Papaya Anthracnose Research Articles

Mechanisms employed by Debaryomyces hansenii in biological control of anthracnose disease on papaya fruit

The mechanisms of action associated with the biocontrol capacity of Debaryomyces hansenii against Colletotrichum gloeosporioides, causal agent of anthracnose in papaya, were studied by means of in vitro and in situ assays. In vitro the yeast exhibited a variety of different antagonistic mechanisms against the phytopathogenic fungus including: volatile organic compounds (VOCs) production, β-1, 3 glucanase and protease activity, inhibition of spore germination, and the competition for saccharose, glucose, fructose and total carbohydrates. Results in situ indicated that disease incidence and lesion diameter of anthracnose on papaya var. Maradol fruit was significantly reduced with a higher concentration of D. hansenii. Our study indicates that D. hansenii is an excellent agent of control to anthracnose disease on papaya var. Maradol fruit.

On mycobiota of fruit, vegetable, ornamental crops and weeds in China (results of 2017 expedition)

Samples of plants damaged with fungi were collected on the Hainan Island in vicinities of the Hainan branch of Jilin Agricultural Academy (Foluo) on 15-16.11.2017. Some samples were also collected in glasshouse farms of the Jilin Province on 12 and 16.11.2017. 40 species of fungi from Zygomycota, Ascomycota, Basidiomycota and Mitosporic fungi group are identified. Some species from Oomycota are also identified. The revealed microorganisms are registered on 36 species of plants from 36 genera, 26 families. In glasshouse farms of the Jilin Province, the most widespread and harmful diseases on vegetable cultures are false mildew of cucumber (Pseudoperonospora cubensis) and powdery mildew of pepper (Leveillula taurica), and also wilt of tomato, eggplant and pepper (Fusarium oxysporum, Verticillium dahliae). In an open ground on Hainan Island, cucumber false mildew and wilt of pepper are the most harmful. Mango leaf spot and dieback (complex of causal agents Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Botryosphaeria dothidea, Pestalotiopsis mangiferae, Phomopsis sp. and others) and papaya anthracnose (Colletotrichum gloeosporioides) have moderate severity. The collection of pure cultures of micromycetes including 106 isolates of 28 species from 27 genera of Oomycota (1), Zygomycota (2), Basidiomycota (1), Ascomycota (18) and Mitosporic fungi (84) has been created.

Effect of the Combination Hot Water - Calcium Chloride on the In Vitro Growth of Colletotrichum gloeosporioides and the Postharvest Quality of Infected Papaya.

Anthracnose of papaya fruit caused by the fungus Colletotrichum gloeosporioides is one of the most economically important postharvest diseases. Hot water immersion (HW) and calcium chloride (Ca) treatments have been used to control papaya postharvest diseases; however, the effect of the combination HW-Ca on the pathogen growth and the development of the disease in infected papaya fruit has been scarcely studied. The aim of this study was to evaluate the effect of the HW-Ca treatment on the in vitro growth of C. gloesporioides conidia and the quality of infected papaya. In vitro, the HW-Ca treated conidia showed reduced mycelial growth and germination. In vivo, the HW-Ca treatment of infected papaya delayed for 5 days the onset of the anthracnose symptoms and improved the papaya postharvest quality. The combined treatment HW-Ca was better than any of the individual treatments to inhibit the in vitro development of C. gloeosporioides and to reduce the negative effects of papaya anthracnose.

Synthesis of Novel Glycerol-Derived 1,2,3-Triazoles and Evaluation of Their Fungicide, Phytotoxic and Cytotoxic Activities.

The synthesis of a series of 1,2,3-triazoles using glycerol as starting material is described. The key step in the preparation of these triazolic derivatives is the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), also known as click reaction, between 4-(azidomethyl)-2,2-dimethyl-1,3-dioxolane (3) and different terminal alkynes. The eight prepared derivatives were evaluated with regard to their fungicide, phytotoxic and cytotoxic activities. The fungicidal activity was assessed in vitro against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. It was found that the compounds 1-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)-cyclo-hexanol (4g) and 2-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)propan-2-ol (4h) demonstrated high efficiency in controlling C. gloeosporioides when compared to the commercial fungicide tebuconazole. The triazoles did not present any phytotoxic effect when evaluated against Lactuca sativa. However, five derivatives were mitodepressive, inducing cell death detected by the presence of condensed nuclei and acted as aneugenic agents in the cell cycle of L. sativa. It is believed that glycerol derivatives bearing 1,2,3-triazole functionalities may represent a promising scaffold to be explored for the development of new agents to control C. gloeosporioides.

Post-harvest treatment with Ca-phosphite reduces anthracnose without altering papaya fruit quality

ABSTRACTThis study assessed the effect of phosphites (Mg, Zn, Ca, K) on papaya (‘Sunrise Solo’) anthracnose (Colletotrichum gloeosporioides). Surface-sterilised wounded (2mm) fruits were inoculated (50µL; 106 con/mL) with C. gloeosporioides and then the products were applied. The lesion diameters (LD) and the physico-chemical properties were analysed. Assays in vitro and in vivo were carried out with phosphites. The results in vitro indicated that the phosphites were effective in reducing the mycelial growth and conidia production for all doses [Phosphite Mg – 0.75, 1.5, 3 ml/l (40% P2O5 + 6% Mg) Fitofos Mg; Phosphite Zn - 1.25, 2.5, 5 ml/l (40% P2O5 + 10% Zn)]; Phosphite Ca - 1.5, 3, 6 ml/l (30% P2O5 + 7% Ca)]; Phosphite K - 1.25, 2.5, 5 ml/l (40% P2O5 + 20% K2O)]. Concentration experiments on disease control showed that Phosphite-Ca at 6 ml/l (30% P2O5 + 7% Ca) significantly reduced the LD. Fruit treated with phosphite-Ca maintained physico-chemical properties of papaya fruits.

Identificación de especies del género <i>Colletotrichum</i> asociadas a la antracnosis en papaya (<i>Carica papaya L.</i>) en Costa Rica1

La antracnosis, causada por Colletotrichum spp., es una de la enfermedades poscosecha más importantes en papaya. En este estudio, frutas de papaya, híbrido Pococí, recolectados en plantaciones ubicadas en el cantón de Guácimo, provincia de Limón, presentaron 7 síntomas de antracnosis, luego de un período de almacenamiento. De cada síntoma se obtuvieron aislados de Colletotrichum en medio de cultivo PDA (papa-dextrosa-agar). Los aislamientos se clasificaron en 3 grupos según la similitud de los síntomas y la morfología de la colonia. El análisis de la secuencia de la región espaciadora interna transcrita (ITS) del ADN ribosomal reveló que los aislamientos pertenecieron a 3 especies del género Colletotrichum: C. gloeosporioides sensu lato, C. magnum y C. capsici (C. truncatum). La identificación de las especies fue confirmada con imprimadores taxón específico para C. gloeosporioides e imprimadores especie-específicos para C. magnum. Las 3 especies identificadas mostraron ser patogénicas sobre frutas de papaya. Las especies C. magnum y C. capsici (C. truncatum) se registran por primera vez en Costa Rica, como agentes causales de la antracnosis en papaya.

Post-harvest anthracnose of papaya caused by Colletotrichum truncatum in Korea

In October 2016, we collected samples of post-harvest anthracnose of papaya from Gangneung, Gangwon Province, Korea. Infected fruits first showed tiny light brown spots on their surface followed by development of sunken water-soaked lesions with black acervuli. Fungal pathogen was isolated from the infected fruits and cultured on potato dextrose agar (PDA) and synthetic nutrient agar (SNA) medium. For identification of the fungus, morphological assessment and sequencing analysis of 5.8S ribosomal DNA (ITS-5.8S rDNA) and three protein-coding genes: actin (ACT), chitin synthase I (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) were performed. Pathogenicity of the fungal isolate was confirmed according to Koch’s postulates. The results of morphological examination, pathogenicity tests, and the ITS-5.8S rDNA, ACT, CHS-1, and G3PDH sequences confirmed Colletotrichum truncatum as the causal agent. This study provides news information about C. truncatum isolated from post-harvest papaya in Korea.

First report of papaya anthracnose caused by Colletotrichum salsolae in India

Papaya (Carica papaya) is an important fruit crop grown in tropical and subtropical regions of India. India ranks first in papaya production in the world with over 5.63 million tonnes produced annually (FAOSTAT, 2). Anthracnose of papaya caused by Colletotrichum species is an important disease worldwide, resulting in post-harvest fruit decay which severely affects the marketability of the fruits (Ademe et al., 1). In August 2016, papaya fruits showing typical anthracnose symptoms of small sunken spots were observed in two different fields in Badnapur, Jalna, Maharashtra, India (Fig. 1) and around 15% of the papaya plants were affected. The papaya fruits were semi ripe when harvested and ten fruits were incubated at 28°C in the dark for four-five days at 90% humidity to allow for further development of disease symptoms. Sunken necrotic fruit tissue was then examined under a microscope and conidia were inoculated onto potato dextrose agar (PDA) containing 50 mg/l streptomycin sulphate. The plates were incubated at 28°C with a 16/8 hr light/dark cycle for five to seven days and pure cultures were obtained by sub-culturing onto fresh PDA plates. Identification of isolates was based on morphological as well as molecular characterisation. All ten fruits were found to be infected with Colletotrichum gloeosporioides and among them six fruits had a mixed infection of C. gloeosporioides and Colletotrichum salsolae. Only identification of the C. salsolae isolate is described here. The putative C. salsolae isolate had white aerial mycelia with an olive-coloured colony and a light-salmon coloured conidial mass (Fig. 2). The mycelial growth rate on PDA at 28°C with 16 hr photoperiod was 16 mm per day. Conidia obtained from incubated papaya fruits were single celled, cylindrical with a rounded base and apex. The mean length and width of conidia was 16.69 ±1.04 μm and 5.56 ±0.18 μm, respectively (Fig. 3). The morphological characteristics of the isolate matched the description of C. salsolae (Weir et al., 6). Molecular characterisation of the putative C. salsolae isolate involved PCR amplification of the partial β-tubulin gene using the universal primer pair Bt2a/b and GAPDH gene. Both sequences were deposited in GenBank (Accession Nos. KY401636 and KY401637 respectively) and aligned with published sequences using MEGA version 6.0 and phylogenetic analysis was done (Fig. 4). Blast searches in the NCBI database revealed that the β-tubulin and GAPDH gene sequences had 99% and 97% identity to C. salsolae (KC790894 and JX009916, respectively). The pathogenicity of C. salsolae isolated from infected papaya fruit was confirmed on healthy papaya fruits obtained from the local market. The fruits were washed with sterile distilled water and then surface sterilised with 70% ethanol for 30 seconds. Papaya fruits were wounded with a sterile syringe and inoculated with 10 μl of a conidial suspension (c. 105 conidia/ml). Sterile water was used as a control. Inoculated papaya fruits were kept in a chamber at 28°C in the dark with 90% humidity. After seven days typical anthracnose symptoms were observed on the inoculated papaya fruit but not on the controls (Fig. 5). Conidia were re-isolated from the inoculated symptomatic papaya fruits and characterised morphologically as well as molecularly and found to be identical to the original inoculated C. salsolae spores, thereby fulfilling Koch's postulates. In India, Colletotrichum karstii (Sharma & Shenoy, 5), Colletotrichum fructicola and C. gloeosporioides (Saini et al., 4) along with some other unverifiable records (Farr & Rossman, 3) have been reported to cause papaya anthracnose. To our knowledge, this is the first report of papaya anthracnose caused by C. salsolae in India. The pathogen has previously only been reported on Salsola tragus in Hungary (Weir et al., 6). As this was a mixed infection it is not known what proportion of the affected fruits was infected by C. salsolae in the field. However, this new finding shows that C. salsolae is not host-specific and may occur in more geographical locations than is currently recorded.

First Report of Colletotrichum magnum Causing Anthracnose in Papaya in Mexico

First Report of <i>Colletotrichum magnum</i> Causing Anthracnose in Papaya in Mexico

Application of a hydrothermal-calcium chloride treatment to inhibit postharvest anthracnose development in papaya

Anthracnose is considered an important postharvest disease in papaya. The hydrothermal treatment (HT) and calcium chloride (Ca) have been shown to be effective to inhibit anthracnose. The objective of this study was to investigate the effect of the combination HT-Ca on the development of anthracnose in papaya. Fruit were inoculated with Colletotrichum gloeosporioides by immersion in a spore suspension and then were divided into two groups: one received a HT treatment (48°C, 20min) combined with Ca (1% w/v, 20min) and the other was used as control. Afterwards, fruit were stored during 20days at 12°C to allow the development of the fungal infection. Anthracnose incidence and severity were estimated visually while the development of the disease was analyzed by light and electron microscopy. HT-Ca reduced anthracnose incidence and severity compared with the control. Microscopy analysis showed that HT-Ca melted the epicuticular wax, which covered most of the stomata; this resulted in a lower mycelial growth in HT-Ca fruit with respect to the control samples. HT-Ca also induced the formation of round shaped vesicles, which corresponded with the greater accumulation of total phenolics observed in treated fruit. HT-Ca was effective to delay the symptoms of anthracnose up to 10days during storage of papaya at 12°C.

Cassava starch coatings for postharvest control of papaya anthracnose

The effects of coating papaya fruit ( Carica papaya ) with cassava starch were studied, to determine the best concentration and mode of action of this material in postharvest control of anthracnose. The concentrations of starch tested were 1%, 2%, 3% and 4%. These were prepared to give gel consistency. Surface sterilized papaya fruits were inoculated with conidia of Colletotrichum gloeosporioides and incubated for 48 h in a moisture chamber. The were then treated with cassava fruit gels and dried. During the following 14 d storage period, fruit maturation and anthracnose on the fruits were assessed, and electron microscopy was used to examine fruit epicarps. All cassava starch coating concentrations reduced fruit maturation and anthracnose, with the 2%, 3% or 4% coatings giving 100% disease control. The 2% starch coating is likely to be optimum, considering the lower cost efficiency of disease control. The mechanism of disease control provided by the coating is likely to be related to delay of ripening and the formation of a protective layer over the fruit.

First report of papaya anthracnose caused by Colletotrichum fructicola in India

Papaya ( Carica papaya ) is an important fruit crop grown in tropical and subtropical regions of India. India ranks first in papaya production in the world with over 5.54 million tonnes produced annually (FAOSTAT, 2013). In August 2016, a…

CglCUT1 gene required for cutinase activity and pathogenicity of Colletotrichum gloeosporioides causing anthracnose of Camellia oleifera

Colletotrichum gloeosporioides is the causal agent of Camellia oleifera anthracnose, mainly infecting fruits and leaves. The fungus secretes degrading enzymes to destroy the cuticle of aerial plant parts and help infect the host successfully. To validate whether a cutinase gene (CglCUT1) was required for cutinase activity and pathogenicity of C. gloeosporioides, the CglCUT1 gene was cloned and analyzed. The characterization of CglCUT1 predicted protein suggests that the cloned DNA encoded a cutinase in C. gloeosporioides affecting C. oleifera. The CglCUT1 showed a high homology to those from C. gloeosporioides causing papaya anthracnose and C. capsici causing pepper anthracnose, as well as those of other ascomycetes. The whole CglCUT1 gene was knocked-out and the knockout mutant (∆CglCUT39) was subsequently complemented using Agrobacterium tumefaciens mediated transformation. The knockout transformants exhibited significant decreases in cutinase activity and virulence compared with the wild-type strain. The complemented transformants of the disrupted transformant ∆CglCUT39 showed a significant increase in cutinase activity and virulence compared with the disrupted transformant ∆CglCUT39. This study suggests that the CglCUT1 gene has a positive effect on fungal virulence of the hemibiotrophic C. gloeosporioides on C. oleifera.

Effects of Plant Leaf Extract against Colletotrichum gloeosporioides (Penz) Sac. Causing Post-Harvest Disease of Papaya

The antifungal activity of selected weed and other plants leaf extract prepared in distilled water and ethanol were tested against anthracnose, the post-harvest disease of papaya (Carica papaya L.) caused by Colletotrichum gloeosporioides. The result from the experiment proved that ethanol leaf extract of weed plant, Lantana camara L.possess significant fungicidal effect on the radial growth of C. gloeosporioides followed by lemon and avocado leaf extract while Mikania micrantha Kunth, Sphagneticola trilobata (L.) Pruski and Cyperus rotundus L. leaf extract gave an insignificant inhibitory effect on the radial growth the fungus. The result of this study showed that Lantana camara leaf extract has the potential antifungal compound to control C. gloeosporioides which is the casual organism of papaya anthracnose.

Application of lemongrass oil in vapour phase for the effective control of anthracnose of 'Sekaki' papaya.

To evaluate the potential use of lemongrass essential oil vapour as an alternative for synthetic fungicides in controlling anthracnose of papaya. Lemongrass oil used in the study was characterized using gas chromatography-flame ionization detection (GC-FID) before it was tested against anthracnose of papaya in vitro and in vivo. The GC-FID analysis showed that geranial (45·6%) and neral (34·3%) were the major components in lemongrass oil. In vitro study revealed that lemongrass oil vapour at all concentrations tested (33, 66, 132, 264 and 528 μl l(-1) ) suppressed the mycelial growth and conidial germination of Colletotrichum gloeosporioides. For the in vivo study, 'Sekaki' papaya were exposed to lemongrass oil fumigation (0, 7, 14, 28 μl l(-1) ) for 18 h and at room temperature for 9 days. Lemongrass oil vapour at the concentration of 28 μl l(-1) was most effective against anthracnose of artificially inoculated papaya fruit while quality parameters of papaya were not significantly altered. This suggests that lemongrass oil vapour can control anthracnose disease development on papaya without affecting its natural ripening process. The potential practical application of this technology can reduce reliance on synthetic fungicides for the control of postharvest diseases in papaya.

Antifungal action of ozone against Colletotrichum gloeosporioides and control of papaya anthracnose

To elucidate the antifungal action and possible responses of ozone on the fungus, the effect of gaseous ozone on the germination of conidia of Colletotrichum gloeosporioides, anthracnose control in papaya and mitochondrial degradation in spores was studied. Ozone treatment appeared to suppress the growth of C. gloeosporioides in the in vivo study. Ozone also induced the generation of reactive oxygen species (ROS) in the fungal spores as shown by the oxidant-sensitive stain 2,7-dichlorodihydrofluorescein diacetate. Degradation of mitochondria in the spores was observed after 24h of ozone treatment at 3.5 and 5.0μL/L using transmission electron microscopy. Abnormalities in the ultrastructure of spores treated with 5.0μL/L ozone included an increase in mitochondrial degradation, cytoplasmic disintegration and plasmolysis. These results suggest that mitochondria of the spores could be one of the mechanisms involved in the antifungal activity of ozone responses against C. gloeosporioides.

Chemical analysis and toxicity of seaweed extracts with inhibitory activity against tropical fruit anthracnose fungi

Banana and papaya are among the most important crops in the tropics, with a value amounting to millions of dollars per year. However, these fruits suffer significant losses due to anthracnose, a fungal disease. It is well known that certain seaweed extracts possess antifungal activity, but no published data appear to exist on the practical application of this property. In the present study, five organic Brazilian seaweed extracts were screened for their activity against banana and papaya anthracnose fungi. Furthermore, cytotoxic and mutagenic effects of the extracts were evaluated by the brine shrimp lethality assay and the Allium cepa root-tip mutagenicity test respectively, while their major components were identified by gas chromatography/mass spectrometry. Strong fungus-inhibitory effects of Ochtodes secundiramea and Laurencia dendroidea extracts were observed on both papaya (100 and 98% respectively) and banana (89 and 78% respectively). This impressive activity could be associated with halogenated terpenes, the major components of both extracts. Only Hypnea musciformis extract showed cytotoxic and mutagenic effects. The results of this study suggest the potential use of seaweed extracts as a source of antifungal agents with low toxicity to control anthracnose in papaya and banana during storage.

Use of killer yeast in the management of postharvest papaya anthracnose

The efficiency of two killer yeast strains, Wickerhamomyces anomalus (strain 422) and Meyerozyma guilliermondii (strain 443), as biocontrol agents against Colletotrichum gloeosporioides, a postharvest anthracnose agent of papaya and other tropical fruit, was assessed. These strains were previously selected through in vitro assays, but in the present study, their in vivo action was assessed. In addition, the influence of phytopathogen inoculation time on the fruit in combination with the use of the biocontrol agent was also assessed. We assessed mycoparasitism as an antagonistic mechanism of action by scanning electron microscopy (SEM). In addition, two hydrolytic enzymes, chitinase and β-1,3 glucanase, were assayed. Our results indicated that W. anomalus (strain 422) and M. guilliermondii (strain 443) reduced disease incidence by 24.62% and 20.68%, respectively, for up to 6d after inoculation, when applied 3h before the phytopathogen and incubated in a wet chamber (95% RH) at 28°C. The time of yeast inoculation had a significant effect on its antagonistic action. Application of the yeasts 12 or 24h before the phytopathogen inoculation resulted in 13.75% and 30% of disease reductions for W. anomalus (strain 422) and 31.35% and 41.17% reductions for M. guilliermondii (strain 443), respectively. Electron micrographs confirmed mycoparasitism by showing the interaction of the yeasts with C. gloeosporioides hyphae, causing in some cases, a loss of turgor and yeast penetration of walls with marked concavity formation on hypha cell walls.

INTEGRATED DISEASE CONTROL STRATEGIES FOR LENGTHENING THE STORAGE LIFE OF PAPAYA CULTIVARS 'RED LADY' AND 'RATHNA'

Anthracnose (Colletotrichum gloeosporioides), stem-end rot (Phomopsis caricae-papayae and Lasiodiplodia theobromae), and Phomopsis rot of papaya are major diseases resulting in relatively high post-harvest losses (up to 45%) in Sri Lanka. Current consumer preference is for tropical fruits free of agrochemicals. The objectives of the present investigation were to identify the in vitro efficacy of basil oil (Ocimum basillicum) and alum (sodium aluminium sulphate) on fungal pathogens of papaya fruit and to develop a relatively safe, in vivo integrated disease control strategy. Alum (1% (w/v)) and basil oil (0.12-0.16% (v/v)) in a liquid bioassay, indicated fungistatic and fungicidal efficacy on Colletotrichum gloeosporioides, Lasiodiplodia theobromae and Phomopsis caricae-papayae isolated from 'Red Lady' and 'Rathna' cultivars of papaya. In vivo investigation of fruits of both cultivars harvested from orchards in Sri Lanka at 25% maturity level indicated that papaya washed in 1% (w/v) alum and subsequently sprayed with an emulsion solution of 0.16% (v/v) basil oil and enclosed in styrofoam sleeves could be stored for a period of 14 days at 12-14°C. The visual quality rating (VQR) was high (11-13), and shriveling and “green islands” were low on fruits with zero disease severity where results were statistically similar to a Bavistin 500 mg/L (systemic fungicide) treatment. Physico¬chemical properties assessed were unaffected by the treatments and were comparable to the control (washed only in water). The organoleptic properties were slightly low in fruits subjected to cold temperature compared to fruits subjected to ambient temperature. No residues of basil oil could be detected on fruits by gas chromatography at the end of the experimental period. This integrated treatment strategy of papaya could be adopted for sea shipment and temperature-regulated supermarket storage of papaya fruits where storage life could be lengthened by up to 14 days.

Evaluation of Antifungal Activity of Plant Extracts against Papaya Anthracnose (Colletotrichum gloeosporioides)

Antifungal activities of nineteen plant extracts were tested in 2010 with the objectives of screening potential plant extracts against Colletotrichum gloeosporioides under in vitro and anthracnose caused by Colletotrichum gloeosporioides, on papaya (Carica papaya L.) during storage. Ethyl acetate extracts of Lantana camara resulted in the highest inhibition (with inhibition zone of 35.3 mm) and showed strong activity against C. gloeosporioides. Inhibition levels of spore germination that reached 88.7, 85.8, 85.1 and 84.6% were recorded over the control by extracts of Lantana camara, Lantana viburnoides, Echinops sp. and Ruta chalepensis. Four aqueous extracts were evaluated for control of anthracnose under in vivo for 14 days, and Echinops sp. (25%) was found to be most effective in the reduction of disease development and maintaining the overall quality of papaya fruit. Further studies on isolation and characterization of the active (antifungal) compounds are needed.