Colletotrichum Coccodes Research Articles

Analysis of the pathogenicity and phylogeny of Colletotrichum species associated with brown blight of tea (Camellia sinensis) in Taiwan.

Brown blight, a destructive foliar disease of tea, has become a highly limiting factor for tea cultivation in Taiwan. To understand the population composition of the causal agents, Colletotrichum spp., the fungal diversity in the main tea growing regions all over Taiwan was surveyed from 2017 to 2019. A collection of 139 Colletotrichum isolates were obtained from 14 tea cultivars in 86 tea plantations. Phylogenic analysis using the ribosomal internal transcribed spacer, glutamine synthetase gene, the Apn2-Mat1-2 intergenic spacer, beta-tubulin, actin, calmodulin, and glyceraldehyde-3-phosphate dehydrogenase genes together with morphological characterization revealed three species associated with brown blight of tea, namely Colletotrichum camelliae (95.6% of all isolates), Colletotrichum fructicola (3.7%), and Colletotrichum aenigma (0.7%). This is the first report of C. aenigma in Taiwan. The optimal growth temperatures were 25℃ for C. camelliae and 25℃ and 30℃ for C. fructicola and C. aenigma. Although C. fructicola and C. aenigma were more adapted to high temperature, C. camelliae was the most pathogenic across different temperatures. Regardless of whether spore suspensions or mycelial discs were used, significantly larger lesions and higher disease incidences were observed for wounded than for non-wounded inoculation and for the 3rd/4th leaves than for the 5th leaves. Wounded inoculation of detached 3rd/4th tea leaves with mycelial discs was found to be a reliable and efficient method for assessing the pathogenicity of Colletotrichum spp. within four days. Preventive application of fungicides or biocontrol agents immediately after tea pruning and at a young leaf stage would help control the disease.

Potato early dying – agents, causes and symptoms

Climate changes observed for many years adversely affect the development of crops, but also create conditions for the development of individual diseases or their complexes, which so far have not found favorable conditions fot their development. One of such complexes is potato early dying (PED). The fungus Verticillium dahliae is considered to be the main culprit of this disease, but other culprits of PED include Colletotrichum coccodes (Wallr.) Hughes, Verticillium albo-atrum Reinke & Berthold and Fusarium spp. and pectynolytic bacteria Pectobacterium carotovorum subsp. carotovorum. Nematodes Paratylenchus penetrans (Cobb) Sher and Allen play an important role in stimulating the disease and increasing losses. The disease is common in potato-growing areas, causing losses of up to 50%. Due to large amount of infectious material and the possibility of long-term survival in the soil and the wide range of hosts, combating its harmfulness requires the use of all available methods.

Stable biogenic silver nanoparticles from Syzygium nervosum bud extract for enhanced catalytic, antibacterial and antifungal properties.

In the present study, the biosynthesis of stable silver nanoparticles (BioAgNPs) was accomplished successfully for the first time by using an aqueous extract derived from the buds of Syzygium nervosum (SN) as both a reducing and a stabilizing agent. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) investigations revealed that the biosynthesized BioAgNPs were predominantly spherical with an average size of 10-30 nm. It was found that the outstanding stability of the BioAgNPs colloidal solution was assigned to the additive effect of the surrounding protective organic layer and the highly negatively charged surface of the nanoparticles. Consequently, good antibacterial activity was demonstrated by the colloidal BioAgNPs solution against four distinct bacterial strains, including Gram-positive S. aureus and B. subtilis as well as Gram-negative E. coli and S. typhi. Interestingly, the biosynthesized BioAgNPs displayed greater antibacterial activity even when tested at low doses against Gram-negative S. typhi. In addition, the biogenic AgNPs demonstrated a significant level of catalytic activity in the process of converting 2-NP, 3-NP, and 4-NP into aminophenols within 15 min, with reaction rate constants of 9.0 × 10-4, 10 × 10-4, and 9.0 × 10-4 s-1, respectively. BioAgNPs formulations were assessed against anthracnose disease in tea plants and were found to be as effective as the positive control at a dose of 20-fold dilution, but less effective at a dose of 30-fold dilution. Both doses of BioAgNPs formulations significantly suppressed Colletotrichum camelliae (anthracnose disease) without affecting the growth of the tea plants.

In vitro efficacy of herbal plant extracts on some phytopathogenic fungi

Crops are subject to yield losses caused by the presence of pests whose species and population diversity are changing with climate warming. The use of agrochemicals is still the most effective method of plant protection against diseases and pests. However, the intensive use of pesticides in some EU countries makes it necessary to search for alternative methods that can be applied in plant protection for consumer and environmental safety. The aim of the study was the laboratory evaluation of the fungistatic effect of extracts of herbal plants occurring in natural state in Poland: horseradish (Armoracia rusticana L.), yarrow (Achillea millefolium L.) and tansy (Tanacetum vulgare L.) on selected polyphagic phytopathogenic fungi (Alternaria alternata, Botrytis cinerea, Colletotrichum coccodes and Fusarium oxysporum). In this study, 5%, 10% and 20% concentrations of herbal water-extract extracts were applied to evaluate their effects on linear growth of fungi and inhibition of their growth relative to control. Total content of polyphenols and flavonoids was assessed in the extracts using spectrophotometry, and their antioxidant activity by applying the synthetic DPPH radical. The plant extracts of tansy and yarrow leaves were characterized by a higher content of polyphenols and flavonoids compared to horseradish leaf extracts; they also had a higher antioxidant activity. Plant extracts inhibited the growth of fungi to a different extent, depending on the species of fungus, type of extract, its concentration and duration of action. The strongest fungistatic effect was recorded for tansy and yarrow extracts, while the weakest for the extract of horseradish leaves. Plant extracts showed the weakest effect against Botrytis cinerea, inhibiting the development of this fungus only during the first days of the experiment. The present research is a preliminary study that will be used in the further to develop a biological preparation for the protection of agricultural and horticultural plants against fungal pathogens.

Geraniol: A Potential Defense-Related Volatile in “Baiye No. 1” Induced by Colletotrichum camelliae

Plants produce and emit a large variety of volatiles that have multiple defense-related functions in response to abiotic or biotic stresses. In comparison with studies on plant volatile–herbivore interactions, little research has been carried out on plant volatile–microbe interactions. In the present paper, tea volatile–Colletotrichum camelliae interactions were studied. The results of emitted volatiles following infection with C. camelliae in “Baiye No. 1” showed that healthy tea plants contained 68 kinds of volatiles, while infected tea plants contained 76 kinds of volatiles. Five volatiles, namely, geraniol, linalool, methyl salicylate, (E)-3-hexen-1-ol, and α-farnesene, were found to have a relatively large content variation in infected tea plants, with increments of 7.903%, −2.247%, 2.770%, −6.728%, and 3.848%, respectively. The fungicidal activity results of the five volatiles against C. camelliae showed that geraniol had the best activity, with MIC and MBC values of 0.5 and 1 mg·mL−1, respectively. Thus, geraniol was selected for subsequent studies. The effects of geraniol on the mycelia and cell structures of C. camelliae were investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results showed that the mycelia were significantly disrupted, and the cell structures were damaged. The effects of geraniol on the related enzymes of C. camelliae were assessed. The results showed that cellulase activity increased, malondialdehyde content increased, and the activity of defense enzymes was inhibited, thereby inhibiting the growth of pathogens. This study provides the first evidence that geraniol is a defense-related function volatile of “Baiye No. 1” in response to C. camelliae stress. It also provides valuable information and enriches the chemical ecology of tea plant diseases for the research field on defensive substances of microbe-induced plant volatiles.

Onion Thrips (Thysanoptera: Thripidae) Host Plant Preference and Performance are Mediated by a Facultative Plant Pathogen of Onion.

Insect vector and phytopathogen interactions are mediated by host plants. Insects interact with pathogens directly or indirectly and they may prefer host plants based on infection status. Performance on infected hosts varies depending on the type of pathogen involved. Species specific studies of economically important insects and phytopathogens are needed to understand how these interactions impact crop yields. Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is an economically devastating insect pest of onions (Allium cepa L., Asparagales: Amaryllidaceae) worldwide and it co-occurs simultaneously with many different pathogens. Colletotrichum coccodes (Wallr) (Glomerellales: Glomerellaceae) is a generalist fungal pathogen that attacks onion foliage, causing tan lesions and decreasing yield. Onion thrips and C. coccodes represent two important pests of onions, but the relationship between onion thrips and C. coccodes infected onions has not been studied, and it is unclear if onion thrips contribute to the spread of C. coccodes in onion fields. A four-choice test with control, artificially injured, artificially injured + symptomatic, and inoculated-symptomatic onion suggests that onion thrips distinguish between hosts based on health status. Furthermore, a two-choice test with control, inoculated-asymptomatic, and inoculated-symptomatic onion pairings revealed that onion thrips distinguish between hosts based on infection status and prefer inoculated-symptomatic hosts. In a no-choice test, onion thrips numbers increased on inoculated-symptomatic plants compared to control or inoculated-asymptomatic plants. Overall, we found that onion thrips preferred and performed best on C. coccodes infected plants.

Molecular characterization of a novel polymycovirus identified in the phytopathogenic fungus Colletotrichum gloeosporioides.

A novel polymycovirus isolated from the plant-pathogenic fungus Colletotrichum gloeosporioides was identified. The viral genome is composed of nine double-stranded RNA segments, ranging in size from 699 bp to 2,444 bp. With the exception of dsRNA5, which contains two open reading frames (ORF5-1 and ORF5-2), the other dsRNA segments each contain one ORF. The proteins encoded by ORFs 1-8 are homologous to the proteins encoded by ORFs 1-8 of Colletotrichum camelliae filamentous virus 1 (CcFV-1). The amino acid sequences of the RNA-dependent RNA polymerase (RdRp) encoded by ORF1 and the viral methyltransferase encoded by ORF3 share 87.6% and 83.3% identity with CcFV-1. The proline-alanine-serine-rich protein (PASrp) encoded by ORF4 shares 86.6% sequence identity with that of CcFV-1. The proteins encoded by ORFs 2, 5 - 1, 6, 7, and 8 share 86.6%, 82.5%, 89.0%, 45.7%, and 95.5% sequence identity, respectively, with the corresponding proteins of CcFV-1. dsRNA9 is a defective copy of dsRNA2 that lacks a stretch of 1556 bp (nt 519 to nt 2074). Phylogenetic analysis based on the RdRp protein indicated that the novel virus clustered with members of the family Polymycoviridae, and based on the above results, we have tentatively named it "Colletotrichum gloeosporioides polymycovirus virus 1" (CgPmV1). To our knowledge, this is the first report of a polymycovirus with a defective dsRNA genome in C. gloeosporioides.

Metschnikowia pulcherrima as a Biocontrol Agent against Potato (Solanum tuberosum) Pathogens

An increasing trend in protecting plants against phytopathogens is the replacement of chemical pesticides with environmentally acceptable biopreparations. This article focuses on the possible use of yeast Metschnikowia pulcherrima as a biocontrol agent against potato pathogens. The scope included an assessment of the antimicrobial activity of 10 M. pulcherrima isolates against 10 phytopathogens: Fusarium oxysporum, Fusarium sambucinum, Rhizoctonia solani, Alternaria solani, Alternaria, tenuissima, Alternaria alternata, Colletotrichum coccodes, Phoma exigua, Pectobacterium carotovorum, and Streptomyces scabiei, by the agar-well diffusion method. Pulcherrimin formation, enzymatic profiles detected by the API ZYM system, and metabolite formation evaluated by HPLC analysis were conducted for the most active M. pulcherrima isolates. Leucine arylamidase, valine arylamidase, α- and β-glucosidase, and esterases were the most noteworthy in the pattern of activity. In turn, ethanol, glycerol, and organic acids (acetic, succinic, lactic acids) were determined in the largest quantities. The isolate M. pulcherrima TK1 was selected and cultured on supplemented acid whey. An in situ experiment was carried out on the seed potatoes, which showed a 30%–100% reduction in nine phytopathogens; only P. carotovorum was insensitive to yeast treatment. Therefore, M. pulcherrima TK1 was proposed as the potential biological solution for seed potato protection against phytopathogens.

Colletotrichum coccodes causing “black dot” of sugar beet in the Pacific Northwest of the USA

Sugar beet (Beta vulgaris) is an important sugar crop in temperate regions. In 2014, sugar beet roots in Washington and Oregon, U.S.A. were found with a shallow, firm, dark rot with minute black “dots” within the tissue (Figs. 1, 2), similar to “black dot” on potato (Davis & Johnson, 2001). Symptoms were observed in freshly harvested roots in the processing factory. Diseased tissue was surface disinfected with 10% bleach, plated on 2% water agar and incubated at room temperature with ambient lighting. All visible growth from ten tissue pieces (five per beet, one each from Washington and Oregon) was fungal, with hyaline mycelia and numerous dark, spherical sclerotia. Pure cultures were obtained by hyphal tip transfer to malt extract agar (MEA), incubated for seven days in the light at room temperature, and examined for morphological characteristics. Yellow spore clusters with dark setae were observed in culture. Conidia (20-25 × 3–4 µm) were hyaline and straight with evenly rounded ends (Fig. 3) matching those of Colletotrichum coccodes (Chesters & Hornby, 1965). For molecular characterisation, DNA was extracted from seven-day old cultures using a CTAB protocol (Anonymous, 2009). PCR amplification used an Invitrogen High Fidelity PCR mix (Thermo Fisher Scientific Inc., Waltham, USA) with primers ITS1 and ITS4 (White et al., 1990) and the resulting amplicons were sequenced by Sanger sequencing. A BLASTn search with the sequence of isolate Co14-1 (GenBank Accession No. KX011522) showed a 99% identity to CBS369.75 (HM171679), the type strain for C. coccodes (Cannon et al., 2012) as well as to additional C. coccodes isolates (JX294043, JX205194, JX205192, and KJ744346). As initial samples were found at harvest, healthy roots of two sugar beet germplasm (C869 and SR102) that had been grown in the field for five months at the Saginaw Valley Research and Education Center (Frankenmuth, Michigan, USA) were used for pathogenicity testing. After removal from the field, roots were kept at 7°C for one-two months then planted in potting mix and grown in a greenhouse at 22°C ±4°C. After growth of new leaves was visible, two plants of each germplasm were treated with a 10 ml drench of a 103 spores/ml suspension that was produced by growing isolate Co14-1 on MEA for seven-ten days, flooding the surface with sterile distilled water, and dislodging the spores with a sterile plastic cell spreader. Plants were grown for four weeks after inoculation and evaluated. Roots of inoculated plants showed shallow sunken lesions with minute black “dots” similar to those on the initial samples (Fig. 4). A fungus morphologically identified as C. coccodes was isolated from lesions on all inoculated beets, completing Koch's postulates. No Colletotrichum sp. was isolated from control beets. The trial was conducted twice with the same results. To our knowledge this is the first report of C. coccodes on sugar beet from the field. Although there was little root loss observed on beet, black dot infection can impact storage in potato (Davis & Johnson 2001). Therefore, testing the potential impact of black dot on storage of sugar beet is warranted. The authors would like to thank Tom Goodwill for his technical assistance.

First Report of Black Dot Caused by Colletotrichum coccodes on Potato in the Tibet Autonomous Region of China.

Potato black dot causing by Colletotrichum coccodes is a common disease in potato throughout the world, infecting underground stems, tubers, roots and foliage. Potato is becoming the third main food crop produced on ~16,000 ha annually in the Tibet Autonomous Region of China, situated on the world's highest plateau. However, the disease causing by C. coccodes has not been reported in this region. During the disease survey in the Bailang County of Tibet in August, 2020, some potato plants cv. "JiZhang 12" with chlorosis and wilting of foliage were observed. The incidence of affected plants was 20%. Necrotic lesions were also observed on the basal stems of the affected plants. Three affected plants were collected for pathogen isolation and three isolates were obtained for further investigation. The colonies on potato dextrose agar (PDA) were initially white, turning gradually black with age and producing abundant black sclerotia. Conidia were cylindrical, hyaline, aseptate, guttulate, with average size of 13.80 to 18.55×4.94 to 5.35 μm for the three isolates in which 30 conidia each were measured. Such characteristics are similar to C. coccodes (Lees and Hilton, 2003). Mycelial growth rate was 0.69 to 0.74 cm/day at 25 oC over the three isolates. The three isolates were confirmed to be C. coccodes by species-specific PCR using primer set of Cc1NF1/Cc2NR1 producing 350 bp amplicons in the internal transcribed spacer (ITS) region according to Cullen et al. (2002). The Cc1NF1/Cc2NR1 sequences were identical for three isolates, therefore one sequence from isolate BL_JZ_J1 was submitted to the GenBank with accession number OM368349. Additional genes were also sequencing including the actin (ACT), chitin synthase l (CHS1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and another larger ITS region were also amplified from genomic DNA using primers sets ACT512F/ACT783R, CHS-79F/CHS-354R (Carbone and Kohn 1999), GDF1/GDR1 (Templeton et al. 1992) and ITS1/ITS4 (Glass and Donaldson 1995), respectively. Sequences obtained for those four regions were 216 bp, 218bp, 235bp and 576 bp, respectively. Each region in the three isolates were also identical, therefore one sequence for each region was submitted to the GenBank with accession number of OM417059, OM417060, OM417061, and OM349570, respectively, which had 100% similarity with C. coccodes of MN336525 (ACT), KU821274 (CHS1), KU821397 (GAPDH) and KU821175 (ITS), respectively. Phylogenetic analyses based on the concatenated sequences of those four loci showed that the BL_JZ_J1 was close to C. coccodes, a reference isolate of CPOS1 with the accession numbers of GQ856787 (ACT), GQ856723 (CHS1), GQ856744 (GAPDH) and GQ485588 (ITS) (Yang et al. 2009). Pathogenicity was confirmed by inoculating a conidia suspension (100 µl of 105 conidia/ml) on three stems of 6-week-old potato plant cv. 'Favorita' with an artificial wound generated by sterile toothpick for each isolate. An equal volume of sterile water was injected on the wound of three stems as a noninoculated control. Brownish necrotic lesions were observed on all inoculated stems 3 days post-inoculation under natural conditions, whereas control stems remained symptomless. Reisolation of the fungus from all inoculated symptomatic plants confirmed Koch's Postulates. To our knowledge, this is the first report of C. coccodes in potato in Tibet Autonomous Region of China. The finding of black dot in this region has important management implications for the growers since the pathogen can survive for long periods in the field both on potato debris and in soil.

Lactic Acid Bacteria as Biocontrol Agents against Potato (Solanum tuberosum L.) Pathogens

Biological control offers an alternative to chemical pesticides, which are inconsistent with the global trend of “going green”. Biological control includes various approaches, from natural predators to biologically produced molecules. This article focuses on the selection of lactic acid bacteria (LAB) as biological control agents against potato pathogens. The scope included evaluating the antimicrobial activity of 100 LAB strains against ten phytopatogens (Pectobacterium carotovorum, Streptomyces scabiei, Fusarium oxysporum, Fusarium sambucinum, Alternaria solani, Alternaria, tenuissima, Alternaria alternata, Phoma exigua, Rhizoctonia solani, Colletotrichum coccodes) by cross-streak plate method. HPLC determined the metabolic profiles for the most active LAB strains, and lactic acid, acetic acid, propionic acid and ethanol were found in the largest quantities. The strain Lactiplantibacillus plantarum KB2 LAB 03 was finally selected and cultured on supplemented acid whey. After the selection in laboratory tests, the strain KB2 LAB 03 was assessed in situ on seed potatoes against phytopathogens. The test showed a 40–90% reduction of eight potato pathogens infestation; only F. sambucinum and F. oxysporum were not inhibited at all. L. plantarum KB2 LAB 03 was proposed as the potential biocontrol agent for the potato protection against phytopathogens.

Curvicollide D, a new modified γ-lactone from the culture broth of Albifimbria verrucaria and its antifungal activity against plant pathogenic fungi.

In our screening program for new antifungal active compounds, a new modified γ-lactone curvicollide D (1) together with five known trichothecenes (2-6) were isolated from the culture filtrate of fungus Albifimbria verrucaria based on the in vitro antifungal assay. The chemical structure of new compound 1 was elucidated by NMR and HR-MS spectroscopic analyses, and the relative configurations of 1 were deduced from NOE experiments and coupling constant analysis. Compound 1 exhibited moderate antifungal activities against plant pathogenic fungi Botrytis cinerea, Colletotrichum coccodes, and Magnaporthe oryzae with MIC value in a range of 100-200 µg ml-1. Moreover, trichothecene compounds (2-6) displayed a broad spectrum of antifungal activities with MIC values in a range of 6.3-100 µg ml-1.

Pathogenicity of Colletotrichum coccodes causing anthracnose disease and its effect on growth and yield of sweet potato [Ipomoea batatas (L.) Lam

The disease causing ability of Colletotrichum coccodes and the effect of anthracnose on growth and yield of sweet potato accessions were evaluated in a two-year field trial. Field layout was a randomized complete block design with 16 sweet potato accessions replicated thrice. Young leaves of sweet potato accessions were sprayed with an inoculum concentration of 2.1 × 107 in a two-split application in the field with growth, yield, and disease indices recorded. Pathogenicity of C. coccodes was significantly highest among four accessions; OW4, SE10, SE12 and SPK-004 with abundant necrosis on leaves and stems of inoculated plants. Disease incidence varied between 2.48% - 52.83%, and 2.77% - 50.73%, during the 2018 and 2019 planting seasons respectively, with host response ranging from being susceptible to resistant. Accessions OW5 and OS15 had significantly lower disease incidence and severity than other treatments (p = 0.031 and 0.28 respectively) and also produced the highest yield ranging between 15.84 - 17.29, and 14.88 - 15.72 t/ha-1, in 2018 and 2019, respectively. This study has shown that anthracnose causes significant reduction in expected yield in sweet potato cultivation and also identified two resistant sweet potato accessions that can be useful sources in breeding for resistance to the disease.

Synthesis and Bioactivity of Novel Sulfonate Scaffold-Containing Pyrazolecarbamide Derivatives as Antifungal and Antiviral Agents.

Novel pyrazolecarbamide derivatives bearing a sulfonate fragment were synthesized to identify potential antifungal and antiviral agents. All the structures of the key intermediates and target compounds were confirmed by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). The single-crystal X-ray diffraction of the compound T22 showed that pyrazole carbamide is a sulfonate. The in vitro antifungal activities of the target compounds against Colletotrichum camelliae, Pestalotiopsis theae, Gibberella zeae, and Rhizoctonia solani were evaluated at 50 μg/ml. Among the four pathogens, the target compounds exhibited the highest antifungal activity against Rhizoctonia solani. The compound T24 (EC50 = 0.45 mg/L) had higher antifungal activity than the commercial fungicide hymexazol (EC50 = 10.49 mg/L) against R. solani, almost similar to bixafen (EC50 = 0.25 mg/L). Additionally, the target compounds exhibited protective effects in vivo against TMV. Thus, this study reveals that pyrazolecarbamide derivatives bearing a sulfonate fragment exhibit potential antifungal and antiviral activities.

Control of Antracnose Disease in Tomato (Solanum Lycopersicum) Using Endophytic Fungi

Anthracnose is a disease that affects tomato plants and causes farmers to lose money. The fungus Colletotrichum coccodes causes this disease, which manifests as small blackish spots on the tomato. The fruit then becomes shrivelled and dry, and it rots. One of the safest and most environmentally friendly methods of biological control is the use of endophytic fungi. These fungi are found in living plant tissue and can form colonies in the tissue without harming the host or causing disease symptoms. The goal of this study was to identify the different types of endophytic fungi found in tomatoes, as well as the role of endophytic fungi in the control of anthracnose disease. Plant samples were collected in Lempake Village in North Samarinda District, and antagonists between the endophytic fungi found in tomatoes and pathogens that cause anthracnose disease were tested. In the tomato plants, the researchers discovered four genera of endophytic fungi: Aspergillus flavus, Aspergillus niger, Trichoderma sp., and Rhizopus sp. Antagonist tests revealed that Aspergillus flavus, Aspergillus niger, and Rhizopus sp. fungi suppressed pathogenic fungi that cause anthracnose disease by 33.17%, 36.43%, and 38.37%, respectively. The fungus Trichoderma sp. had the best ability to control anthracnose.
 Keywords: tomatoes, endophytic fungi, anthracnose, Colletotrichum coccodes Wallr. S. Hughes

Soil-borne and compost-borne Penicillium sp. and Gliocladium spp. as potential microbial biocontrol agents for the suppression of anthracnose-induced decay on tomato fruits

BackgroundAnthracnose is a soil-borne tomato (Solanum lycopersicum L.) disease caused by Colletotrichum coccodes and associated with early dying syndrome and postharvest fruits decays leading to significant yield losses. A biocontrol trial was conducted using Penicillium sp. and Gliocladium spp. isolates recovered from soil and compost for the evaluation of their antifungal potential against the target pathogen.ResultsCell-free culture filtrates of the microbial agents tested at different concentrations displayed an important antifungal activity based on pathogen mycelial growth inhibition and spore germination suppression. The highest antifungal potential was induced by Penicillium sp. CH6, G. catenulatum Gc1 and G. virens Gv1 cell-free filtrates applied at 3 concentrations (10, 15 and 20% v/v). C. coccodes mycelial growth was significantly reduced by 16 to 84% with chloroform and ethyl acetate extracts of Penicillium sp. CH6 and G. catenulatum Gc1 isolates applied at the concentrations 1, 2.5 and 5% v/v. These treatments had induced an important morphological alteration to pathogen mycelium expressed mainly by a decrease in colony melanization. Testing on pathogen-inoculated fruits, treatment based on cell-free culture filtrates and organic extracts had significantly reduced anthracnose severity as compared to control. Rot lesion diameter was significantly decreased about 22% following treatments with Penicillium sp. CH6 and G. catenulatum Gc1 cell-free filtrates. All chloroform and ethyl acetate extracts of isolates tested had suppressed disease severity by 11 to 59% and 14 to 85%, respectively, as compared to the untreated control.ConclusionsThe results demonstrated the involvement of bioactive compounds in the cultural filtrates and organic extracts tested. These microbial agents may be explored as an alternative tool for the protection of tomato fruits from fungi-associated decays.

Dose optimisation of volatile molecules-based bio-fungicide product formulations against anthracnose (Colletotrichum coccodes) in tomato fruits

Objective of study was to optimise the dose of EC37, EC39 and EC40 against Colletotrichum coccodes in tomato fruit by response surface methodology. In the in-vitro assay, three products were tested against C. coccodes by minimum inhibition concentration, then by using model to test the effects of three levels of two factors (concentration and treatment time) for post-harvest treatment of tomato fruits. The results indicated that 0.55% product concentration with 15 min exposure time was the effective optimised dose treatment with least fruit rot spoilage with retention of fruit texture and colour during storage, on par with the positive control (0.1% Difenoconazole). Storage studies (28 ± 2 °C, 70 ± 5% RH) with above optimised dosage of these product treatments showed less anthracnose incidence, better retention of fruit quality of treated tomato fruits as compared with the positive control and the control fruits after 12 days of storage. Supplemental data for this article is available online at https://doi.org/10.1080/03235408.2022.2033566 .

Molecular characterization of a novel penoulivirus from the phytopathogenic fungus Colletotrichum camelliae.

Colletotrichum camelliae is a widespread filamentous phytopathogenic fungus. In this study, a novel mycovirus designated as "Colletotrichum camelliae botourmiavirus 1" (CcBV1) was isolated from strain ZJQT11 of C. camelliae, and its complete genome sequence was determined. CcBV1 has a genome of 2,506 nucleotides and contains a large open reading frame (ORF) that encodes an RNA-dependent RNA polymerase (RdRp) with 672 amino acids and a predicted molecular mass of 75.23 kDa. A BLASTp search showed that RdRp encoded by CcBV1 is closely related to that of Pyricularia oryzae ourmia-like virus 1 with 73.22% identity. Phylogenetic analysis indicated that CcBV1 clustered in the penoulivirus clade within the family Botourmiaviridae. To the best of our knowledge, this is the first report of a penoulivirus in C. camelliae.

Molecular Characterization, Pathogenicity and Biological Characterization of Colletotrichum Species Associated with Anthracnose of Camellia yuhsienensis Hu in China

Camellia yuhsienensis Hu, a species of tea oil tree with resistance to anthracnose, is widely used to breed disease-resistant Camellia varieties. In 2019, anthracnose symptoms were observed on Ca. yuhsienensis for the first time. However, the species and biological characteristics of Colletotrichum spp. isolated from Ca. yuhsienensis (YX-Colletotrichum spp.) have not been elucidated. In this study, five isolates (YX2-5-2, 2YX-3-1, 2YX-5-1, 2YX-8-1-1 and 2YX-8-1-2), which were consistent with the morphological characteristics of Colletotrichum spp., were obtained from Ca. yuhsienensis. A phylogenetic analysis demonstrated that YX2-5-2, 2YX-3-1 and 2YX-8-1-2 belonged to first clade along with Colletotrichum fructicola. 2YX-8-1-1 belonged to the second clade along with Colletotrichum siamense. 2YX-5-1 belonged to the third clade with Colletotrichum camelliae. Pathogenicity tests revealed that the pathogenicity of YX-Colletotrichum spp. was stronger than that of Colletotrichum spp. isolated from Camellia oleifera (GD-Colletotrichum spp.). Biological characteristics illustrated that the mycelial growth of YX-Co. camelliae (2YX-5-1) was slower than that of GD-Co. camelliae when the temperature exceeded 20 °C. In addition, in the presence of ions, the mycelial growth of YX-Co. fructicola (YX2-5-2) and YX-Co. siamense (2YX-8-1-1) was also slower than that of GD-Co. fructicola and GD-Co. siamense. Furthermore, the ability of YX-Colletotrichum spp. to utilize lactose and mannitol was weaker than that of GD-Colletotrichum spp., while the ability to utilize NH4+ was generally stronger than that of GD-Colletotrichum spp. This is the first report of anthracnose of Ca. yuhsienensis induced by Co. fructicola, Co. siamense and Co. camelliae in China. These results will provide theoretical guidance for the study of the pathogenesis and control of anthracnose on Ca. yuhsienensis.

Corylus avellana leaf extract-mediated green synthesis of antifungal silver nanoparticles using microwave irradiation and assessment of their properties

Abstract Due to high antimicrobial activity against numerous microorganisms, silver nanoparticles (AgNPs) are being utilized in various areas. Microwave-accelerated AgNPs synthesis using Corylus avellana leaf extract was evaluated. Based on randomly central composite design, 13 mixture solutions containing different amounts of the prepared extract (0.10–0.90 mL) and 1 mM silver nitrate solution (15–25 mL) were prepared and exposed to microwave irradiation for 180 s. Response surface methodology was utilized to evaluate the effects of the two independent variables on particle size and concentration of the synthesized AgNPs, as manifested in the place of broad emission peak (λ max) and its absorbance unit, respectively. Fourier transform infrared spectroscopy analysis indicated that the two hydroxyl and carboxylic acid functional groups with reducing activity existed in the prepared extract. Dynamic light scattering and transmission electron microscopy analyses revealed that the formed spherical AgNPs using optimum amounts of C. avellana leaf extract (0.9 mL) and 1 mM silver nitrate solution (25 mL) had minimum particle size (103.5 nm) and polydispersity index (PDI) (0.209), and maximum concentration (140 ppm) and zeta potential (−21.8 mV). Results indicated that the formed AgNPs had high fungicidal effects against the spoiled fungi of Colletotrichum coccodes and Penicillium digitatum.