Search Results (120)

Brassica napus L. is one of the world’s most important oilseed crops. Blackleg disease is a serious, yield-limiting factor in the cultivation of oilseed rape. Genetic resistance is primarily conferred by major resistance (R) genes. In this study, we analyzed the expression of the blackleg resistance genes Rlm3, Rlm4, and Rlm7 following inoculation with the Leptosphaeria maculans isolate using the RT-qPCR method. Additionally, we demonstrated and assessed their interactions. The results showed that, while Rlm3 was weakly induced, Rlm4 and Rlm7 displayed variable expression post-inoculation. The correlation between phenotypic and genotypic similarity was low. This suggests that transcriptional responses do not fully explain resistance patterns. Furthermore, significant main effects of the analyzed genes, as well as two- and three-way interactions, were indicated. These results support current knowledge of gene-mediated resistance to blackleg in oilseed rape. Full article

Succinate dehydrogenase inhibitor (SDHI) fungicides are widely used in Australia for the control of blackleg disease (caused by Leptosphaeria maculans, also called Plenodomus lingam). Populations of L. maculans are highly variable and therefore at risk of evolving fungicide resistance. The baseline sensitivities of L. maculans isolates towards the SDHI fungicides pydiflumetofen and bixafen were determined through in vitro mycelial growth assays, and the mean EC₅₀s were found to be 4.89 and 2.71 ng mL⁻¹, respectively. L. maculans populations were also screened against three commercial SDHI fungicides, Saltro^®, ILeVO^®, and Aviator^®, using an in planta assay to reveal very low levels of resistance. Nineteen of these ascospore populations from 2022 were analysed in a deep amplicon sequencing (DAS) assay and showed no mutations in the genes likely to be associated with resistance to SDHI chemistries. This study establishes baseline sensitivities of L. maculans isolates towards commonly used SDHI fungicides, importantly before and during the introduction of these new chemistries for blackleg control, and outlines monitoring techniques to allow timely identification of resistance if it evolves. Full article

The RasGAP SH3 domain binding protein (G3BP) is a highly conserved family of proteins in eukaryotic organisms that coordinates signal transduction and post-transcriptional gene regulation and functions in the formation of stress granules. G3BPs have important roles in abiotic/biotic stresses in mammals, and recent research suggests that they have similar functions in higher plants. Brassica contains many important oilseeds, vegetables, and ornamental plants, but there are no reports on the G3BP family in Brassica species. In this study, we identified G3BP family genes from six species of the U’s triangle (B. rapa, B. oleracea, B. nigra, B. napus, B. juncea, and B. carinata) at the genome-wide level. We then analyzed their gene structure, protein motifs, gene duplication type, phylogeny, subcellular localization, SSR loci, and upstream miRNAs. Based on transcriptome data, we analyzed the expression patterns of B. napus G3BP (BnaG3BP) genes in various tissues/organs in response to Sclerotinia disease, blackleg disease, powdery mildew, dehydration, drought, heat, cold, and ABA treatments, and its involvement in seed traits including germination, α-linolenic acid content, oil content, and yellow seed. Several BnaG3BP DEGs might be regulated by BnaTT1. The qRT-PCR assay validated the inducibility of two cold-responsive BnaG3BP DEGs. This study will enrich the systematic understanding of Brassica G3BP family genes and lay a molecular basis for the application of BnaG3BP genes in stress tolerance, disease resistance, and quality improvement in rapeseed. Full article

Blackleg caused by a hemi-biotrophic fungus Plenodomus lingam (syn. Leptosphaeria maculans) poses a significant threat to global canola production. Changing climatic conditions further exacerbate the intensity and prevalence of blackleg epidemics. Shifts in temperature, humidity, and precipitation patterns can enhance pathogen virulence and disease spread. This review synthesizes the knowledge on integrated disease management (IDM) approaches for blackleg, including crop rotation, resistant cultivars, and chemical and biological controls, with an emphasis on advanced strategies such as disease forecasting models, remote sensing, and climate-adapted breeding. Notably, bibliometric analysis reveals an increasing research focus on the intersection of blackleg, climate change, and sustainable disease management. However, critical research gaps remain, which include the lack of region-specific forecasting models, the limited availability of effective biological control agents, and underexplored socio-economic factors limiting farmer adoption of IDM. Additionally, the review identifies an urgent need for policy support and investment in breeding programs using emerging tools like AI-driven decision support systems, CRISPR/Cas9, and gene stacking to optimize fungicide use and resistance deployment. Overall, this review highlights the importance of coordinated, multidisciplinary efforts, integrating plant pathology, breeding, climate modeling, and socio-economic analysis to develop climate-resilient, locally adapted, and economically viable IDM strategies for sustainable canola production. Full article

Blackleg disease poses a major threat to global canola production. The resistance gene Rlm1, corresponding to the avirulence gene AvrLm1 in the pathogen Leptosphaeria maculans, has been widely used to mitigate the impact of the disease. To investigate the biochemical basis of Rlm1-mediated resistance against blackleg, we conducted an LC-MS–based analysis of a susceptible Topas double haploid (DH) line and its isogenic Rlm1-carrying resistant counterpart for metabolomic profiles during the infection process. Samples were labeled with ¹²C- and ¹³C for LC-MS analyses to enhance both chemical and physical properties of metabolites for improved quantification and detection sensitivity. Resistant plants showed early and sustained accumulation of several defense metabolites, notably pipecolic acid (PA, up to 326-fold), salicylic acid (SA), and gentisic acid (GA) in L. maculans-inoculated Topas–Rlm1 plants compared to mock-inoculated Topas–Rlm1 controls (adjusted p < 0.05), indicating activation of lysine degradation and hormonal defense pathways. Elevated glucosinolates (GLS), γ-aminobutyric acid (GABA), and melatonin precursors may further contribute to antimicrobial defense and cell-wall reinforcement. In contrast, flavonoid and phenylpropanoid pathways were down-regulated, suggesting metabolic reallocation during resistance. Exogenous application of PA, SA, GA, ferulic acid, and piperonylic acid (a known inhibitor of the phenylpropanoid pathway in plants) significantly reduced infection in susceptible canola varieties, validating their defense roles against blackleg. These results offer new insights into Rlm1-mediated resistance and support metabolic targets for breeding durable blackleg resistance in canola. Full article

Papillomaviruses are small, circular DNA viruses that infect epithelial and mucosal cells, which have co-evolved with their hosts over time. While certain mammalian papillomaviruses—especially those linked to disease—are well studied, there is limited knowledge about papillomaviruses associated with avian species. In this study, we identified two avian papillomaviruses from eye/choana swabs of the sacred kingfisher (Todiramphus sanctus) and the little corella (Cacatua sanguinea), collected in Queensland, Australia. The genomes of these viruses, designated as todiramphus sanctus papillomavirus 1 (TsPV1) and cacatua sanguinea papillomavirus 1 (CsPV1), were found to be 7883 and 7825 base pairs in length, respectively. The TsPV1 and CsPV1 genomes exhibited the highest nucleotide sequence identity (>56%) with papillomavirus genomes previously sequenced from mallards or wild ducks in the United States, followed by those from black-legged kittiwakes and Atlantic puffins (>54%) in Newfoundland, Canada. Both TsPV1 and CsPV1 share approximately a 65% nucleotide sequence identity in the L1 gene with anas platyrhynchos papillomavirus 3 (AplaPV3), indicating that they represent novel avian papillomaviruses. Notably, the two genomes in this study were nearly identical (99.69%), and their L1 proteins shared 100% sequence identity. Phylogenetic analysis positioned TsPV1 and CsPV1 within a clade of avian papillomaviruses associated with closely related avian hosts, including the mallard, African grey parrot, common chaffinch, and Atlantic canary. These findings underscore the importance of further research on studying additional Australian bird species longitudinally, which will help to establish potential disease associations and ecological impacts of previously unrecognised and novel papillomaviruses in Australian wild birds. Full article

Blackleg disease, caused by the hemibiotrophic fungal pathogen Leptosphaeria maculans, poses a serious threat to Brassica crops and requires a broad understanding of the plant defence mechanisms. The Brassica. napus-L. maculans pathosystem provides a useful model to understand plant resistance response to hemibiotrophs. This review aims to explain the mechanisms underlying R-Avr interaction, signalling cascades, and the hypersensitive response (HR) produced by B. napus towards L. maculans, causing local cell death that restricts the pathogen to the site of infection. The role of transcription factors is pivotal to the process of HR, coordinating the regulation of genes involved in pathogen recognition and the activation of SA responsive genes and production of secondary metabolites. The R-Avr interaction signalling cascade involves production of reactive oxygen species (ROS), calcium ion influx, Salicylic acid (SA) hormonal signalling and mitogen activated protein kinases (MAPKs), which are critical in the HR in B. napus. The in-depth understanding of molecular signalling pathway of the R-Avr interaction between B. napus-L. maculans pathosystem provides valuable information for future research endeavours regarding enhancing disease resistance in Brassica crops. Full article

The ratio of the innate heterophils to the acquired lymphocytes (the H/L-ratio) has been advocated as a good indicator of physiological stress. Little is known, however, about their development in wild birds. The present study investigates how leucocyte profiles develop in nestlings of a long-lived seabird, the Black-legged Kittiwake (Rissa tridactyla). We counted blood leucocytes in nestlings of about 10 and 25 days of age (n = 23), and in breeding adults around the time of hatching (n = 40) and calculated the H/L-ratio for all three groups. We further investigated if any variation in the leucocyte counts could be explained by body condition or the stress-related hormone corticosterone. 10-day-old nestlings in better body condition showed greater investment in heterophils, which increased their H/L-ratio. The initial focus on innate immunity shifted towards acquired immunity by 25 days, aligning their H/L-ratio with that of adults. In adult Kittiwakes, however, better body condition correlated with lower H/L-ratio, the reverse of the pattern in young nestlings, and this variation was not linked to stress hormone (corticosterone) levels. Overall, our findings suggest that the H/L-ratio reflects the ontogeny of physiological traits and individual condition. As an indicator, values must be interpreted depending on age, in which its sensitivity may also vary. As such, the H/L-ratio may not always be a reliable indicator of physiological stress, in particular related to the release of glucocorticoid hormones. Full article

The effect of chemically synthesized nanocomposites (NCs) of selenium (Se/AG NC), copper oxide (Cu/AG NC) and manganese hydroxide (Mn/AG NC), based on the natural polymer arabinogalactan (AG), on the processes of growth, development and colonization of potato plants in vitro was studied upon infection with the causative agent of potato blackleg—the Gram-negative bacterium Pectobacterium carotovorum—and the causative agent of ring rot—the Gram-positive bacterium Clavibacter sepedonicus (Cms). It was shown that the infection of potatoes with P. carotovorum reduced the root formation of plants and the concentration of pigments in leaf tissues. The treatment of plants with Cu/AG NC before infection with P. carotovorum stimulated leaf formation and increased the concentration of pigments in them. A similar effect was observed when potatoes were exposed to Mn/AG NC, and an increase in growth and root formation was also observed. The infection of plants with Cms inhibited plant growth. Treatment with each of the NCs mitigated this negative effect of the phytopathogen. At the same time, Se/AG and Mn/AG NCs promoted leaf formation. The Se/AG NC increased the biomass of Cms-infected plants. The treatment of plants with NCs before infection showed a decrease in the intensity of the colonization of plants by bacteria. The Se/AG NC had the maximum effect, which is probably due to its high antioxidant capacity. Thus, the NCs are able to mitigate the negative effects of bacterial phytopathogens on vegetation and the intensity of colonization by these bacteria during the infection of cultivated plants. Full article

Alternative splicing (AS) is a prevalent post-transcriptional regulatory mechanism in eukaryotes and plays a crucial role in plant disease resistance. Here, we used the Illumina Novaseq sequencing platform to conduct transcriptome sequencing on canola (Brassica napus) leaves infected with the blackleg pathogen (Leptosphaeria biglobosa strain nm⁻¹) at 0 h, 72 h, 120 h, and 168 h post-inoculation to investigate the mechanism of AS coordination with transcriptional regulation in canola’s response to blackleg disease. The rMATS software (4.1.0) was employed to analyze different AS events in samples taken at 72 h, 120 h, and 168 h. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to elucidate the biological functions of differentially spliced genes at various time points, while Weighted Gene Co-expression Network Analysis (WGCNA) was used to identify key modules and hub genes. As a result, our analysis reveals 16908 AS events across three time points, with 221 being differently spliced. Intron retention (RI) was the most common AS event, accounting for approximately 55% of all events, while alternative 5′ splice site events were least common, comprising only 2%. Furthermore, a total of 213 significantly differentially spliced genes were identified, which were enriched in functions related to protein kinase activity, transferase activity, and pathways such as MAPK signaling pathway—plant and plant hormone signal transduction. WGCNA identified three key modules and ten hub genes, including calcium-binding transcription activator 1, LRR class receptor serine/threonine protein kinase FEI 2, PLATZ transcription factor family proteins, serine/threonine protein kinase PRP4, and E3 ubiquitin ligase SUD1, all of which are associated with canola resistance to L. biglobosa. Thus, this study provides a theoretical basis for identifying disease-resistance genes involved in AS and for exploring the functions of AS gene isoforms in canola. Full article

Clostridial infections in cattle are a significant concern for Brazilian livestock. These diseases are caused by various species of Clostridium, which are known for their ability to produce potent toxins. Botulism in cattle is a serious and often fatal condition caused by the ingestion of neurotoxins produced by C. botulinum. This bacterium thrives in decomposing organic matter, such as spoiled feed, carcasses, and contaminated water. Tetanus is less common, but it is a serious disease that follows the contamination of wounds with Clostridium tetani spores. It results in muscle stiffness, spasms, and often death due to respiratory failure. Blackleg (C. chauvoei) is a disease that primarily affects young cattle, leading to acute lameness, swelling, and high fever. Malignant edema (C. septicum and others) is characterized by rapid onset of swelling at wound sites, and it can occur after injuries or surgical procedures. Enterotoxemia is triggered by the rapid growth of C. perfringens in the gut following excessive carbohydrate intake. This leads to toxin production that causes sudden death. In conclusion, clostridial bovine infections remain a persistent challenge for Brazilian cattle farmers. With continued focus on vaccination, good management practices, and research, the impact of these diseases can be minimized, safeguarding the livestock industry’s economic viability. Full article

Selection is a fundamental part of the plant breeding process, enabling the identification and development of varieties with desirable traits. Thanks to advances in genetics and biotechnology, the selection process has become more precise and efficient, resulting in faster breeding progress and better adaptation of crops to environmental challenges. Genetic parameters related to gene additivity and epistasis play a key role and can influence decisions on the suitability of breeding material. In this study, 188 rapeseed doubled haploid lines were assessed in field conditions for resistance to Leptosphaeria spp. Through next-generation sequencing, a total of 133,764 molecular markers (96,121 SilicoDArT and 37,643 SNP) were obtained. The similarity of the DH lines at the phenotypic and genetic levels was calculated. The results indicate that the similarity at the phenotypic level was markedly different from the similarity at the genetic level. Genetic parameters related to additive gene action effects and epistasis (double and triple) were calculated using two methods: based on phenotypic observations only and using molecular marker observations. All evaluated genetic parameters (additive, additive-additive and additive-additive-additive) were statistically significant for both estimation methods. The parameters associated with the interaction (double and triple) had opposite signs depending on the estimation method. Full article

Crop diseases are a significant constraint to agricultural production globally. Plant disease phenotyping is crucial for the identification, development, and deployment of effective breeding strategies, but phenotyping methodologies have not kept pace with the rapid progress in the genetic and genomic characterization of hosts and pathogens, still largely relying on visual assessment by trained experts. Remote sensing technologies were used to develop an automatic framework for extracting the stems of individual plants from RGB images for use in a pipeline for the automated quantification of blackleg crown canker (Leptopshaeria maculans) in mature Brassica napus plants. RGB images of the internal surfaces of stems cut transversely (cross-section) and vertically (longitudinal) were extracted from 722 and 313 images, respectively. We developed an image processing algorithm for extracting and spatially labeling up to eight individual plants within images. The method combined essential image processing techniques to achieve precise plant extraction. The approach was validated by performance metrics such as true and false positive rates and receiver operating curves. The framework was 98% and 86% accurate for cross-section and longitudinal sections, respectively. This algorithm is fundamental for the development of an accurate and precise quantification of disease in individual plants, with wide applications to plant research, including disease resistance and physiological traits for crop improvement. Full article

In the northeastern USA, the distribution of lone star ticks (Amblyomma americanum) has expanded northward in recent decades, overlapping with the range of blacklegged ticks (Ixodes scapularis). Blacklegged ticks carry pathogens for diseases such as Lyme, babesiosis, and anaplasmosis, while bites from lone star ticks cause other diseases and the alpha-gal syndrome allergy. Lone star ticks can become so abundant that they are perceived as more of a public health threat than blacklegged ticks. Using the island of Martha’s Vineyard, Massachusetts, as a case study, we analyzed data from a total of 1265 yard surveys from 2011 to 2024 to document lone star tick presence and subsequent expansion from two peripheral areas, Chappaquiddick and Aquinnah, to all six towns. The timing of lone star tick expansion on Martha’s Vineyard closely matched an increase in tick submissions to a pathogen testing center. At Chappaquiddick, drag sampling carried out in June 2023 and 2024 showed that both tick species were most common at wooded sites, where blacklegged nymphs were somewhat more abundant than lone star nymphs. However, lone star ticks occurred in a wider range of natural and peridomestic habitats than blacklegged nymphs, making them far more challenging for people to avoid and manage. Full article

Phytopathogenic bacteria of the genus Pectobacterium are responsible for several diseases that affect potato (Solanum tuberosum L.) production worldwide, including blackleg and tuber soft rot. These bacteria are highly diverse, with over 17 different species currently identified. However, some of the recently described species, such as Pectobacterium punjabense, are still poorly understood. In this study, we focused on P. punjabense isolates collected from diseased potato tubers in Russia in 2021. Whole-genome sequencing was used to characterise the genomic diversity of the pathogen and determine the biochemical profiles of the isolated bacteria. The ability of these isolates to cause soft rot symptoms was tested. A comparative assessment of the potential pathogenicity of the Pectobacterium isolates was conducted by infecting potato tubers and measuring the accumulation of biomass in a liquid medium during cultivation at different temperatures. A TaqMan qPCR assay was developed for the highly sensitive and specific characterisation of P. punjabense strains, which can be used in diagnostic systems. This is the first report on P. punjabense causing potato disease in the Russian Federation. Full article