Biology subjects

Pereira, E. C.

Publications and source records attributed to Pereira, E. C..

6 recordsLinked to original sources

bioRxiv2026

The variable wheat stripe rust effector AvrYr7 evades Yr7 recognition through sequence and expression polymorphisms

Introductory paragraphWheat provides about 20% of total dietary calories worldside1. Wheat diseases, including wheat stripe (yellow) rust, cause billions of dollars in losses each year2. Wheat stripe (yellow) rust is caused by the fungal pathogen Puccinia striiformis f. sp. tritici (Pst) which is best controlled by fungicide application and disease resistant wheat cultivars3. To-date, there are over 80 catalogued and >10 cloned yellow rust resistance genes (Yr genes)4. Yet our knowledge of corresponding avirulence (Avr) genes lags far behind5-8. The absence of cloned Avrs reflects Psts complex genome and the lack of robust transformation and genetic systems3. Recent advances in generating high-quality genome assemblies and the development of wheat defense assays have addressed these challenges9-11. Here we clone AvrYr7 which is recognized by Yr712. We further identify six additional alleles of AvrYr7 that escape recognition due to non-synonymous genetic variations, transposable element activity, missense mutation, and expression polymorphism. These findings provide critical insights into virulence evolution in one of the worlds most important wheat pathogens.

plant biology↗

bioRxiv2026

Quantifying the effects of arbuscular mycorrhizal fungi and potato cyst nematodes on root system architecture using X-ray computed tomography

Crop root systems develop in biologically complex soils where beneficial symbionts and pathogenic organisms can jointly influence root architecture and, consequently, belowground function. In this work, we used X-ray computed tomography (CT) to assess how colonisation by the arbuscular mycorrhizal fungus Rhizophagus irregularis (AMF) and infection by the potato cyst nematode Globodera pallida (PCN) influence root system architecture in soil-grown tomato and potato plants. Root architectural traits, including root volume and root surface area, were quantified non-destructively from intact root systems to evaluate the individual and combined effects of AMF colonisation and PCN infection over time. AMF inoculation increased root volume and surface area, whereas PCN infection caused pronounced reductions in these traits, particularly during early development. AMF-associated increases in root system size were maintained in both PCN-free and PCN-infected plants, indicating largely additive effects of beneficial and pathogenic soil biota on root architectural outcomes. These findings show that soil organisms can independently reshape crop root development in ways likely to influence soil exploration and resource acquisition under biologically complex conditions. More broadly, the study highlights the value of X-ray CT as a non-destructive approach for linking belowground biotic interactions with functionally relevant root traits in sustainable agroecosystems.

plant biology↗

bioRxiv2025

A conserved stripe rust effector elicits variable resistance responses in wheat

Plant resistance (R) and pathogen avirulence (Avr) gene interactions are central to pathogen recognition and disease resistance in crops. Functional characterisation of recognised Avr effectors of Puccinia striiformis f. sp. tritici (Pst) lags other key fungal pathogens of wheat. Here, we used a wheat protoplast-based screen to identify Avr/R interactions via the proxy of effector-induced defence responses in a set of diverse wheat cultivars. We identified an Avr candidate, termed AvrPstB48, that triggers defence responses in 16 out of 24 cultivars tested. AvrPstB48 is hemizygous, and the Pst genome carries four divergent paralogs within a gene cluster. Analysis of these paralogs revealed partial redundancy in their ability to activate wheat defences and enabled us to identify a single amino acid in AvrPstB48 that is necessary but not sufficient for defence activation. Notably, the activation of defence signalling by AvrPstB48 in protoplasts did not directly correlate with disease outcomes. Whole-plant infection assays revealed that some cultivars which exhibited strong defence activation in the protoplast assay are susceptible to the Pst isolate Pst104E137A- from which AvrPstB48 is derived. Comparison of infection dynamics of two wheat cultivars that differ in their AvrPstB48 recognition capacity revealed a delay in disease progression in the recognising cultivar Avocet S compared to the non-recognising cultivar Morocco. While correlative only, our observations, combined with other recent reports, support a recognize-then-suppress model of plant-pathogen interaction where disease outcomes are driven not only by simple Avr/R interactions but also by pathogen effectors that suppress defence signalling downstream of effector recognition.

plant biology↗

bioRxiv2024

High Pathogenicity Avian Influenza Virus (HPAIV) H5N1 clade 2.3.4.4b recovered from a kelp gull (Larus dominicanus) in the South Shetland Islands, Antarctica

Whole-genome analysis of the earliest-detected High Pathogenicity Avian Influenza Virus (HPAIV) H5N1 clade 2.3.4.4b detected in Hannah Point, Antarctica (January 2024) reveals close relatedness to strains that circulated in pinnipeds and seabirds along the Atlantic coast of South America during the second half of 2023.

molecular biology↗

bioRxiv2024

The use of X-ray Computed Tomography revolutionises soil pathogen detection

Potato cyst nematodes (PCN), namely Globodera pallida, pose a significant threat to potato production worldwide. Accurately quantifying nematode population densities is crucial for effective management strategies. However, traditional detection methods are time-consuming and often imprecise. X-ray computed tomography (CT) offers high-resolution, non-destructive and three-dimensional (3D) imaging frequently used to visualise internal structures of objects, materials or biological tissues, allowing for detailed analysis of their composition, defects, and morphology. Here, we demonstrate the effectiveness of X-ray CT in detecting and quantifying PCN cysts in different soil types. The ability to achieve 3D imaging and volume quantification of PCN cysts from soils allows accurate enumeration of their egg content. To explore future potential, we propose that when integrated with AI-led quantification of X-ray CT-generated cyst counts, this method could evolve into a next-generation technology to accurately and rapidly quantify these damaging pests in agricultural soils. Combined with the potential to co-analyse other organisms within the same sample, we propose X-ray CT as a fundamental tool for comprehensive soil health assessments and sustainable pest management in agriculture. Author SummaryPotato cyst nematodes are a major threat causing significant crop losses worldwide. Traditionally, detecting this pathogen in soil is challenging, often requiring time-consuming and imprecise. Our study explores a new approach using X-ray computed tomography (CT), a powerful imaging tool that creates detailed 3D images in situ. We observed that X-ray CT can effectively detect and measure the cysts nematodes, even within different soil types. This detailed analysis allows us to determine the cyst structures and estimate the eggs contained. In the future, combining X-ray CT with artificial intelligence could make detecting and quantifying these nematodes even faster and more accurate. This method could also be expanded to study other soil organisms, making it a valuable tool for monitoring soil health and improving agricultural pest management.

plant biology↗

bioRxiv2024

Unique RNA replication characteristics and nucleocapsid protein expression may explain differences in the replication capacity of SARS-COV-2 lineages.

COVID-19 pandemic in Brazil was characterized by the sequential circulation of the SARS-CoV-2 lineages B.1.1.33, and variants Zeta (P.2), Gamma (P.1/P.1.*), Delta (B.1.617.2/AY.*), and Omicron (BA.*). Our research aimed to compare the biological traits of these lineages and variants by analyzing aspects of viral replication including binding, entry, RNA replication, and viral protein production. We demonstrated that the replication capacity of these variants varies depending on the cell type, with Omicron BA.1 exhibiting the lowest replication in the human pulmonary cells. Additionally, the nucleocapsid proteoforms generated during infection exhibit distinct patterns across variants. Our findings suggest that factors beyond the initial stages of virus entry influence the efficiency of viral replication among different SARS-CoV-2 variants. Thus, our study underscores the significance of RNA replication and the role of nucleocapsid proteins in shaping the replicative characteristics of SARS-CoV-2 variants. Author summaryThe COVID-19 pandemic was characterized by the emergence of different viral variants that presents specific properties such as response to antibodies, pathogenicity and detection by diagnostic tests. The circulation of these variants presented a particular pattern depending on the global geographic regions. Despite the cessation of the pandemic, as officially declared by the World Health Organization in 2023, new viral variants continue to emerge while aspects of the virus-cell interaction that contribute to the replication of these variants have not yet been completely understood. In our study, we compared the biological characteristics of SARS-CoV-2 variants that circulated in Brazil during the pandemic, verifying aspects of entry, viral replication and production of viral RNA and proteins. Our results indicate that Omicron BA.1 variant has reduced replication and protein production in human lung cells. We also observed that the viral nucleocapsid protein presents proteoforms that vary according to the variant. These differences could help to explain the differences observed in viral replication in human pulmonary cells.

microbiology↗