Biology subjects

Defossez, E.

Publications and source records attributed to Defossez, E..

4 recordsLinked to original sources

bioRxiv2024

Sanctioning of bacterial cheaters by the host plant in nitrogen-fixing symbiosis between Medicago truncatula and Sinorhizobium meliloti

In plant-microbe interactions, the host plant invests considerable amounts of resources in the microbial partner until the symbiotic machinery is established. If the microbial partner does not reciprocate with a comparable symbiotic benefit, the interaction represents a parasitic relationship. This is thought to elicit a plants response to prevent the selective disadvantage of being parasitized by such microbial cheaters. Indeed, negative feedback against bad mutualists, known as sanctioning, has been observed in interactions such as the arbuscular mycorrhizal and legume-rhizobium symbioses. Here, to study sanctioning by the plant host, we manipulate the exchange of resources between the model legume Medicago truncatula and its bacterial partner Sinorhizobium meliloti by three ways: mutating the bacterial nitrogenase enzyme, replacing nitrogen in the atmosphere with argon gas, and supplying high nitrate to the host. Then, we follow the consequences for the interaction by examining the metabolome, proteome, and phosphoproteome of nodules. We find that such cheating conditions result in sanctioning of the bacterial partner, and observe characteristic shifts including induced defense markers, repressed symbiotic markers, and changes in central metabolism that may be relevant for microbial fitness and that could therefore contribute to sanctioning.

plant biology↗

bioRxiv2024

Odor-based real-time detection and identification of pests and diseases attacking crop plants

Early detection of crop pests and diseases can enable timely, targeted interventions, and help reduce pesticide use. Plants under biotic stress are known to rapidly emit characteristic blends of volatile compounds that could potentially serve as early and attacker-specific cues for precise pest monitoring. Here, we evaluated the feasibility of this approach using two complementary, state-of-the-art sensing technologies: a handheld nanomechanical membrane-based sensor array and chemical ionization time-of-flight mass spectrometry. Under laboratory conditions, with enclosed headspace sampling, both technologies readily distinguished undamaged maize plants from plants infested by caterpillars or infected with a fungal pathogen. Under semi-controlled outdoor open-air conditions, where volatile concentrations were strongly diluted, the membrane-based sensor no longer retained discriminatory power, whereas mass spectrometry predicted herbivory status with more than 90% accuracy using one-second measurements. Finally, in an initial field trial based on simulated herbivory, a compact, field-deployable, real-time mass spectrometer distinguished damaged from undamaged maize plants with highly encouraging performance under real field conditions. Together, these results demonstrate the potential of odor-based detection of pest attacks in maize and identify real-time mass spectrometry as a promising tool for crop monitoring, while pinpointing challenges that remain to be addressed for translation to practical field applications.

plant biology↗

bioRxiv2024

plantMASST - Community-driven chemotaxonomic digitization of plants

Understanding the distribution of hundreds of thousands of plant metabolites across the plant kingdom presents a challenge. To address this, we curated publicly available LC-MS/MS data from 19,075 plant extracts and developed the plantMASST reference database encompassing 246 botanical families, 1,469 genera, and 2,793 species. This taxonomically focused database facilitates the exploration of plant-derived molecules using tandem mass spectrometry (MS/MS) spectra. This tool will aid in drug discovery, biosynthesis, (chemo)taxonomy, and the evolutionary ecology of herbivore interactions.

plant biology↗

bioRxiv2023

Leaf metabolic traits reveal hidden dimensions of plant form and function

The plant metabolome encompasses the biochemical mechanisms through which evolutionary and ecological processes shape plant form and function1,2. However, while the metabolome should thus be an important component of plant life-history variation3, we know little about how it varies across the plant kingdom. Here, we use the plant functional trait concept4 - a powerful framework for describing plant form and function5-7 - to interpret leaf metabolome variation among 457 tropical and 339 temperate plant species. Distilling metabolite chemistry into five discriminant metabolic functional traits reveals that plants vary along two major axes of leaf metabolic specialization - a leaf chemical defense spectrum and an expression of leaf longevity. These axes are qualitatively consistent for tropical and temperate species, with many trait combinations being viable. However, axes of leaf metabolic specialization vary orthogonally to life-history strategies described by widely used functional traits5-7, while being at least equally important to them. Our findings question classical trait6 and plant defense8 theory that predicts relationships between the leaf chemical phenotype, plant productivity, and pace of life. Moreover, we show that metabolic functional traits describe unique dimensions of plant life-history variation that are complementary to, and independent from, those captured by existing plant functional traits.

ecology↗