Non‐volatile metabolites constitute the bulk of plant biomass. From the perspective of plant–insect interactions, these structurally diverse compounds include nutritious core metabolites and defensive specialized metabolites. In this review, we synthesize the current literature on multiple scales of plant–insect interactions mediated by non‐volatile metabolites. At the molecular level, functional genetics studies have revealed a large collection of receptors targeting plant non‐volatile metabolites in model insect species and agricultural pests. By contrast, examples of plant receptors of insect‐derived molecules remain sparse. For insect herbivores, plant non‐volatile metabolites function beyond the dichotomy of core metabolites, classed as nutrients, and specialized metabolites, classed as defensive compounds. Insect feeding tends to elicit evolutionarily conserved changes in plant specialized metabolism, whereas its effect on plant core metabolism varies widely based the interacting species. Finally, several recent studies have demonstrated that non‐volatile metabolites can mediate tripartite communication on the community scale, facilitated by physical connections established through direct root‐to‐root communication, parasitic plants, arbuscular mycorrhizae and the rhizosphere microbiome. Recent advances in both plant and insect molecular biology will facilitate further research on the role of non‐volatile metabolites in mediating plant–insect interactions.
Soil communities are diverse taxonomically and functionally. This ecosystem experiences highly complex networks of interactions, but may also present functionally independent entities. Plant roots, a metabolically active hotspot in the soil, take an essential part in below‐ground interactions. While plants are known to release an extremely high portion of the fixated carbon to the soil, less information is known about the composition and role of C‐containing compounds in the rhizosphere, in particular those involved in chemical communication. Specialized metabolites (or secondary metabolites) produced by plants and their associated microbes have a critical role in various biological activities that modulate the behavior of neighboring organisms. Thus, elucidating the chemical composition and function of specialized metabolites in the rhizosphere is a key element in understanding interactions in this below‐ground environment. Here, we review key classes of specialized metabolites that occur as mostly non‐volatile compounds in root exudates or are emitted as volatile organic compounds (VOCs). The role of these metabolites in below‐ground interactions and response to nutrient deficiency, as well as their tissue and cell type‐specific biosynthesis and release are discussed in detail.
more » « less- PAR ID:
- 10035119
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- The Plant Journal
- Volume:
- 90
- Issue:
- 4
- ISSN:
- 0960-7412
- Page Range / eLocation ID:
- p. 788-807
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Plants deploy both primary and species-specific, specialized metabolites to communicate with other organisms and adapt to environmental challenges, including interactions with soil-dwelling microbial communities. However, the role of specialized metabolites in modulating plant-microbiome interactions often remains elusive. In this study, we report that maize (
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Abstract Premise The specialized metabolites of plants are recognized as key chemical traits in mediating the ecology and evolution of sundry plant–biotic interactions, from pollination to seed predation. Intra‐ and interspecific patterns of specialized metabolite diversity have been studied extensively in leaves, but the diverse biotic interactions that contribute to specialized metabolite diversity encompass all plant organs. Focusing on two species of Psychotria shrubs, we investigated and compared patterns of specialized metabolite diversity in leaves and fruit with respect to each organ's diversity of biotic interactions. Methods To evaluate associations between biotic interaction diversity and specialized metabolite diversity, we combined UPLC‐MS metabolomic analysis of foliar and fruit specialized metabolites with existing surveys of leaf‐ and fruit‐centered biotic interactions. We compared patterns of specialized metabolite richness and variance among vegetative and reproductive tissues, among plants, and between species. Results In our study system, leaves interact with a far larger number of consumer species than do fruit, while fruit‐centric interactions are more ecologically diverse in that they involve antagonistic and mutualistic consumers. This aspect of fruit‐centric interactions was reflected in specialized metabolite richness—leaves contained more than fruit, while each organ contained over 200 organ‐specific specialized metabolites. Within each species, leaf‐ and fruit‐specialized metabolite composition varied independently of one another across individual plants. Contrasts in specialized metabolite composition were stronger between organs than between species. Conclusions As ecologically disparate plant organs with organ‐specific specialized metabolite traits, leaves and fruit can each contribute to the tremendous overall diversity of plant specialized metabolites.more » « less
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Abstract The rhizosphere microbiome influences many aspects of plant fitness, including production of secondary compounds and defence against insect herbivores. Plants also modulate the composition of the microbial community in the rhizosphere via secretion of root exudates. We tested both the effect of the rhizosphere microbiome on plant traits, and host plant effects on rhizosphere microbes using recombinant inbred lines (RILs) of
Brassica rapa that differ in production of glucosinolates (GLS), secondary metabolites that contribute to defence against insect herbivores. First, we investigated the effect of genetic variation in GLS production on the composition of the rhizosphere microbiome. Using a Bayesian Dirichlet‐multinomial regression model (DMBVS), we identified both negative and positive associations between bacteria from six genera and the concentration of five GLS compounds produced in plant roots. Additionally, we tested the effects of microbial inoculation (an intact vs. disrupted soil microbiome) on GLS production and insect damage in these RILs. We found a significant microbial treatment × genotype interaction, in which total GLS was higher in the intact relative to the disrupted microbiome treatment in some RILs. However, despite differences in GLS production between microbial treatments, we observed no difference in insect damage between treatments. Together, these results provide evidence for a full feedback cycle of plant–microbe interactions mediated by GLS; that is, GLS compounds produced by the host plant “feed‐down” to influence rhizosphere microbial community and rhizosphere microbes “feed‐up” to influence GLS production. -
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