Bioresources for a sustainable agriculture: potentialities of Minimedusa polyspora and Chaetomium globosum as plant growth promoting fungi

Feeding a constantly growing global population, while facing global change, without further impairing the environment is probably the greatest challenge our society is facing nowadays. Modern agriculture mostly depends on the use of agrochemicals, including chemical fertilizers, pesticides and herbicides, due to their determinant role in enhancing efficiently and economically crop production, to meet the constantly increasing food demand. However, modern agriculture pressures determine major detrimental impacts on the environment at different spatial and temporal scales, on all the natural matrices: air, soil, and water. Consequently, mitigating agriculture’s impacts on the environment represents an urgent need and a key strategy towards sustainability. Furthermore, this challenge is also concomitant with two other major challenges: increasing food production up to 60% by 2050 due to the world population growth, and adapting to a rapidly evolving climate change. In fact, due to climate change effects, plants are already more frequently subjected to severe abiotic (e.g. drought, flooding, extreme temperature) and biotic (e.g. pathogens and pest outbreaks) stresses, while future scenarios foresee these phenomena to become even more severe. In this context, plant growth promotion represents an interesting sustainable solution that may play a key role in increasing crop resilience and productivity in adverse environmental conditions, minimizing agrochemicals applications and tackling climate change effects. Indeed, in healthy ecosystems soil microorganisms, through the wide array of ecosystem services they provide, express a multifunctionality that support soil productivity and plant growth. In particular, microbial strains with high soil colonization potential and multiple plant growth promoting traits — such as the ability to stimulate the plant, increase nutrient availability, exert biocontrol activity against detrimental microorganisms, and biodegrade organic pollutant and detoxifying inorganic pollutants — present a higher efficacy due to their multipurpose applicability. In this context, fungi as multifunctional microorganisms, perfectly adapted to soil microhabitats, thanks to their functional traits, metabolic plasticity and highly potent and relatively non-specific enzymes, represent valuable and effective potential bioresources. This thesis aimed to characterize Minimedusa polyspora (Hotson) Weresub & P. M. LeClair and Chaetomium globosum Kunze, two strains of soil saprotrophic fungi, for multiple activities — including biostimulation, biocontrol and bioremediation — that may contribute to plant growth promotion, to assess their potential as multifunctional bioresources for biotechnological application aimed at promoting a more sustainable agriculture. Therefore, following a general introduction and literature review on the topic, three chapters, each one addressing these species characterization for a specific activity that may contribute to plant growth promotion, are reported. The first study presented in this thesis focused on assessing the efficacy of M. polyspora and C. globosum culture filtrates as biostimulant for the cultivation Cichorium intybus (L.), a plant of agricultural and medicinal interest. In a pot experiment set up in walk-in chambers, chicory plants, one month after the transfer of the seedlings in pots, were stimulated by soil drenching with 8 ml/pot (30 ml/kg of soil) of the culture filtrates obtained by a 14-days incubation of the fungal strains in Malt Extract Broth (MEB), or the same amount of uninoculated MEB in the control group. Fourteen days after the stimulation, plant biomasses were recovered to estimate several growth parameters and analyze the metabolomic variations occurred in roots and leaves through 1H-NMR 600 MHz. We observed for the first time that M. polyspora culture filtrate promotes an increase of biomass, both in shoots and roots, and of the leaf area, while no increase was observed in plants treated with C. globosum culture filtrate. Based on 1H-NMR metabolomics data, differential metabolites and their related metabolic pathways were highlighted. A common response in C. intybus roots involving the synthesis of 3-OH-butyrate through the decrease of the synthesis of fatty acids and sterols, as a mechanism balancing the NADPH/NADP+ ratio, was observed in both the treatments with C. globosum and M. polyspora culture filtrates. The phenylpropanoid pathway was differently triggered by the fungal culture filtrates. C. globosum culture filtrate increased phenylalanine and chicoric acid in the roots. Chicoric acid, whose biosynthetic pathway in chicory plant is putative and still not well known, is a very promising natural compound playing an important role in plant defense. Instead, M. polyspora culture filtrate interestingly stimulated an increase of 4-OH benzoate, being benzoic acids precursors for a wide variety of essential compounds playing crucial roles in plant fitness and defense response activation. Therefore, both C. globosum and M. polyspora culture filtrates affected C. intybus metabolome and, based on the findings of this study, could be considered as promising fungal bioresources for further studies aimed the development of new biostimulants. Moving on, in the second study presented in this thesis, M. polyspora and C. globosum biocontrol potential against the phytopathogenic fungi Alternaria alternata (Fr.) Keissl., Berkeleyomyces basicola (Berk. & Broome) W.J. Nel, Z.W. de Beer, T.A. Duong & M.J. Wingf. and Botrytis cinerea Pers. was investigated. Plant diseases, resulting in an annual estimated loss of 10–15% of world's major crops, represent a major threat to global crops production and social and political stability of nations. 70–80% of these diseases are caused by pathogenic fungi, numbers that are expected to increase in future years due to the effect of climate change on plant-pathogens interactions. In the effort to transition to a more sustainable and resilient agriculture, the application of biological control agents and their secondary metabolites represent a promising option to support the achievement of food security, without further compromise ecosystems’ health. Therefore, it is important deepening the potential of known fungal biocontrol agents against the existing fungal pathogens, shedding further light on their action mechanisms and discovering new efficient fungal strains suitable for biotechnological applications. In vitro screenings, despite presenting several limitations, constitute valuable methods for the identification of potential biocontrol agents. Therefore, through an array of in vitro plate assays M. polyspora and C. globosum were assessed for their ability to inhibit A. alternata, B. basicola and B. cinerea growth, aiming also to gain insight on possible antimicriobial mechanism/s involved in their biological control action. More specifically, a dual culture assay, a dual culture for volatile antimicrobial compounds (performed in two different conditions), and a culture filtrate antifungal activity assay were designed to try to discriminate the impact of direct and indirect biological control mechanisms. This study results show that both M. polyspora and C. globosum were able to inhibit, to a different extent, all the pathogens’ growth in the dual culture assay, suggesting a mechanism of biocontrol involving competition for nutrients and space. M. polyspora, based on the culture filtrate antifungal activity assay, was found to exert its inhibition on all the pathogens thanks also to an antibiosis mechanism through the release of diffusible compounds. Moreover, M. polyspora culture filtrate resulted to be particularly effective especially against B. basicola whose growth was completely inhibited; furthermore, its high inhibition effect against this species was also observed in the dual culture for volatile antimicrobial compounds assay, suggesting that M. polyspora antagonism against B. basicola occurs through multiple or mixed mechanisms. Therefore, based on this preliminary study’s results M. polyspora and C. globosum are promising biocontrol agents of three fungal phytopathogens of economical and agronomical relevance, and consequently species of interest for further studies in this area aimed at validating their potential as antagonists in in vivo conditions. Finally, the last study focused on evaluating M. polyspora and C. globosum bioremediation potentialities towards glyphosate. Addressing, in particular, their ability to tolerate and utilize glyphosate as a nutritional source and eventually degrade it. Indeed, glyphosate is the most commonly used herbicide worldwide. Its improper use during recent decades has resulted in glyphosate contamination of soils and waters. Fungal bioremediation is an environmentally friendly, cost effective, and feasible solution to glyphosate contamination in soils. In this study, M. polyspora and C. globosum together with other 16 saprotrophic fungal strains were screened in vitro for their ability to tolerate and eventually utilize Roundup at two different concentrations (1 mM and 10 mM) in different cultural conditions as a nutritional source. M. polyspora and C. globosum were found to be tolerant to RoundUp, a glyphosate-based herbicide, only at the concentration of 1 mM, while a concentration of 10 mM completely inhibited their growth. Moreover, Purpureocillium lilacinum was further screened to evaluate the ability to break down and utilize glyphosate as a P source in a liquid medium. The dose-response effect for Roundup, and the difference in toxicity between pure glyphosate and Roundup were also studied. This study’s results highlight the ability of several strains to tolerate 1 mM and 10 mM Roundup and to utilize it as a nutritional source. P. lilacinum was reported for the first time for its ability to degrade glyphosate to a considerable extent (80%) and to utilize it as a P source, without showing dose-dependent negative effects on growth. Pure glyphosate was found to be more toxic than Roundup for P. lilacinum. Our results showed that pure glyphosate toxicity can be only partially addressed by the pH decrease determined in the culture medium. In conclusion, despite the strains studied in this thesis were not able to degrade glyphosate, experimental results emphasized the in vitro noteworthy potential in glyphosate degradation of P. lilacinum, another fungal strain of biotechnological interest. In conclusion, based on this thesis’ results M. polyspora and C. globosum showed promising potentialities as plant growth promoting fungi and should be further studied as bioresources for eventual biotechnological applications towards a sustainable agriculture. This thesis, in addition to the studies addressing its aim, includes also an additional section composed of three published papers dealing with topics regarding fungal species conservation applying IUCN red-listing criteria and the biotechnological potentialities of strains preserved in the culture collection of the Fungal Biodiversity Laboratory of the Department of Environmental Biology, Sapienza University of Rome

Fungi and arsenic. Tolerance and bioaccumulation by soil saprotrophic species

Increasing arsenic environmental concentrations are raising worldwide concern for its impacts on human health and ecosystem functionality. In order to cope with arsenic contamination, bioremediation using fungi can represent an efficient, sustainable, and cost-effective technological solution. Fungi can mitigate arsenic contamination through different mechanisms including bioaccumulation. In this work, four soil saprotrophic fungi Absidia spinosa, Purpureocillium lilacinum, Metarhizium marquandii, and Cephalotrichum nanum, isolated from soils with naturally high arsenic concentrations, were tested for their ability to tolerate different sodium arsenite concentrations and accumulate As in different cultural conditions. pH medium after fungal growth was measured to study pH variation and metabolic responses. Arsenic bioaccumulation and its influence on the uptake of other elements were investigated through multi-elemental analysis using hydride generation atomic fluorescence spectrometry (HG-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Considering the increasing interest in siderophore application for metal bioremediation, the production of siderophores and their affinity for both Fe and As were also evaluated. All species were able to tolerate and accumulate As in their biomass in all of the tested conditions and produced siderophores with different affinities for Fe and As. The results suggest that the tested fungi are attractive potential candidates for the bioremediation of As contaminated soil and worthy of further investigation

Contribution of MUTYH variants to male breast cancer risk: results from a multicenter study in Italy

Inherited mutations in BRCA1, and, mainly, BRCA2 genes are associated with increased risk of male breast cancer (MBC). Mutations in PALB2 and CHEK2 genes may also increase MBC risk. Overall, these genes are functionally linked to DNA repair pathways, highlighting the central role of genome maintenance in MBC genetic predisposition. MUTYH is a DNA repair gene whose biallelic germline variants cause MUTYH-associated polyposis (MAP) syndrome. Monoallelic MUTYH variants have been reported in families with both colorectal and breast cancer and there is some evidence on increased breast cancer risk in women with monoallelic variants. In this study, we aimed to investigate whether MUTYH germline variants may contribute to MBC susceptibility. To this aim, we screened the entire coding region of MUTYH in 503 BRCA1/2 mutation negative MBC cases by multigene panel analysis. Moreover, we genotyped selected variants, including p.Tyr179Cys, p.Gly396Asp, p.Arg245His, p.Gly264Trpfs*7, and p.Gln338His, in a total of 560 MBC cases and 1,540 male controls. Biallelic MUTYH pathogenic variants (p.Tyr179Cys/p.Arg241Trp) were identified in one MBC patient with phenotypic manifestation of adenomatous polyposis. Monoallelic pathogenic variants were identified in 14 (2.5%) MBC patients, in particular, p.Tyr179Cys was detected in seven cases, p.Gly396Asp in five cases, p.Arg245His and p.Gly264Trpfs*7 in one case each. The majority of MBC cases with MUTYH pathogenic variants had family history of cancer including breast, colorectal, and gastric cancers. In the case-control study, an association between the variant p.Tyr179Cys and increased MBC risk emerged by multivariate analysis [odds ratio (OR) = 4.54; 95% confidence interval (CI): 1.17-17.58; p = 0.028]. Overall, our study suggests that MUTYH pathogenic variants may have a role in MBC and, in particular, the p.Tyr179Cys variant may be a low/moderate penetrance risk allele for MBC. Moreover, our results suggest that MBC may be part of the tumor spectrum associated with MAP syndrome, with implication in the clinical management of patients and their relatives. Large-scale collaborative studies are needed to validate these findings

A novel GRN mutation in an Italian patient with non-fluent variant of primary progressive aphasia at onset: a longitudinal case report

ObjectivesWe report the clinical presentation and evolution of a case with a novel Progranulin gene (GRN) mutation and non-fluent language disturbances at onset.Materials and methodsA 60 year-old, white patient was followed due to a history of language disturbances. Eighteen months after onset, the patient underwent FDG positron emission tomography (PET), and at month 24 was hospitalized to perform neuropsychological evaluation, brain 3 T MRI, lumbar puncture for cerebrospinal fluid (CSF) analysis, and genotyping. At month 31, the patient repeated the neuropsychological evaluation and brain MRI.ResultsAt onset the patient complained prominent language production difficulties, such as effortful speech and anomia. At month 18, FDG-PET showed left fronto-temporal and striatal hypometabolism. At month 24, the neuropsychological evaluation reported prevalent speech and comprehension deficits. Brain MRI reported left fronto-opercular and striatal atrophy, and left frontal periventricular white matter hyperintensities (WMHs). Increased CSF total tau level was observed. Genotyping revealed a new GRN c.1018delC (p.H340TfsX21) mutation. The patient received a diagnosis of non-fluent variant of primary progressive aphasia (nfvPPA). At month 31, language deficits worsened, together with attention and executive functions. The patient presented also with behavioral disturbances, and a progressive atrophy in the left frontal-opercular and temporo-mesial region.Discussion and conclusionThe new GRN p.H340TfsX21 mutation resulted in a case of nfvPPA characterized by fronto-temporal and striatal alterations, typical frontal asymmetric WMHs, and a fast progression toward a widespread cognitive and behavioral impairment, which reflects a frontotemporal lobar degeneration. Our findings extend the current knowledge of the phenotypic heterogeneity among GRN mutation carriers

822 Local radiotherapy synergizes with tumor-specific TCR redirected T cells in the rejection of prostate cancer

Background Adoptive T cell therapy (ACT) has become a promising option for cancer patients. While tumor-infiltrating lymphocytes were initially exploited as a source of tumor reactive lymphocytes, T cells genetically redirected to the tumor by TCR/CAR gene transfer are now in clinical validation. In the case of solid tumors, unfavorable immunosuppressive microenvironments remain recognized barriers to therapeutic efficacy. We have recently reported that the therapeutic activity of ACT against poorly immunogenic and indolent prostate cancer is improved by the concurrent targeting of the tumor stroma by mean of T cells redirected to an ubiquitously expressed minor histocompatibility antigen or a tumor vessel targeted TNF derivative. We have now taken the concept further and hypothesized that local radiotherapy (RT), might also synergize with ACT by promoting lymphocyte endothelial transmigration and tumor recognition, and ultimately favor abscopal effects. Methods We investigated the combination of local RT and ACT in TRAMP (Transgenic Adenocarcinoma of the Mouse Prostate) mice and in mice bearing subcutaneous B16/B16-OVA (MO4) or TRAMP-C2/TRAMP-C2-OVA tumors. Local RT was delivered by X-RAD SmART (the Small Animal Radiation Therapy) microirradiator in single dose or hypo-fractioned regimens. ACT consisted of T cells engineered with tumor-specific TCRs. Immunogenic consequences were analyzed by Real-Time PCR, and flow cytometry (FACS) analyses. Prostate tumor debulking was evaluated by histological analyses. Results We found that local hypofractionated RT and ACT, while individually inefficacious in controlling tumor growth, concurred to the debulking of advanced prostate adenocarcinoma when used in combination in treating TRAMP mice. Mechanistically, exposing isolated tumor cells, or the TRAMP mouse prostate to hypo-fractionated RT regimens induced stronger type-I interferon (IFN-I) responses, when compared to single high dose. Acutely, hypofractionated RT promoted better immune tumor infiltration, among which TCR redirected effector cells. Conclusions Data support feasibility and efficacy of combining hypo-fractionated local RT with ACT in the form of TCR engineered T cells to promote prostate cancer recognition and eradication. Tumor debulking was observed in the absence of treatment-related toxicity. Systemic recirculation of TCR redirected T cells was observed. We are now investigating therapeutic effects at distal (metastatic) sites. Acknowledgements The authors acknowledge the support of the Italian Association for Cancer Research (AIRC) Ethics Approval The studies involving animals were approved by The Institutional Ethical Committee (IACUC#999)

Smell and taste changes are early indicators of the COVID-19 pandemic and political decision effectiveness

In response to the COVID-19 pandemic, many governments have taken drastic measures to avoid an overflow of intensive care units. Accurate metrics of disease spread are critical for the reopening strategies. Here, we show that self-reports of smell/taste changes are more closely associated with hospital overload and are earlier markers of the spread of infection of SARS-CoV-2 than current governmental indicators. We also report a decrease in self-reports of new onset smell/taste changes as early as 5 days after lockdown enforcement. Cross-country comparisons demonstrate that countries that adopted the most stringent lockdown measures had faster declines in new reports of smell/taste changes following lockdown than a country that adopted less stringent lockdown measures. We propose that an increase in the incidence of sudden smell and taste change in the general population may be used as an indicator of COVID-19 spread in the population

4D Multimodal Nanomedicines Made of Nonequilibrium Au-Fe Alloy Nanoparticles

Several examples of nanosized therapeutic and imaging agents have been proposed to date, yet for most of them there is a low chance of clinical translation due to long-term in vivo retention and toxicity risks. The realization of nanoagents that can be removed from the body after use remains thus a great challenge. Here, we demonstrate that nonequilibrium gold–iron alloys behave as shape-morphing nanocrystals with the properties of self-degradable multifunctional nanomedicines. DFT calculations combined with mixing enthalpy-weighted alloying simulations predict that Au–Fe solid solutions can exhibit self-degradation in an aqueous environment if the Fe content exceeds a threshold that depends upon element topology in the nanocrystals. Exploiting a laser-assisted synthesis route, we experimentally confirm that nonequilibrium Au–Fe nanoalloys have a 4D behavior, that is, the ability to change shape, size, and structure over time, becoming ultrasmall Au-rich nanocrystals. In vivo tests show the potential of these transformable Au–Fe nanoalloys as efficient multimodal contrast agents for magnetic resonance imaging and computed X-ray absorption tomography and further demonstrate their self-degradation over time, with a significant reduction of long-term accumulation in the body, when compared to benchmark gold or iron oxide contrast agents. Hence, Au–Fe alloy nanoparticles exhibiting 4D behavior can respond to the need for safe and degradable inorganic multifunctional nanomedicines required in clinical translation.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física La Plat