Biology subjects

Chesneau, G.

Publications and source records attributed to Chesneau, G..

6 recordsLinked to original sources

bioRxiv2025

Genetic factors driving multi-host infection in a core member of the root mycobiota

Core members of the fungal root microbiota include pathogens capable of colonizing multiple hosts, yet the underlying genetic determinants remain unknown. We report that Plectosphaerella cucumerina is a core member of the Arabidopsis thaliana root microbiota displaying high pathogenic potential and multi-host colonization capabilities. Establishment of a Plectosphaerella reference culture collection, followed by whole-genome sequencing of 72 strains reveals subtle phenotypic and genotypic variation that associate with fungal phylogeny, but not host plant identity. Transcriptome profiling of a model P. cucumerina isolate in roots of multiple hosts identifies core and host-specific fungal processes linked to carbon catabolism and root cell wall deconstruction of the hosts. A fungal gene encoding a candidate {beta}-1,3-glucanase (GH64) was identified as a key genetic factor driving infection and disease in plants that diverged 110 million years ago. The gene is enriched in plant-colonizing fungi and consistently functions as a disease determinant in the root pathogen Colletotrichum incanum. We conclude that diverse and tunable fungal repertoires of carbohydrate-active enzymes act as disease determinants and drive multi-host compatibility belowground.

microbiology↗

bioRxiv2025

Lactuchelins: New lipopeptide siderophores from Pseudomonas lactucae inhibit Xanthomonas campestris pv. campestris 8004

Seeds harbor diverse microbial communities, including beneficial microbes that play a vital role in protecting plants from seed-borne pathogens. Despite their critical importance, the molecular mechanisms driving intermicrobial competition within the seed microbiome remain poorly understood, limiting the potential to optimize seed inoculation strategies. In this study, we evaluated the inhibitory potential of 30 seed-borne bacterial strains against the phytopathogen Xanthomonas campestris pv. campestris 8004 (Xcc8004). We identified Pseudomonas lactucae CFBP13502 as a potent inhibitor of Xcc8004, mediated by exometabolites specifically induced in the presence of Lysobacterales (formerly Xanthomonadales). Transcriptomic analysis of CFBP13502 revealed upregulation of a gene cluster involved in the biosynthesis of a lipopeptide siderophore biosynthesis. Gene deletion confirmed that this cluster is essential for the growth inhibition of Xcc8004. Furthermore, iron supplementation abolished this inhibitory effect, providing strong evidence for the role of iron chelation. Through comparative metabolomics, we elucidated the structure of a novel family of lipopeptide siderophores, which we named lactuchelins, produced by CFBP13502. Our findings provide the first molecular evidence of competitive exclusion mechanisms at the seed microbiome interface, highlighting lactuchelins as a promising avenue for the development of seed-based biocontrol strategies against seed-borne phytopathogens.

microbiology↗

bioRxiv2024

Plant phenotypic differentiation outweighs genetic variation in shaping the lettuce leaf microbiota

Lettuce is a widely consumed raw vegetable, making it crucial to understand and predict its leaf-associated microbial communities for the benefit of both plant and human health. While environmental factors are known to strongly influence plant leaf microbiomes, the role of plant-specific determinants in shaping microbial diversity remains unclear. In this study, we investigated the impact of three key plant factors -genetic distance, morphology and leaf micro- and macronutrient content- on the composition and diversity of lettuce leaf bacterial communities. Using 131 fully-sequenced Lactuca sativa genotypes, we analyzed their leaf-associated bacterial communities via 16S rRNA amplicon sequencing. Our findings revealed that morphological classification, as defined by breeders, exerts a greater influence on bacterial community diversity than genetic distance or variations in leaf nutrient levels. Together with shoot traits they explained 13.9% of the observed bacterial diversity. Further analysis of 10 specific leaf morphological traits showed that heart formation, head height, and venation types significantly shaped bacterial richness and evenness, mainly acting on non-hub members. The strong association between leaf morphology and bacterial community structure suggests that phenotypic traits play a disproportionately large, yet understudied, role in leaf microbiota establishment offering new potential for manipulation by breeders.

plant biology↗

bioRxiv2024

A molecular basis for plant SCAR/WAVE functional divergence

Dynamic actin cytoskeleton reorganisation enables plant developmental processes requiring polarised transport such as root hair and leaf trichome formation. The SCAR/WAVE complex plays a crucial role in regulating these dynamics through ARP2/3-mediated actin branching. SCAR/WAVE genes occur as small families across a wide range of plant species but whether and how they fulfil different functions remains unclear. We utilise a systematic chimaera approach to define the differential functionality of two closely related Medicago truncatula SCAR proteins in plant development. We show that SCAR/WAVE contribution to Medicago truncatula root hair or Arabidopsis thaliana trichome formation is dependent on two central intrinsically disordered regions (IDRs). Differential functionalities of Medicago truncatula SCAR proteins were furthermore associated with the presence/absence of a 42-amino acid sequence within the IDR that impacted protein stability. Through uncovering a molecular basis for functional differences, we advance our understanding of plant SCAR/WAVE complexes. One Sentence SummaryIntrinsically disordered regions in SCAR/WAVE proteins drive diverse functions in root hair and leaf trichome development.

plant biology↗

bioRxiv2021

Seed microbiota revealed by a large-scale meta-analysis including 50 plant species

Seed microbiota constitutes a primary inoculum for plants that is gaining attention due to its role for plant health and productivity. Here, we performed a meta-analysis on 63 seed microbiota studies covering 50 plant species to synthesize knowledge on the diversity of this habitat. Seed microbiota are diverse and extremely variable, with taxa richness varying from one to thousands of taxa. Hence, seed microbiota presents a variable (i.e flexible) microbial fraction but we also identified a stable (i.e. core) fraction across samples. Around 30 bacterial and fungal taxa are present in most plant species and in samples from all over the world. Core taxa, such as Pantoea agglomerans, Pseudomonas viridiflava, P. fluorescens, Cladosporium perangustum and Alternaria sp., are dominant seed taxa. The characterization of the core and flexible seed microbiota provided here will help uncover seed microbiota roles for plant health and design effective microbiome engineering.

microbiology↗

bioRxiv2021

Single seed microbiota: assembly and transmission from parent plant to seedling

Gaining basic understanding of processes involved in seed microbiota assembly is a prerequisite for improving crop establishment. Investigation of microbiota structure during seed development revealed that individual seeds of bean and radish were associated with a dominant bacterial taxon representing more than 75% of all reads. The identity of this taxon was highly variable between plants and within seeds of the same plant. Succession of dominant taxa occurred during seed filling and maturation through Selection. In a second step, we evaluated seed to seedling transmission of these dominant seed-borne taxa. We showed that initial bacterial abundance on seeds was not a good predictor of seedling transmission and that the identity of seed-borne taxa can impact seedling phenotype. Altogether this work unveiled that seeds are colonized by few bacterial taxa of highly variable identity, which appears to be important for the early stages of plant development.

microbiology↗