Nuria Escudero

Hyalomma lusitanicum is a characteristic tick species of the western Mediterranean region, with a well-established distribution across the Iberian Peninsula. It is strongly associated with wild ungulates, particularly red deer, as well as livestock, to which it can transmit a wide range of pathogens, including viruses, bacteria, and protozoa. Here, we present three genomic resources for H. lusitanicum: a scaffold-scale nuclear genome, the complete mitochondrial genome, and the complete genome of its associated Francisella bacterial endosymbiont. The nuclear genome assembly spans 1.81 Gb and comprises 59 scaffolds, with a scaffold N50 of 153.6 Mb (L50 = 5) and no gaps, indicating high contiguity and completeness with a gene annotation completeness BUSCO score of 97.1 %. Genome annotation of the nuclear assembly identified 20,638 protein-coding genes, 1,422 non-coding genes, and 5,775 pseudogenes. A total of 18 scaffolds were assembled as putative chromosomes, exceeding the 11 chromosomes inferred as ancestral; however, synteny analyses suggest that several scaffolds likely represent fragmented portions of the same chromosome, probably due to incomplete Hi-C scaffolding. Despite this, the assembly represents one of the most complete tick nuclear genomes generated to date. In addition, we report the complete genome of a Francisella endosymbiont (1.51 Mb, 1,679 genes), characterized by a high proportion of pseudogenes and reduced genome size, consistent with patterns of genome reduction associated with obligate symbiosis. Together, these genomic resources provide a framework to investigate local adaptation and host-symbiont evolution, and to support improved surveillance, control, and management strategies for species of public health relevance.

Understanding the genomic toolkit that enabled animal terrestrialization, the shift from aquatic to terrestrial habitats, is key to uncovering the evolutionary origins of land biodiversity. Yet, the genomic basis of the physiological and metabolic adaptations required for life on land remains poorly understood across most terrestrial animal phyla. Planarians (Platyhelminthes) offer a powerful model, as only one terrestrial lineage, the Geoplanidae (order Tricladida), is known. Here, we integrated genomics, transcriptomics, and proteomics to explore the genetic changes potentially supporting terrestrial adaptation. We identified a major burst of gene gain in the lineage leading to Tricladida, preceding the radiation of terrestrial planarians. Upon abiotic stress exposure, terrestrial and freshwater species exhibited distinct responses: most differentially expressed genes belonged to orthogroups gained in Tricladida, with over half under strong directional selection in terrestrial flatworms, suggesting their adaptive relevance. Transcriptomic profiles revealed divergent strategies: terrestrial species upregulated ancient genes, while freshwater species downregulated a separate set of ancestral genes. Across all datasets, the abiotic stress–response toolkit in terrestrial planarians was markedly different from freshwater relatives, with significant regulatory divergence. Our results highlight gene gain and co-option, rather than lineage-specific innovations, as key drivers of terrestrial flatworm evolution, emphasizing genomic exaptation and regulatory shifts as central to terrestrialization in Platyhelminthes. This study provides the first genome-wide view of the genetic basis of flatworm terrestrialization and sheds light on broader patterns of animal terrestrial adaptation.

The Stigmatoteuthis arcturi reference genome offers a valuable resource for understanding the evolutionary patterns of oceanic squids, who perform important ecological roles as both predators and prey in mesopelagic and deep-sea environments, while their genomes remain understudied. The entirety of the genome sequence was assembled into 46 contiguous chromosomal pseudomolecules. This chromosome-level assembly encompasses 3.25 Gb, composed of 1,268 contigs and 497 scaffolds, with contig and scaffold N50 values of 11.0 Mb and 74.6 Mb, respectively.

A global genome database of all of Earth's species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic information available. To contribute to a more complete planetary genomic database, scientists and institutions across the world have united under the Earth BioGenome Project (EBP), which plans to sequence and assemble high-quality reference genomes for all ~1.5 million recognized eukaryotic species through a stepwise phased approach. As the initiative transitions into Phase II, where 150,000 species are to be sequenced in just four years, worldwide participation in the project will be fundamental to success. As the European node of the EBP, the European Reference Genome Atlas (ERGA) seeks to implement a new decentralised, accessible, equitable and inclusive model for producing high-quality reference genomes, which will inform EBP as it scales. To embark on this mission, ERGA launched a Pilot Project to establish a network across Europe to develop and test the first infrastructure of its kind for the coordinated and distributed reference genome production on 98 European eukaryotic species from sample providers across 34 European countries. Here we outline the process and challenges faced during the development of a pilot infrastructure for the production of reference genome resources, and explore the effectiveness of this approach in terms of high-quality reference genome production, considering also equity and inclusion. The outcomes and lessons learned during this pilot provide a solid foundation for ERGA while offering key learnings to other transnational and national genomic resource projects.

Summary: Pochonia chlamydosporia is a soil fungus with a multitrophic lifestyle combining endophytic and saprophytic behaviors, in addition to a nematophagous activity directed against eggs of root‐knot and other plant parasitic nematodes. The carbohydrate‐active enzymes encoded by the genome of P. chlamydosporia suggest that the endophytic and saprophytic lifestyles make use of a plant cell wall polysaccharide degradation machinery that can target cellulose, xylan and, to a lesser extent, pectin. This enzymatic machinery is completed by a chitin breakdown system that involves not only chitinases, but also chitin deacetylases and a large number of chitosanases. P. chlamydosporia can degrade and grow on chitin and is particularly efficient on chitosan. The relevance of chitosan breakdown during nematode egg infection is supported by the immunolocalization of chitosan in Meloidogyne javanica eggs infected by P. chlamydosporia and by the fact that the fungus expresses chitosanase and chitin deacetylase genes during egg infection. This suggests that these enzymes are important for the nematophagous activity of the fungus and they are targets for improving the capabilities of P. chlamydosporia as a biocontrol agent in agriculture.

Summary: Pochonia chlamydosporiahas been intensively studied in nematode control of different crops. We have investigated the interaction betweenP. chlamydosporiaand the model systemArabidopsis thalianaunder laboratory conditions in the absence of nematodes. This study demonstrates thatP. chlamydosporiacolonizesA. thaliana. Root colonization monitored with green fluorescent protein‐taggedP. chlamydosporiaand quantitative PCR (qPCR) quantitation methods revealed root cell invasion. Fungal inoculation reduced flowering time and stimulated plant growth, as determined by total FW increase, faster development of inflorescences and siliques, and a higher yield in terms of seed production per plant. Precocious flowering was associated with significant expression changes in key flowering‐time genes. In addition, we also provided molecular and genetic evidence that point towards jasmonate signaling as an important factor to modulate progression of plant colonization by the fungus. Our results indicate thatP. chlamydosporiaprovides benefits to the plant in addition to its nematophagous activity. This report highlights the potential ofP. chlamydosporiato improve yield in economically important crops.

The fungal parasite of nematode eggsPochonia chlamydosporiais also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nineP.chlamydosporiaisolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). SevenP.chlamydosporiaisolates significantly (P< 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. SixP.chlamydosporiaisolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. AgainP.chlamydosporiasignificantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants.P. chlamydosporiaincreased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found thatP. chlamydosporiacan produce Indole‐3‐acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance ofP. chlamydosporiaas biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.