Search Results (46)

Walnut anthracnose (Colletotrichum gloeosporioides and C. siamense) and brown spot (Alternaria alternata) cause severe yield losses globally. Conventional fungicides face the challenges of pathogen resistance and environmental toxicity. This study evaluates 4-propylphenol, a plant-derived phenolic compound, as an eco-friendly alternative against key fungal pathogens of walnut. In vitro assays determined EC₅₀ values against target pathogens (29.11–31.89 mg·L⁻¹) via mycelial growth inhibition and conidial germination suppression (EC₅₀ = 55.04–71.85 mg·L⁻¹). Mechanistic analyses confirmed membrane disruption through propidium iodide staining (9.5-to-14.0-fold fluorescence intensity increase), DNA leakage (77.82–85.15% at 250 mg·L⁻¹), and protein efflux (58.10–66.49%). In field trials, we implemented a phenology-driven strategy: 100 mg·L⁻¹ ground/canopy spray at flowering to reduce primary inoculum, followed by 400 mg·L⁻¹ canopy application at fruiting. This protocol achieved 86.67% control efficacy against disease complexes with negligible phytotoxicity (SPAD variation < 5%). 4-propylphenol provides a sustainable solution through membrane-targeting action, effectively overcoming fungicide resistance in woody crops. Full article

Culinary melon (Cucumis melo subsp. agrestis var. conomon) is widely cultivated throughout Thailand and represents an important agricultural crop. During 2023–2024, anthracnose, charcoal rot, and fruit rot caused by fungi were observed on postharvest culinary melon fruits in northern Thailand. This study aimed to isolate and identify fungal pathogens associated with these postharvest diseases in culinary melons, as well as to assess their pathogenicity. Eight fungal strains were isolated and identified through morphological characterization and multi-gene phylogenetic analysis. Colletotrichum chlorophyti and C. siamense were identified as the causal agents of anthracnose, Fusarium sulawesiense caused fruit rot, and Macrophomina phaseolina was responsible for charcoal rot. Pathogenicity tests were conducted, and the fungi were successfully re-isolated from the symptomatic lesions. Moreover, sensitivity tests for fungicides revealed that C. siamense was completely inhibited by copper oxychloride and copper hydroxide. Colletotrichum chlorophyti was inhibited by benalaxyl-M + mancozeb, copper hydroxide, and mancozeb. In the case of M. phaseolina, complete inhibition was observed with the use of benalaxyl-M + mancozeb, mancozeb, and propineb. Copper hydroxide successfully inhibited F. sulawesiense completely. To our knowledge, this study is the first to report C. siamense and C. chlorophyti as causes of anthracnose, F. sulawesiense as a cause of fruit rot, and M. phaseolina as a cause of charcoal rot in postharvest culinary melon fruits in Thailand. It also marks the first global report of C. siamense, M. phaseolina, and F. sulawesiense as causal agents of these respective diseases in culinary melon. Furthermore, the results of the fungicide sensitivity tests provide valuable information for developing effective management strategies to control these postharvest diseases in the future. Full article

Anthracnose is a disease caused by phytopathogenic fungi such as Colletotrichum siamense that attacks plants and fruits causing great postharvest losses. Different alternatives for the control of this fungus have been studied. In the present study, we evaluated the in vitro antifungal activity of the methanolic extracts of Baccharis glutinosa (ExB) and Jacquinia macrocarpa (ExJ) individually, as well as in combination with chitosan (CS), along with their toxicity in different models. Using the radial growth technique, it was observed that the mycelial development of C. siamense was altered and reduced during exposure to the different treatments evaluated during the first hours of incubation, indicating a fungistatic effect. While the cell viability, by colorimetric assay using the XTT salt, showed alteration since the chitosan reduced proliferation by 50%, while the plant extracts and their mixtures with chitosan reduced approximately 40% indicating cell damage, which was confirmed by fluorescence microscopy. In addition, toxicity tests demonstrated that the J. macrocarpa extract significantly affected the germination percentage of Lactuca sativa seeds, whereas radicle length was reduced in all treatments except for chitosan. The larval survival test for Artemia salina with the extracts indicated their potential toxicity by causing up to 60% mortality. The results indicate that ExB and ExJ mixed with CS are a good option for controlling C. siamense; however, at the concentrations used, they exhibit a toxic effect on the evaluated models. Full article

This study aimed to identify the pathogen of oil palm (Elaeis guineensis) leaf spot disease in Hainan Province, China and examine the effects of environmental factors and fungicide sensitivity on the pathogen. The research confirmed that the pathogen responsible for this novel leaf spot disease was Colletotrichum siamense, marking the first report of this pathogen on oil palm in China. Field observations revealed summer-onset disease symptoms with concomitant leaf damage. The pathogen demonstrated optimal growth at a temperature of 30 °C and pH of 7.0, indicating its adaptability to prevailing climatic conditions in the region. Laboratory tests assessed the effects of various environmental factors on mycelial growth, revealing a marked decline in growth at temperatures below 20 °C and above 35 °C, as well as at acidic pH levels. Fungicide sensitivity assays identified pyraclostrobin, tebuconazole, prochloraz, and carbendazim as the most effective compounds, significantly inhibiting the growth of C. siamense with low EC₅₀ values. These findings provide essential information for developing effective disease management strategies to combat leaf spot disease in oil palm plantations. Full article

Anthracnose significantly threatens the cultivation of Polygonatum cyrtonema, severely impacting its quality and yield. Between 2022 and 2023, 50 Colletotrichum isolates were obtained from diseased leaves collected in three P. cyrtonema production areas within the Two Lakes region of China (Hubei and Hunan provinces). Morphological and molecular analyses identified six Colletotrichum species as the causative agents of anthracnose: C. aenigma, C. siamense, C. gloeosporioides, C. spaethianum, C. fructicola, and C. karsti. Among these pathogens, C. fructicola and C. spaethianum were predominant (82%), while C. siamense and C. fructicola exhibited the highest aggressiveness. Physiological investigations revealed that the optimal temperature range for all six pathogens was 25–28 °C. C. spaethianum thrived under acidic conditions, whereas C. aenigma, C. siamense, and C. gloeosporioides preferred alkaline environments. In contrast, C. fructicola and C. karsti showed no significant response to pH variations. Fungicide screening demonstrated that pyraclostrobin, prochloraz, and carbendazim effectively inhibited the growth of Colletotrichum species. These findings elucidate the epidemiological factors, primary pathogens, and effective control agents for P. cyrtonema anthracnose in the Two Lakes region, providing a basis for developing targeted prevention and control strategies. Full article

Coffee is a significant traded commodity for developing countries. Among the various diseases affecting coffee, anthracnose caused by Colletotrichum spp. has re-emerged as a major constraint on global coffee production. To better understand the Colletotrichum species complex associated with coffee anthracnose, we characterized Colletotrichum spp. using a combination of phenotypic traits, MAT1-2 (ApMat) gene analysis, multi-locus phylogenetic (ITS, ACT, CHS-1, and GAPDH), and pathogenicity assays. A total of 74 Colletotrichum isolates were collected from coffee plants exhibiting anthracnose symptoms across nine coffee plantations in China. Among these, 55 isolates were identified as the C. gloeosporioides species complex using the ApMat locus, while the remaining 19 isolates were identified through multi-locus phylogenetic analyses. The isolates represented seven Colletotrichum species from five species complexes: C. gloeosporioides (including C. siamense, C. nupharicola, and C. theobromicola), C. boninens (C. karstii), C. gigasporum (C. gigasporum), C. orchidearum (C. cliviicola), and C. magnum (C. brevisporum). This is the first report of C. nupharicola and C. cliviicola causing coffee anthracnose worldwide, and the first report of C. nupharicola in China. Pathogenicity tests confirmed that all seven species were capable of infecting coffee leaves. This research enhances our understanding of the Colletotrichum species responsible for coffee anthracnose, and provides valuable insights for developing effective disease management strategies. Full article

Currently, approximately one third of food is wasted; to counteract this, several novel packaging technologies have been developed to extend its shelf life, among which active packaging stands out. In this research, filmogenic solutions of pectin and beeswax with the addition of bioactive compounds as anthocyanins were developed and characterized to evaluate their potential application as active coatings. The antioxidant and antifungal activity of anthocyanins and coatings were determined, and the rheological properties, pH, color, SEM and FT-IR of the coatings were evaluated. The antioxidant activity of the anthocyanins had IC50 values of 79.52 and 56.14 μg/mL for DPPH^• and ABTS^•+, respectively, and 0.25% (w/v) for the antifungal activity against Colletotrichum siamense, which was inhibited by 32.16% and had morphological affectations in the fungus. The best formulation for coating was obtained with 3% (w/v) pectin, 1% (w/v) wax, and 1% (w/v) Tween 80, and 0.1, 0.25, and 0.5% anthocyanins were added. The rheological properties showed adequate viscosity values (0.08–0.12 Pa·s), and the pH values were acidic (3.05–3.78) and showed reddish tones. FT-IR analysis showed that the interactions between the components included the C=O stretching band being shifted due to intermolecular interactions and SEM micrographs showed that the film coatings presented continuous areas of pectin with embedded wax crystals. Promising results were obtained for antioxidant and antifungal activity for the coatings. The formulations presented suitable characteristics for their use as active coating in food. Full article

Colletotrichum species are the most common cause of maize anthracnose, which often manifests as leaf spots. However, field observations often reveal symptoms similar to those caused by other leaf spot pathogens, such as Curvularia and Bipolaris. In this study, 99 isolates were identified using tissue separation and single-spore isolation techniques. As preliminary measures of species diversity, all 99 isolates were identified morphologically, and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene sequences were phylogenetically analyzed. Furthermore, 48 representative strains were selected for molecular identification using multi-locus phylogenetic analyses based on five gene loci (ITS, TUB, ACT, GAPDH, and CAL). Finally, 10 species of Colletotrichum isolated from maize leaf spots were identified. Colletotrichum cliviicola was the most dominant species (24.2%), followed by C. fructicola (18.2%), C. karstii (16.1%), C. siamense (13.1%), C. boninense (7.1%), C. kahawae (7.1%), C. brevisporum (6.1%), C. truncatum (5.1%), C. gigasporum (2.0%), and C. gloeosporioides (1.0%). For the first time, pathogenicity tests revealed that C. cliviicola, C. fructicola, C. siamense, C. karstii, and C. truncatum are the causative agents of maize anthracnose. Additionally, C. boninense was identified as an endophytic fungus on healthy maize. In conclusion, this study is the first to identify the pathogen of maize anthracnose in Sichuan Province. It provides valuable insights for accurately diagnosing and managing maize anthracnose. Full article

Powdery mildew and anthracnose are the main diseases of rubber trees. In recent years, there have been large outbreaks in the rubber-planting areas of Asia, seriously affecting the yield and quality of rubber latex. ZAR1 is a conserved and distinctive coiled-coil nucleotide-binding leucine-rich (CNL) repeat in the plant kingdom, playing a crucial role in disease-resistance processes. To elucidate the function of the HbZAR1 gene in rubber trees (Hevea brasiliensis), three candidate HbZAR1 genes were identified using bioinformatics methods and comprehensively analyzed. The results indicate that the HbZAR1 protein is conserved in different plant species. Examination of cis-regulatory element sequences of HbZAR1genes reveals that the HbZAR1 gene promoter exhibits a remarkable enrichment of stress, light, and hormone elements. An expression analysis shows that the expression levels of the three HbZAR1 genes are highest in the bark and lowest in latex. Three HbZAR1 genes can respond to both rubber tree Erysiphe quercicola and Colletotrichum siamense infection; especially, HbZAR1.1 and HbZAR1.2 show significant upregulation in expression levels during the early stages of infection. These findings suggest that the three HbZAR1 genes may be involved in rubber tree susceptibility to E. quercicola and C. siamense through different immune mechanisms. Subcellular localization results indicate that the HbZAR1 genes are expressed in the nucleus and plasma membrane. This study also shows that the three HbZAR1 genes and activated mutant HbZAR1.1^D481V do not induce stable ROS production and cell death, suggesting possible gene degradation, functional redundancy, or acting as minor genes in disease resistance. This research provides valuable insights for further studying the function of HbZAR1 genes in rubber trees and the mechanisms of immune molecules. Full article

Background: Tea plants (Camellia sinensis) are widely cultivated cash crops. However, fungal diseases lead to significant reductions in both the yield and quality of tea. Therefore, searching for economical, eco-friendly, and efficient biological control measures is crucial for protecting tea plants from pathogenic fungi. Methods: The confrontation assays were performed to identify the antagonistic bacteria against tea pathogenic fungi and evaluate the antifungal activity of these bacteria. Results: Here, three tea pathogenic fungi were identified: Colletotrichum siamense HT-1, Diaporthe phaseolorum HT-3, and Fusarium fujikuroi HT-4. Notably, D. phaseolorum was the first to be reported in tea plants in China. Some tea pathogenic fungi showed a high relative abundance, suggesting a potential disease risk in tea plantations. Strain GS2Y, isolated from tea rhizosphere soil, exhibited strong antifungal activity against tea pathogenic fungi and represented a novel species within the genus Burkholderia, designated as Burkholderia theae. GS2Y could directly inhibit tea pathogenic fungi by disrupting the cellular structures and protect tea plants from fungal diseases caused by C. siamense HT-1 and D. phaseolorum HT-3. Conclusions: B. theae GS2Y might function as a potentially valuable resource for biocontrol agents, laying the foundation for the development of strategies to manage fungal diseases in tea plants. Full article

The Colletotrichum genus is listed as one of the top 10 important plant pathogens, causing significant economic losses worldwide. The C₂H₂ zinc finger protein serves as a crucial transcription factor regulating growth and development in fungi. In this study, we identified two C₂H₂ transcription factors, CgrCon7 and CsCon7, in Colletotrichum graminicola and Colletotrichum siamense, as the orthologs of Con7p in Magnaporthe oryzae. Both CgrCon7 and CsCon7 have a typical C₂H₂ zinc finger domain and exhibit visible nuclear localization. Disrupting Cgrcon7 or Cscon7 led to a decreased growth rate, changes in cell wall integrity, and low tolerance to H₂O₂. Moreover, the deletion of Cgrcon7 or Cscon7 dramatically decreased conidial production, and their knockout mutants also lost the ability to produce appressoria and hyphopodia. Pathogenicity assays displayed that deleting Cgrcon7 or Cscon7 resulted in a complete loss of virulence. Transcriptome analysis showed that CgrCon7 and CsCon7 were involved in regulating many genes related to ROS detoxification, chitin synthesis, and cell wall degradation, etc. In conclusion, CgrCon7 and CsCon7 act as master transcription factors coordinating vegetative growth, oxidative stress response, cell wall integrity, asexual sporulation, appressorium formation, and pathogenicity in C. graminicola and C. siamense. Full article

Strawberry anthracnose caused by Colletotrichum spp. has resulted in significant losses in strawberry production worldwide. Strawberry anthracnose occurs mainly at the seedling and early planting stages, and Colletotrichum siamense is the main pathogen in North China, where mycelia, anamorphic nuclei, and conidia produced in the soil are the main sources of infection. The detection of pathogens in soil is crucial for predicting the prevalence of anthracnose. In this study, a visualized loop-mediated isothermal amplification (LAMP) assay and a loop-mediated isothermal amplification method combined with a TaqMan probe (LAMP-TaqMan) assay were developed for the β-tubulin sequence of C. siamense. Both methods can detect Colletotrichum siamense genomic DNA at very low concentrations (10⁴ copies/g) in soil, while both the visualized LAMP and LAMP-TaqMan assays exhibited a detection limit of 50 copies/μL, surpassing the sensitivity of conventional PCR and qPCR techniques, and both methods showed high specificity for C. siamense. The two methods were compared: LAMP-TaqMan exhibited enhanced specificity due to the incorporation of fluorescent molecular beacons, while visualized LAMP solely necessitated uncomplicated incubation at a constant temperature, with the results determined by the color change; therefore, the requirements for the instrument are relatively straightforward and user-friendly. In conclusion, both assays will help monitor populations of C. siamense in China and control strawberry anthracnose in the field. Full article

Cassava (Manihot esculenta Crantz) is a staple crop widely cultivated by small farmers in tropical countries. However, despite the low level of technology required for its management, it can be affected by several diseases, with anthracnose as the main threat. There is little information about the main species of Colletotrichum that infect cassava in Brazil. Thus, the objective of this work was to study the diversity, prevalence and virulence of Colletotrichum species that cause anthracnose in cassava leaves in northern Brazil. Twenty municipalities of the Pará and Tocantins states were selected, and leaves with symptoms were collected in those locations. Pure cultures were isolated in the laboratory. Species were identified using phylogenetic analyses of multiple loci, and their pathogenicity, aggressivity and virulence levels were assessed. Our results showed the greatest diversity of Colletotrichum associated with anthracnose in cassava plants of the “Formosa” cultivar in the Tocantins and Pará states. We determined the presence of Colletotrichum chrysophilum, C. truncatum, C. siamense, C. fructicola, C. plurivorum, C. musicola and C. karsti, with C. chrysophilum as the most aggressive and virulent. Our findings provide accurate identifications of species of Colletotrichum causing anthracnose in cassava crops, which are of great relevance for cassava breeding programs (e.g., the search for genotypes with polygenic resistance since the pathogen is so diverse) and for developing anthracnose management strategies that can work efficiently against species complexes of Colletotrichum. Full article

Bitter rot of apple is an economically important worldwide disease caused by different Colletotrichum species, depending on many factors such as climate, geography, other hosts, and crop management practices. Culture, morphology, and single-locus sequencing-based methods for identifying the Colletotrichum species are severely limited in effectiveness, while the multilocus sequence typing methods available for delineating species are costly, time-intensive, and require high expertise. We developed species-specific hydrolysis probe real-time PCR assays for the following nine Colletotrichum species causing bitter rot in the Mid-Atlantic U.S.A.: C. fructicola, C. chrysophilum, C. noveboracense, C. gloeosporioides s.s., C. henanense, C. siamense and C. theobromicola from the C. gloeosporioides species complex, and C. fioriniae and C. nymphaeae from the C. acutatum species complex. After searching 14 gene regions, we designed primers and probes in 5 of them for the nine target species. Four primer–probe set pairs were able to be duplexed. Sensitivity tests showed as little as 0.5 pg DNA were detectable. These real-time PCR assays will provide rapid and reliable identification of these key Colletotrichum species and will be critically important for studies aiming to elucidate their biology, epidemiology, and management on apples as the number one produced and consumed tree fruit in the U.S.A. Full article

Anthracnose, caused by Colletotrichum siamense, is a destructive disease of Pachira glabra in southern China. Early and proper monitoring and quantification of C. siamense is of importance for disease control. A calmodulin (CAL) gene-based TaqMan real-time PCR assay was developed for efficient detection and quantification of C. siamense, which reliably detected as low as 5 pg of genomic DNA and 12.8 fg (5800 copies) of target DNA. This method could specifically recognize all tested C. siamense isolates, while no amplification was observed in other closely related Colletotrichum species. The assay could still detect C. siamense in plant mixes, of which only 0.01% of the tissue was infected. A dynamic change in the amount of C. siamense population was observed during infection, suggesting that this real-time PCR assay can be used to monitor the fungal growth progression in the whole disease process. Moreover, the method enabled the detection of C. siamense in naturally infected and symptomless leaves of P. glabra trees in fields. Taken together, this specific TaqMan real-time PCR provides a rapid and accurate method for detection and quantification of C. siamense colonization in P. glabra, and will be useful for prediction of the disease to reduce the epidemic risk. Full article