Search Results (311)

Botryosphaeria dothidea is the causative agent of Chinese hickory trunk canker, which poses significant threat to the production of Chinese hickory (Carya cathayensis Sarg.). Previous studies reported that endophytic–pathogenic phase transition, also referred to as latent infection, plays an important role in the interaction of Botryosphaeria dothidea with various host plants, including Chinese hickory. However, the mechanism underlying this phase transition is not well understood. Here, we employed RNA-Seq to investigate transcriptional changes in B. dothidea during its phase transition upon interaction with Chinese hickory. A co-expression network was generated based on 6391 differentially expressed genes (DEGs) identified from different infection stages and temperature treatments. One co-expressed module was found that highly correlated with temperature treatments which simulated conditions of B. dothidea latent infection in the field. Subsequently, 53 hub genes were detected, and gene ontology (GO) enrichment analysis revealed three categories of enriched GO terms: transmembrane transport or activity, ion homeostasis or transport, and carbohydrate metabolism. One PacC transcriptional factor (BDLA_00001555, an ambient pH regulator), and one endo-β-1,3-glucanase (BDLA_00010249) were specifically upregulated under temperature treatments that corresponded with the activation stage of B. dothidea’s pathogenic state. The knockout mutant strain of BDLA_00001555 demonstrated defective capability upon the activation of the pathogenic state. This confirmed that BDLA_00001555, the PacC transcriptional factor, plays an important role in the latent infection phase of B. dothidea. Our findings provide insights into the pathogenic mechanism of Chinese hickory trunk canker disease. Full article

Almond decline and dieback have become significant challenges in newly established orchards, with symptoms including internal necrosis, canker, and external gummosis. This work aims to explore the potential fungal and bacterial causative agents through metabarcoding and traditional culture plate isolation across six almond cultivars. Our results emphasize the multifactorial nature of almond decline and dieback, with possible co-infections by opportunistic fungi and bacteria playing a central role. Classical isolation identified 47 fungal species or genera, including Diaporthe amygdali, Diplodia corticola, Phytophthora sp., and several Fusarium species. Almond metabarcoding revealed a more diverse microbial community, highlighting the prevalence of soilborne pathogens such as Neocosmospora rubicola, Dactylonectria estremocensis, and Plectosphaerella niemeijerarum. Soil metabarcoding suggested that these pathogens likely originate from nursery substrates or soils shared with other crops, such as olives and vineyards, that serve as a source of inoculum. ‘Soleta’ generally presented lower richness when compared to the other tested cultivars, suggesting a higher degree of biotic stress and decreased plant resilience. This study highlights the value of integrating NGS approaches to comprehensively study complex diseases and the need for further research on pathogen interactions and cultivar susceptibility for the future development of new sustainable, targeted management strategies in almond orchards. Full article

Common buckthorn (Rhamnus cathartica L.) is a small tree that forms dense stands, displacing native plant species and threatening natural forest habitats in its introduced range in North America. Removal via cutting is labor intensive and often ineffective due to vigorous resprouting. Although chemical control methods are effective, they can negatively affect sensitive ecosystems. A mycoherbicide that selectively kills buckthorn would provide an additional method for control. In the present study, fungi were collected from dying buckthorn species (Frangula alnus Mill., Rhamnus cathartica, Ventia alnifolia L’Hér) located at 19 sites across Minnesota and Wisconsin for their potential use as mycoherbicides for common buckthorn. A total of 412 fungi were isolated from samples of diseased tissue and identified via DNA extraction and sequencing. These fungi were identified as 120 unique taxa belonging to 81 genera. Of these fungi, 46 species belonging to 26 genera were considered to be canker or root-rot pathogens of woody plants, including species in Cytospora, Diaporthe, Diplodia, Dothiorella, Eutypella, Fusarium, Hymenochaete, Irpex, Phaeoacemonium, and others. A future study testing the pathogenicity of these putative pathogens of buckthorn is now needed to assess their utility as potential mycoherbicide agents for control of common buckthorn. Full article

Citrus Huanglongbing (HLB) is one of the most devastating diseases in the global citrus industry, but its early detection under complex field conditions remains a major challenge. Existing methods often suffer from insufficient dataset diversity and poor generalization, and struggle to accurately detect subtle early-stage lesions and multiple HLB symptoms in natural backgrounds. To address these issues, we propose an enhanced YOLO11-based framework, DCH-YOLO11. We constructed a multi-symptom HLB leaf dataset (MS-HLBD) containing 9219 annotated images across five classes: Healthy (1862), HLB blotchy mottling (2040), HLB Zinc deficiency (1988), HLB yellowing (1768), and Canker (1561), collected under diverse field conditions. To improve detection performance, the DCH-YOLO11 framework incorporates three novel modules: the C3k2 Dynamic Feature Fusion (C3k2_DFF) module, which enhances early and subtle lesion detection through dynamic feature fusion; the C2PSA Context Anchor Attention (C2PSA_CAA) module, which leverages context anchor attention to strengthen feature extraction in complex vein regions; and the High-efficiency Dynamic Feature Pyramid Network (HDFPN) module, which optimizes multi-scale feature interaction to boost detection accuracy across different object sizes. On the MS-HLBD dataset, DCH-YOLO11 achieved a precision of 91.6%, recall of 87.1%, F1-score of 89.3, and mAP50 of 93.1%, surpassing Faster R-CNN, SSD, RT-DETR, YOLOv7-tiny, YOLOv8n, YOLOv9-tiny, YOLOv10n, YOLO11n, and YOLOv12n by 13.6%, 8.8%, 5.3%, 3.2%, 2.0%, 1.6%, 2.6%, 1.8%, and 1.6% in mAP50, respectively. On a publicly available citrus HLB dataset, DCH-YOLO11 achieved a precision of 82.7%, recall of 81.8%, F1-score of 82.2, and mAP50 of 89.4%, with mAP50 improvements of 8.9%, 4.0%, 3.8%, 3.2%, 4.7%, 3.2%, and 3.4% over RT-DETR, YOLOv7-tiny, YOLOv8n, YOLOv9-tiny, YOLOv10n, YOLO11n, and YOLOv12n, respectively. These results demonstrate that DCH-YOLO11 achieves both state-of-the-art accuracy and excellent generalization, highlighting its strong potential for robust and practical citrus HLB detection in real-world applications. Full article

Citrus diseases can lead to surface defects on citrus fruits, adversely affecting their quality. This study aims to accurately identify citrus defects against varying backgrounds by focusing on four types of diseases: citrus black spot, citrus canker, citrus greening, and citrus melanose. We propose an improved YOLOv10-based disease detection method that replaces the traditional convolutional layers in the Backbone network with LDConv to enhance feature extraction capabilities. Additionally, we introduce the GFPN module to strengthen multi-scale information interaction through cross-scale feature fusion, thereby improving detection accuracy for small-target diseases. The incorporation of the DAT mechanism is designed to achieve higher efficiency and accuracy in handling complex visual tasks. Furthermore, we integrate the AFPN module to enhance the model’s detection capability for targets of varying scales. Lastly, we employ the Slide Loss function to adaptively adjust sample weights, focusing on hard-to-detect samples such as blurred features and subtle lesions in citrus disease images, effectively alleviating issues related to sample imbalance. The experimental results indicate that the enhanced model YOLOv10-LGDA achieves impressive performance metrics in citrus disease detection, with accuracy, recall, mAP@50, and mAP@50:95 rates of 98.7%, 95.9%, 97.7%, and 94%, respectively. These results represent improvements of 4.2%, 3.8%, 4.5%, and 2.4% compared to the original YOLOv10 model. Furthermore, when compared to various other object detection algorithms, YOLOv10-LGDA demonstrates superior recognition accuracy, facilitating precise identification of citrus diseases. This advancement provides substantial technical support for enhancing the quality of citrus fruit and ensuring the sustainable development of the industry. Full article

Mexico is the world’s leading producer of avocado (Persea americana); however, its productivity is threatened by various diseases, especially root rot caused by Phytophthora. While P. cinnamomi is the most commonly reported species worldwide, this study identified P. mengei for the first time as a causal agent of root rot and trunk canker in avocado orchards in the state of Michoacán, México. The morphological and molecular characterization of four isolates (three from canker and one from root rot) confirmed their identity: semi-papillate sporangia and plerotic oospores with paragynous antheridia, with sequence identities of 99.87% (ITS) and 100% (COI) with type sequences of P. mengei. Pathogenicity tests demonstrated the ability to infect roots, stems, and fruits, although with a low reisolation percentage in roots (10%), suggesting an opportunistic pathogen behavior. Sensitivity tests to potassium phosphite (EC₅₀ of 3.67 μg/mL⁻¹ a.i.) and metalaxyl-M (0.737 μg/mL⁻¹ a.i.) revealed possible limitations for chemical control. These findings position P. mengei as an emerging pathogen with important implications for integrated crop management. To the best of our knowledge, this is the first report of P. mengei causing root rot and trunk canker in avocado in Michoacán, Mexico. Full article

In recent years, severe decline and mortality events have been observed in holm oak (Quercus ilex L.) ecosystems in different Italian regions, including Puglia (southern Italy). Given the landscape and ecological relevance of holm oak forests in Apulia, a study was conducted to identify the causal agents related to this complex disease syndrome. The surveys, conducted in winter 2024 in three different woodlands, revealed the widespread occurrence of mature holm oak trees showing sudden death, crown thinning, shoot and branch dieback, sunken cankers, and root rot symptoms. Isolations performed from symptomatic samples collected from both stem and small roots yielded fungal and fungal-like colonies representing two distinct families: Botryosphaeriaceae and Peronosporaceae. Analysis of morphological and DNA sequence data allowed us to identify six distinct species, including Diplodia corticola and D. quercivora (Botryosphaeriaceae), Phytophthora cinnamomi, P. multivora, P. psychrophila, and P. asparagi (Peronosporaceae). For P. asparagi and P. psychrophila, isolated for the first time from declining holm oak trees in Italy, Koch’s postulates were satisfied by inoculating 1-year-old seedlings at the collar in controlled conditions. Thirty days after inoculation, all plants showed the same symptoms observed in the field. Overall, the data obtained highlights the co-occurrence of multiple Botryosphaeriaceae and Phytophthora species on declining holm oak trees and the discovery of a new haplotype of Diplodia quercivora. Full article

Phytopythium vexans is a plant pathogen responsible for a variety of destructive diseases in crops worldwide. This includes patch canker, damping-off, root, and crown rots in economically important crops, such as apple, pear, grapevine, citrus, avocado, and kiwi. The pathogen has a global distribution, and a recent report confirmed its presence in southern Ontario, Canada. This study presents the first genome sequencing, assembly, and annotation of the Canadian P. vexans strain SS21. To explore how variation in secreted protein repertoires may relate to infection strategies and host adaptation, we compared the predicted secretome of SS21 with reference strains from Iran (CBS 119.80) and China (HF1). The analysis revealed that HF1 harbors a larger set of CAZymes, sterol-binding proteins, and predicted effectors, which may suggest broader adaptive potential. In contrast, strain SS21 appears to have adapted to a niche-specific strategy, with fewer necrosis-inducing proteins, glucanase inhibitors, and effectors, possibly indicating adaptation to specific hosts or ecological conditions. Comparative genome data highlight distinct evolutionary trajectories that may have shaped each strain’s infection strategy, with SS21 potentially serving as a robust additional reference for future studies on P. vexans biology and host interactions. While this analysis identifies key candidate effectors, gene expression studies are required to validate their functional roles in infection and host manipulation. Full article

Plant fungal diseases remain a major threat to global agricultural production, necessitating eco-friendly and sustainable strategies. Conventional chemical fungicides often lead to the development of resistant pathogen strains and cause environmental contamination. Therefore, the development of biocontrol agents is particularly important. In this study, we identified Burkholderia stagnalis YJ-2 from the rhizosphere soil of Woodsia ilvensis as a promising biocontrol strain using 16S rRNA and whole-genome sequencing. This strain demonstrated broad-spectrum antifungal activity against plant fungal pathogens, with its bioactive extracts maintaining high stability across a temperature range of 25–100 °C and pH range of 2–12. We used in vitro assays to further show that the metabolites of B. stagnalis YJ-2 disrupted the hyphal morphology of Valsa mali, resulting in swelling, reduced branching, and increased pigmentation. Fluorescence labeling confirmed that B. stagnalis YJ-2 stably colonized the roots and stems of tomato and wheat plants. Furthermore, various formulations of microbial agents based on B. stagnalis YJ-2 were evaluated for their efficacy against plant pathogens. The seed-coating formulation notably protected tomato seedlings from Alternaria solani infection without affecting germination (p > 0.1), while the wettable powder exhibited significant control effects on early blight in tomatoes, with the preventive treatment showing better efficacy than the therapeutic treatment. Additionally, the B. stagnalis YJ-2 bone glue agent showed a substantial inhibitory effect on apple tree canker. Whole-genome analysis of B. stagnalis YJ-2 revealed a 7,705,355 bp genome (67.68% GC content) with 6858 coding genes and 20 secondary metabolite clusters, including three clusters (YJ-2_GM002015-YJ-2_GM002048, YJ-2_GM0020090-YJ-2_GM002133, and YJ-2_GM06534-YJ-2_GM006569) that are related to the antifungal activity of YJ-2 and are homologous to the biosynthetic gene clusters of known secondary metabolites, such as icosalide, ornibactin, and sinapigladioside. We further knocked out core biosynthetic genes of two secondary metabolic gene clusters and found that only the YJ-2_GM006534-YJ-2_GM006569 gene cluster had a corresponding function in two potential antifungal gene clusters. In contrast to the wild-type strain YJ-2, only deletion of the YJ-2_GM006563 gene reduced the antifungal activity of B. stagnalis YJ-2 by 8.79%. These findings highlight the biocontrol potential of B. stagnalis YJ-2, supporting a theoretical foundation for its development as a biocontrol agent against plant fungal diseases and thereby promoting sustainable agricultural disease management. Full article

Many stressors contribute to productivity and quality losses in agricultural production, ranging from the rising global population to shrinking agricultural lands. To boost yield and quality, plants must be protected from abiotic and biotic stressors. Seed priming is the process of boosting germination and seedling development by treating seeds with particular pre-treatments before germination. Seed priming is used to improve plant yield and germination. Plant defense elicitors stimulate the plant’s natural immune system when administered externally, strengthening the plant and making it more resistant/tolerant to diseases. β-Aminobutyric Acid (BABA) is a plant defense elicitor, and in this study, the effect of BABA seed priming on Clavibacter michiganensis ssp. michiganensis (Cmm), which causes bacterial cancer in tomato (Solanum lycopersicum L.), was investigated. Tomato seeds were subjected to seed priming for 72 h with 12 mM BABA (BABA priming) or water (water priming) as the control group. Tomato seedlings that germinated normally were utilized as a positive control. When the plants reached the 3–4 leaf stage, they were infected with Cmm. According to the data, BABA priming was the most effective experimental group in reducing disease severity. Furthermore, it has been shown that the use of BABA as a spray or water-priming application gives better protection than the control treatment. To understand the molecular basis of this suppression, plant samples were obtained at two separate time points (0th and the 7th day), and transcriptional changes of essential plant immunity genes (NPR1, PAL, PR1, WRKY70, WRKY33b, TPK1b, and PR5) were studied. The qRT-PCR results showed that NPR1 gene expression increased considerably with the BABA priming treatment compared to the control. BABA priming at the 0th hour enhanced NPR1 gene expression by approximately five times. In addition, BABA priming increased PR1 gene expression. Furthermore, foliar spraying of BABA (BABA priming+BABA-Sp) on seed-primed plants resulted in a nine-fold increase in PR1 gene expression. At day 7, the BABA priming+Cmm treatment increased PR5 gene expression. Along with the control of other genes, the molecular architecture of BABA seed priming has been attempted to be discovered. The application of BABA seed priming is expected to contribute to the literature and have favorable impacts on plant protection against Cmm. Full article

Citrus pests and diseases severely impact fruit yield and quality. However, existing object detection models face limitations in complex backgrounds, target occlusion, and small target recognition, and they struggle to be efficiently deployed on resource-constrained devices. To address these issues, this study proposes a lightweight pest and disease detection model, YOLOv11-RDTNet, based on the improved YOLOv11n. This model integrates multi-scale features and attention mechanisms to enhance recognition performance in complex scenarios, while adopting a lightweight design to reduce computational costs and improve deployment adaptability. The model introduces three key enhancement features: First, shallow RFD (SRFD) and deep RFD (DRFD) downsampling modules replace traditional convolution modules, improving image feature extraction accuracy and robustness. Second, the Dynamic Group Shuffle Transformer (DGST) module replaces the original C3k2 module, reducing the model’s parameter count and computational demand, further enhancing efficiency and performance. Lastly, the lightweight Task Align Dynamic Detection Head (TADDH) replaces the original detection head, significantly reducing the parameter count and improving accuracy in small-object detection. After processing the collected images, we obtained 1382 images and constructed a dataset containing five types of citrus pests and diseases: anthracnose, canker, yellow vein disease, coal pollution disease, and leaf miner moth. We applied data augmentation on the dataset and conducted experimental validation. Experimental results showed that the YOLOv11-RDTNet model had a parameter count of 1.54 MB, an mAP50 of 87.0%, and a model size of 3.4 MB. Compared to the original YOLOv11 model, the YOLOv11-RDTNet model reduced the parameter count by 40.3%, improved mAP50 by 4.8%, and reduced the model size from 5.5 MB to 3.4 MB. This model not only improved detection accuracy and reduced computational load but also achieved a balance in performance, size, and speed, making it more suitable for deployment on mobile devices. Additionally, the research findings provided an effective tool for citrus pest and disease detection with small sample sizes, offering valuable insights for citrus pest and disease detection in agricultural practices. Full article

Citrus canker, caused by Xanthomonas citri subsp. citri, is a devastating disease that affects citrus production and trade worldwide. Traditional control methods, based on copper compounds, are effective but pose environmental and health risks due to their toxicity and potential for bioaccumulation. This study evaluates the synergistic potential of essential oils (EOs) and rhamnolipids as sustainable alternatives for disease management. Four EOS (citronella, palmarosa, geranium, and clove) were tested for their antibacterial activity. Citronella EO showed a 90% inhibitory concentration (IC 90) of 0.15% (v/v) and a minimum bactericidal concentration of 0.25% (v/v), while the other EOs showed IC 90 and bactericidal activity at 0.06% (v/v). Rhamnolipids (RHLs), biosurfactants produced by Pseudomonas aeruginosa, inhibited X. citri at a concentration of 0.3% (v/v). The combination of citronella EO and RHLs showed a synergistic effect, reducing the inhibitory concentration of citronella by 50% and that of RHLs by more than 90%. In addition, the combined formulation permeabilized more than 80% of bacterial membranes and reduced biofilm formation. In contrast, other oils tested in combination with rhamnolipid showed independent effects. These results indicate that EOs and rhamnolipids represent an environmentally safe strategy for the control of X. citri subsp. citri that overcomes the limitations of conventional methods while reducing environmental and health impacts. Full article

Idesia polycarpa is an important woody oilseed tree crucial for ensuring China’s grain and oil security. The expansion of I. polycarpa plantations has been accompanied by an increase in pests and diseases, with canker disease recently observed in two forests in Henan Province. Field surveys revealed a disease incidence of 70.12% among 328 surveyed trees, indicating a substantial threat to plantation health. The most virulent pathogen, strain SQ5, was identified as Botryosphaeria dothidea through molecular sequencing and morphological analyses. Strain SQ5 showed an optimum growth temperature of 25 °C and a mycelial lethal temperature of 60 °C. The pathogen thrives in acidic conditions and is promoted by light, with the ability to utilize various carbon and nitrogen sources. In vitro toxicity assessments identified four effective fungicides: 70% thiophanate-methyl (EC50 = 0.0169 µg/mL), 43% tebuconazole (EC50 = 0.0219 µg/mL), 20% octylamine acetate (EC50 = 0.0271 µg/mL), and 40% difenoconazole (EC50 = 0.0954 µg/mL). Field trials demonstrated that 43% tebuconazole (average efficacy = 35.29%) and 40% difenoconazole (average efficacy = 23.53%) exhibited superior control of I. polycarpa canker. This study represents the first systematic analysis of I. polycarpa canker and its control measures, laying a foundation for further research and field management strategies. Given the significance of I. polycarpa in Chinese forestry, this underscores the need for effective management strategies to sustain its productivity and mitigate risks associated with expanding plantations. Full article

Apple Valsa canker, caused by Valsa mali and Valsa pyri, is a devastating disease of apple trees and poses a severe threat to the sustainable development of apple production. Although the two species’ whole genomes have been sequenced, their mitochondrial genomes are still uncharacterized. In this study, the complete mitochondrial genomes of V. mali and V. pyri were assembled, annotated, and compared by bioinformatic methods. The results indicate that the mitogenomes are both circular DNA molecules with sizes of 213,406 bp and 128,022 bp, respectively. The AT skew values of the two Valsa species’ mitogenomes were positive, while the GC skew values were negative. Comparative mitogenome analysis revealed that the length and base composition of protein-coding genes (PCGs), rRNA genes, and tRNA genes differed between the two Valsa species. It was found that the expansion of V. mali was primarily attributable to the intronic regions. There are large numbers of interspersed repetitive sequences (IRS) in both Valsa mitogenomes; however, the proportion of IRS in V. mali (43.56%) was much higher than that in V. pyri (2.41%). The alignment of large fragments between the mitochondrial and nuclear genomes of both V. mali (1.73 kb) and V. pyri (5.17 kb) indicates that gene transfer between mitochondrial and nuclear genomes occurred during evolution. The ka/ks ratios for 15 core PCGs were below one, suggesting that these genes were subjected to purifying selection pressure. Comparative mitogenomics revealed that the two fungi had significant mitogenomic collinearity and large-scale gene rearrangements. The results of phylogenetic analysis based on Bayesian inference (BI) and maximum likelihood (ML) using a combined mitochondrial gene set confirmed that V. mali and V. pyri were fully independent taxa with a high bootstrap value of 100 (ML) and a high posterior probability of 1.0 (BI). This is the first report on the mitogenomes within the genus Valsa. These results will pave the way to understanding the evolution and differentiation of mitogenomes in the genus Valsa. Full article

The aim of this study was to investigate the factors affecting the occurrence of walnut canker disease and the effect of low-temperature treatment on its occurrence in Hotan County, and provide a theoretical basis for the prevention and control of the disease. The occurrence of canker disease was investigated in walnut plantations of different varieties, plant and row spacing, and diameter at breast height (DBH) from April to August of 2023 and 2024. In laboratory research, the spread area of disease spots on isolated branches of peach was studied under different temperature treatments and different treatment times. The occurrences of walnut canker for the two consecutive years were basically the same. The number of new lesions showed an upward trend in April and May and reached its highest in May. The number of new lesions tended to stabilize in June and July in Hotan County. The walnut variety with more severe disease was “Xinfeng”. The disease was most serious in plots with plant spacing and row spacing of 10 m × 7 m. The DBH of the more susceptible walnut trees was >30 cm. Low-temperature treatment and treatment time had a significant impact on the walnut canker lesion expansion area (p < 0.05). The key factor in lesion expansion was low temperature. The maximum lesion expansion area was 1.70 × 10⁴ mm² under treatment at 20 °C for 5 h. The walnut variety and the plant and row spacing were the key factors affecting the occurrence of walnut canker disease, with low temperature being the main factor affecting its spread. Full article