria and, optimally, seed banks; (iii) if possible, inclusion of generally available reference plant material; (iv) transparent, documented state-of-the art chemical analysis, ideally including chemical reference standards; (v) testing for artefacts during preparative extraction and isolation, using gentle analytical methods; (vi) careful chemical data interpretation, avoiding over- and misinterpretation and taking into account phytochemical complexity when assigning identification confidence levels, and (vii) taking all previous scientific knowledge into account in reporting the scientific data. From the current stage of the phytochemical literature, selected comments and suggestions are given. In the past, proposed revisions of botanical taxonomy were sometimes based on metabolite profiles, but this approach ("chemosystematics" or "chemotaxonomy") is outdated due to the advent of DNA sequence-based phylogenies. In contrast, systematic comparisons of plant metabolite profiles in a known phylogenetic framework remain relevant. This approach, known as chemophenetics, allows characterizing species and clades based on their array of specialized metabolites, aids in deducing the evolution of biosynthetic pathways and coevolution, and can serve in identifying new sources of rare and economically interesting natural products.