The miR7125-MdARF1 module enhances the resistance of apple to Colletotrichum gloeosporioides by promoting lignin synthesis in response to salicylic acid signalling.

Apple is an important cash crop in China, and it is susceptible to fungal infections that have deleterious effects on its yield. Apple bitter rot caused by Colletorichum gloeosporioides is one of the most severe fungal diseases of apple. Salicylic acid (SA) is a key signalling molecule in the plant disease resistance signalling pathways. Lignin synthesis also plays a key role in conferring disease resistance. However, few studies have clarified the relationship between the SA disease resistance signalling pathway and the lignin disease resistance pathway in apple. MdMYB46 has previously been shown to promote lignin accumulation in apple and enhance salt and osmotic stress tolerance. Here, we investigated the relationship between MdMYB46 and biological stress; we found that MdMYB46 overexpression enhances the resistance of apple to C. gloeosporioides. We also identified MdARF1, a transcription factor upstream of MdMYB46, via yeast library screening and determined that MdARF1 was regulated by miR7125 through psRNATarget prediction. This regulatory relationship was confirmed through LUC and qRT-PCR experiments, demonstrating that miR7125 negatively regulates MdARF1. Analysis of the miR7125 promoter revealed that miR7125 responds to SA signals. The accumulation of SA level will result in the decrease of miR7125 expression level. In sum, the results of our study provide novel insights into the molecular mechanisms underlying the resistance of apple to C. gloeosporioides and reveal a new pathway that enhances lignin accumulation in apple in response to SA signals. These findings provide valuable information for future studies aimed at breeding apple for disease resistance.

The new CFEM protein CgCsa required for Fe3+ homeostasis regulates the growth, development, and pathogenicity of Colletotrichum gloeosporioides.

Secreted common fungal extracellular membrane (CFEM) domain proteins have been implicated in multiple biological functions in fungi. However, it is still largely unknown whether the ferric iron (Fe3+), as an important trace element, was involved with the biological function of CFEM proteins. In this study, a new CFEM protein CgCsa, with high expression levels at the early inoculation stage on peppers by Colletotrichum gloeosporioides was investigated. Deletion of the targeted gene CgCsa revealed multiple biological roles in hyphal growth restriction, highly reduced conidial yield, delayed conidial germination, abnormal appressorium with elongated bud tubes, and significantly reduced virulence of C. gloeosporioides. Moreover, in CgCsa mutants, the expression levels of four cell wall synthesis-related genes were downregulated, and cell membrane permeability and electrical conductivity were increased. Compared to the wild-type, the CgCsa mutants downregulated expressions of iron transport-related genes, in addition, its three-dimensional structure was capable binding with iron. Increase in the Fe3+ concentration in the culture medium partially recovered the functions of ΔCgCsa mutant. This is probably the first report to show the association between CgCsa and iron homeostasis in C. gloeosporioides. The results suggest an alternative pathway for controlling plant fungal diseases by deplete their trace elements.

Design and Synthesis of Eugenol Derivatives Bearing a 1,2,3-Triazole Moiety for Papaya Protection against Colletotrichum gloeosporioides.

A series of 19 novel eugenol derivatives containing a 1,2,3-triazole moiety was synthesized via a two-step process, with the key step being a copper(I)-catalyzed azide-alkyne cycloaddition reaction. The compounds were assessed for their antifungal activities against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. Triazoles 2k, 2m, 2l, and 2n, at 100 ppm, were the most effective, reducing mycelial growth by 88.3, 85.5, 82.4, and 81.4%, respectively. Molecular docking calculations allowed us to elucidate the binding mode of these derivatives in the catalytic pocket of C. gloeosporioides CYP51. The best-docked compounds bind closely to the heme cofactor and within the channel access of the lanosterol (LAN) substrate, with crucial interactions involving residues Tyr102, Ile355, Met485, and Phe486. From such studies, the antifungal activity is likely attributed to the prevention of substrate LAN entry by the 1,2,3-triazole derivatives. The triazoles derived from natural eugenol represent a novel lead in the search for environmentally safe agents for controlling C. gloeosporioides.

First Report of Anthracnose on Wurfbainia villosa var. villosa Caused by Colletotrichum gloeosporioides in China.

Wurfbainia villosa var. villosa is a traditional Chinese herbal medicine under the family Zingiberaceae, and its ripe fruits (called Fructus Amomi) are widely used clinically for the treatment of gastrointestinal disorders (Yang et al. 2023; Chen et al. 2023). In September 2023, plants of W. villosa var. villosa exhibited anthracnose-like symptoms on leaf with a disease incidence of 35% (n = 100 investigated plants) in an approximately 90 m2 field in Guangning, China (N23°42'51.70″, E112°26'35.75″). Light yellowish-green spots (~2 mm diameter) initially appeared on the infected leaves, gradually formed sub-circular or irregular spots, then fused and expanded, resulting in wilting of the leaves. To identify the causal agent, 10 symptomatic leaves were collected and transferred to the laboratory. The symptomatic leaf samples were surface sterilized in 0.5% NaClO for 2 min, and in 70% ethanol for 30 s, then washed three times with sterile water and air-dried on sterile filter paper. The leaf tissues were placed on potato dextrose agar (PDA) medium containing 100 µg mL-1 of ampicillin (Sigma-Aldrich, St. Louis, MO) and incubated for 7 days at 28°C in darkness. Nine isolates with similar colony morphology were isolated from the 10 plated leaves. Three representative isolates (GNAF03, GNAF06, GNAF09 with approximately 3.5 cm in diameter after 3 days of incubation) appeared gray to dark brown with dense aerial hyphae at the front and gray to black colonies on the reverse of the plates. Conidia were cylindrical and measured 21.2 to 29.3 µm long × 7.1 to 9.6 µm wide (n = 50). Appressoria were formed by the tips of germ tubes or hyphae and were brown, ellipsoid, thick-walled, and smooth-margined, measuring 10.2 to 12.3 µm long × 6.4 to 8.2 µm wide (n = 50). Morphologically, the fungal isolates resembled Colletotrichum sp. (Weir et al. 2012). For molecular analysis, genomic DNA was extracted from fresh mycelia of the three isolates, and the primers ACT-512F/ACT-783R, CL1/CL2A, GDF/GDR, and ITS1/ITS4 were used to amplify partial regions of rDNA-ITS, actin (ACT), calmodulin (CAL), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) regions, respectively (Weir et al. 2012). The resulting sequences with more than 99% nucleotide identity to C. gloeosporioides were submitted to GenBank (accession numbers PP552725, PP552726, and OR827444 for ACT; PP552727, PP552728, and OR827443 for CAL; PP552729, PP552730, and OR827445 for GAPDH; PP549996, PP549999, and OR841394 for ITS). A phylogenetic tree was generated by the maximum likelihood method using the concatenated sequences of ACT, CAL, GADPH, and ITS by Polysuite software (Damm et al. 2020). Based on morphological and molecular analysis, the three isolates were characterized as C. gloeosporioides. The pathogenicity of the GNAF09 isolate was assessed on W. villosa var. villosa seedling leaves inoculated by spraying with 40 µL of conidial suspension at 106 conidia mL-1 or wounded with a sterile toothpick then inoculated with mycelial agar plugs (5 mm diameter). Control leaves were inoculated with 40 µL of sterile distilled water or agar plugs without mycelia. The inoculated plants were placed in a humid chamber at 28°C with 80% humidity and a 12 h light-dark photoperiod. Symptoms similar to those seen on naturally infected leaves were observed on all inoculated leaves after 7 days inoculation. Re-isolation was performed from 80% of the inoculated leaves and isolates were confirmed as C. gloeosporioides morphologically, confirming Koch's postulates, and by sequencing the ACT, CAL, GADPH, and ITS regions. The control groups remained asymptomatic. In previous studies, C. gloeosporioides has also caused anthracnose on Chinese medicinal plants, including Baishao (Radix paeoniae alba) (Zhang et al. 2017) and Rubia cordifolia L. (Tang et al. 2020). To our knowledge, this is the first report of C. gloeosporioides causing anthracnose on W. villosa var. villosa in China. The results of our report serve as valuable references for further research on this disease.

Genome-Wide Identification and Evolutionary Analysis of Receptor-like Kinase Family Genes Provides Insights into Anthracnose Resistance of Dioscorea alata.

Dioscorea alata, commonly known as "greater yam", is a vital crop in tropical and subtropical regions of the world, yet it faces significant threats from anthracnose disease, mainly caused by Colletotrichum gloeosporioides. However, exploring disease resistance genes in this species has been challenging due to the difficulty of genetic mapping resulting from the loss of the flowering trait in many varieties. The receptor-like kinase (RLK) gene family represents essential immune receptors in plants. In this study, genomic analysis revealed 467 RLK genes in D. alata. The identified RLKs were distributed unevenly across chromosomes, likely due to tandem duplication events. However, a considerable number of ancient whole-genome or segmental duplications dating back over 100 million years contributed to the diversity of RLK genes. Phylogenetic analysis unveiled at least 356 ancient RLK lineages in the common ancestor of Dioscoreaceae, which differentially inherited and expanded to form the current RLK profiles of D. alata and its relatives. The analysis of cis-regulatory elements indicated the involvement of RLK genes in diverse stress responses. Transcriptome analysis identified RLKs that were up-regulated in response to C. gloeosporioides infection, suggesting their potential role in resisting anthracnose disease. These findings provide novel insights into the evolution of RLK genes in D. alata and their potential contribution to disease resistance.

Production and Physicochemical Characterization of the Gel Obtained in the Fermentation Process of Blue Corn Flour (Zea mays L.) with Colletotrichum gloeosporioides.

Food gels are viscoelastic substances used in various gelled products manufactured around the world. Polysaccharides are the most common food gelling agents. The aim of this work was the production and characterization of a gel produced in a blue corn flour fermentation process, where different proportions were used of blue corn (Zea mays L.) flour and Czapek Dox culture medium (90 mL of culture medium with 10 g of blue corn flour, 80 mL of culture medium with 20 g of blue corn flour, and 70 mL of culture medium with 30 g of blue corn flour) and were fermented for three different durations (20, 25, and 30 days) with the Colletotrichum gloeosporioides fungus. A characterization of the gel was carried out studying the rheological properties, proximal analysis, toxicological analysis, microscopic structure, and molecular characterization, in addition to a solubility test with three different organic solvents (ethanol, hexane, and ethyl acetate, in addition to water). The results obtained showed in the rheological analysis that the gel could have resistance to high temperatures and a reversible behavior. The gel is soluble in polar solvents (ethanol and water). The main chemical components of the gel are carbohydrates, especially polysaccharides, and it was confirmed by FT-IR spectroscopy that the gel may be composed of pectin.

A Lateral Flow-Recombinase Polymerase Amplification Method for Colletotrichum gloeosporioides Detection.

The greater yam (Dioscorea alata), a widely cultivated and nutritious food crop, suffers from widespread yield reduction due to anthracnose caused by Colletotrichum gloeosporioides. Latent infection often occurs before anthracnose phenotypes can be detected, making early prevention difficult and causing significant harm to agricultural production. Through comparative genomic analysis of 60 genomes of 38 species from the Colletotrichum genus, this study identified 17 orthologous gene groups (orthogroups) that were shared by all investigated C. gloeosporioides strains but absent from all other Colletotrichum species. Four of the 17 C. gloeosporioides-specific orthogroups were used as molecular markers for PCR primer designation and C. gloeosporioides detection. All of them can specifically detect C. gloeosporioides out of microbes within and beyond the Colletotrichum genus with different sensitivities. To establish a rapid, portable, and operable anthracnose diagnostic method suitable for field use, specific recombinase polymerase amplification (RPA) primer probe combinations were designed, and a lateral flow (LF)-RPA detection kit for C. gloeosporioides was developed, with the sensitivity reaching the picogram (pg) level. In conclusion, this study identified C. gloeosporioides-specific molecular markers and developed an efficient method for C. gloeosporioides detection, which can be applied to the prevention and control of yam anthracnose as well as anthracnose caused by C. gloeosporioides in other crops. The strategy adopted by this study also serves as a reference for the identification of molecular markers and diagnosis of other plant pathogens.

Combined control of plant diseases by Bacillus subtilis SL44 and Enterobacter hormaechei Wu15.

Co-incubation of plant growth promoting rhizobacteria (PGPRs) have been proposed as a potential alternative to pesticides for controlling fungal pathogens in crops, but their synergism mechanisms are not yet fully understood. In this study, combined use of Bacillus subtilis SL44 and Enterobacter hormaechei Wu15 could decrease the density of Colletotrichum gloeosporioides and Rhizoctonia solani and enhance the growth of beneficial bacteria on the mycelial surface, thereby mitigating disease severity. Meanwhile, PGPR application led to a reorganization of the rhizosphere microbial community through modulating its metabolites, such as extracellular polymeric substances and chitinase. These metabolites demonstrated positive effects on attracting and enhancing conventional periphery bacteria, inhibiting fungal pathogens and promoting soil health effectively. The improvement in the microbial community structure altered the trophic mode of soil fungal communities, effectively decreasing the proportion of saprotrophic soil and reducing fungal plant diseases. Certain combinations of PGPR have the potential to serve as precise instruments for managing plant pathogens.

[Identification and antifungal activity of halophilic bacteria isolated from saline soils in Campeche, México]. / Identificación y actividad antifúngica de bacterias halófilas aisladas de suelos salinos en Campeche, México.

Phytopathogenic fungi Alternaria alternata and Colletotrichum gloeosporioides cause diseases in plant tissues as well as significant postharvest losses. The use of chemical fungicides for their control has negative effects on health and the environment. Secondary metabolites from halophilic bacteria are a promising alternative for new antifungal compounds. In the present study, halophilic bacteria were isolated and characterized from two sites with saline soils called branquizales in Campeche, Mexico. A total of 64 bacteria were isolated. Agrobacterium, Bacillus, Inquilinus, Gracilibacillus, Metabacillus, Neobacillus, Paenibacillus, Priestia, Staphylococcus, Streptomyces and Virgibacillus were among the identified genera. The antifungal potential of the culture supernatant (CS) of 39 halophilic bacteria was investigated against C. gloeosporioides and A. alternata. The bacteria showing the greatest inhibition of mycelial growth corresponded to Bacillus subtilis CPO 4292, Metabacillus sp. CPO 4266, Bacillus sp. CPO 4295 and Bacillus sp. CPO 4279. The CS of Bacillus sp. CPO 4279 exhibited the highest activity and its ethyl acetate extract (AcOEt) inhibited the germination of C. gloeosporioides, with IC50 values of 8,630µg/ml and IC90 of 10,720µg/ml. The organic partition of the AcOEt extract led to three fractions, with acetonitrile (FAcB9) showing the highest antifungal activity, with values exceeding 66%. Halophilic bacteria from 'blanquizales' soils of the genus Bacillus sp. produce metabolites with antifungal properties that inhibit the phytopathogenic fungus C. gloeosporioides.

First Report of Colletotrichum gloeosporioides Causing Anthracnose on Euphorbia lathyris in China.

Euphorbia lathyris L. is a biennial herb in the Euphorbiaceae that has been used as a medicinal plant. It is distributed or cultivated worldwide, and the seeds of E. lathyris are the main source of ingenol, which is the precursor of Picato, the first medicine approved by USFDA for the treatment of solar keratosis (Abramovits et al. 2013). However, the production of E. lathyris can be severely hampered by the occurrence of plant diseases. Between 2020-2022 (specifically in October-November of each year), anthracnose-like symptoms were observed on E. lathyris in fields (E 118°49'50″, N 32°3'33″) in Nanjing, Jiangsu Province, China. The incidence of E. lathyris with disease symptoms was between 25%-30% (n = 100). The lesions on the leaves were evident initially as dark brown spots, which expanded into larger necrotic spots, finally resulting in leaves withering and dropping off. In severe cases, stem wilting was also observed. To determine the causal agent, we collected diseased leaf samples (n = 20) from different E. lathyris plants in the field (~ 1800 m2). After cleaning, the junctions of the diseased and healthy parts were excised and sterilized in 75% ethanol for 20-25 seconds, and rinsed with sterile water. After that, they were transferred onto potato sucrose agar (PSA) plates and placed at 25℃ for 3-4 days, until fungal growth was evident. The fungus was purified by recovering single conidia and growing them on PSA (Hu et al. 2015). A consistent fungal colony, based on morphological characteristics, was recovered from 17 samples. The colony color was initially white, green in the middle, and gradually changed into gray green as the colony matured. Conidia were transparent and cylindrical (22-28 µm × 7-9 µm, n = 50). Five loci informative (ITS, TUB, ACT, GAPDH, and CHS-1) (Weir et al. 2012) for Colletotrichum spp. identification were sequenced from two isolates ELC-1 and ELC-2 obtained from different plant individuals. Compared with a reference isolate (Colletotrichum gloeosporioides ZH3), the GAPDH, CHS-1, and TUB2 sequences of ELC-1 and ELC-2 showed 95% (263 bp out of 275 bp), 98% (295 bp out of 299 bp), and 99% (711 bp out of 712 bp and 717 bp out of 719 bp) similarity, respectively. The ITS sequence identities were 100% (577 bp out of 577 bp) and 99% (594 bp out of 597 bp), while the ACT sequence identities were 100% (281 bp out of 281 bp) and 98% (279 bp out of 284 bp). All sequences have been deposited in Genbank database (OR865865-OR865866 and OR873625-OR873632). After performing phylogenetic analysis with Mega 11, the pathogen was confirmed as C. gloeosporioides. To fulfil Koch's postulates, we sprayed six-week-old healthy plants with a conidia suspension of C. gloeosporioides (106 spores/mL) or sterile water (serve as control). The inoculated plants were placed at 25℃, 100% relative humidity, and 12-h photoperiod (Zhang et al. 2021). Six plants were inoculated for each treatment, and the experiment was repeated three times. After 6-8 days, the plants inoculated with C. gloeosporioides showed similar symptoms to those observed on diseased plants in the field, while the control plants remained healthy and free of disease. The pathogens were then re-isolated and identified as C. gloeosporioides. To our knowledge, this is the first report of C. gloeosporioides causing anthracnose on E. lathyris. Anthracnose may cause significant yield losses in E. lathyris production, and our results will provide experimental and theoretical basis for the management of the disease.

Application of Silica Nanoparticles in Combination with Bacillus velezensis and Bacillus thuringiensis for Anthracnose Disease Control in Shallot.

<b>Background and Objective:</b> Anthracnose in shallot contributes to significant losses. To solve this issue, silica nanoparticles, in combination with <i>Bacillus velezensis</i> and <i>Bacillus thuringiensis</i> were used together. <b>Materials and Methods:</b> <i>In vitro</i> antagonistic test of <i>Bacillus velezensis</i> B-27 with <i>Colletotrichum gloeosporioides</i> was carried out using dual culture and co-culture methods. Treatment in greenhouse experiments was carried out using single application of silica, <i>B. thuringiensis</i>, <i>B. velezensis</i>, a combination of <i>B. thuringiensis</i> and <i>B. velezensis</i> and a combination of <i>B. thuringiensis</i>, <i>B. velezensis</i> and silica. Detection of <i>B. velezensis</i> in the roots of shallot plants was carried out by PCR using a pair of specific primers. <b>Results:</b> <i>Bacillus velezensis</i> was able to inhibit the growth of <i>C. gloeosporioides</i> mycelium <i>in vitro</i>, both in the dual culture and co-culture methods, by 62.8 and 77.17%, respectively. Treatment of <i>B. thuringiensis</i> and <i>B. velezensis</i>, either individually or in combination with silica, could reduce the intensity of anthracnose disease by 20% each and stimulate the growth of shallot plants. The PCR detection using specific primers on the roots of shallot plants showed that <i>B. velezensis</i> was detected with a DNA band length of ±576 bp. <b>Conclusion:</b> <i>Bacillus velezensis</i> can inhibit the growth of <i>C. gloeosporioides</i> mycelium <i>in vitro</i>. Applying <i>B. velezensis</i>, <i>B. thuringiensis</i> and silica can reduce the intensity of anthracnose disease, promote plant growth and increase plant productivity. Furthermore, <i>B. velezensis</i> was detected in the roots of shallot plants, revealing that the bacteria are well-established.

CgCFEM1 Is Required for the Full Virulence of Colletotrichum gloeosporioides.

Colletotrichum gloeosporioides is widely distributed and causes anthracnose on many crops, resulting in serious economic losses. Common fungal extracellular membrane (CFEM) domain proteins have been implicated in virulence and their interaction with the host plant, but their roles in C. gloeosporioides are still unknown. In this study, a CFEM-containing protein of C. gloeosporioides was identified and named as CgCFEM1. The expression levels of CgCFEM1 were found to be markedly higher in appressoria, and this elevated expression was particularly pronounced during the initial stages of infection in the rubber tree. Absence of CgCFEM1 resulted in impaired pathogenicity, accompanied by notable perturbations in spore morphogenesis, conidiation, appressorium development and primary invasion. During the process of appressorium development, the absence of CgCFEM1 enhanced the mitotic activity in both conidia and germ tubes, as well as compromised conidia autophagy. Rapamycin was found to basically restore the appressorium formation, and the activity of target of rapamycin (TOR) kinase was significantly induced in the CgCFEM1 knockout mutant (∆CgCFEM1). Furthermore, CgCFEM1 was proved to suppress chitin-triggered reactive oxygen species (ROS) accumulation and change the expression patterns of defense-related genes. Collectively, we identified a fungal effector CgCFEM1 that contributed to pathogenicity by regulating TOR-mediated conidia and appressorium morphogenesis of C. gloeosporioides and inhibiting the defense responses of the rubber tree.

Roles of CgEde1 and CgMca in Development and Virulence of Colletotrichum gloeosporioides.

Anthracnose, induced by Colletotrichum gloeosporioides, poses a substantial economic threat to rubber tree yields and various other tropical crops. Ede1, an endocytic scaffolding protein, plays a crucial role in endocytic site initiation and maturation in yeast. Metacaspases, sharing structural similarities with caspase family proteases, are essential for maintaining cell fitness. To enhance our understanding of the growth and virulence of C. gloeosporioides, we identified a homologue of Ede1 (CgEde1) in C. gloeosporioides. The knockout of CgEde1 led to impairments in vegetative growth, conidiation, and pathogenicity. Furthermore, we characterized a weakly interacted partner of CgEde1 and CgMca (orthologue of metacaspase). Notably, both the single mutant ΔCgMca and the double mutant ΔCgEde1/ΔCgMca exhibited severe defects in conidiation and germination. Polarity establishment and pathogenicity were also disrupted in these mutants. Moreover, a significantly insoluble protein accumulation was observed in ΔCgMca and ΔCgEde1/ΔCgMca strains. These findings elucidate the mechanism by which CgEde1 and CgMca regulates the growth and pathogenicity of C. gloeosporioides. Their regulation involves influencing conidiation, polarity establishment, and maintaining cell fitness, providing valuable insights into the intricate interplay between CgEde1 and CgMca in C. gloeosporioides.

Comparative transcriptome analysis reveals the importance of phenylpropanoid biosynthesis for the induced resistance of 84K poplar to anthracnose.

BACKGROUND: Poplar anthracnose, which is one of the most important tree diseases, is primarily caused by Colletotrichum gloeosporioides, which has been detected in poplar plantations in China and is responsible for serious economic losses. The characteristics of 84K poplar that have made it one of the typical woody model plants used for investigating stress resistance include its rapid growth, simple reproduction, and adaptability. RESULTS: In this study, we found that the resistance of 84K poplar to anthracnose varied considerably depending on how the samples were inoculated of the two seedlings in each tissue culture bottle, one (84K-Cg) was inoculated for 6 days, whereas the 84K-DCg samples were another seedling inoculated at the 6th day and incubated for another 6 days under the same conditions. It was showed that the average anthracnose spot diameter on 84K-Cg and 84K-DCg leaves was 1.23 ± 0.0577 cm and 0.67 ± 0.1154 cm, respectively. Based on the transcriptome sequencing analysis, it was indicated that the upregulated phenylpropanoid biosynthesis-related genes in 84K poplar infected with C. gloeosporioides, including genes encoding PAL, C4H, 4CL, HCT, CCR, COMT, F5H, and CAD, are also involved in other KEGG pathways (i.e., flavonoid biosynthesis and phenylalanine metabolism). The expression levels of these genes were lowest in 84K-Cg and highest in 84K-DCg. CONCLUSIONS: It was found that PAL-related genes may be crucial for the induced resistance of 84K poplar to anthracnose, which enriched in the phenylpropanoid biosynthesis. These results will provide the basis for future research conducted to verify the contribution of phenylpropanoid biosynthesis to induced resistance and explore plant immune resistance-related signals that may regulate plant defense capabilities, which may provide valuable insights relevant to the development of effective and environmentally friendly methods for controlling poplar anthracnose.

Field and postharvest application of microencapsulated Yamadazyma mexicana LPa14: anthracnose control and effect on postharvest quality in avocado (Persea americana Mill. cv. Hass).

BACKGROUND: Anthracnose caused by species of Colletotrichum is the most important disease of avocado fruit. The quiescent infection develops in the field, hence, its control from the preharvest stage is necessary. The field application of microencapsulated Yamadazyma mexicana LPa14 could prevent the establishment of Colletotrichum gloeosporioides and reduce the losses in avocado production. This study aimed to evaluate the effectiveness of microencapsulated Y. mexicana applied in the field and postharvest for the anthracnose control in avocado, to evaluate the population dynamics of Y. mexicana in flowers and fruits and the effect of the yeast on the avocado quality. RESULTS: The concentrations of microencapsulated Y. mexicana after field application ranged from 4.58 to 6.35 log CFU g-1. The population of microencapsulated yeast in flowers and fruits was always higher than treatments with fresh cells. Preharvest application of fresh and microencapsulated Y. mexicana significantly reduced the severity of anthracnose by 71-80% and 84-96%, respectively, in avocado fruits stored at 25 °C. Moreover, at 6 °C and ripening at 25 °C, the fresh yeast reduced the severity by 87-90% and the microencapsulated yeast by 91-93%. However, yeast treatments applied in the field + postharvest under cool conditions were more effective in reducing 100% of anthracnose. Treatments did not negatively affect the quality parameters of the avocado fruits. CONCLUSION: Yamadazyma mexicana microencapsulated by electrospraying is a promising bioformulation for the management of anthracnose in avocados at preharvest and postharvest levels. Yamadazyma mexicana offers a new biological control solution for growers in avocado orchards. © 2024 Society of Chemical Industry.

Near-infrared-responsive CuS@Cu-MOF nanocomposite with high foliar retention and extended persistence for controlling strawberry anthracnose.

Strawberry anthracnose (Colletotrichum gloeosporioides) exhibits a high pathogenicity, capable of directly infecting leaves through natural openings, resulting in devastating impacts on strawberries. Here, nanocomposite (CuS@Cu-MOF) was prepared with a high photothermal conversion efficiency of 35.3% and a strong response to near-infrared light (NIR) by locally growing CuS nanoparticles on the surface of a copper-based metal-organic framework (Cu-MOF) through in situ sulfurization. The porosity of Cu-MOF facilitated efficient encapsulation of the pesticide difenoconazole within CuS@Cu-MOF (DIF/CuS@Cu-MOF), achieving a loading potential of 19.18 ± 1.07%. Under NIR light irradiation, DIF/CuS@Cu-MOF showed an explosive release of DIF, which was 2.7 times higher than that under dark conditions. DIF/CuS@Cu-MOF exhibited a 43.9% increase in efficacy against C. gloeosporioides compared to difenoconazole microemulsion (DIF ME), demonstrating prolonged effectiveness. The EC50 values for DIF and DIF/CuS@Cu-MOF were 0.219 and 0.189 µg/mL, respectively. Confocal laser scanning microscopy demonstrated that the fluorescently labeled CuS@Cu-MOF acted as a penetrative carrier for the uptake of hyphae. Furthermore, DIF/CuS@Cu-MOF exhibited more substantial resistance to rainwater wash-off than DIF ME, with retention levels on the surfaces of cucumber leaves (hydrophilicity) and peanut leaves (hydrophobicity) increasing by 36.5-fold and 9.4-fold, respectively. These findings underscore the potential of nanocomposite to enhance pesticide utilization efficiency and leaf retention.

Biocontrol potential of endophytic bacterium Bacillus altitudinis GS-16 against tea anthracnose caused by Colletotrichum gloeosporioides.

Background: As one of the main pathogens causing tea anthracnose disease, Colletotrichum gloeosporioides has brought immeasurable impact on the sustainable development of agriculture. Given the adverse effects of chemical pesticides to the environment and human health, biological control has been a focus of the research on this pathogen. Bacillus altitudinis GS-16, which was isolated from healthy tea leaves, had exhibited strong antagonistic activity against tea anthracnose disease. Methods: The antifungal mechanism of the endophytic bacterium GS-16 against C. gloeosporioides 1-F was determined by dual-culture assays, pot experiments, cell membrane permeability, cellular contents, cell metabolism, and the activities of the key defense enzymes. Results: We investigated the possible mechanism of strain GS-16 inhibiting 1-F. In vitro, the dual-culture assays revealed that strain GS-16 had significant antagonistic activity (92.03%) against 1-F and broad-spectrum antifungal activity in all tested plant pathogens. In pot experiments, the disease index decreased to 6.12 after treatment with GS-16, indicating that strain GS-16 had a good biocontrol effect against tea anthracnose disease (89.06%). When the PE extract of GS-16 treated mycelial of 1-F, the mycelial appeared deformities, distortions, and swelling by SEM observations. Besides that, compared with the negative control, the contents of nucleic acids, protein, and total soluble sugar of GS-16 group were increased significantly, indicating that the PE extract of GS-16 could cause damage to integrity of 1-F. We also found that GS-16 obviously destroyed cellular metabolism and the normal synthesis of cellular contents. Additionally, treatment with GS-16 induced plant resistance by increasing the activities of the key defense enzymes PPO, SOD, CAT, PAL, and POD. Conclusions: We concluded that GS-16 could damage cell permeability and integrity, destroy the normal synthesis of cellular contents, and induce plant resistance, which contributed to its antagonistic activity. These findings indicated that strain GS-16 could be used as an efficient microorganism for tea anthracnose disease caused by C. gloeosporioides.

First Report of Anthracnose Caused by Colletotrichum gloeosporioides on Cinnamomum camphora in Korea.

Cinnamomum camphora, known as the camphor tree, is an evergreen tree widely cultivated in Asia as an ornamental plant (Singh and Jawaid, 2012). In June 2023, several leaves on a total of 10 trees planted on a street in Suncheon, Jeonnam Province, Korea showed black spots. Disease incidence was observed in at least 15% of the 10 trees. The symptoms included circular spots with a light ash-colored center and dark brown borders. The size of lesions varied depending on the progress of the disease. The disease progressed by 30% on the tree leaves. To isolate the pathogen, we cut out the lesions on the leaf surface sterilized with 70% ethanol for one minute, washed three times with sterilized distilled water, dried, and placed on water agar. Then, it was incubated at 25°C for three days. Emerging hyphae from the samples were subcultured on potato dextrose agar (PDA), resulting in three independent isolates (SYP-F1226-1 to SYP-F1226-3) after single spore isolation from 3 independent trees. The isolates exhibited grayish fluffy mycelium in the center of the colony, while the edges were white on PDA. Conidia had rounded cylindrical shape and were 4.9 to 8.4 µm  1.4 to 3.1 µm (avg. 5.9  2.1 µm, n = 100) in size. Appressoria were round, dark gray, produced at the tip of the germ tube after a septum formed the conidium. The morphological characteristics matched those of Colletotrichum species complexes. (Damm et al., 2012; Weir et al., 2012). For molecular identification, ITS (OR647338 to 40), GAPDH (OR657042 to 44), CHS-1 (OR657045 to 47), ACT (OR657048 to 50), and CAL (OR657051 to 53) sequences from isolates SYP-F1226-1~3 showed a 99.65%, 98.56%, 99.00%, 99.28%, and 99.52% identity with that of type strain C. gloeosporioides ICMP 17821 (JX010152, JX010056, JX009818, JX009531, and JX010445, respectively). Using the MEGA X program (Kumar et al. 2018), maximum likelihood analysis based on the concatenated sequences placed the isolates within a clade comprising C. gloeosporioides. Pathogenicity of SYP-F1226-1 was tested using three leaves from a 1-year-old branch of three independent healthy C. camphora plants. The leaf surfaces were sterilized by rubbing a cotton pad soaked in 70% ethanol and then wiping them with a sterilized cotton pad. The leaves per plant were inoculated with 5 mL of a conidial suspension (1 × 105 conidia/mL), both with and without wounding. Another three control leaves were inoculated with sterile distilled water, both with and without wounding. The inoculated leaves were wrapped in a plastic bag for 48 hours under conditions of 100% relative humidity. Spot symptoms were observed on both wounded and non-wounded leaves 21 days after inoculation. No symptoms were observed in the control on either of the wounded leaves. Pathogenicity tests were performed three times. The pathogen was re-isolated from the lesion after treatment, and its identity was confirmed using the five genes and morphological characteristics. This confirms the fulfillment of Koch's postulates. C. fioriniae (Liu et al, 2022) and C. siamens (Liu et al, 2022; Khoo et al, 2023) have been reported as the causal pathogen of anthracnose in C. camphora, but C. gloeosporioides has not been reported as a pathogen in C. camphora. To our knowledge, this is the first report of anthracnose caused by C. gloeosporioides on C. camphora in Korea. This study will provide symptomatic, mycological, and molecular biological information for the early detection of anthracnose disease in C. camphora plants.

Green synthesis and biological evaluation of glaucanic acid and dihydrocompactin acid by endophytic fungus Penicillium polonicum from Zingiber officinale.

Fungal endophytes are valued for biosynthesizing chemically diverse metabolic cascade with interesting biological activities. In the current investigation, two compounds were isolated from Penicillium polonicum, an endophyte of Zingiber officinale. The active moieties, glaucanic acid (1) and dihydrocompactin acid (2) were isolated from the ethyl acetate extract of P. polonicum and characterized by NMR and mass spectroscopy. Further, bioactive potential of the isolated compounds was evaluated by antimicrobial, antioxidant and cytotoxicity assays. Compounds 1 and 2 displayed antifungal activity against phytopathogen Colletotrichum gloeosporioides with more than 50% reduction in its growth. Both the compounds exhibited antioxidant activity against free radicals (DPPH and ABTS) and cytotoxicity activity against cancer cell lines respectively. The compounds, glaucanic acid and dihydrocompactin acid are being reported for the first time from an endophytic fungus. This is the first report on the biological activities of Dihydrocompactin acid produced by endophytic fungal strain.

Antifungal efficacy of biogenic waste derived colloidal/nanobiochar against Colletotrichum gloeosporioides species complex.

Anthracnose caused by Colletotrichum spp. usually resulting in significant postharvest losses in the banana production chain. This study investigated the inhibitory effect of corn cob colloidal/nanobiochar (CCN) and Gliricidia sepium wood colloidal/nanobiochar (GCN) on the Colletotrichum gloeosporioides species complex. The CCN and GCN materials were synthesized and thoroughly characterized using various techniques, including UV-Vis and Fluorescence spectroscopy. Then after the fungal growth was examined on Potato Dextrose Agar (PDA) media supplemented with different CCN and GCN concentrations of 0.4 - 20 g/L and CCN and GCN with zeolite at various weight percentages of 10% to 50% w/w. Results from the characterization revealed that CCN exhibited a strong UV absorbance peak value of 0.630 at 203 nm, while GCN had a value of 0.305 at 204 nm. In terms of fluorescence emission, CCN displayed a strong peak intensity of 16,371 at 412 nm, whereas GCN exhibited a strong peak intensity of 32,691 at 411 nm. Both CCN and GCN, at concentrations ranging from 1 to 8 and 0.4 - 20 g/L, respectively, displayed notable reductions in mycelial densities and inhibited fungal growth compared to the control. Zeolite incorporation further enhanced the antifungal effect. To the best of our knowledge, this is the first study to demonstrate the promising potential of colloidal/nanobiochar in effectively controlling anthracnose disease. The synthesized CCN and GCN demonstrate promising antifungal potential against Colletotrichum gloeosporioides species complex, offering the potential for the development of novel and effective antifungal strategies for controlling anthracnose disease in Musa spp.