Biology subjects

Pereira, F.

Publications and source records attributed to Pereira, F..

At least 19 recordsLinked to original sources

bioRxiv2026

Chemoselective Halogenation of Premarineosin A for Next-Generation Antimalarial Development

Premarineosin A undergoes rapid, chemoselective C12 halogenation under mild conditions, providing brominated, chlorinated, fluorinated, and iodinated analogs. These derivatives retained potent antiplasmodial activity against both chloroquine-sensitive and -resistant Plasmodium falciparum strains and displayed smaller reductions in potency against the resistant strain than the parent compound.

biochemistry↗

bioRxiv2026

Feeding-mode-defined microbial communities modulate prebiotic responses and alters colonic motility in early life

Prebiotic supplementation a well-established impact on early-life gut microbiota, yet how substrate type and baseline community structure interact to shape microbial and metabolic responses remains incompletely understood. Using donor-derived infant faecal fermentations, a defined synthetic microbial community (SynCom), and multi-layered metabolomics, we demonstrate that prebiotic responses are strongly dependent on feeding-mode and mediated by species-specific metabolic interactions. While both human milk oligosaccharides (HMOs) and galacto-oligosaccharides (GOS) robustly promoted bifidobacterial expansion, modulation of Bacteroides/Phocaeicola species varied according to feeding background and substrate identity with 2'-fucosyllactose (2'FL) selectively alleviating growth inhibition in breast milk-derived communities. Mechanistic dissection using SynCom revealed extensive cross-feeding networks and substrate-dependent interaction rewiring, identifying Phocaeicola vulgatus as a context-dependent ecological hub that disproportionately shaped succinate and propionate production and altered Escherichia coli metabolic activity without affecting its abundance. Competitive outcomes were determined not only by environmental acidification, but also by the chemical identity of fermentation products, with lactate exerting species-specific inhibitory effects independent of bulk pH changes. Using an in-house ex vivo IntestiFlow gut organ platform, we further show that metabolites produced by the defined community induced a strong but reversible suppression of colonic peristaltic activity, an effect not recapitulated by SCFAs alone. Biogenic amine metabolites, including phenethylamine, partially reproduced key aspects of this response, suggesting a role for specific microbial fermentation products in modulating intestinal motility. Together, these findings demonstrate that early-life prebiotic responses extend beyond uniform bifidogenic expansion and instead emerge from interaction-driven metabolic specialization within feeding-mode-specific community contexts, with direct functional consequences for infant intestinal physiology.

microbiology↗

bioRxiv2026

Altered thalamo-prefrontal synchrony dynamics during spatial working memory task performance in a SETD1A loss-of-function mouse model of schizophrenia predisposition

Schizophrenia is associated with profound working memory deficits, for which there are no approved treatments. Rare heterozygous null mutations in SETD1A, a gene encoding a key epigenetic regulatory protein, have been definitively linked to increased risk for schizophrenia and neurodevelopmental disorders. To investigate how SETD1A haploinsufficiency impacts the function of circuits supporting working memory, this study examined neural oscillatory synchrony across a network of brain regions critical for spatial working memory (SWM) in mice carrying a loss-of-function allele in the orthologous SETD1A gene. Local field potential recordings were performed in the prefrontal cortex, dorsal and ventral hippocampus, and thalamic nucleus reuniens in male and female wildtype and Setd1a+/- mice performing a delayed non-match to sample task of SWM. Setd1a+/- mice exhibited unaltered prefrontal-hippocampal neural oscillatory synchrony across frequencies and task epochs. In contrast, Setd1a+/- mice displayed reduced beta-frequency synchrony between the prefrontal cortex and nucleus reuniens during SWM maintenance and blunted bidirectional modulation of prefrontal-reuniens beta- and gamma-frequency synchrony across SWM task epochs. Collectively, this work expands our understanding of how genetic risk for schizophrenia alters functional connectivity within distributed circuits supporting SWM. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/702577v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@8107acorg.highwire.dtl.DTLVardef@11ec407org.highwire.dtl.DTLVardef@d7ce18org.highwire.dtl.DTLVardef@1bb31f_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Capturing instantaneous neural signal-behavior relationships with concurrent functional mixed models

We previously proposed an analysis framework for fiber photometry data based on functional linear mixed models (FLMMs). Functional LMMs allow modeling associations between photometry traces and trial-specific scalar values like behavioral summaries and session number, while also accounting for between-animal heterogeneity. Here, we extend the method to concurrent FLMMs (cFLMMs), a method that can fit the instantaneous relationship between functional outcomes and functional covariates. Concurrent FLMMs enable testing of how the photometry signal is associated with, for example, a behavioral variable that evolves across within-trial timepoints (e.g. animal speed). cFLMMs can also model the relationship between the photometry signal and covariates in experiments with variable trial lengths (e.g., in studies where trials end when an animal responds). We illustrate the application of cFLMMs on two published studies and show the method can identify signal-behavior associations in analyses not possible with FLMMs. We find that analyzing photometry-behavior associations based on behavioral summaries (e.g., latency-to-response, average lick rate) can lead to misleading conclusions. We published our method in the fastFMM package, available as an R package through GitHub (https://github.com/awqx/fastFMM).

neuroscience↗

bioRxiv2025

Hippocampal input-driven plasticity of prefrontal interneurons reveals a circuit basis for impaired spatial working memory.

Long-range projections from ventral hippocampus (vHPC) to medial prefrontal cortex (mPFC) support cognitive functions including spatial working memory (SWM). vHPC input targets multiple prefrontal interneuron classes, yet how hippocampal input recruits these populations in vivo, whether this recruitment is plastic, and how such plasticity influences cognition remain unknown. Here, we combined optical stimulation of mouse vHPC inputs with calcium recordings from discrete mPFC interneuron populations, revealing persistent activity-induced reweighting of hippocampal recruitment across prefrontal inhibitory microcircuits. Ex vivo electrophysiology and computational modeling implicated weakened monosynaptic hippocampal drive onto vasoactive intestinal polypeptide (VIP)-expressing interneurons in this circuit reconfiguration. Prior vHPC input stimulation and the schizophrenia-associated Df(16)A+/- mutation, which also yielded reduced hippocampal input onto VIP interneurons, produced convergent alterations in task-related VIP interneuron activity associated with poorer SWM task learning. These findings implicate hippocampal input to VIP interneurons as a key locus of plasticity capable of reconfiguring inhibitory microcircuit activity linked to impaired working memory task learning. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=189 SRC="FIGDIR/small/665987v2_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@e26cb0org.highwire.dtl.DTLVardef@14d9d6borg.highwire.dtl.DTLVardef@9a0fc2org.highwire.dtl.DTLVardef@80afd1_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO C_FIG

neuroscience↗

bioRxiv2025

Rapid, open-source, and automated quantification of the head twitch response in C57BL/6J mice using DeepLabCut and Simple Behavioral Analysis

Serotonergic psychedelics induce the head twitch response (HTR) in mice, an index of serotonin (5-HT) 2A receptor (5-HT2A) agonism and a behavioral proxy for psychedelic effects in humans. Existing methods for detecting HTRs include time-consuming visual scoring, magnetometer-based approaches, and analysis of videos using semi-automated commercial software. Here, we present a new automated approach for quantifying HTRs from experimental videos using the open-source machine learning-based toolkits, DeepLabCut (DLC) and Simple Behavioral Analysis (SimBA). Pose estimation DLC models were trained to predict X,Y coordinates of 13 body parts of C57BL/6J mice using historical experimental videos of HTRs induced by various psychedelic drugs. Next, a non-overlapping set of historical experimental videos was analyzed and used to train SimBA random forest behavioral classifiers to predict the presence of the HTR. The DLC+SimBA approach was then validated using a separate subset of visually scored videos. DLC+SimBA model performance was assessed at different video resolutions (50%, 25%, 12.5%) and frame rates (120, 60, 30 frames per second or fps). Our results indicate that HTRs can be quantified accurately at 50% resolution and 120 fps (precision = 95.45, recall = 95.56, F1 = 95.51) or at lower frame rates and resolutions (i.e., 50% resolution and 60 fps). The best performing DLC+SimBA model combination was deployed to evaluate the effects of bufotenine, a tryptamine derivative with uncharacterized potency and efficacy in the HTR paradigm. Interestingly, bufotenine only induced elevated HTRs (ED50 = 0.99 mg/kg, max counts = 24) when serotonin 1A receptors (5-HT1A) were pharmacologically blocked and activity at other sites of action may also impact its pharmacological effects (e.g., serotonin transporter). HTR counts for a subset of 21 videos from bufotenine experiments were strongly correlated for DLC+SimBA vs. visual scoring and semi-automated software detection methods (r = 0.98 and 0.99). Finally, the DLC+SimBA approach displayed high accuracy when compared to visual scoring of HTRs for three serotonergic psychedelic drugs with variable HTR frequencies (r = 0.99 vs. mean visual scores from 3 blinded raters). In summary, the DLC+SimBA approach represents a modular, noninvasive, and open-source method of HTR detection from experimental videos with accuracy comparable to magnetometer-based approaches and greater speed than visual scoring.

pharmacology and toxicology↗

bioRxiv2025

Sex differences in human IgG1-mediated angiogenesis inhibition depend on Y chromosome-encoded DDX3Y

Prevalent diseases of angiogenesis such as age-related macular degeneration (AMD) exhibit sex-specific prevalence, with female sex being an independent risk factor for the advanced neovascular form of AMD. The basis for these sex differences is poorly understood. Here, we quantify the impact of sex on suppression of aberrant choroidal angiogenesis by human immunoglobulin 1 (hIgG1), which possesses class-wide, antigen-independent anti-angiogenic activity. Males exhibited significantly more robust hIgG1-induced chemotaxis inhibition in primary human and mouse macrophages and anti-angiogenic activity in mouse laser-induced choroidal neovascularization (CNV). Four core genotypes and XY* Turner Syndrome mouse models revealed the Y chromosome as a sex-biasing factor contributing to hIgG1 responses. Transcriptomic and RNAi screening identified DEAD-Box Helicase 3 Y-Linked (DDX3Y) as necessary for the robust inhibitory effects of hIgG1 in males. Male mice as well as human and mouse macrophages lacking DDX3Y exhibited blunted hIgG1 responses in CNV and macrophage chemotaxis, resembling those of females. These results unveil a novel mechanism through which sex chromosome complement differences can impact key processes involved in AMD, carrying implications for various sex-related disorders and conditions involving angiogenesis.

pathology↗

bioRxiv2025

The encoding of interoceptive-based predictions by the paraventricular nucleus of the thalamus D2+ neurons

Understanding how the brain integrates internal physiological states with external sensory cues to guide behavior is a fundamental question in neuroscience. This process relies on interoceptive predictions, which are internal models that anticipate changes in the bodys physiological state based on sensory inputs and prior experiences. Despite recent advances in identifying the neural substrates of interoceptive predictions, the precise neuronal circuits involved remain elusive. In our study, we demonstrate that Dopamine 2 Receptor (D2R+) expressing neurons in the paraventricular nucleus of the thalamus (PVT) play key roles in interoception and interoceptive predictions. Specifically, these neurons are engaged in behaviors leading to physiologically relevant outcomes, with their activity highly dependent on the interoceptive state of the mice and the expected outcome. Furthermore, we show that chronic inhibition of PVTD2R+ neurons impairs the long-term performance of interoceptive-guided motivated behavior. Collectively, our findings provide insights into the role of PVTD2R+ neurons in learning and updating state-dependent predictions by integrating past experiences with current physiological conditions to optimize goal-directed behavior.

neuroscience↗

bioRxiv2025

Tau-Associated Neuronal Loss in the Intermediate Nucleus of the Human Hypothalamus (VLPO Analog): Unveiling the Basis of NREM Sleep Dysfunction in PSP and Alzheimer's Disease

Sleep disturbances are prevalent in Alzheimers disease (AD) and Progressive Supranuclear Palsy (PSP), often exacerbating disease progression. Understanding the neuropathological basis of these disturbances is essential for identifying potential therapeutic targets. This study investigates the intermediate nucleus (IntN) of the human hypothalamus--a key sleep-regulating region analogous to the rodent ventrolateral preoptic area (VLPO)--to assess neuronal loss and tau pathology in AD and PSP. Using postmortem brain tissue, we applied unbiased stereology to quantify galanin-expressing neurons and phosphorylated tau (p-tau) accumulation. Among 26 cases analyzed, both AD and PSP exhibited significant neuronal loss in the IntN, with PSP showing the most pronounced reduction (84.9% fewer neurons than healthy controls [HC]). In AD, neuronal loss correlated with Braak staging, with late-stage AD cases (Braak 5-6) demonstrating a 76.9% reduction in galanin-expressing neurons compared to HC, while non-galanin neurons exhibited a more moderate decline (45.7%). In PSP, extensive neuronal loss precluded a clear assessment of p-tau burden. These findings suggest a differential neuronal vulnerability to tau pathology across diseases, aligning with distinct sleep disturbances observed in each condition. PSP, characterized by severe insomnia despite preserved wake-promoting neurons, may be explained by the near-total loss of NREM sleep-regulating neurons. In contrast, AD exhibits a progressive decline in both wake- and sleep-promoting neurons, contributing to excessive daytime sleepiness and sleep fragmentation. This study provides critical insights into the selective neuronal vulnerabilities underlying sleep dysfunction in tauopathies, emphasizing the need for targeted interventions to mitigate sleep disturbances in these disorders.

neuroscience↗

bioRxiv2025

Persistent representation of a prior schema in the orbitofrontal cortex facilitates learning of a conflicting schema

Schemas allow efficient behavior in new situations, but reliance on them can impair flexibility when new demands conflict, culminating in psychopathology. Evidence implicates the orbitofrontal cortex (OFC) in deploying schemas in new situations congruent with previously acquired knowledge. But how does this role affect learning of a conflicting behavioral schema? Here we addressed this question by recording single-unit activity in the OFC of rats learning odor problems with identical external information but orthogonal rules governing reward. Consistent with schema formation, OFC representations adapted to track the underlying rules, and both performance and encoding was faster on subsequent than initial problems. Surprisingly however, when the rule governing reward changed, persistent representation of the prior schema was correlated with acquisition of the new. Thus, OFC was not a source of interference and instead supported new learning by accurately and independently representing the old schema as the new was acquired.

neuroscience↗

bioRxiv2025

Distinct prelimbic cortex ensembles encode response execution and inhibition

Learning when to initiate or withhold actions is essential for survival and requires integration of past experiences with new information to adapt to changing environments. While stable prelimbic cortex (PL) ensembles have been identified during reward learning, it remains unclear how they adapt when contingencies shift. Does the same ensemble adjust its activity to support behavioral suppression upon reward omission, or is a distinct ensemble recruited for this new learning? We used single-cell calcium imaging to longitudinally track PL neurons in rats across operant food reward Training, Extinction and Reinstatement, trained rat-specific decoders to predict trial-wise behavior, and implemented an in-silico deletion approach to characterize ensemble contributions to behavior. We show that operant training and extinction recruit distinct PL ensembles that encode response execution and inhibition, and that both ensembles are re-engaged and maintain their roles during Reinstatement. These findings highlight ensemble-based encoding of multiple learned associations within a region, with selective ensemble recruitment supporting behavioral flexibility under changing contingencies.

neuroscience↗

bioRxiv2025

Advancing (-)-Premarineosin A as a Potent Antimalarial Therapeutic via Metabolic Engineering and Late-Stage Derivatization

Diversification of structurally complex natural products remains a key challenge in the discovery of next-generation therapeutics. Premarineosin A, a potent and selective antimalarial natural product, is a promising yet underexplored scaffold due to limited availability and synthetic complexity. In this work, we overcome both barriers by coupling metabolic engineering with late-stage derivatization, enabling the first systematic exploration of the premarineosin A scaffold. Rational engineering of Streptomyces eitanensis, encoding a (-)-premarineosin A biosynthetic gene cluster, increased titers over 200-fold. Sustainable production of (-)-premarineosin A enabled a unique semi-synthetic and biocatalytic derivatization campaign. In this first structure-activity relationship study of premarineosin A, we accessed a suite of novel analogs, including a C12-brominated derivative with nanomolar potency (EC50 < 5 nM). This work establishes (-)-premarineosin A as a tractable and evolvable antimalarial scaffold, demonstrating how chemical biology approaches can unlock new structural and pharmacological space from complex microbial metabolites.

microbiology↗

bioRxiv2024

Engineering a Biosynthetic Pathway for the Production of (+)-Brevianamides A and B in Escherichia coli

The privileged fused-ring system comprising the bicyclo[2.2.2]diazaoctane (BDO) core is prevalent in diketopiperazine (DKP) natural products with potent and diverse biological activities, with some being explored as drug candidates. Typically, only low yields of these compounds can be extracted from native fungal producing strains and the available synthetic routes remain challenging due to their structural complexity. BDO-containing DKPs including (+)-brevianamides A and B are assembled via multi-component biosynthetic pathways incorporating non-ribosomal peptide synthetases, prenyltransferases, flavin monooxygenases, cytochrome P450s and semi-pinacolases. To simplify access to this class of alkaloids, we designed an engineered biosynthetic pathway in Escherichia coli, composed of six enzymes sourced from different kingdoms of life. The pathway includes a cyclodipeptide synthase (NascA), a cyclodipeptide oxidase (DmtD2/DmtE2), a prenyltransferase (NotF), a flavin-dependent monooxygenase (BvnB), and kinases (PhoN and IPK). Cultivated in glycerol supplemented with prenol, the engineered E. coli strain produces 5.3 mg/L of (-)-dehydrobrevianamide E (4), which undergoes a terminal, ex vivo lithium hydroxide catalyzed rearrangement reaction to yield (+)-brevianamides A and B with a 46% yield and a 92:8 diastereomeric ratio. Additionally, titers of 4 were increased eight-fold by enhancing NADPH pools in the engineered E. coli strain. Our study combines synthetic biology, biocatalysis and synthetic chemistry approaches to provide a five-step engineered biosynthetic pathway for producing complex indole alkaloids in E. coli. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/627567v2_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@399e92org.highwire.dtl.DTLVardef@d98faaorg.highwire.dtl.DTLVardef@1671ac1org.highwire.dtl.DTLVardef@d7bc6_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2024

Neural and behavioral reinstatement jointly reflect retrieval of narrative events

When recalling past events, patterns of gaze position and neural activity resemble those observed during the original experience. We hypothesized that these two phenomena, known as gaze reinstatement and neural reactivation, are linked through a common process that underlies the reinstatement of past experiences during memory retrieval. Here, we tested this proposal based on the viewing and recall of a narrative movie, which we assessed through fMRI, deep learningbased gaze prediction, and language modeling of spoken recall. In line with key predictions, gaze behavior adhered to the same principles as neural activity; it was event-specific, robust across individuals, and generalized across viewing and recall. Additionally, gaze-dependent brain activity overlapped substantially across tasks. Collectively, these results suggest that retrieval engages mechanisms that direct our eyes during natural vision, reflecting common constraints within the functional organization of the nervous system. Moreover, they highlight the importance of considering behavioral and neural reinstatement together in our understanding of remembering.

neuroscience↗

bioRxiv2024

In-Scanner Thoughts shape Resting-state Functional Connectivity: how participants rest matters.

Resting-state fMRI (rs-fMRI) scans--namely those lacking experimentally-controlled stimuli or cognitive demands--are often used to identify aberrant patterns of functional connectivity (FC) in clinical populations. To minimize interpretational uncertainty, researchers control for across-cohort disparities in age, gender, co-morbidities, and head motion. Yet, studies rarely, if ever, consider the possibility that systematic differences in inner experience (i.e., what subjects think and feel during the scan) may directly affect FC measures. Here we demonstrate that is the case using a rs-fMRI dataset comprising 471 scans annotated with experiential data. Wide-spread significant differences in FC are observed between scans that systematically differ in terms of reported in-scanner experience. Additionally, we show that FC can successfully predict specific aspects of in-scanner experience in a manner similar to how it predicts demographics, cognitive abilities, clinical outcomes and labels. Together, these results highlight the key role of in-scanner experience in shaping rs-fMRI estimates of FC.

neuroscience↗

bioRxiv2024

Spatially conserved pathoprotein profiling in the human suprachiasmatic nucleus in progressive Alzheimer disease stages

Individuals with Alzheimers Disease (AD) experience circadian rhythm disorder. The circadian rhythm is synchronized by a master clock, the suprachiasmatic nucleus (SCN), which is a tiny hypothalamic nucleus. Little is known about the molecular and pathological changes that occur in the SCN during AD progression. We examined postmortem brains of 12 controls without AD neuropathological changes (Braak stage 0) and 36 subjects at progressive Braak stages (I, II, and VI). To investigate potential AD-specific changes, we measured the neuronal counts of arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP) positive neurons, along with the Braak stages in the SCN. We investigated in adjacent hypothalamic nuclei which are also composed of AVP+ neurons but show more resilience to AD: paraventricular nucleus (PVN) and supraoptic nucleus (SON). To understand the dysregulated proteins associated to AD progression, we performed in-situ proteomics, investigating 57 proteins, including commonly dysregulated in AD, using GeoMx Digital Spatial Profiling (DSP) in the three nuclei (total of 703 area of interests). Neurofibrillary tangles (NFTs) and tau fibrils were found selectively in SCN. We failed to detect NFTs in SON, only a mild dysregulation of p-tau at Braak VI in PVN and SON. Amyloid plaque was absent in the SCN and SON. Additionally, the SCN showed increased glial proteins already at Braak stage I, whereas the level of these proteins sustained in the other nuclei. The SCN is exclusively vulnerable to AD-tau pathology and show immune dysregulation even at Braak I but is protected against amyloid plaque. This finding revealed selectively in amnestic AD, showing more resilience in AD variant. This tau-related molecular dysregulation in the SCN contributes to circadian rhythm disturbances in AD, a phenomenon observed before the onset of cognitive disorder.

neuroscience↗

bioRxiv2023

A Statistical Framework for Analysis of Trial-Level Temporal Dynamics in Fiber Photometry Experiments

Fiber photometry has become a popular technique to measure neural activity in vivo, but common analysis strategies can reduce detection of effects because they condense within-trial signals into summary measures, and discard trial-level information by averaging across-trials. We propose a novel photometry statistical framework based on functional linear mixed modeling, which enables hypothesis testing of variable effects at every trial time-point, and uses trial-level signals without averaging. This makes it possible to compare the timing and magnitude of signals across conditions while accounting for between-animal differences. Our framework produces a series of plots that illustrate covariate effect estimates and statistical significance at each trial time-point. By exploiting signal autocorrelation, our methodology yields joint 95% confidence intervals that account for inspecting effects across the entire trial and improve the detection of event-related signal changes over common multiple comparisons correction strategies. We reanalyze data from a recent study proposing a theory for the role of mesolimbic dopamine in reward learning, and show the capability of our framework to reveal significant effects obscured by standard analysis approaches. For example, our method identifies two dopamine components with distinct temporal dynamics in response to reward delivery. In simulation experiments, our methodology yields improved statistical power over common analysis approaches. Finally, we provide an open-source package and analysis guide for applying our framework.

neuroscience↗

bioRxiv2023

New races with wider virulence indicate local evolution of Puccinia striiformis f. sp. tritici in South America

Wheat yellow (stripe) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat worldwide. Pst populations are composed of multiple genetic groups, each carrying one or more races characterized by different avirulence/virulence combinations. Since the severe epidemics in 2017, yellow rust has become the most economically important wheat foliar disease in Uruguay. Evolution of virulence was investigated based on genotyping and race typing of a representative set of 27 Pst isolates collected from wheat fields in Uruguay between 2017 and 2021. Three genetic groups were identified, i.e., PstS7, PstS10 and PstS13, the latter being the most prevalent. Two races previously reported in Europe, Warrior (PstS7) and Benchmark (PstS10), were detected in four and two isolates, respectively. A third race known as Triticale2015 (PstS13), first detected in Europe in 2015 and in Argentina in 2017, was detected at several locations. Additional virulence to Yr3, Yr17, Yr25, Yr27 or Yr32 was detected in three new race variants within PstS13. The identification of these new races, which have not been reported outside South America, provides strong evidence of the local evolution of virulence in Pst during the recent epidemic years.

pathology↗