Biology subjects

Rosa, C. A.

Publications and source records attributed to Rosa, C. A..

3 recordsLinked to original sources

bioRxiv2024

An integrative taxonomy approach reveals Saccharomyces chiloensis sp. nov. as a newly discovered species from Coastal Patagonia

Species delineation in microorganisms is challenging due to the limited markers available for accurate species assignment. Here, we applied an integrative taxonomy approach, combining extensive sampling, whole-genome sequence-based classification, phenotypic profiling, and assessment of interspecific reproductive isolation. Our work reveals the presence of a distinct Saccharomyces lineage in Nothofagus forests of coastal Patagonia. This lineage, designated Saccharomyces chiloensis sp. nov., exhibits 7% genetic divergence from its sister species S. uvarum, as revealed by whole-genome sequencing and population analyses. The South America-C (SA-C) coastal Patagonia population forms a unique clade closely related to a previously described divergent S. uvarum population from Oceania (AUS, found in Australia and New Zealand). Our species reclassification is supported by a low Ortho Average Nucleotide Identity (OANI) of 93% in SA-C and AUS relative to S. uvarum, which falls below the suggested species delineation threshold of 95%, indicating an independent evolutionary lineage. Hybrid spore viability assessment provided compelling evidence that SA-C and AUS are reproductively isolated from S. uvarum. In addition, we found unique structural variants between S. chiloensis sp. nov. lineages, including large-scale chromosomal translocations and inversions, together with a distinct phenotypic profile, emphasizing their intraspecies genetic distinctiveness. We suggest that S. chiloensis sp. nov diverged from S. uvarum in allopatry due to glaciation, followed by post-glacial dispersal, resulting in distinct lineages on opposite sides of the Pacific Ocean. The discovery of S. chiloensis sp. nov. illustrates the uniqueness of Patagonias coastal biodiversity and underscores the importance of adopting an integrative taxonomic approach in species delineation to unveil cryptic microbial species. The holotype of S. chiloensis sp. nov. is CBS 18620T.

genetics↗

bioRxiv2023

Genomic and ecological factors shaping specialism and generalism across an entire subphylum

Organisms exhibit extensive variation in ecological niche breadth, from very narrow (specialists) to very broad (generalists). Paradigms proposed to explain this variation either invoke trade-offs between performance efficiency and breadth or underlying intrinsic or extrinsic factors. We assembled genomic (1,154 yeast strains from 1,049 species), metabolic (quantitative measures of growth of 843 species in 24 conditions), and ecological (environmental ontology of 1,088 species) data from nearly all known species of the ancient fungal subphylum Saccharomycotina to examine niche breadth evolution. We found large interspecific differences in carbon breadth stem from intrinsic differences in genes encoding specific metabolic pathways but no evidence of trade-offs and a limited role of extrinsic ecological factors. These comprehensive data argue that intrinsic factors driving microbial niche breadth variation. One-Sentence SummaryA nearly complete genomic catalog of the yeast subphylum illuminates the evolution of their diverse ecologies and metabolisms.

evolutionary biology↗

bioRxiv2023

Further evidences of an emerging stingless bee-yeast symbiosis

Symbiotic interactions between microorganisms and social insects have been described as crucial for the maintenance of these multitrophic systems, as observed for the stingless bee Scaptotrigona depilis and the yeast Zygosaccharomyces sp. The larvae of S. depilis ingest fungal filaments of Zygosaccharomyces sp. to obtain ergosterol, which is the precursor for the biosynthesis of ecdysteroids that modulate insect metamorphosis. In this work we verified that nutritional fungal symbioses also occur in other species of stingless bees. We analyzed brood cell samples from 19 species of stingless bees collected in Brazil. The osmophilic yeast Zygosaccharomyces spp. was isolated from eight bee species, namely Scaptotrigona bipuctata, S. postica, S. tubiba, Tetragona clavipes, Melipona quadrifasciata, M. fasciculata, M. bicolor and Partamona helleri. These yeasts form pseudohyphae and also accumulate ergosterol in lipid droplets, similar to the pattern observed for S. depilis. The phylogenetic analyses including various Zygosaccharomyces revealed that strains isolated from the brood cells formed a branch separated from the previously described Zygosaccharomyces species, suggesting that they are new species of this genus and reinforcing the symbiotic interaction with the host insects. ImportanceBenefits exchanged in insect-fungus mutualisms include nutrition, protection, and dispersal. Fungal nutritional roles are well described for some eusocial insects, such as fungus growing ants and termites, but similar interaction in stingless bees was so far observed just in Scaptotrigona depilis. Here we expand the knowledge of yeast-bee symbiosis by analyzing the presence, cell morphologies, lipid accumulation and phylogenetic relationships of fungi isolated from brood cells and other locations of bee colonies. Zygosaccharomyces isolates were recovered from 42% of the bee species assessed, and probably represent new species showing pseudohyphae formation and lipid accumulation similar to S. depilis associated Zygosaccharomyces strains. The phylogenetic analyses suggested an evolutionary adaptation of Zygosaccharomyces spp. to the brood cell environment to provide nutritional benefits for the developing insect. Stingless bees play important ecosystem services, and our results raise the concern that fungicidal agents used in agriculture could disrupt this symbiosis, impacting bee health.

microbiology↗