Search Results (29)

Anthracnose is a leaf fungal disease caused by multiple Colletotrichum species. Currently, the predominant deployment of chemical agents for anthracnose control increases ecological pollution risks and potential food safety concerns. The comprehension of the pathogenic mechanism and physicochemical properties of anthracnose is, therefore, essential for effective prevention and control. In this study, the pathogenic strain (pathogen) was isolated from the infected tea plant (Camellia sinensis) leaves and was identified as Colletotrichum gloeosporioides based on microscope observations and gene sequences. This fungus exhibited optimal growth at 28 °C and a pH of 6, with a lethal temperature threshold of 53 °C on PDA plate medium. The 80% tea saponin and 10% polymycin B could effectively inhibit its mycelium growth. Notably, the 10% polyoxin B exhibits a stronger inhibitory effect with an EC₅₀ value of 1.07 mg mL⁻¹. Following infection with Colletotrichum gloeosporioides, the resistant cultivar ‘Zhongcha 108’ exhibited higher levels of H₂O₂ and O₂⁻ than the susceptible ‘Longjing 43’, with later symptom onset and slower disease progression. Although the exogenous treatment of methyl jasmonate (MeJA) did not inhibit C. gloeosporioides directly, it significantly reduced lesion areas in ‘Longjing 43’ leaves caused by C. gloeosporioides. This treatment increased peroxidase and superoxide dismutase activities, but limited malondialdehyde content, thereby enhancing ‘Longjing 43’ resistance to the pathogen. The findings provide scientific guidance for the anthracnose prevention and control in tea gardens. Full article

Fruit rot seriously damages pomelo production. Given concerns regarding the safety of chemical agents, biological alternatives are becoming more preferable. Therefore, the experiment aimed to (i) identify the pathogens causing pomelo fruit rot disease and (ii) select Trichoderma spp. strains controlling the determined pathogens in Ben Tre, Vietnam. Three pathogenic fungal strains isolated from diseased pomelo fruits were selected. The three pathogenic fungal strains were randomly injected into 9 healthy pomelo fruits. The strain PCP-B02-A2 led to a completely rotten fruit on day 17 after infection, while strains PCP-B02-B2 and PCP-B03-A1 had infected spots whose lengths were 17.5 and 28.1 mm, became larger, and eventually led to the whole fruit rot. The pathogens were identified by the internal transcribed spacer (ITS) technique as Colletotrichum gloeosporioides PCP-B02-A2, Pseudopestalotiopsis camelliae sinensis PCP-B03-A1, and P. chinensis PCP-B02-B2. Twenty-five Trichoderma spp. strains were isolated. The ITS technique identified four strains, including Trichoderma asperellum TP-B01, T. harzianum TP-B08, T. harzianum TP-B09, and T. asperellum TP-C25. The PCP-B02-A2 strain had antagonism at 66.7–68.7%, while those of PCP-B02-B2 and PCP-B03-A1 were 64.2–71.1% and 55.7–57.4%, respectively. Full article

Anthracnose of Camellia plants is caused by the Colletotrichum species. The fungal pathogens mainly infect the leaves of plants and lead to serious economic losses. However, knowledge of Camellia phyllosphere microbial community after Colletotrichum infection has not been explored which limited our understanding of the relationship between the Camellia anthracnose outbreak and interacting microorganisms. In this study, three economically and ecologically important Camellia species with anthracnose symptoms were collected and subjected to bacterial and fungal composition analysis, diversity, co-occurrence characteristics, isolation of key strains, and tie-back pathogenicity test. The results indicated that Sphingomonas and Methylobacterium were the dominant bacterial genera over the three Camellia species and Pallidocercospora, Colletotrichum, and Pichia were the dominant fungal genera. The co-occurrence analysis showed that Methylobacterium, Sphingomonas, Massilia, and Allorhizobium were the key bacterial taxa and Colletotrichum, Pallidocercospora, Pichia, Septophoma, and Septoria were the key fungal taxa over the three infected plants. The hub taxa, including the species significantly associated with the Colletotrichum abundance, were mostly beneficial bacteria over the three Camellia species. Further co-culture and tie-back pathogenicity tests verified that the hub taxa associated with pathogenic Colletotrichum in the microbial networks may play promoting/inhibiting roles on Colletotrichum infection. The results highlight the importance of phytopathological conditions for the interactions between microbial members of foliar fungal and bacterial communities. 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

Anthracnose of the tea plant (Camellia sinensis), caused by Colletotrichum spp., poses a significant threat to both the yield and quality of tea production. To address this challenge, researchers have looked to the application of endophytic bacteria as a natural alternative to the use chemical pesticides, offering potential for enhancing disease resistance and abiotic stress tolerance in tea plants. This study focused on identifying effective microbial agents to combat tea anthracnose caused by Colletotrichum fructicola. A total of 38 Bacillus-like strains were isolated from the tea rhizosphere, with 8 isolates showing substantial inhibitory effects against the mycelial growth of C. fructicola, achieving an average inhibition rate of 60.68%. Among these, strain T3 was particularly effective, with a 69.86% inhibition rate. Through morphological, physiological, and biochemical characterization, along with 16S rRNA gene phylogenetics analysis, these strains were identified as B. inaquosorum (T1 and T2), B. tequilensis (T3, T5, T7, T8, and T19), and B. spizizenii (T6). Biological and molecular assays confirmed that these strains could induce the expression of genes associated with antimicrobial compounds like iturin, fengycin, subtilosin, and alkaline protease, which effectively reduced the disease index of tea anthracnose and enhanced tea plant growth. In conclusion, this study demonstrates that B. inaquosorum, B. tequilensis, and B. spizizenii strains are promising biocontrol agents for managing tea anthracnose. Full article

Camellia oleifera C. Abel is a woody oil crop with multiple purposes. This study aims to investigate the mutagenic effects of ⁶⁰Co-γ radiation on C. oleifera seedlings and to screen anthracnose-resistant mutants. Two C. oleifera varieties were investigated: ‘Xianglin 1’ (XL1) and ‘Xianglin 210’ (XL210). Seeds were irradiated with 0 Gy, 30 Gy, 50 Gy, and 80 Gy of ⁶⁰Co-γ, and after one year of planting, the mutagenic lines were studied, and disease-resistant mutants were screened. Results showed that as the radiation intensity was increased, the emergence percentage of both C. oleifera XL210 and XL1 was significantly decreased. Radiation significantly changed the SOD and POD activities in both varieties. Furthermore, 80 Gy irradiated lines showed reduced anthracnose resistance in both varieties. However, 50 Gy irradiated lines showed enhanced disease resistance in XL210 while reducing it in XL1. The 30 Gy irradiated lines did not affect the disease resistance of either variety. Colletotrichum gloeosporioides infection tests were conducted on 94 mutant C. oleifera seedlings, resulting in 8 highly resistant mutants (A3, A8, A10, A19, A21, A32, A35, B17) and 3 susceptible mutants (A4, B15, B27) in XL210 and XL1. Differences in SOD and POD activities led to variations in disease resistance among different mutants. Additionally, the expression levels of CoSOD1, CoPOD, CoIDD4, and CoWKRY78 were varied among the different mutants. This study delivers the screening of disease-resistant mutants in C. oleifera through mutagenic breeding, providing material for the development of new C. oleifera varieties and serving as a resource for further research in mutagenic breeding. Full article

Camellia oleifera is a native woody oil plant in southern China and is infected with anthracnose wherever it is grown. We previously identified Colletotrichum fructicola as the major causal agent of anthracnose on C. oleifera and found that CfAtg8 regulates the pathogenicity and development of C. fructicola. Here, we revealed that CfAtg4 interacts with CfAtg8, contributing to the formation of autophagosomes. The CfAtg8^1–160 allele, which only contains 1–160 amino acids of the CfAtg8, partially recovered the autophagosome numbers and autophagy defects of the ΔCfatg4 mutant. Consequently, these recoveries resulted in the restoration of the defects of the ΔCfatg4 mutant in growth and responses to different external stresses, albeit to an extent. Importantly, we illustrated the critical roles of CfAtg8^1–160 in appressoria formation, and pathogenicity. Collectively, our findings provide new insights into the importance of the interaction between CfAtg8 and CfAtg4 in the growth, autophagy and pathogenicity of the phytopathogenic fungi. Full article

To better assess the practical value and avoid potential risks of the traditionally medicinal and edible basidiomycete Schizophyllum commune, which may arise from undescribed metabolites, a combination of elicitors was introduced for the first time to discover products from cryptic and low-expressed gene clusters under laboratory cultivation. Treating S. commune NJFU21 with the combination of five elicitors led to the upregulated production of a class of unusual linear diterpene-derived variants, including eleven new ones (1–11), along with three known ones (12–14). The structures and stereochemistry were determined by 1D and 2D NMR, HRESIMS, ECD, OR and VCD calculations. Notably, the elongation terminus of all the diterpenes was decorated by an unusual butenedioic acid moiety. Compound 1 was a rare monocyclic diterpene, while 2–6 possessed a tetrahydrofuran moiety. The truncated metabolites 4, 5 and 13 belong to the trinorditerpenes. All the diterpenes displayed approximately 70% scavenging of hydroxyl radicals at 50 μM and null cytotoxic activity at 10 μM. In addition, compound 1 exhibited potent antifungal activity against the plant pathogenic fungi Colletotrichum camelliae, with MIC values of 8 μg/mL. Our findings indicated that this class of diterpenes could provide valuable protectants for cosmetic ingredients and the lead compounds for agricultural fungicide development. Full article

Camellia oleifera is a woody, edible-oil plant native to China. Anthracnose is the major disease of Ca. oleifera, and Colletotrichum fructicola is the main epidemic pathogen. Our previous research indicated that CfHac1 (homologous to ATF/CREB1) and CfGcn5 (general control nonderepressible 5, Gcn5) are integral to key cellular processes that govern fungal development and pathogenesis. Further transcriptomic analyses of the CfHac1 and CfGcn5 mutants, particularly under conditions of endoplasmic reticulum (ER) stress, hold the potential to unveil additional genes implicated in this critical cellular response. We identified all OST/PMT (oligosaccharyltransferase/Protein O-Mannosyltransferases) genes in C. fructicola and analyzed their expression levels. To elucidate novel glycosylation-related genes that may be important for the virulence of C. fructicola, we took an unbiased transcriptomic approach comparing wild-type and the ∆Cfhac1 mutant. Notably, all OST/PMT genes were induced by dithiothreitol and down-regulated in the ΔCfhac1 mutant, yet only the CfPMT4 (Protein O-Mannosyltransferases 4) gene (A04626) was unaffected in the ΔCfgcn5. The results of targeted gene deletion experiments indicate that CfPMT4 plays a crucial role in both vegetative growth and conidiation. Additionally, our investigation revealed that the ΔCfpmt4 exhibits deficiencies in appressorium formation, as well as in its response to cell wall integrity and endoplasmic reticulum stresses. Furthermore, the mutant displayed impaired glycogen metabolism, which may contribute to reduced penetration ability. Overall, CfPmt4, an O-mannosyltransferase, controls the growth, development, and pathogenicity of Colletotrichum fructicola. Understanding the function of the CfPMT4 homolog could provide a potential molecular target for controlling Ca. oleifera anthracnose. Full article

Camellia oleifera (C. oleifera) is one of the four main, woody, edible oil tree species in the world, while C. oleifera anthracnose is mainly caused by the fungus Colletotrichum fructicola (C. fructicola), which severely affects the yield of C. oleifera and the quality of tea oil. Bacillus velezensis (B. velezensis) CSUFT-BV4 is an antagonistic endophytic bacterium isolated from healthy C. oleifera leaves. This study aimed to investigate the biocontrol potential of strain CSUFT-BV4 against C. oleifera anthracnose and its possible functional mechanism, and to determine its growth-promoting characteristics in host plants. In vitro, CSUFT-BV4 was shown to have efficient biofilm formation ability, as well as significant functions in the synthesis of metabolic substances and the secretion of probiotic substances. In addition, the CSUFT-BV4 fermentation broth also presented efficient antagonistic activities against five major C. oleifera anthracnose pathogens, including C. fructicola, C. gloeosporioides, C. siamense, C. camelliae, and C. kahawae, and the inhibition rate was up to 73.2%. In vivo, it demonstrated that the growth of C. oleifera treated with CSUFT-BV4 fermentation broth was increased in terms of stem width, plant height, and maximum leaf area, while the activities of various defense enzymes, e.g., superoxide dismutase (SOD), phenylalanine aminotransferase (PAL), and polyphenol oxidase (PPO), were effectively increased. The remarkable antagonistic activities against C. oleifera anthracnose, the growth-promoting characteristics, and the induction of host defense responses indicate that endophytic bacterium CSUFT-BV4 can be effectively used in the biological control of C. oleifera anthracnose in the future, which will have a positive impact on the development of the C. oleifera industry. Full article

Photosynthesis plays vital roles in plant growth and development. Stay-green (SGR) proteins are responsible for chlorophyll degradation and photosynthetic metabolism. To identify SGR family members and determine their potential functions in tea plants, we identified and cloned three SGR genes. Phylogenetic analysis revealed that the tea SGR homologs were classified into the SGR subfamily (named CsSGR1 and CsSGR2) and the SGRL subfamily (named CsSGRL). Cis-element analysis indicated that the promoters of CsSGR1, CsSGR2 and CsSGRL contained light-, phytohormone- and stress-related elements. Subcellular localization confirmed that CsSGR1 was localized in the chloroplast, while CsSGR2 and CsSGRL were localized in the chloroplast, membrane and nucleus. The RT-qPCR results showed that the three genes in the matures of albino tea cultivars were expressed higher than in the green tea cultivar. However, only CsSGR2-overexpressing tobacco leaves exhibited a yellowish phenotype and significantly lower Fv/Fm values. CsSGR1 and CsSGR2 exhibited similar expression patterns in different tissues after infection with the pathogen Colletotrichum camelliae, which was opposite to the pattern observed for CsSGRL. In addition, CsSGR1 was significantly induced in response to cold stress, SA, JA and ABA in C. camelliae. These findings identified valuable candidate genes for elucidating the mechanism of leaf albinism, stress response and phytohormone signaling in tea plants. Full article

Anthracnose is one of the primary diseases in tea plants that affect tea yield and quality. The geographical distribution, occurrence regularity, and agronomic measures of tea plants with anthracnose have been researched for decades. However, the pathogenic cause of anthracnose in tea plants is diverse in different regions of the world. Identifying the specific pathogenic fungi causing tea anthracnose is an essential control measure to mitigate this disease. In this study, 66 Discula theae-sinensis and 45 Colletotrichum isolates were obtained from three different types of diseased tea leaves. Based on multilocus phylogenetic and morphological analysis, eight known species of Colletotrichum, Colletotrichum fructicola, C. camelliae, C. aenigma, C. siamense, C. henanense, C. karstii, C. tropicicola, and C. gigasporum were identified. This study is the first to report C. tropicicola and C. gigasporum in tea plants in China. Discula theae-sinensis was the most common species in this study and caused disease lesions around wounded areas of tea leaves. The dual trials in vitro indicated Discula theae-sinensis and Colletotrichum were slightly inhibited. Co-inoculating Discula theae-sinensis and C. fructicola was superior to single inoculation at low concentrations. The main cause of anthracnose might be the concerted action of a variety of fungi. Full article

Camellia oleifera, a woody plant indigenous to China, is primarily utilized for the production of cooking oil. However, it is frequently afflicted by anthracnose, a highly detrimental disease that leads to significant annual losses. Colletotrichum fructicola is the predominant etiological agent responsible for anthracnose in Ca. oleifera. Additionally, our investigation has revealed that a bZIP transcription factor CfHac1 in C. fructicola governs the pathogenicity and response to endoplasmic reticulum stress. In this study, we conducted an investigation of the role of the CfPDI1 gene in C. fructicola, which was significantly downregulated in ΔCfhac1 under endoplasmic reticulum stress. The CfPDI1 gene was deleted, resulting in reduced vegetative growth, conidiation, appressoria formation, and appressorium turgor generation. Furthermore, it was observed that the ΔCfpdi1 mutant exhibited impaired responsiveness to endoplasmic reticulum stresses, and the expression of UPR-related genes in C. fructicola was influenced by CfPdi1. Cytological investigations indicated that CfPdi1 is localized in the endoplasmic reticulum. Further analysis revealed that the ΔCfpdi1 mutant displays significantly reduced pathogenicity in Ca. oleifera. Taken together, this study illustrated crucial functions of CfPdi1 in development, response to ER stress, autophagy, and pathogenicity in C. fructicola. Full article

Camellia oleifera, a woody plant that produces edible oil, is indigenous to China. The devastating disease of anthracnose inflicts significant financial losses on Ca. oleifera. The primary causative agent of anthracnose on Ca. oleifera is Colletotrichum fructicola. Chitin, a pivotal constituent of fungal cell walls, assumes a critical function in their proliferation and maturation. To study the biological functions of chitin synthase 1(Chs1) in C. fructicola, the CfCHS1 gene knockout mutants, ∆Cfchs1-1 and ∆Cfchs1-2, and their complementary strain, ∆Cfchs1/CfCHS1, of C. fructicola were generated. Our results showed that the colony diameters of wild-type and complement-strain ∆Cfchs1/CfCHS1, mutant ∆Cfchs1-1 and ∆Cfchs1-2 cultured on the CM and MM medium were 5.2, 5.0, 2.2 and 2.4 cm and 4.0, 4.0, 2.1 and 2.6 cm, respectively, which were significantly smaller for the mutant than for the wild type and complement strain; the inhibition rates on the CM medium supplemented with H₂O₂, DTT, SDS and CR were 87.0% and 88.5%, 29.6% and 27.1%, 88.0% and 89.4%, and 41.7% and 28.7%, respectively, for the mutant strains, ∆Cfchs1-1 and ∆Cfchs1-2, which were significantly higher than those for the other two strains; the rate of hyphal tips with CFW fluorescence in ∆Cfchs1-1 and ∆Cfchs1-2 was 13.3% and 15.0%, which was significantly lower than those for the other two strains; the mutant strains, ∆Cfchs1-1 and ∆Cfchs1-2, lost the ability to produce conidia; the mutant strains showed weaker pathogenicity on wounded and unwounded Ca. oleifera leaves than the wild type and complement strain. The findings of this study suggest that CfChs1 plays a crucial role in the growth and development, stress responses, and pathogenicity of C. fructicola. Thus, this gene could be a potential target for developing novel fungicide. Full article

Camellia oleifera C.Abel, commonly known as tea-oil camellia, is a type of significant woody oil crop that is widely cultivated in southern China. During 2017–2021, a fungal foliar disease was detected in routine surveys in Hainan. However, diseases of tea-oil camellia are seldom reported in Hainan. In this study, 51 Colletotrichum spp. isolates were obtained from the symptomatic samples of tea-oil camellia, collected from three production sites located in Hainan. A polyphasic approach was applied to distinguish Colletotrichum species. All 51 isolates were primarily characterized morphologically, and six gene regions, including an internally transcribed space of ribosomal DNA (ITS), chitinsynthase (CHS-1), β-tubulin (TUB), actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and manganese-superoxide (SOD2), were sequenced for each isolate. By combining morphological characterization with multilocus sequence analysis (MLSA) based on the six genes, the fungal isolates were identified, representing three Colletrotrichum species: C. fructicola, C. siamense, and C. cordylinicola. The most predominant species was C. fructicola. In pathogenicity tests on the tea-oil camellia cultivar (Reyan1), all collected isolates were pathogenic on tea-oil camellia leaves and were reisolated from symptomatic leaves. Colletotrichum fructicola was the most aggressive species on the attached leaves. This is the first report of C. cordylinicola affecting tea-oil camellia anthracnose worldwide. These results will improve our understanding of the pathogens and provide important insights on the diagnosis and efficient disease management of tea-oil camellia anthracnose. Full article