Barriers to family planning through structural health vulnerabilities: findings from case studies from rural Uganda.

The burden of maternal mortality in sub-Saharan Africa is the highest in the world. As high fertility rates present an increased risk to women's health, programmes and services have been put in place to increase access to family planning. Several studies have identified sociocultural factors as limiting access to family planning, including male resistance and women's low decision-making power. However, these studies have often used a behavioural approach that anchors barriers to access in women's attitudes or motivations. In 2019, a qualitative evaluation of a family planning programme using a behavioural approach was conducted in rural Uganda, focusing on women's attitudes and unmet needs. With hindsight, we realised that our evaluation was insufficient to adequately capture barriers that extend beyond women's motivations. This paper shares three case studies that we analysed using a structural health vulnerabilities approach. Our analysis highlights political, economic, social and cultural structures that can impede access to family planning. Using a structural health vulnerabilities approach, we identify structural barriers which have their roots in the local realities women face and propose context-specific structural recommendations. Finally, we contrast our initial results with findings the case studies presented to highlight the relevance of taking structural vulnerabilities into account in future family planning programme evaluation and women's sexual and reproductive health studies.

Considering social inequalities in health in large-scale testing for COVID-19 in Montréal: a qualitative case study.

BACKGROUND: Evidence continues to demonstrate that certain marginalised populations are disproportionately affected by COVID-19. While many studies document the impacts of COVID-19 on social inequalities in health, none has examined how public health responses to the pandemic have unfolded to address these inequities in Canada. The purpose of our study was to assess how social inequalities in health were considered in the design and planning of large-scale COVID-19 testing programs in Montréal (Québec, Canada). METHODS: Part of the multicountry study HoSPiCOVID, this article reports on a qualitative case study of large-scale testing for COVID-19 in Montréal. We conducted semi-structured interviews with 19 stakeholders involved in planning large-scale testing or working with vulnerable populations during the pandemic. We developed interview guides and a codebook using existing literature on policy design and planning, and analysed data deductively and inductively using thematic analysis in NVivo. RESULTS: Our findings suggest that large-scale COVID-19 testing in Montréal did not initially consider social inequalities in health in its design and planning phases. Considering the sense of urgency brought by the pandemic, participants noted the challenges linked to the uptake of an intersectoral approach and of a unified vision of social inequalities in health. However, adaptations were gradually made to large-scale testing to improve its accessibility, acceptability, and availability. Actors from the community sector, among others, played an important role in supporting the health sector to address the needs of specific subgroups of the population. CONCLUSIONS: These findings contribute to the reflections on the lessons learned from COVID-19, highlighting that public health programs must tackle structural barriers to accessing healthcare services during health crises. This will be necessary to ensure that pandemic preparedness and response, including large-scale testing, do not further increase social inequalities in health.

Straw Competition and Wheat Root Endophytism of Trichoderma gamsii T6085 as Useful Traits in the Biological Control of Fusarium Head Blight.

Trichoderma gamsii T6085 has been investigated for many years as a beneficial isolate for use in the biocontrol of Fusarium head blight (FHB) of wheat caused primarily by Fusarium graminearum. Previous work focused on application of T6085 to wheat spikes at anthesis, whereas application to soil before or at sowing has received limited attention. In the present study, the competitive ability of T6085 on plant residues against F. graminearum was investigated. Results showed a significant reduction of wheat straw colonization by the pathogen and of the development of perithecia, not only when T6085 was applied alone but also in the presence of a F. oxysporum isolate (7121), well known as a natural competitor on wheat plant residues. T6085 was able to endophytically colonize wheat roots, resulting in internal colonization of the radical cortex area, without reaching the vascular system, as confirmed by confocal microscopy. This intimate interaction with the plant resulted in a significant increase of the expression of the plant defense-related genes PAL1 and PR1. Taken together, competitive ability, endophytic behavior, and host resistance induction represent three important traits that can be of great use in the application of T6085 against FHB not only on spikes at anthesis but potentially also in soil before or at sowing.

A Brachypodium UDP-Glycosyltransferase Confers Root Tolerance to Deoxynivalenol and Resistance to Fusarium Infection.

Fusarium head blight (FHB) is a cereal disease caused by Fusarium graminearum, a fungus able to produce type B trichothecenes on cereals, including deoxynivalenol (DON), which is harmful for humans and animals. Resistance to FHB is quantitative, and the mechanisms underlying resistance are poorly understood. Resistance has been related to the ability to conjugate DON into a glucosylated form, deoxynivalenol-3-O-glucose (D3G), by secondary metabolism UDP-glucosyltransferases (UGTs). However, functional analyses have never been performed within a single host species. Here, using the model cereal species Brachypodium distachyon, we show that the Bradi5g03300 UGT converts DON into D3G in planta. We present evidence that a mutation in Bradi5g03300 increases root sensitivity to DON and the susceptibility of spikes to F. graminearum, while overexpression confers increased root tolerance to the mycotoxin and spike resistance to the fungus. The dynamics of expression and conjugation suggest that the speed of DON conjugation rather than the increase of D3G per se is a critical factor explaining the higher resistance of the overexpressing lines. A detached glumes assay showed that overexpression but not mutation of the Bradi5g03300 gene alters primary infection by F. graminearum, highlighting the involvement of DON in early steps of infection. Together, these results indicate that early and efficient UGT-mediated conjugation of DON is necessary and sufficient to establish resistance to primary infection by F. graminearum and highlight a novel strategy to promote FHB resistance in cereals.

Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium.

Fusarium species are among the most important phytopathogenic and toxigenic fungi. To understand the molecular underpinnings of pathogenicity in the genus Fusarium, we compared the genomes of three phenotypically diverse species: Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum f. sp. lycopersici. Our analysis revealed lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity, indicative of horizontal acquisition. Experimentally, we demonstrate the transfer of two LS chromosomes between strains of F. oxysporum, converting a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in F. oxysporum. These findings put the evolution of fungal pathogenicity into a new perspective.

Differential gene expression and metabolomic analyses of Brachypodium distachyon infected by deoxynivalenol producing and non-producing strains of Fusarium graminearum.

BACKGROUND: Fusarium Head Blight (FHB) caused primarily by Fusarium graminearum (Fg) is one of the major diseases of small-grain cereals including bread wheat. This disease both reduces yields and causes quality losses due to the production of deoxynivalenol (DON), the major type B trichothecene mycotoxin. DON has been described as a virulence factor enabling efficient colonization of spikes by the fungus in wheat, but its precise role during the infection process is still elusive. Brachypodium distachyon (Bd) is a model cereal species which has been shown to be susceptible to FHB. Here, a functional genomics approach was performed in order to characterize the responses of Bd to Fg infection using a global transcriptional and metabolomic profiling of B. distachyon plants infected by two strains of F. graminearum: a wild-type strain producing DON (Fgdon+) and a mutant strain impaired in the production of the mycotoxin (Fgdon-). RESULTS: Histological analysis of the interaction of the Bd21 ecotype with both Fg strains showed extensive fungal tissue colonization with the Fgdon+ strain while the florets infected with the Fgdon- strain exhibited a reduced hyphal extension and cell death on palea and lemma tissues. Fungal biomass was reduced in spikes inoculated with the Fgdon- strain as compared with the wild-type strain. The transcriptional analysis showed that jasmonate and ethylene-signalling pathways are induced upon infection, together with genes encoding putative detoxification and transport proteins, antioxidant functions as well as secondary metabolite pathways. In particular, our metabolite profiling analysis showed that tryptophan-derived metabolites, tryptamine, serotonin, coumaroyl-serotonin and feruloyl-serotonin, are more induced upon infection by the Fgdon+ strain than by the Fgdon- strain. Serotonin was shown to exhibit a slight direct antimicrobial effect against Fg. CONCLUSION: Our results show that Bd exhibits defense hallmarks similar to those already identified in cereal crops. While the fungus uses DON as a virulence factor, the host plant preferentially induces detoxification and the phenylpropanoid and phenolamide pathways as resistance mechanisms. Together with its amenability in laboratory conditions, this makes Bd a very good model to study cereal resistance mechanisms towards the major disease FHB.

Fuzzy cognitive mapping in participatory research and decision making: a practice review.

BACKGROUND: Fuzzy cognitive mapping (FCM) is a graphic technique to describe causal understanding in a wide range of applications. This practice review summarises the experience of a group of participatory research specialists and trainees who used FCM to include stakeholder views in addressing health challenges. From a meeting of the research group, this practice review reports 25 experiences with FCM in nine countries between 2016 and 2023. RESULTS: The methods, challenges and adjustments focus on participatory research practice. FCM portrayed multiple sources of knowledge: stakeholder knowledge, systematic reviews of literature, and survey data. Methodological advances included techniques to contrast and combine maps from different sources using Bayesian procedures, protocols to enhance the quality of data collection, and tools to facilitate analysis. Summary graphs communicating FCM findings sacrificed detail but facilitated stakeholder discussion of the most important relationships. We used maps not as predictive models but to surface and share perspectives of how change could happen and to inform dialogue. Analysis included simple manual techniques and sophisticated computer-based solutions. A wide range of experience in initiating, drawing, analysing, and communicating the maps illustrates FCM flexibility for different contexts and skill bases. CONCLUSIONS: A strong core procedure can contribute to more robust applications of the technique while adapting FCM for different research settings. Decision-making often involves choices between plausible interventions in a context of uncertainty and multiple possible answers to the same question. FCM offers systematic and traceable ways to document, contrast and sometimes to combine perspectives, incorporating stakeholder experience and causal models to inform decision-making. Different depths of FCM analysis open opportunities for applying the technique in skill-limited settings.

Functional characterization of two clusters of Brachypodium distachyon UDP-glycosyltransferases encoding putative deoxynivalenol detoxification genes.

Plant small-molecule UDP-glycosyltransferases (UGT) glycosylate a vast number of endogenous substances but also act in detoxification of metabolites produced by plant-pathogenic microorganisms. The ability to inactivate the Fusarium graminearum mycotoxin deoxynivalenol (DON) into DON-3-O-glucoside is crucial for resistance of cereals. We analyzed the UGT gene family of the monocot model species Brachypodium distachyon and functionally characterized two gene clusters containing putative orthologs of previously identified DON-detoxification genes from Arabidopsis thaliana and barley. Analysis of transcription showed that UGT encoded in both clusters are highly inducible by DON and expressed at much higher levels upon infection with a wild-type DON-producing F. graminearum strain compared with infection with a mutant deficient in DON production. Expression of these genes in a toxin-sensitive strain of Saccharomyces cerevisiae revealed that only two B. distachyon UGT encoded by members of a cluster of six genes homologous to the DON-inactivating barley HvUGT13248 were able to convert DON into DON-3-O-glucoside. Also, a single copy gene from Sorghum bicolor orthologous to this cluster and one of three putative orthologs of rice exhibit this ability. Seemingly, the UGT genes undergo rapid evolution and changes in copy number, making it difficult to identify orthologs with conserved substrate specificity.

Impact of high atmospheric carbon dioxide on the biotic stress response of the model cereal species Brachypodium distachyon.

Losses due to disease and climate change are among the most important issues currently facing crop production. It is therefore important to establish the impact of climate change, and particularly of high carbon dioxide (hCO2), on plant immunity in cereals, which provide 60% of human calories. The aim of this study was to determine if hCO2 impacts Brachypodium distachyon immunity, a model plant for temperate cereals. Plants were grown in air (430 ppm CO2) and at two high CO2 conditions, one that is relevant to projections within the coming century (1000 ppm) and a concentration sufficient to saturate photosynthesis (3000 ppm). The following measurements were performed: phenotyping and growth, salicylic acid contents, pathogen resistance tests, and RNAseq analysis of the transcriptome. Improved shoot development was observed at both 1000 and 3000 ppm. A transcriptomic analysis pointed to an increase in primary metabolism capacity under hCO2. Alongside this effect, up-regulation of genes associated with secondary metabolism was also observed. This effect was especially evident for the terpenoid and phenylpropanoid pathways, and was accompanied by enhanced expression of immunity-related genes and accumulation of salicylic acid. Pathogen tests using the fungus Magnaporthe oryzae revealed that hCO2 had a complex effect, with enhanced susceptibility to infection but no increase in fungal development. The study reveals that immunity in B. distachyon is modulated by growth at hCO2 and allows identification of pathways that might play a role in this effect.

Why urban communities from low-income and middle-income countries participate in public and global health research: protocol for a scoping review.

INTRODUCTION: As the number of people living in cities increases worldwide, particularly in low-income and middle-income countries (LMICs), urban health is a growing priority of public and global health. Rapid unplanned urbanisation in LMICs has exacerbated inequalities, putting the urban poor at increased risk of ill health due to difficult living conditions in cities. Collaboration with communities in research is a key strategy for addressing the challenges they face. The objective of this scoping review is, therefore, to identify factors that influence the participation of urban communities from LMICs in public and global health research. METHODS AND ANALYSIS: We will develop a search strategy with a health librarian to explore the following databases: MEDLINE, Embase, Web of Science, Cochrane, Global Health and CINAHL. We will use MeSH terms and keywords exploring the concepts of 'low-income and middle-income countries', 'community participation in research' and 'urban settings' to look at empirical research conducted in English or French. There will be no restriction in terms of dates of publication. Two independent reviewers will screen and select studies, first based on titles and abstracts, and then on full text. Two reviewers will extract data. We will summarise the results using tables and fuzzy cognitive mapping. ETHICS AND DISSEMINATION: This scoping review is part of a larger project to be approved by the University of Montréal's Research Ethics Committee for Science and Health in Montréal (Canada), and the Institutional Review Board of the James P Grant School of Public Health at BRAC University in Dhaka (Bangladesh). Results from the review will contribute to a participatory process seeking to combine scientific evidence with experiential knowledge of stakeholders in Dhaka to understand how to better collaborate with communities for research. The review could contribute to a shift toward research that is more inclusive and beneficial for communities.

"It felt like building a plane while in flight": the consideration of social inequalities in the design and planning of a contact-tracing intervention for COVID-19 in Montreal, Quebec.

OBJECTIVE: In Canada and globally, the COVID-19 pandemic has increased social inequalities in health (SIH), furthering the vulnerability of certain groups and communities. Contact-tracing is a cornerstone intervention with COVID-19 prevention and control programs. The aim of this study was to describe whether and how SIH were considered during the design of the COVID-19 contact-tracing intervention in Montreal. METHODS: This study is part of the multi-country research program HoSPiCOVID, looking at the resilience of public health systems during the COVID-19 pandemic. A descriptive qualitative study was carried out in Montreal, based on a "bricolage" conceptual framework describing the consideration for SIH in intervention and policy design. Qualitative data were collected using semi-structured interviews with 16 public health practitioners, recruited using both purposive and snowball sampling. Data were analyzed thematically, both inductively and deductively. RESULTS: According to participants, SIH were not initially considered during the design of the contract-tracing intervention in Montreal. The participants were frustrated by the Minister of Health's initial resistance to integrating SIH into their public health response. However, adaptations were gradually made to better meet the needs of underserved populations. CONCLUSION: There is a need for a clear and common vision of SIH within the public health system. Decision-makers need to consider SIH prior to designing public health interventions in order for these not to further increase SIH in the future, especially in the face of a health crisis.

RéSUMé: OBJECTIF: Au Canada et dans le monde, la pandémie de COVID-19 a augmenté les inégalités sociales de santé (ISS), aggravant la vulnérabilité de certains groupes et communautés. Le suivi des contacts est une intervention fondamentale des programmes de prévention et de contrôle de la COVID-19. L'objectif de cette étude était de décrire si et comment les ISS ont été prises en compte lors de la conception de l'intervention de suivi des contacts pour la COVID-19 à Montréal. MéTHODES: Cette étude fait partie du programme de recherche multi-pays HoSPiCOVID, portant sur la résilience des systèmes de santé publique pendant la pandémie de COVID-19. Une étude qualitative descriptive a été menée à Montréal, sur la base d'un cadre conceptuel « bricolage ¼ décrivant la prise en compte des ISS dans la conception des interventions et des politiques. Des données qualitatives ont été recueillies au moyen d'entrevues semi-structurés avec 16 praticiens de la santé publique, recrutés par échantillonnage raisonné et en boule de neige. Les données ont été analysées de manière thématique, de façon inductive et déductive. RéSULTATS: Selon les participants, les ISS n'ont pas été initialement prises en compte lors de la conception de l'intervention de suivi des contacts à Montréal. Les professionnels de santé publique ont déploré le manque de volonté du Ministère de la Santé d'intégrer les ISS dans la réponse de santé publique. Toutefois, des adaptations ont été progressivement apportées pour mieux répondre aux besoins des populations vulnérables. CONCLUSION: Il est nécessaire d'avoir une vision claire et commune des ISS au sein du système de santé. Les décideurs doivent prendre en compte activement les ISS pour que celles-ci soient mieux conceptualisées, et que les interventions de santé publique n'aggravent pas les ISS, surtout en période de crise sanitaire.

Did the design and planning of testing and contact tracing interventions for COVID-19 consider social inequalities in health? A multiple case study from Brazil, Canada, France & Mali.

The COVID-19 pandemic has led to an unprecedented global crisis. It has exposed and exacerbated weaknesses in public health systems worldwide, particularly with regards to reaching the most vulnerable populations, disproportionately impacted by the pandemic. The objective of our study was to examine whether and how social inequalities in health (SIH) were considered in the design and planning of public health responses to COVID-19 in jurisdictions of Brazil, Canada, France, and Mali. This article reports on a qualitative multiple case study of testing and contact tracing interventions in regions with high COVID-19 incidence in each country, namely: Manaus (Brazil), Montréal (Canada), Île-de-France (France), and Bamako (Mali). We conducted interviews with 108 key informants involved in these interventions in the four jurisdictions, focusing on the first and second waves of the pandemic. We analyzed our data thematically using a theoretical bricolage framework. Our analysis suggests that the lack of a common understanding of SIH among all actors involved and the sense of urgency brought by the pandemic eclipsed the prioritization of SIH in the initial responses. The pandemic increased intersectoral collaboration, but decision-making power was often unequal between Ministries of Health and other actors in each jurisdiction. Various adaptations to COVID-19 interventions were implemented to reach certain population groups, therefore improving the accessibility, availability, and acceptability of testing and contact tracing. Our study contributes to identifying lessons learned from the current pandemic, namely that the ways in which SIH are understood shape how interventions are planned; that having clear guidelines on how to integrate SIH into public health interventions could lead to more inclusive pandemic responses; that for intersectoral collaboration to be fruitful, there needs to be sufficient resources and equitable decision-making power between partners; and that interventions must be flexible to respond to emerging needs while considering long-standing structural inequalities.

Social Media and the Influence of Fake News on Global Health Interventions: Implications for a Study on Dengue in Brazil.

Social media usage is growing globally, with an exponential increase in low- and middle-income countries. Social media changes the ways in which information-sharing occurs, intensifying the population's exposure to misinformation, including fake news. This has important repercussions for global health. The spread of fake news can undermine the implementation of evidence-based interventions and weaken the credibility of scientific expertise. This is particularly worrisome in countries, such as Brazil, in a sociopolitical context characterized by a lack of popular trust in public institutions. In this project report, we describe our experience with the spread of fake news through the social media platform WhatsApp during the implementation of a cluster randomized controlled trial aimed at reducing dengue incidence in children in Fortaleza (Brazil). During initial visits to selected clusters, the research team was met with resistance. Then, soon after data collection started, fake news began circulating about the study. As a result, the research team developed strategies to dispel suspicion and further promote the study. However, the climate of violence and mistrust, coupled with the COVID-19 pandemic, forced the interruption of the study in 2019. The lessons learned from our experience in Fortaleza can be useful to other researchers and practitioners implementing large-scale interventions in this era of health-related misinformation.

Lipase is essential for the study of in vitro release kinetics from organogels.

In vitro drug release studies remain indispensable in the development of drug delivery systems, even if correlations between in vitro and in vivo results are often imperfect. In this work, an improved in vitro analysis method for studying in situ-forming lipid-based implants was developed. More specifically, lipase was found to be an essential additive for evidencing differences in drug release kinetics from organogels of different amino acid-based organogelators, organogelator concentrations, drug loadings, and volumes. Lipases are thought to participate in the degradation of and release from amino acid-based organogel implants in vivo. Our experimental conditions allowed for the rapid and reliable screening of in vitro parameters that may be optimized to slow or accelerate drug release, once preliminary in vivo data are available.

Understanding malnutrition management through a socioecological lens: Evaluation of a community-based child malnutrition program in rural Uganda.

In Uganda, almost half of children under 5 years old suffer from undernutrition. Undernutrition, a common form of malnutrition in children, encompasses stunting, wasting and underweight. The causes of child undernutrition are complex, suggesting that interventions to tackle malnutrition must be multifaceted. Furthermore, limited access to healthcare for vulnerable populations restricts the potential of hospital-based strategies. Community-based management of acute malnutrition (CMAM), which includes nutritional counselling, ready-to-use therapeutic foods and the outpatient management of malnutrition by caregivers, is recognised as an effective approach for children's recovery. However, evaluations of CMAM programs are largely based on biomedical and behavioural health models, failing to incorporate structural factors that influence malnutrition management. The objective of this evaluation was to understand the factors influencing malnutrition management in a CMAM program in rural Uganda, using the socioecological model to assess the multilevel determinants of outpatient malnutrition management. This evaluation used qualitative methods to identify factors related to caregivers, healthcare providers and societal structures that influence children's outpatient care. Data were collected at a community health clinic in 2019 through observations and interviews with caregivers of malnourished children. We observed 14 caregiver-provider encounters and interviewed 15 caregivers to examine factors hindering outpatient malnutrition management. Data were thematically analysed informed by the socioecological model. Findings showed that caregivers had a limited understanding of malnutrition. Counselling offered to caregivers was inconsistent and insufficient. Poverty and gender inequality limited caregivers' access to healthcare and their ability to care for their children. Factors at the caregiver and healthcare levels interacted with societal factors to shape malnutrition management. Results suggest that CMAM programs would benefit from providing holistic interventions to tackle the structural barriers to children's care. Using a socioecological approach to program evaluation could help move beyond individual determinants to address the social dynamics shaping malnutrition management in low- and middle-income countries.

Identification of beneficial Lebanese Trichoderma spp. wheat endophytes.

Wheat is one of the most important crops in the world. Its production can be influenced by a diversity of beneficial and pathogenic rhizospheric microbes, including fungi. Amongst them, beneficial Trichoderma spp. can be used as alternatives to chemical fertilizers, as they are cheap and harmless to the environment. Our study aimed to isolate, identify, and characterize Trichoderma spp. from Lebanon associated with wheat. Two Trichoderma strains belonging to T. afroharzianum, and T. guizhouense species, were isolated and found to be endophytes, enhancing root growth and producing Indole-3-acetic acid. Inoculation also improved seedling development, and increased plant growth and yield. Furthermore, the two strains inhibit Fusarium growth in vitro. These Trichoderma spp. have thus the capacity to be used as organic fertilizers for wheat.

Genome-wide comparative analysis of pogo-like transposable elements in different Fusarium species.

The recent availability of genome sequences of four different Fusarium species offers the opportunity to perform extensive comparative analyses, in particular of repeated sequences. In a recent work, the overall content of such sequences in the genomes of three phylogenetically related Fusarium species, F. graminearum, F. verticillioides, and F. oxysporum f. sp. lycopersici has been estimated. In this study, we present an exhaustive characterization of pogo-like elements, named Fots, in four Fusarium genomes. Overall 10 Fot and two Fot-related miniature inverted-repeat transposable element families were identified, revealing a diversification of multiple lineages of pogo-like elements, some of which accompanied by a gain of introns. This analysis also showed that such elements are present in an unusual high proportion in the genomes of F. oxysporum f. sp. lycopersici and Nectria haematococca (anamorph F. solani f. sp. pisi) in contrast with most other fungal genomes in which retroelements are the most represented. Interestingly, our analysis showed that the most numerous Fot families all contain potentially active or mobilisable copies, thus conferring a mutagenic potential of these transposable elements and consequently a role in strain adaptation and genome evolution. This role is strongly reinforced when examining their genomic distribution which is clearly biased with a high proportion (more than 80%) located on strain- or species-specific regions enriched in genes involved in pathogenicity and/or adaptation. Finally, the different reproductive characteristics of the four Fusarium species allowed us to investigate the impact of the process of repeat-induced point mutations on the expansion and diversification of Fot elements.

Overexpression of a Cytochrome P450 Monooxygenase Involved in Orobanchol Biosynthesis Increases Susceptibility to Fusarium Head Blight.

Fusarium Head Blight (FHB) is a cereal disease caused primarily by the ascomycete fungus Fusarium graminearum with public health issues due to the production of mycotoxins including deoxynivalenol (DON). Genetic resistance is an efficient protection means and numerous quantitative trait loci have been identified, some of them related to the production of resistance metabolites. In this study, we have functionally characterized the Brachypodium distachyon BdCYP711A29 gene encoding a cytochrome P450 monooxygenase (CYP). We showed that BdCYP711A29 belongs to an oligogenic family of five members. However, following infection by F. graminearum, BdCYP711A29 is the only copy strongly transcriptionally induced in a DON-dependent manner. The BdCYP711A29 protein is homologous to the Arabidopsis thaliana MAX1 and Oryza sativa MAX1-like CYPs representing key components of the strigolactone biosynthesis. We show that BdCYP711A29 is likely involved in orobanchol biosynthesis. Alteration of the BdCYP711A29 sequence or expression alone does not modify plant architecture, most likely because of functional redundancy with the other copies. B. distachyon lines overexpressing BdCYP711A29 exhibit an increased susceptibility to F. graminearum, although no significant changes in defense gene expression were detected. We demonstrate that both orobanchol and exudates of Bd711A29 overexpressing lines stimulate the germination of F. graminearum macroconidia. We therefore hypothesize that orobanchol is a susceptibility factor to FHB.

Transposon-tagging identifies novel pathogenicity genes in Fusarium graminearum.

With the increase of sequenced fungal genomes, high-throughput methods for functional analyses of genes are needed. We assessed the potential of a new transposon mutagenesis tool deploying a Fusarium oxysporum miniature inverted-repeat transposable element mimp1, mobilized by the transposase of impala, a Tc1-like transposon, to obtain knock-out mutants in Fusarium graminearum. We localized 91 mimp1 insertions which showed good distribution over the entire genome. The main exception was a major hotspot on chromosome 2 where independent insertions occurred at exactly the same nucleotide position. Furthermore insertions in promoter regions were over-represented. Screening 331 mutants for sexual development, radial growth and pathogenicity on wheat resulted in 19 mutants (5.7%) with altered phenotypes. Complementation with the original gene restored the wild-type phenotype in two selected mutants demonstrating the high tagging efficiency. This is the first report of a MITE transposon tagging system as an efficient mutagenesis tool in F. graminearum.

Transposition of a fungal miniature inverted-repeat transposable element through the action of a Tc1-like transposase.

The mimp1 element previously identified in the ascomycete fungus Fusarium oxysporum has hallmarks of miniature inverted-repeat transposable elements (MITEs): short size, terminal inverted repeats (TIRs), structural homogeneity, and a stable secondary structure. Since mimp1 has no coding capacity, its mobilization requires a transposase-encoding element. On the basis of the similarity of TIRs and target-site preference with the autonomous Tc1-like element impala, together with a correlated distribution of both elements among the Fusarium genus, we investigated the ability of mimp1 to jump upon expression of the impala transposase provided in trans. Under these conditions, we present evidence that mimp1 transposes by a cut-and-paste mechanism into TA dinucleotides, which are duplicated upon insertion. Our results also show that mimp1 reinserts very frequently in genic regions for at least one-third of the cases. We also show that the mimp1/impala double-component system is fully functional in the heterologous species F. graminearum, allowing the development of a highly efficient tool for gene tagging in filamentous fungi.