Biology subjects

Lopez-Berges, M. S.

Publications and source records attributed to Lopez-Berges, M. S..

6 recordsLinked to original sources

bioRxiv2026

Killer meiotic driver prevents chromosome loss and enhances fitness in a fungal pathogen

Fungal pathogens often carry dispensable chromosomes (DCs) that confer a selective advantage in adverse environments or during host infection but can be spontaneously lost under non-selective conditions. How DCs are maintained in evolving populations remains poorly understood. Here we show that a meiotic driver known as Spore Killer (spok), located on a giant Starship transposon, limits spontaneous loss of a conserved DC in the cross-kingdom pathogen Fusarium oxysporum. Transfer of a functional spok gene, but not of a killing-deficient mutant allele, to a mitotically unstable DC significantly reduced its loss rate, while spok deletion from a stably maintained DC increased loss frequency. Competition experiments between isogenic strains carrying a functional or a killing-deficient spok allele revealed a dramatic fitness gain conferred by Spok killing activity, which required transmission by hyphal fusion. Thus, spoks and their Starship carriers benefit fungal hosts by preventing DC loss and preserving long-term metabolic and pathogenic plasticity.

microbiology↗

bioRxiv2026

A near-complete genome assembly of the Fusarium oxysporum keratitis isolate MRL8996

Fusarium oxysporum MRL8996 is a fungal strain isolated from a severe case of contact lens-associated keratitis. Here we report a near-complete genome assembly of this isolate using a hybrid Nanopore and Hi-C scaffolding approach. The assembly resolves the genome into 16 distinct chromosomes, including 11 core and 5 lineage-specific chromosomes. This high-quality reference genome provides an unprecedented tool for investigating the large-scale structural variations and evolutionary mechanisms driving adaptation in this highly versatile fungal lineage.

genomics↗

bioRxiv2024

Copper acquisition is essential for plant colonization and virulence in a root-infecting vascular wilt fungus

Phytopathogenic fungi provoke devastating agricultural losses and are difficult to control. How fungal pathogens adapt to the plant environment to cause disease and complete their life cycle on the host remains poorly understood. Here we show that efficient acquisition of copper, mediated by the transcriptional regulator Mac1, is crucial for plant colonization and virulence in Fusarium oxysporum, a soilborne ascomycete that causes vascular wilt on more than 150 different crops. RNA-seq and ChIP-seq establish a direct role of Mac1 in activation of copper deficiency response genes, many of which are induced during plant infection. Loss of Mac1 impairs growth of F. oxysporum under copper-limiting condition as well as vascular colonization and virulence on tomato plants. Importantly, Mac1-independent overexpression of a copper reductase and a copper transporter restores growth under copper limitation and virulence in the mac1 null mutant background. These findings establish a key role for copper acquisition in fungal pathogenicity on plants and reveal new ways to protect crops from phytopathogens.

genetics↗

bioRxiv2022

Constitutive activation of TORC1 signaling attenuates virulence in the cross-kingdom fungal pathogen Fusarium oxysporum

The filamentous fungus Fusarium oxysporum causes vascular wilt disease in a wide range of plant species and opportunistic infections in humans. Previous work suggested that invasive growth in this pathogen is controlled by environmental cues such as pH and nutrient status. Here we investigated the role of Target Of Rapamycin Complex 1 (TORC1), a global regulator of eukaryotic cell growth and development. Inactivation of the negative regulator Tuberous Sclerosis Complex 2 (Tsc2), but not constitutive activation of the positive regulator Gtr1, in F. oxysporum resulted in inappropriate activation of TORC1 signaling under nutrient limiting conditions. The tsc2{Delta} mutants showed reduced colony growth on minimal medium with different nitrogen sources and increased sensitivity to cell wall or high temperature stress. Furthermore, these mutants were impaired in invasive hyphal growth across cellophane membranes and exhibited a marked decrease in virulence, both on tomato plants and on the invertebrate animal host Galleria mellonella. Importantly, invasive hyphal growth in tsc2{Delta} strains was rescued by rapamycin-mediated inhibition of TORC1. Collectively, these results reveal a key role of TORC1 signaling in development and pathogenicity of F. oxysporum and suggest new potential targets for controlling fungal infections. AUTHOR SUMMARYFilamentous fungal pathogens cause devastating losses in agriculture and lethal infections in humans. A prerequisite of fungal infection is invasive hyphal growth, a process that is exquisitely controlled by environmental cues including nutrients and host signals. Here we examined the role of TOR complex 1 (TORC1), a conserved pathway that regulates cell growth in response to nutrient status. We show that deregulation of TORC1 signaling impairs pathogenicity in Fusarium oxysporum, a cross-kingdom fungal pathogen that attacks more than 150 different crops as well as immunocompromised humans. Inactivation of Tsc2, a negative regulator of TORC1, led to constitutive TORC1 activation, reduced growth under nutrient-limiting conditions and increased sensitivity to cell wall stress. Importantly, tsc2{Delta} mutants were impaired in invasive hyphal growth and in virulence on plant and animal hosts. Our results support a conserved role of TORC1 as a negative regulator of pathogenicity-related functions and reveal new leads for antifungal drug discovery.

genetics↗

bioRxiv2021

Conserved secreted effectors determine endophytic growth and multi-host plant compatibility in a vascular wilt fungus

Fungal interactions with plant roots, either beneficial or detrimental, have a major impact on agriculture and ecosystems. The soil inhabiting ascomycete Fusarium oxysporum (Fo) constitutes a species complex of worldwide distribution causing vascular wilt in more than a hundred different crops. Individual isolates of the fungus exhibit host-specific pathogenicity, determined by proteinaceous effectors termed secreted in xylem (SIX). However, such isolates can also colonize roots of non-host plants asymptomatically as endophytes, or even protect them against pathogenic isolates. The molecular determinants of multi-host plant colonization are currently unknown. Here, we identified a set of fungal effectors termed ERCs (Early Root Compatibility effectors), which are secreted during early biotrophic growth of Fo on both host and non-host plants. In contrast to the strain-specific SIX effectors, which are encoded on accessory genomic regions, ERCs are encoded on core regions and are found across the entire Fo species complex as well as in other phytopathogens, suggesting a conserved role in fungus-plant associations. Targeted deletion of ERC genes in a pathogenic Fo isolate resulted in reduced virulence on the host plant and rapid activation of plant immune responses, while in a non-pathogenic isolate it led to impaired root colonization and loss of biocontrol ability. Strikingly, some ERCs also contribute to Fo infection on the non-vascular land plant Marchantia polymorpha. Our results reveal an evolutionarily conserved mechanism for multi-host colonization by root infecting fungi.

plant biology↗

bioRxiv2020

Multiplex genetic engineering exploiting pyrimidine salvage pathway-based self-encoded selectable markers

Selectable markers are indispensable for genetic engineering, yet their number and variety is limited. Most selection procedures for prototrophic cells rely on the introduction of antibiotic resistance genes. New minimally invasive tools are needed to facilitate sophisticated genetic manipulations. Here, we characterized three endogenous genes in the human fungal pathogen Aspergillus fumigatus for their potential as markers for targeted genomic insertions of DNAs-of-interest (DOIs). Since these genes are involved in uptake and metabolization of pyrimidines, resistance to the toxic effects of prodrugs 5-fluorocytosine and 5-fluorouracil can be used to select successfully integrated DOIs. We show that DOI integration, resulting in the inactivation of these genes, caused no adverse effects with respect to nutrient requirements, growth or virulence. Beside the individual use of markers for site-directed integration of reporter cassettes including the 17-kb penicillin biosynthetic cluster, we demonstrate their sequential use inserting three fluorescent protein encoding genes into a single strain for simultaneous multicolor localization microscopy. In addition to A. fumigatus, we validated the applicability of this novel toolbox in Penicillium chrysogenum and Fusarium oxysporum. Enabling multiple targeted insertions of DOIs without the necessity for exogenous markers, this technology has the potential to significantly advance genetic engineering.

genetics↗