Biology subjects

Hofte, M.

Publications and source records attributed to Hofte, M..

5 recordsLinked to original sources

bioRxiv2026

Polyphyletic origin and horizontal exchange drive the emergence of a novel resistance-breaking Fusarium oxysporum f. sp. lactucae race

Fusarium oxysporum f. sp. lactucae (Fola), the cause of lettuce fusarium wilt, poses an increasing threat to global production due to the rapid emergence of resistance breaking isolates. However, the evolutionary origins and mechanisms underpinning this diversification remain poorly understood. We characterised 103 Fola isolates using molecular profiling, selecting ten key isolates for long-read whole-genome sequencing and performed in planta virulence assays for selected isolates. This included the first assemblies for Fola2 and Fola3, recent resistance-breaking variants and a highly divergent isolate from France designated as a putative novel race, FolaX. Phylogenomic analysis revealed that Fola is polyphyletic, with lettuce pathogenicity acquired independently across divergent F. oxysporum clades. Despite this, all lineages share a conserved "PanFola" effector set with near-identical sequences, indicating extensive horizontal gene transfer. Resistance-breaking Fola variants within established races were linked to copy number variations and targeted deletions, such as the loss of the SIX8/PSE1 locus in Fola4+. Conversely, FolaX possessed a divergent core genome and a chimeric accessory genome derived from multiple Fola lineages via segmental chromosome transfer and transposon-mediated reshuffling. Our findings highlight the remarkable evolutionary plasticity of Fola and the need for breeding strategies that address the dynamic nature of effector repertoires.

pathology↗

bioRxiv2025

Starship giant transposons dominate plastic genomic regions in a fungal plant pathogen and drive virulence evolution

Starships form a recently discovered superfamily of giant transposons in Pezizomycotina fungi, implicated in mediating horizontal transfer of diverse cargo genes between fungal genomes. Their elusive nature has long obscured their significance, and their impact on genome evolution remains poorly understood. Here, we reveal a surprising abundance and diversity of Starships in the phytopathogenic fungus Verticillium dahliae. Remarkably, Starships dominate the plastic genomic compartments involved in host colonization, are enriched in virulence-associated genes, and exhibit genetic and epigenetic characteristics associated with adaptive genome evolution. We further uncover extensive horizontal transfer of Starships between Verticillium species and, strikingly, from distantly related Fusarium fungi. Finally, we demonstrate how Starship activity facilitated the de novo formation of a novel virulence gene. Our findings illuminate the profound influence of Starship dynamics on fungal genome evolution and the development of virulence.

microbiology↗

bioRxiv2023

Mechanosensing and Sphingolipid-Docking Mediate Lipopetide-Induced Immunity in Arabidopsis

Bacteria-derived lipopeptides are immunogenic triggers of host defenses in metazoans and plants. Root-associated rhizobacteria produce cyclic lipopeptides that activate systemically induced resistance (IR) against microbial infection in various plants. How these molecules are perceived by plant cells remains elusive. Here, we reveal that immunity activation in Arabidopsis thaliana by the lipopeptide elicitor surfactin is mediated by docking into specific sphingolipid-enriched domains and relies on host membrane deformation and subsequent activation of mechanosensitive ion channels. This mechanism leads to host defense potentiation and resistance to the necrotroph B. cinerea but is distinct from host pattern recognition receptor-mediated immune activation and reminiscent of damage-induced plant immunity.

plant biology↗

bioRxiv2022

An NMR fingerprint matching approach for the identification and structural re-evaluation of Pseudomonas lipopeptides.

Cyclic lipopeptides (CLiPs) are secondary metabolites secreted by a range of bacterial phyla. CLiPs from Pseudomonas in particular display diverse structural variations in terms of the number of amino acid residues, macrocycle size, amino acid identity and stereochemistry (e.g. D- vs. L-amino acids). Reports detailing the discovery of novel or already characterized CLiPs from new sources appear regularly in literature. Increasingly however, the lack of detailed characterization threatens to cause considerable confusion, especially if configurational heterogeneity is present for one or more amino acids. Using Pseudomonas CLiPs from the Bananamide, Orfamide and Xantholysin groups as test cases, we demonstrate and validate that 1H and 13C NMR chemical shifts of CLiPs are sufficiently sensitive to differentiate between possible diastereomers of a particular sequence even when they only differ in a single D/L configuration. Rapid screening, involving simple comparison of the NMR fingerprint of a newly isolated CLiP with that of a reference CLiP of known stereochemistry, can then be applied to resolve dead-ends in configurational characterization and avoid the much more cumbersome chemical characterization protocols. Even when the stereochemistry of a particular reference CLiP remains to be established, NMR fingerprinting still allows verifying whether a CLiP from a novel source is already present in the reference collection, thus contributing to dereplication. To benefit research involving CLiPs, we have made a publicly available knowledge base at https://www.rhizoclip.be, where we present an overview of published NMR fingerprint data of characterized CLiPs, together with literature data on the originally determined structures. Significance StatementPseudomonas CLiPs, are ubiquitous specialized metabolites, impacting the producers lifestyle and interactions with the (a)biotic environment. Consequently, they generate interest for agricultural and clinical applications. Establishing structure-activity relationships as premise to their development is hindered because full structural characterization including stereochemistry requires labor-intensive analyses, without guarantee for success. Moreover, increasing use of superficial comparison with previously characterized CLiPs introduces or propagates erroneous attributions, clouding further scientific progress. We provide a generally applicable characterization methodology for structural comparison of newly isolated CLiPs to reference compounds with (un)known stereochemistry based on NMR fingerprints. The reference compound database available for the wide scientific community promises to facilitate structural assessment and dereplication of newly isolated CLiPs, and to support genome mining for novel CLiPs.

microbiology↗

bioRxiv2021

Chelator sensing and lipopeptide interplay mediates molecular interspecies interactions between soil bacilli and pseudomonads

AbstractSome bacterial species are important members of the rhizosphere microbiome and confer protection to the host plant against pathogens. However, our knowledge of the multitrophic interactions determining the ecological fitness of these biocontrol bacteria in their highly competitive natural niche is still limited. In this work, we investigated the molecular mechanisms underlying interactions between B. velezensis, considered as model plant-associated and beneficial species in the Bacillus genus, and Pseudomonas as a rhizosphere-dwelling competitor. Our data show that B. velezensis boosts its arsenal of specialized antibacterials upon the perception of the secondary siderophore enantio-pyochelin produced by phylogenetically distinct pseudomonads and some other genera. We postulate that B. velezensis has developed some chelator sensing systems to learn about the identity of its surrounding competitors. Illustrating the multifaceted molecular response of Bacillus, surfactin is another crucial component of the secondary metabolome mobilized in interbacteria competition. Its accumulation not only enhances motility but, unexpectedly, the lipopeptide also acts as a chemical trap that reduces the toxicity of other lipopeptides released by Pseudomonas challengers. This in turn favors the persistence of Bacillus populations upon competitive root colonization. Our work thus highlights new ecological roles for bacterial secondary metabolites acting as key drivers of social interactions.

microbiology↗