Biology subjects

Perotto, S.

Publications and source records attributed to Perotto, S..

4 recordsLinked to original sources

bioRxiv2025

Breaking boundaries: fungi in the ''rhizoctonia'' species complex exhibit systemic colonization in three terrestrial orchid species

O_LIMost green orchids associate with orchid mycorrhizal (OrM) fungi belonging to the rhizoctonia complex, a polyphyletic group of Tulasnellaceae, Ceratobasidiaceae and Serendipitaceae (Agaricomycotina), which are generally assumed to live as saprotrophs in soil. However, OrM rhizoctonias were rarely detected by metabarcoding in soil around orchid roots, and we have tested the hypothesis that these fungi may use adult orchid plants as a niche by colonizing not only their roots, but also other organs. C_LIO_LIThe occurrence of OrM rhizoctonias inside roots, stems and leaves of three terrestrial orchid species (Spiranthes spiralis, Serapias vomeracea and Neottia ovata) was therefore investigated by metabarcoding. To test the possibility of a vertical transmission of OrM fungi, reproductive structures (capsules, as well as seeds in S. spiralis) were also analyzed in a subset of plants. C_LIO_LIIn all orchid species, a broad majority of OrM fungi found in roots was also detected in either stems or leaves of the same plant. OrM fungi were also detected in capsules/seeds. C_LIO_LISystemic colonization of orchid tissues by OrM symbionts is a novel finding that raises important questions on the plant-fungus relationship in the aerial organs and opens intriguing perspectives on the potential modes of fungal transmission to the orchid progeny. C_LI

ecology↗

bioRxiv2022

Extant hybrids of RNA viruses and viroid-like elements

Earths life may have originated as self-replicating RNA. Some of the simplest current RNA replicators are RNA viruses, defined by linear RNA genomes encoding an RNA-dependent RNA polymerase (RdRP), and subviral agents with single-stranded, circular RNA genomes, such as viroids encoding paired self-cleaving ribozymes. Amongst a massive expansion of candidate viroid and viroid-like elements, we report that fungal pathogens, ambiviruses, are viroid-like elements which undergo rolling circle replication and encode their own viral RdRP, thus they are a distinct hybrid infectious agent. These findings point to a deep evolutionary history between modern RNA viruses and sub-viral elements and offer new perspectives on the evolution of primordial infectious agents, and RNA life. One-Sentence SummaryNovel infectious agents resembling self-cleaving viroid-like RNAs whilst encoding a viral RNA-dependent RNA polymerase.

microbiology↗

bioRxiv2018

Expression of mammalian Onzin and Fungal Cadmium Resistance 1 in S. cerevisiae suggests ancestral functions of PLAC8 proteins in regulating mitochondrial metabolism and DNA damage repair

Protein domains are structurally and functionally distinct units responsible for particular protein functions or interactions. Although protein domains contribute to the overall protein function(s) and can be used for protein classification, about 20% of protein domains are currently annotated as \"domains of an unknown function\" (DUFs). DUF 614, a cysteine-rich domain better known as PLAC8 (Placenta-Specific Gene 8), occurs in proteins found in the majority of Eukaryotes. PLAC8-containing proteins play important yet diverse roles in different organisms, such as control of cell proliferation in animals and plants or heavy metal resistance in plants and fungi. For example, Onzin from Mus musculus is a key regulator of cell proliferation, whereas FCR1 from the ascomycete Oidiodendron maius confers cadmium resistance. Onzin and FCR1 are small, single-domain PLAC8 proteins and we hypothesized that, despite their apparently different role, a common molecular function of these proteins may be linked to the PLAC8 domain. To address this hypothesis, we compared these two PLAC8-containing proteins by heterologous expression in the PLAC8-free yeast Saccharomyces cerevisiae. When expressed in yeast, both Onzin and FCR1 improved cadmium resistance, reduced cadmium-induced DNA mutagenesis, localized in the nucleus and induced similar transcriptional changes. Our results support the hypothesis of a common ancestral function of the PLAC8 domain that may link some mitochondrial biosynthetic pathways (i.e. leucine biosynthesis and Fe-S cluster biogenesis) with the control of DNA damage, thus opening new perspectives to understand the role of this protein domain in the cellular biology of Eukaryotes.\n\nAuthor SummaryProtein domains are the functional units of proteins and typically have distinct structure and function. However, many widely distributed protein domains are currently annotated as \"domains of unknown function\" (DUFs). We have focused on DUF 614, a protein domain found in many Eukaryotes and better known as PLAC8 (Placenta-Specific Gene 8). The functional role of DUF 614 is unclear because PLAC8 proteins seem to play important yet different roles in taxonomically distant organisms such as animals, plants and fungi. We used S. cerevisiae to test whether these apparently different functions, namely in cell proliferation and metal tolerance, respectively reported for the murine Onzin and the fungal FCR1, are mediated by the same molecular mechanisms. Our data demonstrate that the two PLAC8 proteins induced the same growth phenotype and transcriptional changes in S. cerevisiae. In particular, they both induced the biosynthesis of the amino acid leucine and of the iron-sulfur cluster, one of the most ancient protein cofactors. These similarities support the hypothesis of an ancestral function of the DUF 164 domain, whereas the transcriptomic data open new perspectives to understand the role of PLAC8-proteins in Eukaryotes.

cell biology↗

bioRxiv2017

The hydrophobin-like OmSSP1 may be an effector in the ericoid mycorrhizal symbiosis

Mutualistic and pathogenic plant-colonizing fungi use effector molecules to manipulate the host cell metabolism to allow plant tissue invasion. Some small secreted proteins (SSPs) have been identified as fungal effectors in both ectomycorrhizal and arbuscular mycorrhizal fungi, but it is currently unknown whether SSPs also play a role as effectors in other mycorrhizal associations. Ericoid mycorrhiza is a specific endomycorrhizal type that involves symbiotic fungi mostly belonging to the Leotiomycetes (Ascomycetes) and plants in the family Ericaceae. Genomic and RNASeq data from the ericoid mycorrhizal fungus Oidiodendron maius led to the identification of several symbiosis-upregulated genes encoding putative SSPs. OmSSP1, the most highly symbiosis up-regulated SSP, was found to share some features with fungal hydrophobins, even though it lacks the Pfam hydrophobin domain. Sequence alignment with other hydrophobins and hydrophobin-like fungal proteins placed OmSSP1 within Class I hydrophobins. However, the predicted features of OmSSP1 may suggest a distinct type of hydrophobin-like proteins. The presence of a predicted signal peptide and a yeast-based signal sequence trap assay demonstrate that OmSSP1 is secreted during symbiosis. OmSSP1 null-mutants showed a reduced capacity to form ericoid mycorrhiza with Vaccinium myrtillus roots, suggesting a role as effectors in the ericoid mycorrhizal interaction.

plant biology↗