2025-09-09 浙江大学(ZJU)
Web要約 の発言:
<関連情報>
- https://www.zju.edu.cn/english/2025/0909/c19573a3079243/page.psp
- https://www.science.org/doi/10.1126/science.adv6675
リナロール誘発の植物-土壌フィードバックが、高密度トウモロコシ栽培における防御適応を促進する Linalool-triggered plant-soil feedback drives defense adaptation in dense maize plantings
Dongsheng Guo, Zilin Liu, Jos M. Raaijmakers, Yachun Xu, […] , and Lingfei Hu
Science Published:14 Aug 2025
DOI:https://doi.org/10.1126/science.adv6675
Editor’s summary
Maize plants emit a volatile gas called linalool, which can influence the growth and development of neighboring plants. Guo et al. found that at high planting densities, high linalool concentrations triggered neighboring plants to release benzoxazinoids into the soil (see the Perspective by Schandry and Becker). These compounds cause the soil microbiota to change composition, with knock-on effects for plants that are subsequently grown there. The altered microbiome enhances defense responses to herbivores but reduces plant growth. These findings demonstrate the implications of high planting density on multiple facets of the plant growth environment. —Madeleine Seale
Structured Abstract
INTRODUCTION
Planting crops more densely increases overall yields, but it also raises the risk of pest and pathogen outbreaks. Although plants can modify their architecture to adapt to crowded conditions, how they adjust their immune responses remains largely unknown. Understanding how plants manage these trade-offs is critical for sustainable agriculture, especially in the context of increasing global food demands.
RATIONALE
Plants release chemical cues, such as volatiles, that inform neighbors of environmental conditions. One such compound, linalool, is a constitutively emitted leaf volatile in maize and other grasses. We hypothesized that linalool could act as a signal in densely planted fields, triggering plant-soil feedback that prepares neighboring plants for potential biotic stress. We explored how linalool shapes root signaling, soil microbiota, and ultimately plant defense and growth.
RESULTS
Field surveys revealed that maize plants in the inner rows of densely planted fields suffered less herbivore damage than those at the edges but that they also had reduced growth. Laboratory soil–transplantation experiments confirmed that soils conditioned by high-density plantings decreased plant biomass while enhancing resistance to insects, nematodes, and pathogens. These effects extended across genotypes and species.
Volatile profiling identified linalool as a key compound increasing with planting density. Exposure of maize to synthetic linalool reproduced the feedback effects, which required the presence of a living plant. Mechanistically, linalool activated jasmonate signaling in roots and up-regulated genes that drive the biosynthesis and exudation of the specialized metabolite HDMBOA-Glc. This exudate reshaped the rhizosphere microbiome, selectively enriching bacteria that suppressed plant growth but increased resistance in subsequently grown plants. Soil sterilization and microbial inoculation confirmed that these microbes were essential for the feedback loop.
In plants grown in linalool-conditioned soil, defense-related signaling, particularly salicylic acid signaling, was up-regulated, whereas growth-promoting metabolic pathways were down-regulated. Plants lacking salicylic acid signaling did not show growth-defense trade-offs, confirming salicylic acid’s role in expressing the feedback-triggered defense.
CONCLUSION
This study uncovers a volatile-triggered feedback mechanism through which maize adapts its defense in crowded environments. The constitutive emission of linalool primes neighboring plants by activating root jasmonate signaling, promoting HDMBOA-Glc exudation, and altering the rhizosphere microbiome. This, in turn, leads to elevated defense and suppressed growth in subsequent plants through salicylic acid signaling. These findings shed light on how plants integrate aboveground cues and belowground processes to optimize defense in high-density settings. Harnessing this natural defense pathway through breeding, microbial inoculants, or synthetic biology could enable the development of crops that are more resilient and require fewer chemical inputs.
Model illustrating how dense planting triggers plant-soil feedback to enhance maize resistance.
High-density planting increases canopy linalool, which activates systemic jasmonic acid (JA) signaling and HDMBOA-Glc exudation from roots. These exudates selectively enrich rhizosphere bacteria that induce salicylic acid (SA) signaling, thereby enhancing maize resistance. This defense-promoting feedback comes at a cost to maize growth. Some components of this figure were created by BioRender.com.
Abstract
High planting density boosts crop yields but also heightens pest and pathogen risks. How plants adapt their defenses under these conditions remains unclear. In this study, we reveal that maize enhances its defense in high-density conditions through a plant-soil feedback mechanism triggered by the leaf volatile linalool. Linalool activates jasmonate signaling in neighboring plants and promotes root exudation of benzoxazinoids, especially 2-(2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one)-β-d-glucopyranose (HDMBOA-Glc). These exudates in turn reshape the rhizosphere microbiome composition to favor growth of specific bacterial taxa that trigger broad-spectrum resistance, albeit at the cost of maize growth. This microbiome-driven feedback loop is governed by salicylic acid signaling. Our findings uncover intricate chemical signaling in high-density cropping, which is instrumental for improving soil health and designing sustainable strategies that balance the trade-off between plant growth and defense.
