Papaya Anthracnose Research Articles

Transcription factor CpWRKY50 enhances anthracnose resistance by promoting jasmonic acid signaling in papaya

Abstract Colletotrichum brevisporum is an important fungal pathogen that causes anthracnose and has led to serious postharvest losses of papaya (Carica papaya L.) fruit in recent years. WRKY transcription factors (TFs) play vital roles in regulating plant resistance to pathogens, but their functions in papaya anthracnose resistance need further exploration. In this study, we identified a WRKY TF, CpWRKY50, which belongs to the WRKY IIc subfamily. During infection with C. brevisporum, expression of CpWRKY50 in anthracnose-resistant papaya cultivars was significantly higher than that in susceptible cultivars. CpWRKY50 was induced by methyl jasmonate, and CpWRKY50 localized in the nucleus. In yeast, full-length CpWRKY50 had transactivation activity, but CpWRKY50 variants truncated at the N or C termini did not. CpWRKY50 positively regulated papaya resistance to C. brevisporum, as demonstrated by transient overexpression of CpWRKY50 in papaya and heterologous expression of CpWRKY50 in tomato. Moreover, endogenous jasmonic acid (JA) and JA-isoleucine levels in the fruits of transgenic tomato OE lines were higher than in wild type both before and after inoculation with C. brevisporum, indicating that increased CpWRKY50 expression promotes JA accumulation. Furthermore, our results revealed CpWRKY50 directly binds to W-box motifs (TTGACC) in the promoters of two JA signaling-related genes, CpMYC2 and pathogenesis-related 4 CpPR4, thereby activating their expression. Our data support that CpWRKY50 positively regulates anthracnose resistance in papaya by promoting JA signaling. These results broaden our understanding of papaya disease resistance mechanisms and will facilitate the genetic improvement of papaya through molecular breeding.

Research on the Isolation of Endophytic Fungi from Papaya and the Prevention of Colletotrichum gloeosporioides.

Endophytic fungi can be used as a source of herbal antioxidants to overcome the limitations of low yield and lengthy growth cycles associated with using plants as raw materials for antioxidant production. Papaya fruit is often susceptible to infection by Colletotrichum gloeosporioides after harvest, leading to postharvest rot. Endophytic fungi were extracted with ethyl acetate, and the initial screening concentration was 100 mg/L. Seven strains were identified, with scavenging rates exceeding 50% and strong antioxidant activity. The IC50 values in DPPH and ABTS free radical scavenging assays ranged from 19.72 to 84.06 mg/L and from 14.34 to 64.63 mg/L, respectively. Strain Y17 exhibited robust antioxidant activity (IC50 < 20 mg/L) and was identified as Penicillium rolfsii (MT729953) through ITS sequencing. Treatment of papaya fruit wounds with a fermentation broth of strain Y17 significantly inhibited the infection and colonization of anthracnose pathogens, resulting in a slowed disease incidence rate. This promoted the activity of protective enzymes, such as CAT, POD, and SOD, in the papaya fruit and slowed down the rate of MDA accumulation. This strain, which was found to have antioxidant activity in this study, has the potential to control anthracnose in papaya and has value in terms of further development and utilization.

EVALUACIÓN DE ESTRATEGIAS DE MANEJO ECOLÓGICO DE ANTRACNOSIS DE LA PAPAYA EN CAMPO Y POSCOSECHA

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; Mexico is the third producer and the first exporter of papaya in the world. The crop has multiple phytosanitary limitations, among which anthracnose stands out, which can cause substantial production losses. The main management method is with chemical synthesis fungicides. &lt;strong&gt;Objective:&lt;/strong&gt; To evaluate treatments with biorational characteristics to control anthracnose in papaya crops in pre- and post-harvest. &lt;strong&gt;Methodology:&lt;/strong&gt; The causal agent of anthracnose was isolated and identified, the growth inhibitory effect of&lt;em&gt; &lt;/em&gt;&lt;em&gt;C. gloeosporioides&lt;/em&gt;&lt;em&gt; &lt;/em&gt;was evaluated &lt;em&gt;in vitro&lt;/em&gt; with extracts of &lt;em&gt;Datura stramonium&lt;/em&gt;, &lt;em&gt;Argemone mexicana&lt;/em&gt;, &lt;em&gt;Citrus sinensis&lt;/em&gt; essential oil and &lt;em&gt;Eucalyptus globulus&lt;/em&gt; essential oil; In addition, biorational treatments were applied pre- and post-harvest (botanical extracts, essential oils and &lt;em&gt;Trichoderma harzianum&lt;/em&gt;); The incidence and severity were evaluated and the percentage of efficacy was calculated. A randomized complete block design was used and analysis of variances and comparisons of means were performed (Tukey, P ≤ 0.05). &lt;strong&gt;Results:&lt;/strong&gt; The &lt;em&gt;E. globulus&lt;/em&gt; oil extract reached the highest in vitro growth inhibition levels, followed by the &lt;em&gt;C. sinensis&lt;/em&gt; essential oil and the &lt;em&gt;A.&lt;/em&gt;&lt;em&gt; mexicana&lt;/em&gt; extract; In the field phase, &lt;em&gt;T. harzianum&lt;/em&gt; reached 80.7% efficacy and 8% incidence, the essential oil of &lt;em&gt;E. globulus&lt;/em&gt; and the essential oil of &lt;em&gt;C. sinensis&lt;/em&gt; reached 73 and 66% efficacy, respectively. The effect of the treatments applied in pre-harvest demonstrated that successive applications of &lt;em&gt;T. harzianum&lt;/em&gt; reduced severity by 81% and incidence on papaya fruits by 30%, the essential oil of &lt;em&gt;E. globulus&lt;/em&gt; and that of &lt;em&gt;C. sinensis&lt;/em&gt; achieved efficacy of 64 and 68%, in their order. Finally, in the storage phase, &lt;em&gt;T. harzianum&lt;/em&gt; achieved a control efficiency of 89%, &lt;em&gt;C. sinensis&lt;/em&gt; oil 84% and 85% for the essential oil of &lt;em&gt;E. globulus&lt;/em&gt;, &lt;em&gt;A. mexicana&lt;/em&gt; managed to inhibit 76.46%. &lt;strong&gt;Implications:&lt;/strong&gt; Comparison of other biorational management treatments such as the use of essential elements (silicon, sulfur, etc.), nanotechnology, UV irradiation and resistance inducers is suggested. &lt;strong&gt;Conclusion:&lt;/strong&gt; These results support that a successful and biorational control of anthracnose in papaya must be based on comprehensive management that considered the preharvest and storage phases.&lt;/p&gt;

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.

Status of postharvest papaya anthracnose (Colletotrichum gloeosporioides) in Assosa Zone, Western Ethiopia

Papaya is among the most economically important fruit crops cultivated in Ethiopia supporting the livelihood of thousands of people. Anthracnose of papaya caused by Colletotrichum gloeosporioides is the major limitation that threatens the production and consumption of papaya fruit worldwide. This investigation was initiated to determine the current status of papaya anthracnose and identify factors influencing postharvest loss of papaya fruit in Assosa Zone, western Ethiopia. Field and market assessments were conducted in three major papaya-producing districts of Assosa Zone namely Assosa, Bambasi, and Homosha. Data on the disease intensity of anthracnose was recorded both in the field and in the market. Furthermore, factors associated with postharvest disease development were recorded through administration of a pretested semi-structured questionnaire to randomly selected papaya producers, wholesalers, and retailers. The results revealed that anthracnose of papaya was prevalent in all assessed localities, nevertheless, there was a significant (p < 0.05) difference between districts and peasant association in intensity of disease. At the orchard level, the disease incidence and severity ranged between 21.30–33.87% and 10.90–20.83%, respectively. Similarly, postharvest anthracnose incidence and severity ranged between 47.04–60.85% and 28.84–47.95%, respectively. Morphological and pathological identification of pure cultures from symptomatic fruits revealed that C. gloeosporioides was the causal agent of postharvest anthracnose of papaya in the Assosa Zone. Moreover, poor postharvest practices such as wrong methods of harvesting, improper handling of produce, and poor or improper transportation facilities are some factors that significantly influence postharvest disease development. This empirical evidence revealed that anthracnose is the major challenge to papaya production and utilization in Assosa, Western Ethiopia.

Evaluation of Antifungal Activity of Plant Extracts against Papaya Anthracnose (Colletotrichum gloeosporioides) under In-vitro Condition

The study aimed to assess the effectiveness of various plant extracts against Colletotrichum gloeosporioides in papaya. This investigation employed a completely randomized design and took place at the College of Agriculture in Pune-05 during the academic year 2021-22.Among the six plant extracts tested, garlic (Allium sativum) was found to be superior to the rest, exhibiting the minimum mycelium growth (5.30 mm) and the highest percentage inhibition (94.11%) at a 20% concentration. However, the drumstick leaf (Moringa oleifera) extract was the least effective, with the maximum radial mycelial growth of 44.00 mm (51.11% inhibition) observed. The study indicates that the radial mycelial growth of Colletotrichum gloeosporioides decreases with rise in the concentration of plant extracts.

Whole-Genome Sequence of Colletotrichum brevisporum Causing Anthracnose on Papaya (Carica papaya)

Colletotrichum spp. are the causal agents of papaya anthracnose, which seriously affects the quality and economic value of papaya fruits. Among them, Colletotrichum brevisporum is a new and important causal pathogen of anthracnose in papaya. The infection mechanisms of C. brevisporum are still unclear, and the genome sequence of C. brevisporum has not been released. In order to systemically explore the interaction between papaya and C. brevisporum, we sequenced the whole genome of the C. brevisporum strain C1, which was isolated from an infected papaya fruit in Guangdong Province, China. The assembly consists of 18 scaffolds with a genome size of 62.66 Mb. Furthermore, we identified genes that may be associated with pathogenicity, such as carbohydrate-active enzymes, secreted proteins, and secondary metabolite gene clusters. This genome resource will provide a valuable resource for future studies on the pathogenesis of C. brevisporum and comparative genomic analyses of the Colletotrichum genus. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Studies on biochemical changes and eco-friendly management of post-harvest anthracnose in papaya

Studies on biochemical changes and eco-friendly management of post-harvest anthracnose in papaya

First report of papaya anthracnose caused by Colletotrichum salsolae in Mauritius

First report of papaya anthracnose caused by <i>Colletotrichum salsolae</i> in Mauritius

Secondary Metabolites Application of Two Pseudomonas fluorescens isolates and Two Trichoderma Harzianum Isolates in Combination Against Postharvest Anthracnose in Papaya

The occurrence of papaya anthracnose is a significant post-harvest ailment, necessitating the effective disease management. The aim was to determine the ability of secondary metabolites combination of Pseudomonas fluorescens and Trichoderma harzianum isolates against the disease. A completely randomized design was used for in vitro experiments and a randomized block design for in vivo experiments. The treatments consisted of P. fluorescens P60 and T. harzianum T10, P. fluorescens P60 and T. harzianum T213, P. fluorescens P32 and T. harzianum T10, P. fluorescens P32 and T. harzianum T213 secondary metabolites and fungicides (a.i. maneb). The observed variables included the pathosystem component and papaya character and organoleptic test. The in vitro test results showed that P. fluorescens P60 and T. harzianum T10 and P. fluorescens P60 and T. harzianum T213 secondary metabolites inhibited the pathogen growth by 48.1075 and 43.4625%, respectively. The secondary metabolites of P. fluorescens P60 and T. harzianum T10 in vivo test results could delay the germination time by 12.63% and reduce the invasion area by 44.29%. All secondary metabolites had no effect on sugar content, hardness and sensory test. The combined secondary metabolites of P. fluorescens and T. harzianum are safe and does not affect papaya fruit quality.

Effect of combined application of carbonate salts and hot water treatment for the management of postharvest anthracnose (Colletotrichum gloeosporioides) of papaya.

Postharvest anthracnose (Colletotrichum gloeosporioides Penz.Sacc) is the most economically important biological constraint to papaya production and consumption, which causes substantial yield loss worldwide. The effect of combined application of carbonate salts and hot water treatments on the development of postharvest anthracnose and maintenances of postharvest quality of papaya fruit was studied in completely randomized design (CRD) under laboratory condition. The results revealed that combined application of hot water treatment and carbonate salts significantly (p < .05) reduced the incidence and severity of postharvest papaya anthracnose disease. The disease incidence reached 100% 21 days after inoculation in the control treatment; this level was significantly reduced to 26.70% by dipping the fruits in NH4CO3 at 50°C and NH4CO3 at 54°C. Similarly, treatments significantly (p < .05) reduced the disease severity in different degrees from the first day of disease appearance to the date of 100% unmarketability of control fruits. Furthermore, the combined application of carbonate salt and hot water treatments significantly improves fruit marketability by 93.33%. Moreover, the treatments showed significant (p < .05) effect on maintaining pH, TSS, TA, and reducing postharvest weight loss of papaya fruit. In conclusion, postharvest treatment of papaya fruit with NH4CO3 at 54°C, NH4CO3 at 52°C, and NaCO3 at 54°C can significantly reduce anthracnose development and improve marketability of the fruits without pronounced effect on their edible qualities.

Colletotrichum brevisporum causing anthracnose of papaya (Carica papaya L.) in Mexico

Papaya fruit cv. Maradol showing typical symptoms of anthracnose were observed in a commercial orchard located in the municipality of Pinotepa Nacional at the coastal region of Oaxaca, Mexico in September 2020. The incidence rate of anthracnose reached 60%. The symptoms consisted of sunken, water-soaked lesions with salmon-coloured conidia masses on the surface of papaya fruit. The aim of this study was to identify the causal agent of papaya anthracnose based on the phylogenetic analysis of four concatenated datasets. The isolate exhibited sparse white to greyish aerial mycelium and clearly shaped concentric rings with exudate of orange conidia on potato dextrose agar. The fungus was identified as Colletotrichum brevisporum using sequence data of the internal transcribed spacer (ITS) region, and part of the actin (act), glyceraldehyde-3-phosphate dehydrogenase (gapdh), and chitin synthase (chs-1) genes. The fungus isolated from diseased fruit produced lesions on wounded fruit and unwounded fruit. The pathogen was re-isolated from lesions on inoculated fruit to fulfill Koch’s postulates. To our knowledge, this is the first report of C. brevisporum causing anthracnose disease on papaya fruit in Mexico.

Comparative transcriptomics and genomic analyses reveal differential gene expression related to Colletotrichum brevisporum resistance in papaya (Carica papaya L.).

Colletotrichum brevisporum is an important causal pathogen of anthracnose that seriously affects the fruit quality and yield of papaya (Carica papaya L.). Although many genes and biological processes involved in anthracnose resistance have been reported in other species, the molecular mechanisms involved in the response or resistance to anthracnose in post-harvest papaya fruits remain unclear. In this study, we compared transcriptome changes in the post-harvest fruits of the anthracnose-susceptible papaya cultivar Y61 and the anthracnose-resistant cultivar G20 following C. brevisporum inoculation. More differentially expressed genes (DEGs) and differentially expressed long non-coding RNAs (DElnRNAs) were identified in G20 than in Y61, especially at 24h post-inoculation (hpi), suggesting a prompt activation of defense responses in G20 in the first 24h after C. brevisporum inoculation. These DEGs were mainly enriched in plant-pathogen interaction, phenylpropanoid biosynthesis/metabolism, and peroxisome and flavonoid biosynthesis pathways in both cultivars. However, in the first 24 hpi, the number of DEGs related to anthracnose resistance was greater in G20 than in Y61, and changes in their expression levels were faster in G20 than in Y61. We also identified a candidate anthracnose-resistant gene cluster, which consisted of 12 genes, 11 in G20 and Y61, in response to C. brevisporum inoculation. Moreover, 529 resistance gene analogs were identified in papaya genome, most of which responded to C. brevisporum inoculation and were genetically different between papaya cultivars and wild-type populations. The total expression dose of the resistance gene analogs may help papaya resist C. brevisporum infection. This study revealed the mechanisms underlying different anthracnose resistance between the anthracnose-resistant and anthracnose-susceptible cultivars based on gene expression, and identified some potential anthracnose resistance-related candidate genes/major regulatory factors. Our findings provided potential targets for developing novel genetic strategies to overcome anthracnose in papaya.

First Report of Colletotrichum chrysophilum Causing Papaya Anthracnose in Mexico.

Anthracnose, caused by Colletotrichum spp., is the most important fungal disease of papaya (Carica papaya L.) worldwide. In March 2020, mature papaya fruit (cv. Maradol) showing typical symptoms of anthracnose were observed in an orchard located in Pinotepa Nacional, Oaxaca, Mexico. Disease incidence of 100 papaya plants surveyed in the orchard was estimated at about 45%. Initially, small and water-soaked lesions appeared on the fruit surface, which later enlarged to circular sunken lesions with translucent light brown margins. On advanced infections, salmon-pink masses of spores were observed on the lesions. Twenty Colletotrichum-like colonies were consistently isolated on potato dextrose agar (PDA) medium at 25°C in the dark for 6 days and 10 monoconidial isolates were obtained. An isolate was selected as representative for further characterization. The isolate was deposited as CPM-H4 in the Culture Collection of Phytopathogenic Fungi of Plant Pathology Laboratory of the CIIDIR-Oaxaca of the Instituto Politécnico Nacional. On PDA, the colonies were initially light grey then later became dark grey with orange conidial masses after incubation for 7 days. Conidia (n= 50) were hyaline, aseptate, cylindrical with rounded ends, and measured 10.2 to 13.6 × 4.1 to 5.3 μm. Appressoria (n= 20) were mostly simple, solitary and smooth-walled, dark brown, and clavate, measuring 6.8 to 14.8 × 5.5 to 7.7 μm. Based on morphology, the isolate was tentatively identified as belonging to the Colletotrichum gloeosporioides species complex (Weir et al. 2012). For molecular identification, total DNA was extracted, and the internal transcribed spacer (ITS) region (White et al. 1990), and partial sequences of actin (ACT), β-tubulin (TUB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and chitin synthase (CHS-1) genes were amplified (Weir et al. 2012), and sequenced. The sequences were deposited in GenBank (accessions nos. OM965612 (ITS), OM959540 (ACT), ON065005 (TUB2), ON065003 (CHS-1), ON065004 (GAPDH). A phylogenetic tree based on Bayesian inference and including published ITS, ACT, TUB2, GAPDH, and CHS-1 sequence dataset for Colletotrichum spp. was constructed. The multilocus phylogenetic analysis clearly distinguished the isolate CPM-H4 as Colletotrichum chrysophilum. Pathogenicity of the fungus was verified on 10 healthy papaya fruits (cv. Maradol) without wounds. A drop of a conidial suspension (1 × 105 spores/ml) was placed on three locations on each fruit. Ten control fruit were treated in the same way but with sterilized water. The fruits were kept in a moist plastic chamber at 25°C and 12 h light/dark for 8 days. The pathogenicity test was repeated twice. All inoculated papaya fruits developed sunken necrotic lesions 6 days after inoculation, whereas no symptoms were observed on the control fruits. The fungus was consistently re-isolated only from the diseased fruits and found to be morphologically identical to the isolate used for inoculation, fulfilling Koch´s postulates. Colletotrichum chrysophilum has been previously reported to cause anthracnose on mango (Fuentes-Aragón et al. 2020a), avocado (Fuentes-Aragón et al. 2020b), and banana (Fuentes-Aragón et al. 2021) in Mexico; however, to our knowledge, this is the first report of C. chrysophilum causing papaya anthracnose in Mexico. Therefore, it is necessary to explore the diversity of Colletotrichum species associated with papaya in Mexico through subsequent phylogenetic studies as well as to monitor the possible movement and distribution of this pathogen into other Mexican regions.

Elucidating the Colletotrichum spp. diversity responsible for papaya anthracnose in Brazil.

Papaya (Carica papaya L.) is among the most important tropical fruits produced in Brazil and is grown in nearly every state. However, several diseases can affect papaya production. Anthracnose stands out among these diseases due to high postharvest yield losses. Previous studies identified Colletotrichum magna (invalid name) and Colletotrichum gloeosporioides causing anthracnose of papaya in Brazil, but species identification was inadequate due to reliance on nuclear ribosomal internal transcribed space (nrITS) and glutamine synthetase (GS) sequences. Thus, the diversity of Colletotrichum spp. causing papaya anthracnose in Brazil may be underestimated. The present study aims to identify the Colletotrichum species associated with papaya anthracnose in Brazil based on broad geographical sampling and multilocus phylogenetic analysis, as well as to assess the prevalence and aggressiveness of the species found. Here, we report C.chrysophilum, C. fructicola, C. gloeosporioides, C. karsti, C. okinawense, C. plurivorum, C. queenslandicum, C. siamense, C. theobromicola, Colletotrichum truncatum causing papaya anthracnose in Brazil. We are also synonymizing Colletotrichum corchorum-capsularis under C.truncatum. Colletotrichum okinawense was the most prevalent species in general and in most sampled locations, and with C.truncatum represents the most aggressive species.

Use of Ficus Septica Leaf Extract for Biological Control of Anthracnose Disease in Carica Papaya Caused by Colletotrichum spp

The fig (Ficus septica) is a widespread wild plant whose leaf extract contains bioactive compounds with antifungal properties, including alkaloid and phenolic compounds, both of which are antioxidants. Colletothricum spp. is a pathogenic fungus found in cultivated plants that can cause anthracnose, a plant disease. Papaya (Carica papaya) is one of the cultivated plants that frequently displays symptoms of anthracnose disease caused by Colletothricum spp. The focus of this research was to determine whether F. septica leaf extract could inhibit the growth of Colletothricum spp. on C. papaya. The antifungal activity of F. septica leaf extract against Colletothricum spp. was measured using the well diffusion method. The extract concentrations, which were determined by measuring the extract’s MIC value, were 0.5%, 1%, 2%, 3%, 4% and 5% (b/v), with methanol and synthetic fungicides serving as controls. According to the findings, the MIC value of the F. septica leaf extract on Colletothricum spp. growth was 0.4%, with an inhibition zone of 2.37 mm. Meanwhile, the inhibition zones formed by the F. septica leaf extract treatment were 2.5 mm, 3.4 mm, 7.6 mm, 9.7 mm, 12.7 mm, and 13.5 mm, respectively, and 0 mm for the negative control and 30 mm for the positive control. According to the analysis of variance results, all of the treatments produced results that were significantly different from those of the negative control, and the 4% extract was the most effective in vitro. We conclude that F. septica crude leaf extract contains bioactive compounds with antifungal properties and it can be used as a safe alternative to control Carica papaya anthracnose disease.&#x0D; Keywords: anthracnose, Carica papaya, Colletothricum spp., Ficus septica.

First report of Colletotrichum siamense causing papaya anthracnose in Mexico

First report of Colletotrichum siamense causing papaya anthracnose in Mexico

Encapsulation of wild oregano, Plectranthus amboinicus (Lour.) Spreng, phenolic extract in baker's yeast for the postharvest control of anthracnose in papaya

Anthracnose caused by Colletotrichum gloeosporioides is considered as a major postharvest disease affecting many fruits. This plant disease is traditionally managed with synthetic fungicides, which are generally toxic and are linked to pathogen resistance. Recently, microencapsulated bioactives have been developed as potential alternative strategies to these methods, while utilizing natural fungicides and other phytochemicals. Wild oregano, Plectranthus amboinicus (Lour.) Spreng, contains potent antimicrobial phenolics, but these compounds are volatile and relatively unstable, which limits their efficacy during application. Herein, a baker's yeast microencapsulation system was applied to improve the stability of wild oregano phenolic extract (WOPE) and enhance its antifungal activity against anthracnose. Encapsulation of WOPE in plasmolyzed yeast cells afforded a high encapsulation efficiency (93%) and yielded WOPE-loaded yeast microcapsules (WLYMs) with an average diameter of 2.65 μm. Storage stability studies showed WLYMs are stable for at least 4 months. A 24 -h in vitro release experiment showed that WLYMs had an initial burst release upon redispersion in water, followed by a controlled release to about 80% of the loaded WOPE. Upon application as a spray-type postharvest treatment for papaya, WLYMs exhibited a significantly improved mycelial inhibitory action against C.gloeosporioides and greatly reduced the anthracnose symptoms in papaya fruits. This study presented a yeast microencapsulation system that can effectively stabilize WOPE and enhance its antifungal activity, making this microparticle formulation a promising environmentally safe postharvest treatment option to combat anthracnose symptoms in papaya fruits. © 2022 Society of Chemical Industry.

DISTRIBUTION AND IDENTIFICATION OF ANTHRACNOSE OF PAPAYA CAUSED BY COLLETOTRICHUM GLOEOSPORIOIDES IN THE CENTRAL RIFT VALLEY OF ETHIOPIA

Papaya (Carica papaya L.) is one of the most important fruit crops in Ethiopia. Despite its importance, papaya production is hampered by different biotic and abiotic factors. Among biotic factors, anthracnose is an important disease, causing serious damage to papaya, especially in the postharvest stage. The surveys were conducted in eight kebeles (smallest administrative unit) of three districts (Adama, Adamitulu Jidokombolcha, and Dugda) in the East Shewa Zone of the Oromia regional state, Ethiopia from August to September 2016 and August to September 2021, to assess the prevalence, incidence, and severity of papaya anthracnose disease. Disease incidence and severity on leaves and fruits were determined using random sampling techniques. Cultural and morphological characterization of the causal agent of papaya anthracnose was also done. The survey results showed that all the eight kebeles assessed during 2016 and 2021 were affected by papaya anthracnose disease. The overall mean incidences of the disease were 63.9% on the leaves and 40.3% on the fruits while average disease severities were 24.8% and 22.8%, respectively. Disease incidences in different kebeles ranged from 60 to 66.7% on leaves and from 30 to 48.9% on fruits. Disease severity also varied from 21.1 to 29.8% on leaves and from 20 to 26.7% on fruits. Disease incidences and severities were generally higher in Wolda Kelina kebele. In 2021, the assessment result indicated that in Dugda and Adamitulu Jidokombolcha districts anthracnose was a major papaya production constraint. Based on field symptomatic assessment as well as cultural and morphological characterization, Colletotrichum gloeosporioides was identified as the causal agent of the disease threatening papaya production in the surveyed areas. These findings provide information on the magnitude of the damage due to papaya anthracnose disease and will be useful to devise disease management strategies. It is necessary to investigate the reactions of the available papaya cultivars against the pathogen and select disease tolerant papaya materials.

Chitosan Coating Enriched With Ruta graveolens L. Essential Oil Reduces Postharvest Anthracnose of Papaya (Carica papaya L.) and Modulates Defense-Related Gene Expression.

Anthracnose of papaya (Carica papaya L.) caused by the fungus Colletotrichum spp. is one of the most economically important postharvest diseases. Coating with chitosan (CS) and Ruta graveolens essential oil (REO) might represent a novel eco-friendly method to prevent postharvest anthracnose infection. These compounds show both antimicrobial and eliciting activities, although the molecular mechanisms in papaya have not been investigated to date. In this study, the effectiveness of CS and REO alone and combined (CS-REO) on postharvest anthracnose of papaya fruit during storage were investigated, along with the expression of selected genes involved in plant defense mechanisms. Anthracnose incidence was reduced with CS, REO, and CS-REO emulsions after 9 days storage at 25°C, by 8, 21, and 37%, respectively, with disease severity reduced by 22, 29, and 44%, respectively. Thus, McKinney’s decay index was reduced by 22, 30, and 44%, respectively. A protocol based on reverse transcription quantitative real-time PCR (RT-qPCR) was validated for 17 papaya target genes linked to signaling pathways that regulate plant defense, pathogenesis-related protein, cell wall-degrading enzymes, oxidative stress, abiotic stress, and the phenylpropanoid pathway. CS induced gene upregulation mainly at 6 h posttreatment (hpt) and 48 hpt, while REO induced the highest upregulation at 0.5 hpt, which then decreased over time. Furthermore, CS-REO treatment delayed gene upregulation by REO alone, from 0.5 to 6 hpt, and kept that longer over time. This study suggests that CS stabilizes the volatile and/or hydrophobic substances of highly reactive essential oils. The additive effects of CS and REO were able to reduce postharvest decay and affect gene expression in papaya fruit.