Biology subjects

Tralamazza, S. M.

Publications and source records attributed to Tralamazza, S. M..

4 recordsLinked to original sources

bioRxiv2025

Wheat infection by Fusarium graminearum species complex members is facilitated by a transcriptionally conserved non-ribosomal peptide synthetase gene cluster

Biosynthetic gene clusters (BGCs) are often found in fungal pathogens and encode secondary (or specialized) metabolites that play crucial roles in host and niche adaptation. However, the regulatory dynamics and functions of these BGCs during host infection remain largely unknown. To address this gap, we employed interspecies comparative transcriptomics to identify BGCs involved in host-pathogen interactions mediated by the Fusarium graminearum species complex (FGSC). We conducted joint transcriptomic and metabolomic analyses during wheat infection and in vitro experiments with five members of the FGSC to understand gene regulation during host infection. Our findings revealed that expression regulation was predominantly species-specific, but we also identified a set of shared upregulated genes that were common to all five FGSC species showing enrichment for metabolic and pathogenicity-associated functions. We focused on jointly upregulated BGC during infection and identified a NRPS-like gene cluster named SM3. The cluster was highly conserved within FGSC and shared by the more distant F. sambucinum species complex. We show that inactivation of the BGC core gene significantly impairs F. graminearum sensu stricto (s.s.) spore production, reduces fungal spread and Fusarium Head Blight symptoms on wheat kernels. Our results highlight that comparative infection transcriptomes can reveal conserved metabolic functions mediating the host infection process of a plant pathogen.

microbiology↗

bioRxiv2022

Genome-wide association mapping reveals genes underlying population-level metabolome diversity in a fungal crop pathogen

BackgroundFungi produce a wide range of specialized metabolites (SMs) involved in biotic interactions. Pathways for the production of SMs are often encoded in clusters of tightly arranged genes identified as biosynthetic gene clusters. Such gene clusters can undergo horizontal gene transfers between species and rapid evolutionary change within species. The acquisition, rearrangement and deletion of gene clusters can generate significant metabolome diversity. However, the genetic basis underlying variation in SM production remains poorly understood. ResultsHere, we analyzed metabolite production of a large population of the fungal pathogen of wheat, Zymoseptoria tritici. The pathogen causes major yield losses and shows variation in gene clusters. We performed untargeted ultra-high performance liquid chromatography-high resolution mass spectrometry to profile the metabolite diversity among 102 isolates of the same species. We found substantial variation in the abundance of the detected metabolites among isolates. Integrating whole-genome sequencing data, we performed metabolite genome-wide association mapping to identify loci underlying variation in metabolite production (i.e. metabolite-GWAS). We found that significantly associated SNP reside mostly in coding and gene regulatory regions. Associated genes encode mainly transport and catalytic activities. The metabolite-GWAS identified also a polymorphism in the 3UTR region of a virulence gene related to metabolite production and showing expression variation. ConclusionsTaken together, our study provides a significant resource to unravel polymorphism underlying metabolome diversity within a species. Integrating metabolome screens should be feasible for a range of different plant pathogens and help prioritize molecular studies.

microbiology↗

bioRxiv2021

Histone H3K27 methylation perturbs transcriptional robustness and underpins dispensability of highly conserved genes in fungi

Epigenetic modifications are key regulators of gene expression and underpin genome integrity. Yet, how epigenetic changes affect the evolution and transcriptional robustness of genes remains largely unknown. Here, we show how the repressive histone mark H3K27me3 influences the trajectory of highly conserved genes in fungi. We first performed transcriptomic profiling on closely related species of the plant pathogen Fusarium graminearum species complex. We determined transcriptional responsiveness of genes across environmental conditions to determine expression robustness. To infer evolutionary conservation of coding sequences, we used a comparative genomics framework of 23 species across the Fusarium genus. We integrated histone methylation data from three Fusarium species across the phylogenetic breadth of the genus. Gene expression variation is negatively correlated with gene conservation confirming that highly conserved genes show higher expression robustness. Furthermore, we show that highly conserved genes marked by H3K27me3 deviate from the typical housekeeping gene archetype. Compared to the genomic background, H3K27me3 marked genes encode smaller proteins, exhibit lower GC content, weaker codon usage bias, higher levels of hydrophobicity and are enriched for functions related to regulation and membrane transport. The evolutionary age of conserved genes with H3K27me3 histone marks falls typically within the origins of the Fusarium genus. We show that highly conserved genes marked by H3K27me3 are more likely to be dispensable for survival. Lastly, we show that conserved genes exposed to repressive H3K27me3 marks across distantly related fungi predict transcriptional perturbation at the microevolutionary scale in Fusarium fungi. In conclusion, we establish how repressive histone marks determine the evolutionary fate of highly conserved genes across evolutionary timescales.

genomics↗

bioRxiv2020

Wild rice (O. latifolia) from natural ecosystems in the Pantanal region of Brazil: host to Fusarium incarnatum-equiseti species complex and highly contaminated by zearalenone.

We assessed the mycobiota diversity and mycotoxin levels present in wild rice (Oryza latifolia) from the Pantanal region of Brazil; fundamental aspects of which are severely understudied as an edible plant from a natural ecosystem. We found a variety of fungal species contaminating the rice samples; the most frequent genera being Fusarium, Nigrospora and Cladosporium (35.9%, 26.1% and 15%, respectively). Within the Fusarium genus, the wild rice samples were mostly contaminated by the Fusarium incarnatum-equiseti species complex (FIESC) (80%) along with Fusarium fujikuroi species complex (20%). Phylogenetic analysis supported multiple FIESC species and gave strong support to the presence of two previously uncharacterized lineages within the complex (LN1 and LN2). Deoxynivalenol (DON) and zearalenone (ZEA) chemical analysis showed that most of the isolates were DON/ZEA producers and some were defined as high ZEA producers, displaying abundant ZEA levels over DON (over 19 times more). Suggesting that ZEA likely has a key adaptive role for FIESC in wild rice (O. latifolia). Mycotoxin determination in the rice samples revealed high frequency of ZEA, and 85% of rice samples had levels >100 μg/kg; the recommended limit set by regulatory agencies. DON was only detected in 5.2% of the samples. Our data shows that FIESC species are the main source of ZEA contamination in wild rice and the excessive levels of ZEA found in the rice samples raises considerable safety concerns regarding wild rice consumption by humans and animals.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology↗