Antarctica's hidden mycoviral treasures in fungi isolated from mosses: A first genomic approach.

This study investigates the presence of mycoviruses in Antarctic fungi and elucidates their evolutionary relationships. To achieve this, we aligned mycoviral gene sequences with genomes of previously sequenced Antarctic endophytic fungi, made available by our research group and accessible via Joint Genome Institute. Our findings reveal that the most prevalent genetic regions in all endophytic fungi are homologous to Partitiviruses, Baculoviridae, and Phycodnaviridae. These regions display evidence of positive selection pressure, suggesting genetic diversity and the accumulation of nonsynonymous mutations. This phenomenon implies a crucial role for these regions in the adaptation and survival of these fungi in the challenging Antarctic ecosystems. The presence of mycoviruses in Antarctic endophytic fungi may indicate shared survival strategies between the virus and its host, shedding light on their evolutionary dynamics. This study underscores the significance of exploring mycoviruses within endophytic fungi and their contributions to genetic diversity. Future research avenues could delve into the functional implications of these conserved mycoviral genetic regions in Antarctic endophytic fungi, providing a comprehensive understanding of this intriguing association and genomic retention of viral region in fungi.

Screening of endophytic fungi from Antarctic mosses: Potential production for L-asparaginase free of glutaminase and urease activity.

Studies involving endophytic fungi aim to identify organisms inhabiting extreme and relatively unexplored environments, as these fungi possess unique characteristics and uncommon biochemical pathways that enable them to produce compounds with biotechnological potential. Among various enzymes, L-Asparaginase is employed in the treatment of Acute Lymphoblastic Leukemia. In this study, we identified endophytic fungi from Sanionia uncinata and Polytrichastrum alpinum collected on King George Island in Antarctica. The fungi were categorized into morphological groups based on their characteristics, molecularly identified, and assessed for L-Asparaginase (L-ASNase) enzyme production. Subsequently, production optimization was conducted. A total of 161 endophytes were isolated from 504 moss gametophytes, with 107 originating from P. alpinum and 54 from S. uncinata. These isolates were categorized into 31 morphotypes. Fungi exhibiting high enzyme production were identified molecularly. Among them, nine identified isolates belonged to the genera Aspergillus, Collariella, Diaporthe, Epicoccum, Peroneutypa, Xylaria, and Trametes. Three of these isolates were identified at the species level through multigene phylogeny, namely Epicoccum nigrum, Collariella virescens, and Peroneutypa scoparia. All 31 fungi were subjected to solid media testing for L-ASNase enzyme production, with 22 isolates demonstrating production capability, and 13 of them produced L-ASNase free from Urease and Glutaminase. The isolates displaying solid media production underwent further testing in liquid media, all of which exhibited enzyme production ranging from 0.75 to 1.29 U g-1. Notably, the three fungi identified at the species level were the highest producers of the enzyme (1.29, 1.17, and 1.13 U g-1). The production of these fungi was optimized using the Taguchi method, resulting in production values ranging from 0.687 to 2.461 U g-1. In conclusion, our findings indicate that Antarctic moss endophytic fungi exhibit significant potential for the production of the anti-leukemic enzyme L-ASNase.

Impact of the Temperature in Endophytic Ascomycota Isolated from Antarctic Hair-Grass.

Antarctica is one of the most inhospitable continents on the planet, with lichens and mosses being the most common terrestrial organisms in ice-free areas. Antarctica is represented by only two species of Angiosperms, Deschampsia antarctica Desv. (Poaceae) and Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae). In this study, we characterized fungi isolated from the fresh leaves of this grass species. The fungi were isolated from four individual plants from Half Moon Island (246 leaf fragments investigated), and seven from King George Island-Keller Peninsula (with 111 leaf fragments investigated) Antarctica. Neoascochyta paspali, Septoriella elongata, Pyrenophora cf. chaetomioides and Alternaria sp. were associated with the plant and identified through analysis of the sequences of the internal transcribed spacer region (ITS) of the rDNA and nuclear ribosomal large subunit rRNA gene (LSU) as well as through macro and micro-morphological characteristics. The isolates showed higher growth rate ranging from 10 to 20 °C. An interesting result was that the aforementioned fungi are already recognized as both plant pathogens and endophytic fungi. The results demonstrate that D. antarctica is an interesting fungal source. Those species might provide important information about the relationship on the endemic Antarctic biota.

An empirical analysis of mtSSRs: could microsatellite distribution patterns explain the evolution of mitogenomes in plants?

Microsatellites (SSRs) are tandem repeat sequences in eukaryote genomes, including plant cytoplasmic genomes. The mitochondrial genome (mtDNA) has been shown to vary in size, number, and distribution of SSRs among different plant groups. Thus, SSRs contribute with genomic diversity in mtDNAs. However, the abundance, distribution, and evolutionary significance of SSRs in mtDNA from a wide range of algae and plants have not been explored. In this study, the mtDNAs of 204 plant and algal species were investigated related to the presence of SSRs. The number of SSRs was positively correlated with genome size. Its distribution is dependent on plant and algal groups analyzed, although the cluster analysis indicates the conservation of some common motifs in algal and terrestrial plants that reflect common ancestry of groups. Many SSRs in coding and non-coding regions can be useful for molecular markers. Moreover, mitochondrial SSRs are highly abundant, representing an important source for natural or induced genetic variation, i.e., for biotechnological approaches that can modulate mtDNA gene regulation. Thus, this comparative study increases the understanding of the plant and algal SSR evolution and brings perspectives for further studies.

Starch Synthesis-Related Genes (SSRG) Evolution in the Genus Oryza.

Cooking quality is an important attribute in Common/Asian rice (Oryzasativa L.) varieties, being highly dependent on grain starch composition. This composition is known to be highly dependent on a cultivar's genetics, but the way in which their genes express different phenotypes is not well understood. Further analysis of variation of grain quality genes using new information obtained from the wild relatives of rice should provide important insights into the evolution and potential use of these genetic resources. All analyses were conducted using bioinformatics approaches. The analysis of the protein sequences of grain quality genes across the Oryza suggest that the deletion/mutation of amino acids in active sites result in variations that can negatively affect specific steps of starch biosynthesis in the endosperm. On the other hand, the complete deletion of some genes in the wild species may not affect the amylose content. Here we present new insights for Starch Synthesis-Related Genes (SSRGs) evolution from starch-specific rice phenotypes.

Distribution of aerophilous diatom communities associated with terrestrial green macroalgae in the South Shetland Islands, Maritime Antarctica.

The establishment of diatom communities depends on environmental factors such as the type of substrate and geographic conditions that influence the dispersal processes of these organisms. The main goal of this study was to evaluate the similarity between diatom communities associated with the macroalgae Prasiola crispa (Lightfoot) Kützing in relation to spatial distance from six sampled sites located in the South Shetland Islands, Maritime Antarctica. The diatom flora associated with Prasiola crispa was represented by 23 species distributed in 15 genera. Pinnularia australoschoenfelderi Zidarova, Kopalová & Van de Vijver, Luticola austroatlantica Van de Vijver, Kopalová, S.A.Spaulding & Esposito, Luticola amoena Van der Vijver, Kopalová, Zidarova & Levkov, Pinnularia austroshetlandica (Carlson) Cleve-Euler and Psammothidium papilio (D.E. Kellogg et al.) Kopalová & Zidarova were the most abundant species in our samples, together they represented 68% of the total number of individuals collected. There was great similarity and abundance of the diatom communites among the sampled points, which resulted in the absence of a linear relationship pattern with distance between sampling points. We conclude that distance was not a factor of differentiation of Antarctic diatom communities associated with terrestrial green macroalgae. This suggests that Antarctic environments may have unique characteristics with homogeneous abiotic factors, at least in relation to this substrate.

Entomotoxic Activity of Prasiola crispa (Antarctic Algae) in Nauphoeta cinerea Cockroaches: Identification of Main Steroidal Compounds.

Prasiola crispa is a macroscopic green algae found in abundance in Antarctica ice free areas. Prasiola crispan-hexaneextract (HPC) induced insecticidal activity in Nauphoeta cinerea cockroaches after 24 h of exposure. The chemical analysis of HPC revealed the presence of the followingphytosterols: ß-sitosterol, campesterol and stigmasterol. The incubation of cockroach semi-isolated heart preparations with HPC caused a significant negative chronotropic activity in the heartbeats. HPC affected the insect neuromuscular function by inducing a complete inhibition of the cockroach leg-muscle twitch tension. When the isolated phytosterols were injected at in vivo cockroach neuromuscular preparations, there was a progressive inhibition of muscle twitches on the following order of potency: ß-sitosterol > campesterol > stigmasterol. HPC also provoked significant behavioral alterations, characterized by the increase or decrease of cockroach grooming activity, depending on the dose assayed. Altogether, the results presented here corroborate the insecticide potential of Prasiola crispa Antarctic algae. They also revealed the presence of phytosterols and the involvement of these steroidal compounds in the entomotoxic activity of the algae, potentially by modulating octopaminergic-cholinergic pathways. Further phytochemical-combined bioguided analysis of the HPC will unveil novel bioactive compounds that might be an accessory to the insecticide activity of the algae.

Morphological and Molecular Characterization of Three Endolichenic Isolates of Xylaria (Xylariaceae), from Cladonia curta Ahti & Marcelli (Cladoniaceae).

Endophyte biology is a branch of science that contributes to the understanding of the diversity and ecology of microorganisms that live inside plants, fungi, and lichen. Considering that the diversity of endolichenic fungi is little explored, and its phylogenetic relationship with other lifestyles (endophytism and saprotrophism) is still to be explored in detail, this paper presents data on axenic cultures and phylogenetic relationships of three endolichenic fungi, isolated in laboratory. Cladonia curta Ahti & Marcelli, a species of lichen described in Brazil, is distributed at three sites in the Southeast of the country, in mesophilous forests and the Cerrado. Initial hyphal growth of Xylaria spp. on C. curta podetia started four days after inoculation and continued for the next 13 days until the hyphae completely covered the podetia. Stromata formation and differentiation was observed, occurring approximately after one year of isolation and consecutive subculture of lineages. Phylogenetic analyses indicate lineages of endolichenic fungi in the genus Xylaria, even as the morphological characteristics of the colonies and anamorphous stromata confirm this classification. Our preliminary results provide evidence that these endolichenic fungi are closely related to endophytic fungi, suggesting that the associations are not purely incidental. Further studies, especially phylogenetic analyses using robust multi-locus datasets, are needed to accept or reject the hypothesis that endolichenic fungi isolated from Xylaria spp. and X. berteri are conspecific.

Differences in bacterial composition between men's and women's restrooms and other common areas within a public building.

Humans distribute a wide range of microorganisms around building interiors, and some of these are potentially pathogenic. Recent research established that humans are the main drivers of the indoor microbiome and up to now significant literature has been produced about this topic. Here we analyzed differences in bacterial composition between men's and women's restrooms and other common areas within the same public building. Bacterial DNA samples were collected from restrooms and halls of a three-floor building from the Federal University of Pampa, RS, Brazil. The bacterial community was characterized by amplification of the V4 region of the 16S rRNA gene and sequencing. Throughout all samples, the most abundant phylum was Proteobacteria, followed by Actinobacteria, Bacteroidetes and Firmicutes. Beta diversity metrics showed that the structure of the bacterial communities were different among the areas and floors tested, however, only 6-9% of the variation in bacterial communities was explained by the area and floors sampled. A few microorganisms showed significantly differential abundance between men's and women's restrooms, but in general, the bacterial communities from both places were very similar. Finally, significant differences among the microbial community profile from different floors were reported, suggesting that the type of use and occupant demographic within the building may directly influence bacterial dispersion and establishment.

Growth and development of halophyte Funaria hygrometrica Hedw. (Funariaceae) under salt stress / Crescimento e desenvolvimento da halofita Funaria hygrometrica Hedw. (Funariaceae) sob estresse salino

The ability of bryophytes to tolerate salt is determined by a number of biochemical routes, whereas the salt ends up driving the activation of adaptive responses to tolerate this adverse condition. Salinity is the main limiting environmental factor under plant development, and is caused by excess salt ions in the environment, mainly Na + and Cl-. The optimal growth of plants in saline environment is obtained in concentrations of 50% of NaCl. Due to these findings, the importance of the study of the effect of salinity on the germination of plants, in this case in Funaria hygrometrica Hedw., is noticed.

A capacidade das briófitas para tolerar meios salinos é determinada por uma série de vias bioquímicas, uma vez que o sal acaba por conduzir a ativação de respostas adaptativas para tolerar esta condição adversa. A salinidade é o principal fator ambiental limitante no desenvolvimento da planta e é causada pelo excesso de íons salinos no ambiente, principalmente Na+ e Cl-. O crescimento ótimo de plantas em ambiente salino foi obtido em concentrações de 50% de NaCl. Devido a essas descobertas esses achados, observa-se a importância do estudo do efeito da salinidade sobre a germinação de plantas, neste caso em Funaria hygrometrica Hedw.

Phylogenetic positioning of the Antarctic alga Prasiola crispa (Trebouxiophyceae) using organellar genomes and their structural analysis.

Antarctica is one of the most difficult habitats for sustaining life on earth; organisms that live there have developed different strategies for survival. Among these organisms is the green alga Prasiola crispa, belonging to the class Trebouxiophyceae. The literature on P. crispa taxonomy is scarce, and many gaps in the evolutionary relationship with its closest relatives remain. The goal of this study was to analyze the evolutionary relationships between P. crispa and other green algae using plastid and mitochondrial genomes. In addition, we analyzed the synteny conservation of these genomes of P. crispa with those of closely related species. Based on the plastid genome, P. crispa grouped with Prasiolopsis sp. SAG 84.81, another Trebouxiophyceaen species from the Prasiola clade. Based on the mitochondrial genome analysis, P. crispa grouped with other Trebouxiophyceaen species but had a basal position. The structure of the P. crispa chloroplast genome had low synteny with Prasiolopsis sp. SAG 84.81, despite some conserved gene blocks. The same was observed in the mitochondrial genome compared with Coccomyxa subellipsoidea C-169. We were able to establish the phylogenetic position of P. crispa with other species of Trebouxiophyceae using its genomes. In addition, we described the plasticity of these genomes using a structural analysis. The plastid and mitochondrial genomes of P. crispa will be useful for further genetic studies, phylogenetic analysis and resource protection of P. crispa as well as for further phylogenetic analysis of Trebouxiophyceaen green algae.

Draft Genome of Rhodococcus rhodochrous TRN7, Isolated from the Coast of Trindade Island, Brazil.

Here, we present a draft genome and annotation of Rhodococcus rhodochrous TRN7, isolated from Trindade Island, Brazil, which will provide genetic data to benefit the understanding of its metabolism.

Draft Plastid and Mitochondrial Genome Sequences from Antarctic Alga Prasiola crispa.

The organelle genomes of the Antarctic alga Prasiola crispa (Lightfoot) Kützing have been sequenced. The plastid and mitochondrial genomes have a total length of 196,502 bp and 89,819 bp, respectively. These genomes have 19 putative photosynthesis-related genes and 17 oxidative metabolism-related genes, respectively.

Toxicity induced by Prasiola crispa to fruit fly Drosophila melanogaster and cockroach Nauphoeta cinerea: evidence for bioinsecticide action.

The adverse effects of the alga Prasiola crispa extract (PcE) were investigated in a fruit fly (Drosophila melanogaster) and cockroach (Nauphoeta cinerea) model. In flies, toxicity was assessed as mortality and biochemical alterations including acetylcholinesterase (AChE) activity and oxidative stress markers. The cardiotoxic action of PcE was also examined in a model of semi-isolated cockroach heart. The administration of PcE (2 mg/ml) to flies for 24 h resulted in a marked increase in mortality rate (7.6-fold rise compared to control). AChE activity, glutathione (GSH) levels, and hydroperoxide formation remained unchanged. Fly glutathione S-transferase (GST) and catalase (CAT) activity were significantly altered after PcE treatment. Fraction III (ethyl acetate) of PcE was significantly more toxic to flies compared to fractions I (methanol) and II (ethanol). A significant decrease was noted in cockroach semi-isolated heart function. The addition of 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB), an oxidizing agent, concomitant with the extract significantly blocked this effect, suggesting that reduced compounds may be involved in the cardiotoxic action produced by PcE. Our results show for the first time the adverse effects of PcE in two insect models, Drosophila melanogaster and Nauphoetacinerea. The insecticidal properties of PcE may be related to changes in important antioxidant/detoxifying systems, as well as to changes in insect cardiac function.

A change in SHATTERPROOF protein lies at the origin of a fruit morphological novelty and a new strategy for seed dispersal in medicago genus.

Angiosperms are the most diverse and numerous group of plants, and it is generally accepted that this evolutionary success owes in part to the diversity found in fruits, key for protecting the developing seeds and ensuring seed dispersal. Although studies on the molecular basis of morphological innovations are few, they all illustrate the central role played by transcription factors acting as developmental regulators. Here, we show that a small change in the protein sequence of a MADS-box transcription factor correlates with the origin of a highly modified fruit morphology and the change in seed dispersal strategies that occurred in Medicago, a genus belonging to the large legume family. This protein sequence modification alters the functional properties of the protein, affecting the affinities for other protein partners involved in high-order complexes. Our work illustrates that variation in coding regions can generate evolutionary novelties not based on gene duplication/subfunctionalization but by interactions in complex networks, contributing also to the current debate on the relative importance of changes in regulatory or coding regions of master regulators in generating morphological novelties.

In situ methane and nitrous oxide fluxes in soil from a transect in Hennequin Point, King George Island, Antarctic.

The study aimed at to determine the magnitude of the methane (CH(4)) and nitrous oxide (N(2)O) flux rates in soils at Hennequin Point, King George Island, Antarctic, under different slope positions, vegetal covers and presence of skuas, as well as to evaluate the main soil and climate factors that are involved with the flux of such gases. In situ gas sampling (closed chamber method) was performed in four sites along a transect involving a skua nesting field in a moraine with 5% and 100% of surface covered by vegetal, and two poor-drained soils in the toeslope (a bare alluvium soil and a poor-drained moss field with 100% soil cover). Flux rates ranged from -0.86±0.45 to 2.75±1.52 µg N(2)O-N m(-2) h(-1) and -12.26±3.05 to 1.42±1.31 µg CH(4)-C m(-2) h(-1). The soil totally covered by vegetal in the skua field had the largest CH(4) influx rates. However, this benefic effect was counterbalanced by the greatest N(2)O efflux rates from this soil, resulting in the largest contribution to the global warming potential among the soils evaluated. Flux rates were closely related to soil temperature, but no significant relation was observed with mineral N contents and water-filled pore space. In turn, accumulated CH(4) and N(2)O emissions were closely related to the total N and total organic C stocks in the soil. Net CH(4) influx predominated even in the poor-drained soils, suggesting that the coarse soil texture avoided critical anaerobic conditions. No significant changes in flux rates were observed for sampling time along the day.

Phylogenetic relationships and selective pressure on gene families related to iron homeostasis in land plants.

Iron is involved in many metabolic processes, such as respiration and photosynthesis, and therefore an essential element for plant development. Comparative analysis of gene copies between crops and lower plant groups can shed light on the evolution of genes important to iron homeostasis. A phylogenetic analysis of five metal homeostasis gene families (NAS, NRAMP, YSL, FRO, and IRT) selected in monocots, dicots, gymnosperms, and bryophytes was performed. The homologous genes were found using known iron homeostasis gene sequences of Oryza sativa, Arabidopsis thaliana, and Physcomitrella patens as queries. The phylogeny was constructed using bioinfomatics tools. A total of 243 gene sequences for 30 plant species were found. The evolutionary fingerprint analysis suggested a purifying selective pressure of iron homeostasis genes for most of the plant gene homologues. The NAS and YSL genes appear to accumulate more negative selection sites, suggesting a strong selective pressure on these two gene families. The divergence time analysis indicates IRT as the most ancient gene family and FRO as the most recent. NRAMP and YSL genes appear to share a close relationship in the evolution of iron homeostasis gene families.

Establishment of the moss Polytrichum juniperinum Hedw. under axenic conditions / Estabelecimento e desenvolvimento do musgo Polytrichum juniperinum Hedw. sob condições de cultivo axênico

Polytrichum juniperinum Hedw. (Polytrichaceae) é uma espécie de musgo de ampla distribuição, ocorrendo em ambos os hemisférios. Culturas in vitro foram estabelecidas a partir de esporos de espécimes coletados na natureza. O desenvolvimento, tanto de protonema quanto de gametófitos, foi observado utilizando o meio básico MS em três tratamentos, livre de fitorreguladores, suplementados com uma fonte de auxina (AIA), suplementados com uma fonte de citocinina (BAP) e suplementado com ambos reguladores. Nos cultivos resultantes de meio livre de reguladores e de meios contendo auxina, foi observado o desenvolvimento total dos gametófitos, enquanto nos meios contendo citocinina não foram observados desenvolvimento e regeneração de gametófitos. Estes resultados sugerem a utilização do meio livre de reguladores para cultivo de Polytrichum juniperinum em cultivos axênicos.

Polytrichum juniperinum Hedw. (Polytrichaceae) is a moss with a worldwide distribution. In vitro culture was established from P. juniperinum spores collected in nature. Both protonema and gametophore stages of gametophyte development were obtained. The Murashige-Skoog regulator-free nutrient medium or supplemented with AIA and BAP conferred a fully development and regeneration of gametophytes. Tissues grown on cytokinin did not produce any gametophytes. These results indicate the possibility to use a medium without growth regulators to obtain gametophytes for this species in axenic conditions.

In silico comparative analysis of SSR markers in plants.

BACKGROUND: The adverse environmental conditions impose extreme limitation to growth and plant development, restricting the genetic potential and reflecting on plant yield losses. The progress obtained by classic plant breeding methods aiming at increasing abiotic stress tolerances have not been enough to cope with increasing food demands. New target genes need to be identified to reach this goal, which requires extensive studies of the related biological mechanisms. Comparative analyses in ancestral plant groups can help to elucidate yet unclear biological processes. RESULTS: In this study, we surveyed the occurrence patterns of expressed sequence tag-derived microsatellite markers for model plants. A total of 13,133 SSR markers were discovered using the SSRLocator software in non-redundant EST databases made for all eleven species chosen for this study. The dimer motifs are more frequent in lower plant species, such as green algae and mosses, and the trimer motifs are more frequent for the majority of higher plant groups, such as monocots and dicots. With this in silico study we confirm several microsatellite plant survey results made with available bioinformatics tools. CONCLUSIONS: The comparative studies of EST-SSR markers among all plant lineages is well suited for plant evolution studies as well as for future studies of transferability of molecular markers.