No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Plant pathogenic Paramyrothecium species: distribution, biology, epidemiology and disease management
Abstract
Paramyrothecium comprises saprobic and plant pathogenic members. Eight plant-pathogenic Paramyrothecium species have been recorded in Asia, America, and some parts of Africa and Europe. Among the commonly reported species are P. roridum and P. foliicola. Several Paramyrothecium species are associated with coffee leaf spots, muskmelon crown rot, and eggplant crater rot. Paramyrothecium is commonly found in soil, decaying plant material, and diseased fruits, stems, and leaves of several plant species. The life cycle of Paramyrothecium species includes an asexual stage throughout disease development, with no sexual morphs reported. Environmental factors, such as temperature and humidity, influence the distribution and prevalence of Paramyrothecium. Paramyrothecium-associated diseases occur through various mechanisms, including wind and rain dispersal of conidia, contaminated soil, and plant debris. Paramyrothecium disease development can be exacerbated when the soil is wet and plant tissues are damaged, which served as pathogen entry. Adequate water management, soil sanitation, and proper handling of crops are important to minimize losses in commercial crop production. Several biological control agents and pesticides have also been reported to control the pathogen and the associated disease.
ResearchGate has not been able to resolve any citations for this publication.
Novel species of fungi described in this study include those from various countries as follows: Argentina, Neocamarosporium halophilum in leaf spots of Atriplex undulata. Australia, Aschersonia merianiae on scale insect (Coccoidea), Curvularia huamulaniae isolated from air, Hevansia mainiae on dead spider, Ophiocordyceps poecilometigena on Poecilometis sp. Bolivia, Lecanora menthoides on sandstone, in open semi-desert montane areas, Sticta monlueckiorum corticolous in a forest, Trichonectria epimegalosporae on apothecia of corticolous Megalospora sulphurata var. sulphurata, Trichonectria puncteliae on the thallus of Punctelia borreri. Brazil, Catenomargarita
pseudocercosporicola (incl. Catenomargarita gen. nov.) hyperparasitic on Pseudocercospora fijiensis on leaves of
Musa acuminata, Tulasnella restingae on protocorms and roots of Epidendrum fulgens. Bulgaria, Anthracoidea umbrosae on Carex spp. Croatia, Hymenoscyphus radicis from surface-sterilised, asymptomatic roots of Microthlaspi erraticum, Orbilia multiserpentina on wood of decorticated branches of Quercus pubescens. France, Calosporella punctatispora on dead corticated twigs of Acer opalus. French West Indies (Martinique), Eutypella lechatii on dead corticated palm stem. Germany, Arrhenia alcalinophila on loamy soil. Iceland, Cistella blauvikensis on dead grass (Poaceae). India, Fulvifomes maritimus on living Peltophorum pterocarpum, Fulvifomes natarajanii on dead wood
of Prosopis juliflora, Fulvifomes subazonatus on trunk of Azadirachta indica, Macrolepiota bharadwajii on moist soil near the forest, Narcissea delicata on decaying elephant dung, Paramyrothecium indicum on living leaves of Hibiscus hispidissimus, Trichoglossum syamviswanathii on moist soil near the base of a bamboo plantation. Iran, Vacuiphoma astragalicola from stem canker of Astragalus sarcocolla. Malaysia, Neoeriomycopsis fissistigmae (incl. Neoeriomycopsidaceae fam. nov.) on leaf spots on flower Fissistigma sp. Namibia, Exophiala lichenicola lichenicolous on Acarospora cf. luederitzensis. Netherlands, Entoloma occultatum on soil, Extremus caricis on dead leaves of Carex sp., Inocybe pseudomytiliodora on loamy soil. Norway, Inocybe guldeniae on calcareous soil, Inocybe rupestroides on gravelly soil. Pakistan, Hymenagaricus brunneodiscus on soil. Philippines, Ophiocordyceps philippinensis parasitic on Asilus sp. Poland, Hawksworthiomyces ciconiae isolated from Ciconia ciconia nest, Plectosphaerella vigrensis from leaf spots on Impatiens noli-tangere, Xenoramularia epitaxicola from sooty mould community on Taxus baccata. Portugal, Inocybe dagamae on clay soil. Saudi Arabia, Diaporthe jazanensis on
branches of Coffea arabica. South Africa, Alternaria moraeae on dead leaves of Moraea sp., Bonitomyces buffelskloofinus (incl. Bonitomyces gen. nov.) on dead twigs of unknown tree, Constrictochalara koukolii on living leaves of Itea rhamnoides colonised by a Meliola sp., Cylindromonium lichenophilum on Parmelina tiliacea, Gamszarella buffelskloofina (incl. Gamszarella gen. nov.) on dead insect, Isthmosporiella africana (incl. Isthmosporiella gen. nov.) on dead twigs of unknown tree, Nothoeucasphaeria buffelskloofina (incl. Nothoeucasphaeria gen. nov.), on dead twigs of unknown tree, Nothomicrothyrium beaucarneae (incl. Nothomicrothyrium gen. nov.) on dead leaves
of Beaucarnea stricta, Paramycosphaerella proteae on living leaves of Protea caffra, Querciphoma foliicola on leaf litter, Rachicladosporium conostomii on dead twigs of Conostomium natalense var. glabrum, Rhamphoriopsis synnematosa on dead twig of unknown tree, Waltergamsia mpumalanga on dead leaves of unknown tree. Spain, Amanita fulvogrisea on limestone soil, in mixed forest, Amanita herculis in open Quercus forest, Vuilleminia beltraniae on Cistus symphytifolius. Sweden, Pachyella pulchella on decaying wood on sand-silt riverbank. Thailand, Deniquelata cassiae on dead stem of Cassia fistula, Stomiopeltis thailandica on dead twigs of Magnolia champaca. Ukraine, Circinaria podoliana on natural limestone outcrops, Neonematogonum carpinicola (incl. Neonematogonum gen. nov.) on dead branches of Carpinus betulus. USA, Exophiala wilsonii water from cooling tower, Hygrophorus aesculeticola on soil in mixed forest, and Neocelosporium aereum from air in a house attic. Morphological and culture characteristics are supported by DNA barcodes.
Paramyrothecium was introduced in 2016 containing 20 species and many species have been reported as plant pathogens, causing leaf blight and leaf spots on different plant species. This study revealed a new species Paramyrothecium amorphophalli from symptomatic leaves of elephant foot yam (Amorphophallus sp.), collected from Chiang Rai, Thailand based on distinct morphological characteristics and phylogenetic analyses. The isolate formed a distinct lineage from Paramyrothecium eichhorniae and P. vignicola based on maximum likelihood, maximum parsimony and Bayesian posterior probability analyses of ITS, cmdA, rpb2 and tub2 sequence data. Furthermore, pathogenicity assays confirmed that P. amorphophalli is pathogenic to the original host, causing leaf blight.
Paramyrothecium foliicola is reported for the first time in Brazil and worldwide causing leaf spots on hop (Humulus lupulus). The fungus was identified with a combination of morphological and molecular information. The pathogenicity of P. foliicola to hop was demonstrated through inoculations under controlled conditions.
In spring 2018, melon (Cucumis melo L.) plants with wilting of the leaves and dry rot of the crowns were observed in Dashti county, Bushehr province, southern Iran. Nine fungal isolates were recovered from the symptomatic crowns. Based on the morphological characteristics and DNA sequences of the internal transcribed spacer (ITS) region of ribosomal RNA gene, the fungus was identified as Paramyrothecium foliicola L. Lombard and Crous. The pathogenicity of the isolates was confirmed on melon under greenhouse conditions to fulfil the Koch's postulates. Host range determination showed except for pumpkin (Cucurbita moschata L.) and bottle gourd (Lagenaria siceraria L.), several other cucurbit crops exhibited high disease incidence. To our knowledge, this is the first report of crown dry rot of melon caused by P. foliicola in Iran.
Species of Paramyrothecium that are reported as plant pathogens and cause leaf spot or leaf blight have been reported on many commercial crops worldwide. In 2019, during a survey of fungi causing leaf spots on plants in Chiang Mai and Mae Hong Son provinces, northern Thailand, 16 isolates from 14 host species across nine plant families were collected. A new species Paramyrothecium vignicola sp. nov. was identified based on morphology and concatenated (ITS, cmdA, rpb2, and tub2) phylogeny. Further, P. breviseta and P. foliicola represented novel geographic records to Thailand, while P. eichhorniae represented a novel host record (Psophocarpus sp., Centrosema sp., Aristolochia sp.). These species were confirmed to be the causal agents of the leaf spot disease through pathogenicity assay. Furthermore, cross pathogenicity tests on Coffea arabica L., Commelina benghalensis L., Glycine max (L.) Merr., and Dieffenbachia seguine (Jacq.) Schott revealed multiple host ranges for these pathogens. Further research is required into the host–pathogen relationship of Paramyrothecium species that cause leaf spot and their management. Biotic and abiotic stresses caused by climate change may affect plant health and disease susceptibility. Hence, proper identification and monitoring of fungal communities in the environment are important to understand emerging diseases and for implementation of disease management strategies.
Peru is the ninth exporter of coffee (Coffea arabica) in the world, and Amazonas is among its most important producing departments (INIA 2019). In July 2021, in the nursery of the “Instituto de Investigación para el Desarrollo Sustentable de Ceja de Selva”, in Huambo district (6° 26' 11.19'' S; 77° 31' 24.18'' W), four-month-old coffee seedlings cv. Catimor with 0.5–2.0 cm brown concentric leaf spots and rotten stems, bearing white mycelial tufts and black sporodochia, were observed at 30% incidence. Infected seedlings were collected. Foliar sections of 2–3 mm with infected tissue were surfaced disinfected in 2% NaClO and transferred onto Petri plates containing potato dextrose agar medium (PDA). The plates were incubated at 25° C for 7 days. We obtained three isolates (INDES-AFHP61, INDES-AFHP62 and INDES-AFHP66) with similar morphology from different seedlings. Colonies (16–17 mm diam.) formed concentric rings with white aerial mycelium, giving rise to viscous and olivaceous dark green sporodochial conidiomata. Conidia (4.82–5.77 × 1.34–1.65 µm; n = 30) were cylindric, hyaline, smooth, and aseptate. These morphological features correspond to Paramyrothecium spp. (Lombard et al. 2016). The DNA of isolates was extracted using the Wizard® Purification Kit (Promega Corp., Madison, Wisconsin), and the internal transcribed spacer 1 and 2 intervening the 5.8S subunit rDNA region (Accession numbers: OM892830 to OM892832), and part of the second-largest subunit of the RNA polymerase II, the calmodulin and the β-tubulin genes (OM919453 to OM919461) were sequenced following Lombard et al. (2016). All sequences had a percent identity greater than or equal to 99% to corresponding sequences of the P. roridum type specimen (CBS 357.89). Additionally, a multilocus Maximum Likelihood phylogenetic analysis incorporating sequence data from previous relevant studies (Lombard et al. 2016; Pinruan et al. 2022) grouped our three isolates together with the type and other specimens of P. roridum in a strongly supported clade, confirming the species identification. To evaluate pathogenicity, four-month-old coffee seedlings cv. Catimor were sprayed with 10 mL of conidial suspensions at 1 x 10 ⁶ /mL. A set of control seedlings were inoculated with sterile water. Seedlings were maintained in a humidity chamber at 25 °C. After 15 days brown concentric foliar spots, stem rotting, mycelial tufts and sporodochia (same symptoms and signs observed originally at the nursery) arose in the non-control seedlings. The pathogen was re-isolated on PDA, confirming P. roridum was the causal agent of leaf spot and stem rot diseases of coffee. Paramyrothecium roridum has wide geographic distribution and host range (Lombard et al. 2016). This pathogen was reported to infect C. arabica in Mexico and Coffea sp. in Colombia (Pelayo-Sánchez et al. 2017; Lombard et al. 2016; Huaman et al. 2021). It was also reported in Africa infecting soybeans (Haudenshield et al. 2018), in Brazil infecting Tectona grandis (Borges et al. 2018), in Egypt infecting strawberries (Soliman 2020), and in Malaysia infecting Eichhornia crassipes (Hassan et al. 2021). To the best of our knowledge, this is the first time P. roridum is reported on coffee in Peru.
Paramyrothecium eichhorniae sp. nov. was observed and collected from Chiang Mai and Phetchaburi Provinces, Thailand. This new species is introduced based on morphological and molecular evidence. This fungus is characterized by its production of sporodochium conidiomata with a white setose fringe surrounding an olivaceous green to dark green slimy mass of conidia, penicillately branched conidiophores, and aseptate and cylindrical to ellipsoid conidia. Phylogenetic analyses of combined LSU rDNA, ITS rDNA, tef1, rpb2, tub2 and cmdA sequence data using maximum parsimony, maximum likelihood and Bayesian approaches placed the fungus in a strongly supported clade with other Paramyrothecium species in Stachybotryaceae (Hypocreales, Sordariomycetes). The descriptions of the species are accompanied by illustrations of morphological features, and a discussion of the related taxa is presented.
Water hyacinth (Eichhornia crassipes) is a free-floating aquatic plant and is also widely cultivated as an aquatic ornamental plant in Malaysia. In June 2018, a severe foliar disease with typical leaf blight symptoms were observed on leaves of water hyacinth plants (approximately 50%) in waterways adjacent to two rice fields located at Tanjung Karang and Sungai Besar, Selangor province, Malaysia. Symptoms appeared irregular necrotic lesions with concentric rings, later lesions expanded to entire leaves and became blighted. Twenty symptomatic leaves were collected from two sampling locations. Symptomatic leaf tissue was cut into small pieces (5 × 5 mm), surface sterilized with 0.5% sodium hypochlorite (NaOCl) for 2 min, rinsed three times with sterile distilled water, plated on potato dextrose agar (PDA), and incubated at 25 °C with a 12-h light/dark cycle for 7 days. Twenty single-spore isolates were recovered from sampled leaves, all isolates exhibited Paramyrothecium-like morphology and two representative isolates, PR1 and PR2 were used for further studies. Fungal colonies were initially white aerial mycelia with sporodochia bearing olivaceous green conidial masses formed on PDA after 5 days of incubation. Conidiogenous cells were phialidic, hyaline, smooth, straight to slightly curved, 13 to 20 × 1.0 to 1.8 μm and setae were absent. Conidia were aseptate, hyaline to pale green, smooth, cylindrical to ellipsoidal with rounded ends, and measured 5.8 to 8.0 μm × 1.8 to 2.2 μm (n=50). These morphological characteristics were consistent with the description of Paramyrothecium roridum (Tode) L. Lombard & Crous (Lombard et al. 2016). Total genomic DNA of the isolates was extracted from fresh mycelium using DNeasy Plant Mini kit (Qiagen, USA). The internal transcribed spacer (ITS) and calmodulin (cmdA) gene regions were amplified using the ITS5/ITS4 (White et al.1990) and CAL-228F/CAL2Rd primer sets (Carbone and Kohn 1999; Groenewald et al., 2013), respectively. BLASTn analysis showed that the ITS and cmdA sequences of the isolates were 100% identity with Paramyrothecium roridum ex-epitype strain CBS 357.89 (GenBank accession nos. KU846300 and KU846270), respectively. The resulting sequences were deposited in GenBank (ITS: Accession nos. MW850370, MW850371; cmdA Accession nos. MW854363, MW854364). Pathogenicity tests of the two isolates were performed by spray inoculation on healthy leaves of each five potted water hyacinth plants using a 3-ml conidial suspension (1 × 106 conidia/ml) produced on 7-day-old PDA cultures incubated at 25 °C with a 12-h light/dark cycle. Five potted water hyacinth plants inoculated with sterile water served as controls. Inoculated plants were covered with plastic bags for 48 h to maintain high humidity and kept in a growth chamber for 2 weeks at 25 ± 1°C, 95% relative humidity and a 12-h light/dark period. The experiment was repeated twice. Eight days post-inoculation, symptoms on inoculated leaves developed necrotic brown lesions similar to those observed in the field, while control leaves remained asymptomatic. After 2 weeks of inoculation, lesions enlarged into severe blighting until all leaves died. Paramyrothecium roridum was re-isolated from randomly selected symptomatic tissues and verified by morphology and sequencing of ITS (MZ675387, MZ706462) and cmdA (MZ686706, MZ712041) loci, confirming Koch’s postulates. The fungus was not re-isolated from non-inoculated control plants. Pa. roridum is distributed on a wide range of plants (Farr and Rossman 2021) and has been reported to cause leaf spot of water hyacinth in Nigeria (Okunowo et al. 2013) and Sri Lanka (Adikaram and Yakandawala 2020). To our knowledge, this is the first report of Pa. roridum causing leaf blight of water hyacinth in Malaysia. This disease is an emerging threat to water hyacinth and it reduces the leaf quality, therefore, appropriate management should be developed to control this disease.
The One Health approach to understanding disease epidemiology and achieving surveillance and prevention is holistic all while focusing on zoonotic diseases. Many of its principles are similar to those espoused in Agroecology, begetting the question of what One Health can contribute ‐ in practice ‐ to preventing plant disease. Here we describe four knowledge challenges for plant health management that have arisen from the One Health experience for zoonotic diseases that could boost prospects for novel approaches to plant disease surveillance, prediction and prevention. The challenges are to i) uncover reservoirs and revise pathogen life histories, ii) elucidate drivers of virulence beyond the context of direct host‐pathogen interactions, iii) account for the natural highways of long distance dissemination (i.e., surface water and air mass movement), and iv) update disease forecasts in the face of changing land use, cultivation practices and climate. Furthermore, we note that implementation of a One Health approach to disease surveillance and prevention will require mobilization of tools to deal with the representation and accessibility of massive and heterogeneous data and knowledge; with knowledge inference, data science, modelling, and pattern recognition; and multi‐actor approaches that unite different sectors of society as well as different scientific disciplines. The infrastructure to build and the obstacles to overcome for a bona fide One Health approach to disease surveillance and prevention are key commonalities where actors in the efforts to prevent zoonotic diseases and plant disease can work together for the management of biodiversity and consequently human, animal and plant health.
Quantified global scenarios and projections are used to assess long-term future global food security under a range of socio-economic and climate change scenarios. Here, we conducted a systematic literature review and meta-analysis to assess the range of future global food security projections to 2050. We reviewed 57 global food security projection and quantitative scenario studies that have been published in the past two decades and discussed the methods, underlying drivers, indicators and projections. Across five representative scenarios that span divergent but plausible socio-economic futures, the total global food demand is expected to increase by 35% to 56% between 2010 and 2050, while population at risk of hunger is expected to change by −91% to +8% over the same period. If climate change is taken into account, the ranges change slightly (+30% to +62% for total food demand and −91% to +30% for population at risk of hunger) but with no statistical differences overall. The results of our review can be used to benchmark new global food security projections and quantitative scenario studies and inform policy analysis and the public debate on the future of food.
Coffee pulp is one of the most underutilised by-products from coffee processing. For coffee growers, disposing of this agro-industrial biomass has become one of the most difficult challenges. This study utilised this potential biomass as raw material for polyphenolic antifungal agents. First, the proportion of biomass was obtained from the Arabica green bean processing. The yield of by-products was recorded, and the high-potency biomass was serially extracted with organic solvents for the polyphenol fraction. Quantification of the polyphenols was performed by High Performance Liquid Chromatography (HPLC), then further confirmed by mass spectrometry modes of the liquid chromatography–quadrupole time-of-flight (QTOF). Then, the fraction was used to test antifungal activities against Alternaria brassicicola, Pestalotiopsis sp. and Paramyrothecium breviseta. The results illustrated that caffeic acid and epigallocatechin gallate represented in the polyphenol fraction actively inhibited these fungi with an inhibitory concentration (IC50) of 0.09, 0.31 and 0.14, respectively. This study is also the first report on the alternative use of natural biocontrol agent of P. breviseta, the pathogen causing leaf spot in the Arabica coffee.
The quality of raising seedlings in a perennial crop like coffee may be affected by several abiotic and biotic factors. In India, coffee seedlings are affected by three different diseases in the nursery viz., collar rot, brown eye spot, stem necrosis and leaf spot. The stem necrosis and leaf spot disease caused by the fungus Myrothecium roridum Tode ex Fr. is posing a serious problem in coffee nurseries particularly during rainy period of July and August months. The present study was under taken with a fixed plot survey to assess the distribution, incidence and severity of stem necrosis and leaf spot disease in major coffee growing taluks of Chikmagalur district in the year 2016 and 2017. Out of 22 coffee nurseries surveyed in four major coffee growing taluks of Chikmagalur district, the survey results (pooled data analysis of two years 2016 & 2017) indicated that maximum leaf spot incidence (23.98%) was recorded on Chandragiri cultivar of arabica coffee in Koppa taluk and minimum incidence (16.40%) in Mudigere taluk on C×R cultivar of robusta coffee. Maximum leaf spot severity (30.34%) was recorded on Chandragiri in Chikmagalur taluk and minimum severity (14.87%) in Koppa taluk on C×R. Maximum stem necrosis incidence (22.00%) was observed in Koppa taluk on Chandragiri and minimum incidence (3.60%) on coffee cultivar C×R from N. R. Pura taluk of Chikmagalur district. The data recorded on Myrothecium leaf spot incidence and severity and stem necrosis disease data recorded on the coffee cultivars Chandragiri and C×R were subjected to correlation analysis in relation to rainfall received during the months of July and August in the years 2016 and 2017. The analysis indicated that total rainfall was positively correlated with the disease incidence and severity in all the taluks of Chikmagalur district. Further, the analysis clearly indicated that rainfall plays a major role in the occurrence of the disease and has an effect on incidence and severity of the pathogen M. roridum on coffee seedlings.
In April 2017, stem canker symptoms were observed on cucumber seedings grown in a greenhouse (0.1 ha) in Wuqing District, Tianjin(39°34′ N; 117°07′ E), China. Initially, the observed symptoms included small necrotic lesions of a light brown color on the stem base. These lesions subsequently spread and turned a darker brown. The leaves of the affected plants turned yellow and wilted. As the disease progressed the plants eventually died. Years of growing cucumbers and sufficient soil moisture in the greenhouse, might have led to a disease incidence of approximately 7%. Symptomatic tissue pieces were surface disinfested in 2% sodium hypochlorite for 60 s, rinsed three times in sterile water, and subsequently plated on potato dextrose agar (PDA) incubated at 25°C . At three days of incubation, mycelia appeared, turned into white and floccose isolated colonies around the excised tissue, and developed olivaceous green concentric rings of sporodochia in the following days. A total of 20 isolates with similar morphology were examined. Five single-spore isolates of isolates designated TJWQPF1-TJWQPF5 were obtained and maintained on PDA at 25°C. Hyaline, cylindrical conidiogenous cells measuring 9.53 to 16.51 × 1.51 to 2.49 μm (n=50) developed in whorls of three to six on terminal branches. Conidia were single-celled, hyaline, and rod-shaped with rounded ends. Conidia size averaged 5.07 - 7.15 × 1.13 - 2.32 μm (n=50). These characteristics are similar to the morphology of Paramyrothecium foliicola (Lombard et al. 2016). To further identify the isolate TJWQPF1, genomic DNA was extracted and the internal transcribed spacer (ITS, White et al. 1990), β-tubulin (tub2, Glass & Donaldson 1995), RNA polymerase II largest subunit (rpb2, O’Donnell et al. 2007) and calmodulin (cmdA, Carbone & Kohn 1999; Groenewald et al. 2013) genes regions were amplified using the primer pairs ITS4/ITS5, Bt2a /Bt2b, RPB2-5F2 /RPB2-7cR, CAL-228F /CAL2Rd , respectively. All sequences were obtained and deposited in GenBank. BLAST searches of the NCBI database revealed that the ITS ( MW092223 ), tub2( MW110635 ) , rpb2 ( MW110637 ) and cmdA ( MW110636 ) sequences of the isolate TJWQPF1 were 100% identical to Paramyrothecium foliicola (GenBank accession numbers MT415351 and MT415352 for ITS sequences; MT415353 for tub2 sequences; MN398028-MN398043 for rpb2 sequences; MN593698- MN593713 for cmdA sequences). We also sequenced the other four single isolates and identified them as P. foliicola. Pathogenicity tests were conducted and repeated three times. Briefly, ten healthy 45-day-old cucumber seedlings (cultivar:Jinlv No.3) were inoculated with 100 µL of conidial suspension of P. foliicola (5×105 conidia per ml). Inoculum was applied to the stem with a syringe. Three healthy cucumber seedlings had 100 µL sterile water injected into the stem to serve as controls. All treated plants were incubated in a climate-controlled growth chamber at 25℃ (90% humidity, 12:12 h light:dark). Symptoms appeared on all inoculated plants after 7 days. In contrast, control seedlings exhibited no symptoms. The fungus was re-isolated from symptomatic tissues and re-identified to be P. foliicola, thereby fulfilling Koch’s postulates. To our knowledge, this is the first known instance of P. foliicola inducing stem canker on cucumber plants in China. Stem canker caused by P. foliicola could pose a threat to cucumber production in China. Our results also provide a basis to monitor and manage this potential disease.
Apples are the main horticultural crops grown in West Azarbaijan province of Iran. In recent surveys of apple orchards in Urmia and Miyandoab, West Azarbaijan Province, symptoms including branch and twig bark cracks, cankers, dieback and tree decline were commonly seen. Isolation of the fungi from cracked and cankered branches yielded fungal isolates with typical characteristics of the genera Paecilomyces and Paramyrothecium. Based on combination of morphological characteristics and sequence data obtained from ITS-rDNA and β-tubulin gene sequences for Paecilomyces isolates and ITS-rDNA region for Paramyrothecium isolates, they were identified as Paecilomyces formosus and Paramyrothecium foliicola. Results of the pathogenicity tests on detached shoots of 'Golden Delicious' and 'Red Delicious' cultivars showed that isolates of P. formosus were pathogenic only on 'Red Delicious' cultivar, but Pa. foliicola isolates were pathogenic on both cultivars and showed symptoms of infection. Re-isolation of the fungi from inoculated shoots confirmed Koch's postulates. To the best of our knowledge, the involvement of P. formosus and Pa. foliicola in the development of canker disease of apple trees is reported for the first time. Also, Pa. foliicola is a new record to Iran mycobiota.
This is a continuation of the papers “Towards a classification of Sordariomycetes” (2015) and “Families of Sordariomycetes” (2016) in which we compile a treatment of the class Sordariomycetes. The present treatment is needed as our knowledge has rapidly increased, from 32 orders, 105 families and 1331 genera in 2016, to 45 orders, 167 families and 1499 genera (with 308 genera incertae sedis) at the time of publication. In this treatment we provide notes on each order, families and short notes on each genus. We provide up-to-date DNA based phylogenies for 45 orders and 163 families. Three new genera and 16 new species are introduced with illustrations and descriptions, while 23 new records and three new species combinations are provided. We also list 308 taxa in Sordariomycetes genera incertae sedis. For each family we provide general descriptions and illustrate the type genus or another genus, the latter where the placement has generally been confirmed with molecular data. Both the sexual and asexual morphs representative of a family are illustrated where available. Notes on ecological and economic considerations are also given.
The tropical, warm, and humid conditions that are favorable to the growth and development of mycotoxigenic fungi put the Philippines at a high risk of mycotoxin contamination. To date, seven mycotoxigenic Aspergillus species, four Fusarium species, and one Penicillium species have been isolated from various agricultural crop commodities in the country. There are five mycotoxin groups (aflatoxin, fumonisin, ochratoxin, nivalenol, and zearalenone) that have been detected in both the raw form and the by-products of major crops grown in the country. Since the first scientific report of aflatoxin contamination in the Philippines in 1972, new information has been generated on mycotoxins and mycotoxigenic fungi, but little has been known of other mycotoxins until the last two decades. Further, despite the increase in the understanding of mycotoxigenic fungi and mycotoxins in the country, very limited knowledge exists on practices and measures that control both the fungi and the toxins. This paper reviews the current literature on mycotoxigenic fungi and mycotoxins in the Philippines with emphasis on the last two decades and on other mycotoxins.
Myrothecium sensu lato includes a group of fungal saprophytes and weak pathogens with a worldwide distribution. Myrothecium s.l. includes 18 genera, such as Myrothecium, Septomyrothecium, Myxospora, all currently included in the family Stachybotryaceae. In this study, we identified 84 myrothecium-like strains isolated from turfgrasses and their rhizosphere. Five new species, i.e., Alfaria poae, Alf. humicola, Dimorphiseta acuta, D. obtusa, and Paramyrothecium sinense, are described based on their morphological and phylogenetic distinctions. Phylogenies were inferred based on the analyses of sequences from four DNA loci (ITS, cmdA, rpb2 and tub2). The generic concept of Dimorphiseta is broadened to include a third type of seta, i.e. thin-walled, straight with obtuse apices.
Crop pathogens and pests reduce the yield and quality of agricultural production. They cause substantial economic losses and reduce food security at household, national and global levels. Quantitative, standardized information on crop losses is difficult to compile and compare across crops, agroecosystems and regions. Here, we report on an expert-based assessment of crop health, and provide numerical estimates of yield losses on an individual pathogen and pest basis for five major crops globally and in food security hotspots. Our results document losses associated with 137 pathogens and pests associated with wheat, rice, maize, potato and soybean worldwide. Our yield loss (range) estimates at a global level and per hotspot for wheat (21.5% (10.1–28.1%)), rice (30.0% (24.6–40.9%)), maize (22.5% (19.5–41.1%)), potato (17.2% (8.1–21.0%)) and soybean (21.4% (11.0–32.4%)) suggest that the highest losses are associated with food-deficit regions with fast-growing populations, and frequently with emerging or re-emerging pests and diseases. Our assessment highlights differences in impacts among crop pathogens and pests and among food security hotspots. This analysis contributes critical information to prioritize crop health management to improve the sustainability of agroecosystems in delivering services to societies. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.
The present study introduces seven new species, one new combination, one new variety and several interesting taxonomical notes and/or geographical records. Most of the new taxa are Ascomycetes, but the study also includes a new variety of a Basidiomycete. Novel species include Gyromitra khanspurensis (Discinaceae, Pezizales, Pezizomycetes) from Pakistan growing near Cedrus deoadara and Paramyrothecium guiyangense and Paramyrothecium verruridum (Stachybotriaceae, Hypocreales, Sordariomycetes) both isolated from soil in China. New species from South Africa are Sclerostagonospora elegiae on culm litter of Elegia equisetacea, Sclerostagonospora fusiformis on culm litter of Thamnochortus spicigerus, Sclerostagonospora pinguis on culm litter of Cannomois virgata and Sclerostagonospora sulcata on culm litter of Ischyrolepis subverticellata (Phaeosphaeriaceae, Pleosporales, Dothideomycetes). Hapalocystis berkeleyi var. kickxii with its basionym Hypoxylon kickxii is shown to be a taxon on species level and thus recombined as Hapalocystis kickxii (Sydowiellaceae, Diaporthales, Sordariomycetes), and it is lecto- and epitypified. The new variety Pluteus romellii var. luteoalbus (Pluteaceae, Agaricales, Agaricomycetes) growing on a mossy fallen stem of a deciduous tree is described from Czech Republic. Cortinarius scaurocaninus (Cortinariaceae, Agaricales, Agaricomycetes) is new for Austria, Humicola grisea (Chaetomiaceae, Sordariales, Sordariomycetes) is an interesting new record for Chile. Two taxa are reported as new for Turkey: the lichenicolous fungus Opegrapha parasitica (Opegraphaceae, Arthoniales, Arthoniomycetes) growing partly immersed in the thallus of Aspicilia and the lichen Rinodina zwackhiana (Physciaceae, Teloschistales, Lecanoromycetes) from calcareous rock. Finally, Xerula strigosa (Physalacriaceae, Agaricales, Agaricomycetes), described from China, is confirmed to be present also in Pakistan.
Paramyrothecium foliicola is a species of ascomycete in the family Stachybotryaceae. In recent years, it has been reported as a threat to crop production in different countries. Because of its wide host range and high virulence, this pathogen may present as a major global concern in the near future. Despite its importance, there is no sufficient genomic information for P. foliicola. Our work introduces the initial PacBio-Illumina hybrid draft genome for TJWQPF1, the P. foliicola strain, together with the related annotations. This genome was assembled into 18 contigs, with the largest contig size of 8,042,417 bp. Genome annotation identified 13,330 protein-coding genes. The draft genome data will aid in understanding the pathogenic mechanism of P. foliicola, which is a valuable resource to explore the genetic diversity, pathogenicity, and evolution of this important pathogen.
[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
Peanut (Arachis hypogaea) is an important economic and oil crop in China. In September 2022, leaf spots were observed on peanut in Luoyang city, Henan province, China (34°49'N, 112°37'E). The disease occurred on about 30% of the peanut leaves in only one 0.5-acre field. Symptoms appeared primarily as brown spots, that varied in shape, and appeared round, oval or irregular. In addition, some disease patches exhibited a concentric ring pattern. Small pieces (5×5 mm) of five diseased leaves were surface disinfected in 3% NaClO for 2 minutes, rinsed three times in sterile distilled water, dried on sterilized filter paper, and cultured on potato dextrose agar (PDA) at 25°C for 3 days. Five isolates with uniform characteristics were obtained and subcultured by transferring hyphal tips to fresh PDA. The colonies of the isolates were circular and the margins were clean. The colonies showed white coloration, and after 5-7 days of incubation on PDA plates, concentric rings with dark green sporodochia appeared on the surface of the colonies. The conidiophores branched repeatedly. The conidiophore stipes unbranched, hyaline, 10.0 to 23.2×1.5 to 3.3 μm (n=50). The conidia were rod-shaped or long oval and single-celled, measuring 4.6 to 8.6×1.4 to 3.1 μm (n=100). Based on these characteristics, the five isolates were identified as Paramyrothecium foliicola (Lombard et al 2016). Genomic DNA was extracted from the representative isolates LH-1-1 and LH-1-2. The internal transcribed spacer (ITS), RNA polymerase II second largest subunit (RPB2), calmodulin (CmdA), and translation elongation factor 1-alpha (tef1) loci were amplified and sequenced using the following primer pairs: ITS1/ITS4 (White et al. 1990), RPB2-5F2/RPB2-7cR (O’Donnell et al. 2007), CAL-228F/CAL-2Rd (Carbone & Kohn 1999), and EF1-728F/EF2 (O’Donnell et al. 1998), respectively. BLASTn analysis revealed that the sequences of ITS (OR352397.1 and OR417392.1), RPB2 (OR413573.1 and OR420678.1), CmdA (OR413572.1 and OR420677.1), and tef1 (OR413574.1 and OR420679.1) had 99 to 100% (553/558 bp, 721/721 bp, 597/598 bp, and 384/389 bp) similarity to P. foliicola (MN593634.1, MN398038.1, OM801785.1, MK335967.1). A phylogenetic tree based on the Maximum Likelihood method also confirmed that the two isolates converge on the same branch as P. foliicola. Pathogenicity tests were performed using leaves of 60-day-old peanut plants (cv. Zhonghua 8). Briefly, uninfected healthy leaves (non-wounded) were inoculated with 30-µl drops containing a spore suspension (5×105 conidia/ml) of LH-1-2, and peanut leaves inoculated with sterile distilled water served as controls. All treatments were incubated in an incubator at 25℃ and high relative humidity with a 12:12 hour light-dark cycle. After 5-7 days, inoculated leaves showed symptoms similar to those observed in the field, while no symptoms were observed on control leaves. The pathogenicity tests were repeated three times. The fungus was reisolated from the infected leaves and identified as P. foliicola based on morphological and molecular characteristics, thus fulfilling Koch’s postulates. P. foliicola has previously been reported to cause leaf spot of tomato and mung bean, stem canker of cucumber (Huo et al. 2022; Sun et al.2020; Huo et al. 2021). To our knowledge, this is the first report of P. foliicola causing leaf spot on peanut in the world. Identification of this pathogen will be helpful in monitoring peanut diseases and developing disease control strategies.
Tomato (Solanum lycopersicum) is a staple vegetable across the world. In October 2019, leaf spots were observed on tomato (cv. Tianmi) in a greenhouse in JiZhou District Tianjin, China(117°10 ′E; 39°55 ′N). Symptoms initially appeared as small brown spots, which gradually expanded and turned into circular, oval or irregular spots (some spots with distinct concentric zones). In severe cases, some spots coalesced and eventually covered the whole leaf. Disease incidence ranged between 12 and 18%. Twenty symptomatic leaves from five plants were collected and cut into small pieces, surface disinfested in 2% NaClO for 60 s, rinsed three times in sterile water, and subsequently plated on potato dextrose agar (PDA). Plates were incubated at 25°C in the dark for 7 days. A total of 102 isolates were obtained and 92 isolates had the same morphology. Colonies were initially white with abundant aerial mycelia and formed sporodochia with conidial masses in olivaceous green concentric rings. All isolates formed single-celled, hyaline, and rod-shaped conidia were 4.91 to 7.43 (avg. 6.53±0.72) × 1.41 to 2.45 （avg. 2.11±0.30）μm with rounded ends (n=50). Conidiophores were highly branched. These characteristics resembled a Paramyrothecium-like fungus (Lombard et al. 2016). The genomic DNA of three representative single-spored isolates TJJXPF1-3 were extracted and the internal transcribed spacer (ITS) region, β-tubulin (tub2), large subunit ribosomal RNA (LSU), calmodulin (cmdA) and translation elongation factor 1-alpha (tef1) genes were amplified and sequenced using the primer pairs ITS4/ITS5 (White et al. 1990), Bt2a/Bt2b (Glass and Donaldson 1995), LR0R/LR5 (Rehner and Samuels 1995; Vilgalys and Hester 1990), CAL-228F/CAL2Rd (Carbone and Kohn 1999; Groenewald et al. 2013) and EF1-728F/EF2 (O’Donnell et al. 1998), respectively. All sequences were deposited in GenBank (ITS: MW463444, OM368178, OM368179; tub2: MW269542，OM714930，OM714931; LSU: OM349050, OM397398, OM390582; cmdA: MW280443, OM350474, OM350476; tef1: MW560083, OM350475, OM350477). BLASTN analysis showed 99.3-100% similarity with reference isolate QB1 of P. foliicola (MK335967, MT415353, MT415362, MT415356 and MT415359). Multilocus phylogenetic analysis showed that TJJXPF1-3 best grouped with the P. foliicola clade, which was identified by morphological characteristics and phylogenetic analysis. To fulfill Koch’s postulates, pathogenicity tests were conducted by spray-inoculation with a conidial suspension of isolate TJJXPF1 prepared with distilled water (1×105 conidia/mL) on five 45-day old tomato plants. Three healthy plants were sprayed with sterile water as control. All treatments were incubated in an artificial climate chamber (25°C, 80% RH, 12h light/12h dark ). After two weeks, leaf spots were observed on all inoculated plants, which were similar to those in the greenhouse of JiZhou District, while control plants remained asymptomatic. Additionally, the pathogens were reisolated from symptomatic leaves and three representative isolates TJJXPF4-6 were identified as P. foliicola. The pathogenicity tests were repeated thrice. To our knowledge, this is the first report of leaf spot caused by P. foliicola on tomato in China. This disease could be a serious threat to tomato production in the future. Our findings will help to differentiate this disease from other leaf spot-like diseases and develop disease control strategies.
Fruit diseases are among the major problems that negatively affect eggplants (Solanum melongena L.). With climate change, new pathogens may potentially emerge and threaten the yield and profitability of eggplant production. This study elucidates the causal agent of a crater rot in eggplant fruit. The disease appears as shallow to deep and crater-shaped lesions on infected fruits. Olive-colored sporodochia and dark exudates appeared around the center of the lesion. The fungal pathogen associated with the crater rot was identified as Paramyrothecium foliicola L. Lombard & Crous. The fungus was pathogenic to eggplant in two independent, detached fruit assays. The fungus also induced crater rot on wounded tomato and pepper fruits. The same fungus was consistently re-isolated from the inoculated fruits satisfying Koch’s postulates. In an attempt to determine the potential host range of this fungal pathogen, 45 plant species from 21 plant families were assessed for pathogenicity under detached fruit or leaf assays. A wide range of plant species was susceptible to P. foliicola MBEPFR05 in either wounded or unwounded inoculations. This is the first report of P. foliicola causing crater rot in eggplant. This study also demonstrates the ability of the fungus to infect other economically important plants. Crater rot may become a problem in vegetable production, and thus entails that more research would be needed considering little information on crater rot epidemiology and its management.
Coffee is a tropical plant with two widely cultivated species, namely Coffea arabica and Coffea canephora. A leaf spot disease causing brownish and necrotic lesions was broken out on the C. canephora coffee seedlings in a nursery in Ruili County, Yunnan Province, China, during 2018 to 2019. The incidence of the disease was 15% ~ 20%. Ten diseased leaf samples from five diseased plants were collected for pathogen isolation by tissue separation method. Leaf pieces were cut from the margin of the necrotic lesions (4 × 6 mm), surface-sterilized for 30 s in 75% ethanol, followed by 0.1% arsenic mercury solution for 15 s, then washed 3~4 times with sterilized distilled water and transferred onto potato dextrose agar (PDA) medium in petri plates. Four morphologically similar isolates were obtained from lesions and cultivated on PDA at 25°C. Initial colonies of isolates were round, neat edge, white, floccose mycelium and developed dark green-to-black concentric rings that were sporodochia bearing viscid spore masses after 5~7 days. Conidia were acetates, hyaline and cylindrical with both rounded ends and 4.8 to 6.4 µm long × 1.6 to 2.6 µm wide. Koch's test were conducted on three healthy plants leaves of original source variety C. canephora No.2 and C.arabica Catimor CIFC7963 (control plants) with spore suspension (1 × 106/mL), respectively. Meanwhile, equal numbers of healthy plants were inoculated with water as controls. After inoculation, the plants were transferred into an incubator at 25℃ with saturated humidity. After 10 days of inoculation, all the tested plants presented similar typical symptoms with the diseased leaves under natural conditions; whereas the controls remained healthy. Koch’s postulates were performed by re-isolating the fungus from the inoculated leaves and verifying its colony and morphological characters. Two single spore isolates cultured on PDA medium were selected for DNA extraction. The ribosomal internal transcribed spacer (ITS) was PCR amplified by using primers ITS1 and ITS4 (White et al., 1990), β-tubulin gene by Bt2a and Bt2b (Glass and Donaldson, 1995), the RNA polymerase II second largest subunit (rpb2) by RPB2-5F2 and RPB2-7cR (O’Donnell et al, 2007), calmodulin (cmda) gene by CAL-228F and CAL2Rd (Groenewald et al., 2013). The sequences of ITS (MT853067 ~ MT853068), β-tubulin (MT897899 ~ MT897900), rpb2 (MW256264~ MW286265) and cmda (MT897897~ MT897898) were deposited in GenBank databases. BLAST analysis revealed that the representative isolates sequences shared 99.31%~99.65% similarities to the ITS sequence of Paramyrothecium breviseta (Accession Nos. NR_155670.1), 99.43% similarities to the β-tubulin sequence of P. breviseta (Accession Nos. KU846406.1), 98.98% similarities to the rpb2 sequence of P. breviseta (Accession Nos. KU846351.1), and 98.54%~98.71% similarities to the cmda sequence of P. breviseta (Accession Nos. KU846262.1). As it shown in the phylogenetic tree derived from combined ITS, β-tubulin, rpb2, and cmda gene sequences, the two representative isolates were clustered together with P. breviseta CBS 544.75 with 98% strong bootstrap support, which confirmed that P. breviseta is the causal agent of leaf spot of Coffea canephora. To our knowledge, this is the first report of a leaf spot disease caused by P. breviseta on C. canephora in China, which raised the caution that P. breviseta is also pathogenic to Coffea Arabica.
Watermelon is an important vegetable crop in Mexico and produced on 358,105 ha, with nearly 1.5 x 106 tons. In September 2019, brown, irregular shape to round lesions with concentric rings were observed on the leaves and stems of watermelon plants in Sonora State. The surface of the lesions contained abundant cup-shaped sporodochia covered by masses of olive-green to black conidia. Edge sections of symptomatic tissues were cut from the leaves, disinfected in 70% ethanol for 1 min and subsequently washed twice with distilled water. Disinfected tissue samples were transferred to PDA medium and incubated at 27°C for 15 days. White colonies were observed with spordochia arranged in concentric rings with characteristic of greenish-black masses of conidia. Spore masses stained with lactophenol blue were examined microscopically. Conidia were nonseptate and rod-shaped with rounded ends that measured 6.65 ± 0.54 x 1.56 ± 0.25 μm (n = 100). The characteristics of the fungus were similar to those reported for Paramyrothecium foliicola (Rennberger and Keinath, 2020). Molecular identification was performed on a representative isolate. RNA polymerase II second largest subunit (RPB2), calmodulin (CmdA) and the β-tubulin (B-tub) genes were amplified and sequenced with the primer sets RPB2-5F2-RPB2-7cR, CAL228F-CAL737R and Bt2a-Bt2b, respectively. These sequences were submitted to GenBank with the acc. nos. MW116070 for RPB2, MW116071 for CmdA and MW116072 for B-tub. BLASTn analysis of the sequences demonstrated 99.34 to 100% identity with Paramyrothecium foliicola (acc. nos. MN398043, MN593713 and MN398138). Koch's postulates were verified on 15-day-old watermelon seedlings and mature fruit. One point of each of ten watermelon seedlings and six points of each of five fruit were marked for inoculation. A plug of mycelium obtained from a monosporic pure culture (grown for 15 days in PDA) was applied to each point without wounds. PDA only medium was included as the controls. The pathogenicity tests were repeated twice. Treated seedlings and fruit were kept in plastic bags at 27°C for 15 days. The first symptoms appeared 4 days after inoculation on the seedlings and 3 days after inoculation on the fruit. At the end of the test, the symptoms were similar to those observed initially in the field. The pathogen was re-isolated from lesion edges, and the morphological characteristics of the pathogen were determined to correspond with those of the inoculated fungus. Control seedlings and fruits remained healthy. P. foliicola has been reported to cause leaf spot disease on wild rocket and basil (Matić et al., 2019) and, recently, on watermelon in South Carolina (Rennberger and Keinath, 2020). To the best of our knowledge, this report is the first to describe P. foliicola causing leaf spot and stem canker on watermelon in Mexico.
Mung bean (Vigna radiata L.) is an important legume crop cultivated widely in China (Nair et al. 2013). In September 2018, a severe foliar disease occurred on some mung bean cultivars (Jilv0816, Baolv200810-1, Liaolv10L708-5, and Zhonglv5) in Shijiazhuang (38°03′N, 114°29′E), Hebei Province, China. Initially, lesions were circular to irregular, with dark brown margins and pale centers (Supplementary Fig.1). Later, tiny dark stroma with oval or irregular shape were observed on spots. The infected field was about 0.067 hectare with 50-70% disease incidence, but with no significant yield losses. Several leaves with necrotic spots were collected and cut into 2-3-mm pieces, surface sterilized with 2% NaClO for 2 min, rinsed three times in sterile distilled water, and incubated on potato dextrose agar (PDA) at 25ºC in darkness for 7 days. Three of 10 obtained single spore isolates, QB1, QB2 and QB3, were used for further studies. Colonies had abundant white aerial mycelia and produced black sporodochia bearing masses of viscid spores on PDA after 7-10 days. Conidia were aseptate, hyaline, and cylindrical, with the size of 5.6-7.5 µm × 1.6-3.3 µm (n=50). Conidiophores branched repeatedly. These morphological characteristics resembled that of Paramyrothecium-like isolates (Lombard et al. 2016). Given that P. roridum, P. foliicola, and P. nigrum were all reported to cause leaf spot on leafy vegetables and ornamental crops, five loci (the internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1), β-tubulin (tub2), 28S rRNA (LSU) and calmodulin (cmdA)) were amplified and sequenced for molecular analysis (Mati et al. 2019). The resulting sequences were deposited in GenBank under accession numbers: MK335967, MT415351-MT415364. Among the five loci, ITS and LSU sequences showed 99-100% (584/590, 545/546 base pairs) similarity with P. foliicola type strain CBS113121 (NR_145074.1; KU846324.1) by BLASTn analysis, while the tef1, tub2, and cmdA sequences exhibited high identity (99%) (398/404 bp, 323-324/326 bp, 555-558/560 bp) with P. foliicola strain Bas4_m2 (MH939239.1; MH824739.1; MH807772.1) (Mati et al. 2019). Phylogenetic tree of the five concatenated loci showed that our isolates cluster with P. foliicola, although they show slight difference from other P. foliicola strains (Supplementary Fig.2). Based on morphology and molecular analysis, the pathogen was identified as P. foliicola. Pathogenicity tests of the three isolates were performed by spraying 2 ml of 1.0 × 106/ml spore suspension on each three-week-old seedlings of mung bean cultivar ‘Jilv 7’ (n=5 for each isolate), whereas the controls were inoculated with sterile water (n=3). All inoculations were incubated in a moist chamber at 25ºC with a 12h light cycle. The experiment was repeated twice. After 7 to 10 days, symptoms with necrotic brown spots were observed on plants inoculated with P. foliicola, but not on controls. The pathogen was reisolated from randomly selected diseased leaves and identified as P. foliicola by morphology and DNA sequencing of tub2 and cmdA loci. No pathogens were isolated from controls. Although P. roridum has been reported to cause mung bean leaf spot in India (Singh and Shukla 1997; Singh and Narain 2008), to our knowledge, this is the first report of P. foliicola causing leaf spot on mung bean in China. This finding suggests a potential threat to mung bean production in China and further studies should focus on epidemiology and control of this disease.
Background: Cotton is one of the most important cash crops in India. It is also called as “White gold” because of its agricultural as well as industrial importance. Myrothecium leaf blight is an emerging disease in cotton which is growing consistently throughout the country and has been reported to cause significant losses in major cotton growing tracts of odisha. Considering the importance of the disease, the present investigation has been taken up to study the physiology of the fungus. Methods: An experiment was conducted in-vitro during 2016-18 to investigate the effect of temperature and pH on the growth of M. roridum. Seven different nutrient media viz. Potato Dextrose Agar (PDA) medium, Potato Sucrose Agar (PSA) medium, Host Leaf Extract Agar (HEA) medium, Potato Carrot Agar (PCA) medium, Czapek’sdox Agar (ZA) medium, Richard’s Agar (RA) medium and Oat meal agar medium (OMA) were tested under in-vitro conditions to ascertain a suitable medium for the growth of M. roridum. Result: The investigation in laboratory conditions has revealed that out of seven nutrient media tested, maximum radial growth was recorded in Potato Sucrose Agar (PSA) with an average radial growth of diameter 76.06 mm and the least growth was recorded on Richard’s Agar with a diameter of 23.66 mm. The growth of the fungus was observed to be maximum at a temperature of 28oC with a diameter of 61.09 mm and the minimum average growth of 17.36 mm was recorded at 36oC. Studies on pH revealed that that the fungus grows well in neutral and slight alkaline medium (6.5 - 8.0).
Physostegia virginiana Benth. (false dragon head flower), belonging to the family Lamiaceae, is a perennial plant and is usually used as landscape plant in parks and wetlands in China. It is also widely used as an ornamental plant for cut-flower all over the world (Cardin et al. 2007). In June 2019, leaf spot symptoms were observed on P. virginiana in Zibo botanical garden of Shandong Province, China (36.79°N, 118.02°E). We surveyed about 200 square meters of planting area, and most of the infected plants were close to the water or wet places, with ~20% disease incidence which were concentrated in the lower leaves of plants. The symptoms appeared on leaves were mostly round or oval spots, light to dark brown in color, and 3 to 8 mm in diameter. Severe leaf lesions were linked together, causing early fall of leaves. Small pieces of 15 infected leaves were collected to confirm the causal pathogen. The samples were sterilized by 70% ethanol for 30 s, 5% NaClO for 1 min, then rinsed in sterile water three times, plated on potato dextrose agar (PDA) and incubated at 25℃ in the dark for 7 days (Zhu et al. 2013), and 7 isolates were obtained from 10 diseased samples. The stroma of fungal mycelium was initially white, gradually turning dark green to black, while the margin of colony was regular, with concentric rings which were black sporodochia aggregates. Conidiophore hyaline, produce 2-3 order complex branches, arising as 3-4 conidiogenous cells from the tip of the branches, conidiogenous cells ampulliform to cylindrical. Conidia were aseptate, unicellular, hyaline, cylindrical, and their dimensions varied from 4.8 to 8.2 × 1.7 to 2.4 μm with rounded tips. The morphological characteristics of the isolates matched features described for Paramyrothecium roridum (Tode) L. Lombard & Crous, comb. nov. (Lombard et al. 2016). For molecular identification, genomic DNA was extracted from five representative single spore isolates. The partial coding genes of internal transcribed spacer (ITS) and calmodulin (cmdA) from the original isolates were amplified with primers ITS1/ITS4 and CALDF1/CALDR1 (White et al. 1990; Lawrence et al. 2013), respectively. The sequenced genes (GenBank accession no. MT318535, and MT454826) exhibited 98.71%, and 100.00% homology with type specimen of P. roridum strain CBS372.50 (GenBank accession no. MH856665.1, and KU846271.1), respectively, confirming the morphological identification. Pathogenicity of the fungus was tested indoor by inoculating 5 living, healthy P. virginiana plants with 3 leaves, which were inoculated with 10 µl of conidial suspension (2 × 105 conidia/ml) from a 10-day-old cultures on PDA, while 5 other inoculated plants with 10 µl of sterile water were served as controls. Treated plants with the inoculated leaves were covered by plastic bags in the greenhouse of 14 h light/10 h dark with ~80% relative humidity at 25℃. As time went by (about 3-7 days), the leaves inoculated with conidial suspension appeared similar symptoms as described above, whereas negative controls were still healthy. The same pathogens were isolated from the diseased leaves and repeated three times with same results as those that were obtained previously from the outdoor plants, including morphological and molecular results which confirm Koch’s postulates. To our knowledge, this is the first record of P. roridum causing leaf spot on P. virginiana in China. The finding is beneficial to the better application of P. virginiana, a very common ornamental plant.
Gummy Stem Blight (GSB), caused by Didymella bryoniae, is a devastating disease on watermelon. Pydiflumetofen belongs to SDHI fungicide, which is effective in controlling many plant diseases. The EC50 values of 69 D. bryoniae isolates to pydiflumetofen ranged from 0.0018 to 0.0071 μg/ml and the MIC value of all strains to pydiflumetofen was < 0.05 μg/ml. Eight pydiflumetofen-resistant mutants were obtained and the level of resistant was stable. The mycelial growth, dry weight of mycelia, hyphal morphology and pathogenicity of most resistant mutants did not change significantly compared with their parental strains, which indicated that the resistance risk of D. bryoniae to pydiflumetofen would be medium to high. Sequencing alignment showed that five resistant mutants presented a mutation at codon 277 (H277Y) in SdhB gene. The point mutants FgSdhBH248Y/R exhibited decreased sensitivity to pydiflumetofen in Fusarium graminearum, which indicated that the point mutants of SdhB could reduce sensitivity to pydiflumetofen. These results further increase our understanding about the mode of action and resistance mechanism of pydiflumetofen.
Recently, the incidence of Myrothecium leaf spot, a foliar disease of watermelon, has increased in South Carolina. However, the identity of the fungal species responsible for outbreaks of this disease has not been determined. Sequence data from four partial gene regions were used to conduct Bayesian inference in order to identify 95 isolates of Stachybotriaceae. Isolates were collected in South Carolina between July 2015 and May 2018. In total, six species of Stachybotriaceae were identified on watermelon and two other cucurbits: Albifimbria verrucaria, Gregatothecium humicola, Paramyrothecium foliicola, P. humicola, Xenomyrothecium tongaense, and Xepicula leucotricha. Two species, G. humicola and P. foliicola, were the predominant species found. Within these two species, genetic differences within small spatial scales were detected. Five species (all except Xenomyrothecium tongaense) were tested in experiments to determine their pathogenicity and relative virulence on three hosts grown in rotation in South Carolina. Southern pea plants were less susceptible than watermelon and tomato plants, which were equally susceptible. This constitutes the first reliable report of pathogenicity of any of the five tested species of Stachybotriaceae on these three vegetable crops. Another important finding was that none of the isolates were identified as P. roridum, the species considered to be the only causal agent of Myrothecium leaf spot on cucurbits. We propose the common name "ink spot" for the foliar phase of diseases caused by genera within the family Stachybotriaceae. This name is descriptive and likely to be accepted by growers. To prevent further loss incurred by ink spot, watermelon and tomato crops should be monitored for this disease.
The objective of this study is to evaluate the antagonism of Clonostachys rosea LQC62 and Trichoderma asperellum LQC96 for Botrytis cinerea and Myrothecium roridum, which are begonia leaf pathogens, and to evaluate the application of these antagonists in the management of the disease in commercial cultivation. Under controlled in vitro conditions, the production of soluble and volatile compounds was evaluated along with parasitism in paired cultures, competition by colonization in begonia leaf discs, and the effect of the application of the antagonists in the control of gray mold and Myrothecium leaf spot in the commercial cultivation of begonia. Both LQC62 and LQC96 produced soluble compounds in a culture medium that were capable of inhibiting the development of B. cinerea, which was not observed for M. roridum. Both antagonists produced volatile compounds that led to a reduction in the development of the pathogens. There was an overlap of the colonies of the antagonists with those of the pathogens, indicating hyper-parasitic activity. The antagonists colonized the begonia leaf discs, and the application of these antagonists prior to inoculation promoted a reduction in the sporulation of the pathogens of up to 100%. Weekly foliar sprays of LQC62 reduced the incidence of gray mold and of Myrothecium leaf spot.
Squash is one of the most important crops of tropical and temperate regions, and it can be affected by several fungal pathogens. Most of these infect the seeds, which become an efficient vehicle to disperse seedborne pathogens over long distances, with consequent severe crop losses. The main objective of this study was the identification of the principal seedborne fungi in seeds extracted from 66 samples of asymptomatic and symptomatic squash fruit (Cucurbita maxima, Cucurbita moschata) collected in two countries, Tunisia and Italy. The symptoms of fruit decay were identified and classified according to lesion size. Following the blotter test, 14 fungal species were detected from the seeds. Seedborne fungi were identified in all fruit samples tested, including asymptomatic fruit. The most frequent fungi from Tunisia seeds were Alternaria alternata (25.1%), followed by Stagonosporopsis cucurbitacearum (24.6%), Fusarium solani (16.6%), Rhizopus stolonifer (13.3%), Fusarium fujikuroi (7.8%), Albifimbria verrucaria (3.3%), and Stemphylium vesicarium (2.3%). For the fruits from Italy, the most frequently identified fungal species in seed samples were: A. alternata (40.0%), followed by F. fujikuroi (20.8%), S. vesicarium (3.0%), and Curvularia spicifera (2.1%). Morphological identification was confirmed by molecular diagnosis using the available species-specific primers. Furthermore, specific primers were designed to identify A. verrucaria, Paramyrothecium roridum and S. vesicarium. Application of seed-health testing methods, including such conventional and molecular diagnostic tools, will help to improve seed quality and crop yields.
Keywords: β-tubulin, diseases of Cucurbita species, EF1α, histone H3, ITS, rDNA
Contents
1. Introduction
2. Essential oils
3. Effects of essential oils on Monilinia spp., Penicillium spp., Botrytis cinerea, and Colletotrichum spp.
4. Essential oil treatment and differential responses among cultivars
5. Mechanisms of action of essential oils
6. Influence of essential oil treatment on fruit quality and nutritional compounds
7. Integrated application of essential oils with other postharvest treatments
8. Use of microencapsulated essential oil and essential oil impregnated films in packaging to control postharvest decay
9. Conclusions
Acknowledgements
References
Abstract
Postharvest losses are mostly due to postharvest diseases and impact food availability in domestic markets and also influence the profitability of exported fruit and vegetables. Applications of postharvest fungicide spray or dip treatments have been traditionally used to control postharvest diseases. Increasing consumer concerns regarding food safety and the presence of fungicide residues on these products have motivated a search for natural, environmentally friendly, alternative disease control strategies. The use of essential oil vapors is a novel approach for the management of postharvest diseases of fruit and vegetables. This chapter reviews the use of essential oils as an alternative to synthetic fungicides for the control of postharvest diseases, with special emphasis on strategies that have been developed to provide the avocado industry with a durable and environmentally friendly product that is safe for workers and consumers. This chapter describes the recent developments of the use of essential oils for the control of blue mold of pomes, green mold of citrus fruit, brown rot of stone fruit, gray mold of many hosts, and anthracnose of avocado in vitro and in vivo. Moreover, studies on the mechanisms of action of essential oils with a particular focus on improving the host defense by means of its signaling effects and the integrated application with other postharvest treatments are covered.
Abbreviations
GRAS Generally recognized as safe
LEDP Low-density polyethylene
LOX Lipoxygenases
MAP Modified atmosphere packaging
MIC Minimum inhibitory concentration
PAL Phenylalanine ammonia-lyase
PMF Proton motive force
PR Pathogenesis-related
ROS Reactive oxygen species
TA Titratable acidity
TSS Total soluble solids
US FDA United States Food and Drug Administration
Gummy stem blight, caused by Stagonosporopsis spp., is a major disease of cucurbits in the United States and China that is managed primarily through the use of fungicides. The objective of this study was to monitor and compare the recent fungicide resistance profiles of Stagonosporopsis spp. in Florida open-field and East China protected-structure production systems. Isolates of Stagonosporopsis spp. were evaluated for sensitivity to the commonly used fungicides azoxystrobin, boscalid, tebuconazole, and thiophanate-methyl at discriminatory rates of 0.096, 0.034, 0.128, and 100 mg/liter, respectively. Isolates were collected from Jiangsu, Jiangxi, Zhejiang, and Anhui provinces in China (n = 69), 12 counties in Florida (n = 89), and one county in Georgia (n = 6). More than 50% of isolates from Florida and East China were resistant to thiophanate-methyl. Boscalid resistance was detected in both isolate collections but was two times more frequent in China. Resistance to azoxystrobin was detected in 66% of isolates in Florida but only 7% in China. Tebuconazole was effective in controlling the mycelia growth of Stagonosporopsis spp. in both collections. The results indicate that both production systems currently face similar challenges related to the development of fungicide resistance in Stagonosporopsis spp. However, the resistance profiles are unique for both production systems.
The genera Paramyrothecium and Albifimbria have been established from the former genus Myrothecium and they generally comprise common soil-inhabiting and saprophytic fungi. Within these genera, only two fungi have been recognized as phytopathogenic thus far: P. roridum and A. verrucaria, both of which cause necrotic leaf spots and plant collapse. Severe leaf necrosis and plant decay have been observed in Northern and Southern Italy on leafy vegetable crops. Thirty-six strains of Paramyrothecium- and Albifimbria-like fungi were isolated from affected plants belonging to eight different species. Based on morphological characteristics, 19 strains were assigned to A. verrucaria, whereas the remaining strains, which mostly resembled Paramyrothecium-like fungi, could not be identified precisely. Molecular characterization of six loci (internal transcribed spacer [ITS], β-tubulin [tub2], calmodulin [cmdA], translation elongation factor 1-alpha [tef1], large subunit ribosomal RNA [LSU], and mitochondrial ATP 6synthase 6 [ATP6]) of the 36 new isolates and three previously ITS-characterized isolates assigned all strains to four species: A. verrucaria, P. roridum, P. foliicola, and P. nigrum. Single and concatenated phylogenetic analyses were conducted, and they clearly distinguished the isolated fungi into four different groups. A. verrucaria, P. roridum, P. foliicola, and P. nigrum were able to induce leaf necrosis singly, and they were confirmed to be the causal agents of the leaf spot disease through pathogenicity assays. The involvement of fungi previously considered saprophytic (i.e., P. foliicola and P. nigrum) in the development of plant disease for the first time deserves particular attention because of the possibility of their transmission by seeds and the limited knowledge of their management with chemicals.
A crown canker disease causing yellowing and wilting of the leaves was observed on muskmelon (Cucumis melo) plants in a number of greenhouses in Shouguang county, Shandong province, China, during April 2014 to July 2015, resulting in serious economic losses. Black sporodochia with white mycelial tufts emerged on surfaces of lesions at the base of the stem. Eleven fungal strains were isolated from infected tissues. On the basis of morphological features, ITS-5.8S rDNA and TEF1 sequence analysis, the isolates were identified as Paramyrothecium roridum (Tode) L. Lombard & Crous (syn. Myrothecium roridum Tode). The pathogenicity of the isolates was confirmed. The morphological characteristics of reisolated strains from inoculated muskmelon plants showing symptoms of crown canker were consistent with the original strains. A host range test indicated that strains had a wide range of hosts. To the best of our knowledge, this is the first report of muskmelon crown canker caused by P. roridum in China. This disease could have a significant economic impact on muskmelon production.
Here we report a highly sensitive real-time PCR (qPCR) assay to detect Paramyrothecium roridum from pure culture and infected samples of cotton plants. A specific set of primer pair pMyro F/R is designed to target the 185 bp ITS region of rDNA of Paramyrothecium roridum species and validated using qPCR. The fluorescence signals were detected above the baseline threshold from samples containing Paramyrothecium roridum DNA, whereas other samples did not produce any fluorescence or produced fluorescence which did not reach detection threshold values. A single dissociation peak of increased fluorescence was obtained for the specific primers at 92.2 °C melting temperature. The limit of detection using SYBR Green dye in this assay was up to 0.1 pg per µL of DNA from pure culture of P. roridum. The assay is accurate, sensitive, less laborious and time saving for detection of P. roridum in infected tissues of cotton.
The behaviour of Myrothecium roridum, artificially inoculated on cultivated rocket (Eruca sativa), has been evaluated under eight different temperature and CO2 concentration combinations (from 14-18 °C to 26-30 °C and with 400-450 or 800-850 ppm of CO2). The pathogen isolate used for this study was inoculated on rocket and disease severity increased with high temperatures for both CO2 levels. Verrucarin A and roridin E mycotoxins were produced under all the tested temperatures at high CO2 conditions. The maximum level of verrucarin A was found at 14-18 °C and 800-850 ppm of CO2, and the maximum roridin E production was detected at 26-30 °C with 800-850 ppm of CO2. The results obtained in this study show that both the CO2 concentration and the temperature influence disease severity and mycotoxin production in different ways. An increase in temperature, which is favourable for attacks of the pathogen, could induce the spread of M. roridum in temperate regions, and this pathogen could take on even greater importance in the future, considering its ability to produce mycotoxins.
A series of field surveys were carried out during July-October 2012-14 for the development of disease distribution map and updating the index of Myrothecium leaf spot of Momordica charantia (Bitter gourd) in Punjab province. A total of 29 districts were surveyed belonging to 9 sub agro ecological zones of Punjab. The index was calculated on the basis of incidence, prevalence and severity of the disease. The information from stakeholders was gathered through field scouting, formal and informal discussions. Data on socioeconomics was collected by a structured questionnaire. The symptomatic plants and soil specimens were collected form diseased field and transferred to lab for onward studies on host-pathogen characterization and management. Infection development on the plant was investigated on a (0-5) visual severity rating scale. Fungus was isolated, identified on morphological and molecular characteristics as Myrothecium roridum and cultures were deposited to First Fungal Culture Bank of Pakistan (Accession # FCBP 1155) and Leibniz-institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Germany (Accession # DSM 28971). Data gathered highlighted dominance of the disease in mixed cropping zone of Punjab province. Highest disease index (31%) was recorded in mixed cropping zone and lowest (3%) in D.G khan zone. However its severity may vary due to adopted cultural and chemical practices by individual farmers. The investigations strengthen the involvement of irrigation technique, soil type and cropping history in introduction and sporadic occurrence of the disease.
Petunia hybrida Vilm. is one of the most economically important ornamental plant species, introduced in China starting in the early 20th century. Since 2012, a previously unknown foliar disease has been observed on this plant in greenhouses of Shunyi district in Beijing, China (117°05′E, 40°13′N). The disease incidence varied from 5 to 15% in three different greenhouses. Lesions were visible on both leaf surfaces. The spots were dark brown, circular or subcircular, and 2 to 6 mm in diameter. The grower reported that the disease caused significant leaf drop that was especially serious during a period of humid and cloudy weather, which negatively affected the ornamental market value of P. hybrida. Infected leaf tissue was cut into 2 to 3 mm pieces and surface sterilized with 70% ethanol for 30 s, then rinsed in sterile distilled water three times; segments were plated on potato dextrose agar (PDA) and incubated at 25°C in darkness for 7 days (Zhu et al. 2013). The isolates produced a white, floccose colony with dark green-to-black concentric rings that were viscid conidia masses. Conidia were 5.0 to 7.6 × 2.2 to 2.5 μm, colorless, unicellular, and cylindrical, usually with both rounded ends, occasionally one blunt end. Conidiophores branched repeatedly. Conidiogenous cells were 10.6 to 16.0 × 1.4 to 2.0 μm, colorless, clavate, and in whorls of 3 to 7 on ultimate branches. The morphological characteristics identified the isolated fungi as Myrothecium roridum Tode ex Fr. (Tulloch 1972). Pathogenicity of the fungus was carried out in a greenhouse by inoculating healthy, flowering-age P. hybrida plants with 10⁶ conidia/ml spore suspension prepared from a 10-day-old mycelial cultures. Inoculated plants with sterile water were used as the control treatment. Each treatment repeated three times with four P. hybrida plants each time. Inoculated plants were wrapped in a plastic bag and incubated in a glass cabinet with 21 to 32°C, 80% relative humidity. Three days after inoculation, small lesions were developed on leaves of P. hybrida plants with symptomless stems and flowers and showed the natural infected symptoms after inoculation for 10 to 12 days, while control plants remained healthy. The same fungus was reisolated from symptomatic leaves confirming Koch’s postulates, but not from the controls. In molecular identification, total DNA of the fungus was isolated using the CTAB method (White et al. 1990). PCR amplification was carried out by utilizing universal rDNA-ITS primer pair ITS1/ITS4 (White et al. 1990). After PCR product was sequenced and identified with BLAST analysis, the 405 bp amplicon (GenBank accession no. KJ018792) showed a 100% homology with M. roridum (KM986033.1) from the GenBank database. M. roridum is widely known as a leaf spot pathogen on many horticultural crops, including Anubias barteri, Begonia elatior, Matthiola incana, Citrullus lanatus var. lanatus, Dolichos lablab, Glycine max, Valerianella olitoria, and Arachis hypogaea. In addition, this fungus has been reported as a pathogen of Cucumis melo fruit rot in Brazil and causes crown rot disease of Sinningia speciosa in Florida. To date, M. roridum is known to harm 316 host plants, and has been recorded on P. hybrida in Zambia (Farr and Rossman 2016). To our knowledge, this is the first report of M. roridum causing leaf spot on P. hybrida in China. © 2017, American Phytopathological Society. All rights reserved.
In 2010, a foliar and stem-lesion disease was observed for the first time in Oklahoma causing moderate to severe defoliation. Using microscopic examination, the physical features of the fungus were consistent with Myrothecium roridum. There was a wide range of susceptibility among watermelon cultivars in the field indicating a moderately high level of resistance to Myrothecium leaf spot in some cultivars. In greenhouse inoculation experiments, cantaloupe, honeydew, cucumber, squash, and watermelon were all susceptible to the fungus with cantaloupe and honeydew being the most susceptible and watermelon the most resistant. Furthermore, greenhouse inoculations supported the field observations as differential resistance was exhibited among the watermelon cultivars as well as the cucurbit types. Although cantaloupe was most susceptible to the foliar phase of this disease, watermelon was most susceptible to the fruit-rot phase. Natural infection of watermelon fruit has never been reported.
Accepted for publication 15 December 2011. Published 30 January 2012.