Biology subjects

Bianconi, M.

Publications and source records attributed to Bianconi, M..

5 recordsLinked to original sources

bioRxiv2025

Nissolia brasiliensis as a non-nodulating model legume

The nitrogen-fixing root nodule symbiosis (RNS) is specifically formed by four orders of angiosperms. The largest of these four orders include the legume family, the Fabaceae. Among legumes, historical model species have emerged, such as the RNS-forming Medicago truncatula and Lotus japonicus, or, more recently, Aeschynomene aevenia. By contrast, legume species that have lost RNS have been largely ignored. Here, we describe the first chromosome-level assembly for a non-RNS-forming legume, the tropical papilionoid Nissolia brasiliensis. We compared its genome to closely related legumes and identified genes associated with RNS. Finally, we developed a stable transformation protocol that can be deployed in the future to re-evolve RNS in legumes, a first step toward the goal of engineering RNS in non-legume crops.

plant biology↗

bioRxiv2025

Leafy liverwort genomes shed light on the evolution of ericoid symbiosis

Symbioses have been fundamental to colonization of terrestrial ecosystems by plants and their evolution. Emergence of the ancient arbuscular mycorrhizal symbiosis was followed by the diversification of alternative intracellular symbioses, such as the ericoid mycorrhizae (ErM). We aimed at understanding how these diversifications occurred. We sequenced the genomes of ErM-forming liverworts, and reconstituted symbiosis under laboratory conditions. We demonstrated the existence of a nutrient-regulated symbiotic state that enables ErM and underlies intracellular colonization of plant tissues. Comparative transcriptomic analyses identified an ancestral gene module associated with intracellular symbiosis beyond ErM. Genetic manipulations in the liverwort Marchantia paleacea, phylogenetics and transactivation assays demonstrated its essential function for intracellular symbiosis. We conclude that plant have maintained, and convergently recruited, an ancestral gene module for intracellular symbioses.

plant biology↗

bioRxiv2024

The environmental impact of pharmaceuticals: an evidence-mapping review of recent data on aquatic concentrations and predictable effects

Pharmaceuticals are recognised among emerging contaminants, particularly in water. They have the potential to alter ecosystem dynamics, with notable examples including hormone-induced feminization of male fish and disruptions to oogenesis in invertebrates. To assess the risk posed by pharmaceuticals, it is essential to understand their amount (via Measured Environmental Concentrations - MEC) and their actual effects on target species (via Predicted No Effect Concentrations - PNEC). Recently, many studies have aimed to collect MEC data from around the world, but a comprehensive overview is still lacking. Thus, the objective of this study is to provide a comprehensive overview by examining recently published literature on MEC data for a wide range of pharmaceuticals. Additionally, to enable risk assessment, this study also reviewed the published literature on PNEC data and integrated it with existing databases. A total of 315 substances were selected for MEC data extraction, with the inclusion of 56 articles. The most frequently monitored locations were Cadiz Bay in Spain (90 samples), the River Thames in the UK (51), and Hrd[e]jovice in the Czech Republic (49). Most MEC samples were collected from surface water (N=325), influent wastewater treatment plants (WWTP) (205), and effluent WWTP (118). Based on PNEC values, risk analysis identified 81 pharmaceuticals as high-risk, with the highest risk values for propranolol (risk quotient [RQ]: 29,450,000), diclofenac (395,920), and 17alpha-ethinylestradiol (95,946). Additionally, the ATC classes with the most high-risk substances were anti-infectives (J), nervous system agents (N), cardiovascular agents (C), antineoplastic agents (L), analgesics (M), and sex hormones (G). The findings of this study highlight the widespread impact of pharmaceuticals across the globe and the involvement of multiple therapeutic classes. To move beyond the current point-in-time overview, which is limited to specific locations and sampling periods, systems for continuous monitoring of pharmaceuticals should be developed. This could involve the creation of resource-efficient methods and the integration of sampling data with estimation models. Furthermore, these results could serve as a starting point for developing and implementing actions to prevent and mitigate the environmental impact of pharmaceuticals.

ecology↗

bioRxiv2024

Ectomycorrhizal symbiosis evolved independently and by convergent gene duplication in rosid lineages

Many land plants rely on mutualistic symbiotic associations to thrive, starting with their common ancestor associating with arbuscular mycorrhizal (AM) fungi. Similar to AM symbiosis, multiple other intracellular symbiotic interactions have evolved in a variety of land plants. Ectomycorrhizal (ECM) symbiosis contrasts with these relationships as there is no intracellular accommodation of the symbiont inside the plant cell, but only intercellular colonization. This symbiotic relationship is common in a variety of seed plants, mostly trees and shrubs such as pines, willows and oaks. Although it is known which plant lineages are involved in ECM symbiosis, there has been little investigation into the evolutionary origin of ECM symbiosis in these lineages. Furthermore, the genetic innovations and transcriptomic response related to this symbiosis have been studied largely in a genus or species-specific context, which hinders the study of their evolutionary origins. In this study, we reconstruct the origin of ECM in the rosid clade, showing at least 16 independent origins, resulting in the 17 known extant ECM rosid lineages. Moreover, comparative genomics of these lineages highlight genes involved in cell wall remodeling which underwent duplications in a convergent manner across ectomycorrhizal lineages.

plant biology↗

bioRxiv2020

Physiological diversity enhanced by recurrent divergence and secondary gene flow within a grass species

O_LIC4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this single species encompasses C4 and non-C4 populations. C_LIO_LIUsing phylogenomics and population genomics, we infer the history of dispersal and secondary exchanges before, during, and after photosynthetic divergence in A. semialata. We further establish the genetic origins of polyploids in this species. C_LIO_LIOrganelle phylogenies indicate limited seed dispersal within the Central Zambezian region of Africa, where the species originated [~] 2-3 Ma. Outside this region, the species spread rapidly across the paleotropics to Australia. Comparison of nuclear and organelle phylogenies and analyses of whole genomes reveal extensive secondary gene flow. In particular, the genomic group corresponding to the C4 trait was swept into seeds from distinct geographic regions. Multiple segmental allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. C_LIO_LILimited dispersal and isolation allowed lineage divergence, while episodic secondary exchanges led to the pollen-mediated, rapid spread of the derived C4 physiology. Overall, our study suggests that local adaptation followed by recurrent secondary gene flow promoted physiological diversification in this grass species. C_LI

evolutionary biology↗