scholarly journals Leaf Spot Caused by Boeremia linicola on Siberian ginseng in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yi Ming Guan ◽  
Shu Na Zhang ◽  
Ying Ying Ma ◽  
Yue Zhang
Keyword(s):  
Phylogenetic Analysis ◽  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Management Strategies ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
Siberian Ginseng ◽  
Pathogenicity Testing

Siberian ginseng (Eleutherococcus sessiliflorus (Rupr. & Maxim.) S. Y. Hu, Araliaceae), is a perennial medicinal plant that is widely cultivated in China. Leaf spot was observed in 2- and 3-year-old Siberian ginseng in Zuojia County (126°05′23.2″E, 44°03′09.5″N), northeast China, in August 2019. Polygonal or irregular black spots ranging from 2 to 9 mm in diameter were found on infected leaves, and each leaf had dozens of spots. The green color around the lesions gradually faded. As the disease progressed, the spots withered and multiple lesions merged into large disease spots, causing leaf wilting (Fig. 1). More than 38% of plants in one 25-ha field were infected in 2019. Fifteen diseased leaves were collected from those plants and cut into 5-mm pieces. The pieces were surface-disinfected by immersion in 1% NaOCl for 2 min and then rinsing twice with sterile distilled water. The leaf pieces were placed on acidified potato dextrose agar (PDA, pH 4.7) in Petri plates, and incubated in the dark at 25°C. Nineteen isolates were obtained and all were purified from a single spore in water agar. Isolate CWJ7 was randomly selected for identification and pathogenicity testing. The colonies on PDA were olivaceous gray to olivaceous black, velvet, with dense hyphae and a scalloped or irregular margin. The reverse side was gray-black and surrounded by tawny halos. The conidia were aseptate and variable in shape and dimension: piriform, columnar, drop-shaped, dumbbell-shaped or oval, measuring 4.90 (7.03) 9.50 × 2.10 (2.78) 3.40 µm (n=100), and chlamydospores were absent. Black pycnidia (132.2–241.5 µm in diameter) appeared after 7 days. The pathogen was initially identified as Phoma or Phoma-like (Boerema et al. 2004). Further confirmation was also determined by sequencing the nuclear ribosomal internal transcribed spacer region (GenBank accession no. MT912950), 28S ribosomal RNA gene (MT912968), and genes encoding β-tubulin (MT920618), the second largest subunit of RNA polymerase II (MT920619) and translation elongation factor (MT946526) (de Hoog and Gerrits van den Ende 1998; Rehner & Samuels 1994; Liu et al. 1999; Vilgalys & Hester 1990), and Blast searches showed 90%–100% homology with GU237754, GU237938, KT389780, KT389575, and KY484705, respectively. In a phylogenetic analysis combining all loci, CWJ7 and the type strains of Boeremia linicola clustered in one group (Fig. 2). Based on its morphological characteristics and phylogenetic analysis, isolate CWJ7 was identified as B. linicola as revised in 2019 (Jayawardena et al. 2019). Healthy 2-year-old plants were used for pathogenicity testing. The leaves of nine potted plants (one plant per pot, three plants per replicate) were spray-inoculated with a suspension of conidia (1×105 spores/ml) from colonies on PDA for 7 days and cultured for 48 h under continuous black light. Nine plants were sprayed with sterile water as the control. This experiment was repeated twice. All plants were cultured in a greenhouse (25°C, 12-h photoperiod, 78% relative humidity). Clear plastic bags were used to maintain high humidity. After 7 days, the inoculated plants showed lesions on the leaves, similar to those observed in the field. The control plants remained symptomless. The pathogen was reisolated and identified by sequencing. This is the first report of B.linicola causing Siberian ginseng leaf spot, and a new record of this species in China. This disease poses a threat to production and management strategies should be developed.

scholarly journals First Report of Leaf Spot Caused by Alternaria alternata on Yucca gloriosa in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Qiang Zhang ◽  
Yanru Zhang ◽  
Hongli Shi ◽  
Yunfeng Huo
Keyword(s):  
Alternaria Alternata ◽  
Leaf Spot ◽  
Management Strategies ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Internal Transcribed Spacers ◽  
Molecular Characteristics ◽  
Single Spore ◽  
Tissue Samples ◽  
First Report

Yucca gloriosa L. is introduced to China as a garden plant because of its attractive tubular flowers (Ding et al. 2020). In 2020 and 2021, a foliar disease occurred on approximately 10% of the Y. gloriosa plants in the campus of Henan Institute of Science and Technology, Xinxiang (35°18′N, 113°54′E), Henan Province, China. At the early stages, symptoms appeared as small brown spots on the tip of the leaves. As the disease developed, the spots gradually expanded and turned into necrotic tissue with a clear brown border. The length of lesions ranged from 1 to 3 cm. Infected tissue samples were cut into small pieces, surface sterilized with 75% ethanol for 30 s followed by 0.5% NaClO for 2 min, rinsed thrice with sterile water and plated on potato dextrose agar (PDA). After incubation at 25℃ for 3 days, five fungal isolates were collected and purified using single spore culturing. Morphological observations were made on the 7-day-old cultures. Colonies on PDA were white at first and then turned to dark olive or black along with profuse sporulation. Conidia were borne on branched conidiophores, light brown to dark brown, ellipsoidal to obpyriform, and 20.5 to 43.6 ×7.5 to 15.4 μm in size, with 2-6 transverse septa and 0-3 longitudinal septa (n = 50). The morphological characteristics of the five isolates were consistent with the description for Alternaria alternata (Simmons 2007). One representative isolate (ZQ20) was selected for molecular identification. The internal transcribed spacers (ITS)-rDNA, translation elongation factor-1 alpha (TEF-1α), Alternaria major allergen (Alt a1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene regions were amplified with primer pairs ITS1/ITS4 (White et al. 1990), EFl-728F/ EFI-986R (Carbone and Kohn, 1999), Alt-for/Alt-rev (Hong et al. 2005), and gpd1/gpd2 (Berbee et al. 1999), respectively. Their sequences were submitted to GenBank (ITS, MW832377; TEF-1α, MW848791; Alt a1, MW848792; GAPDH, MW848793). BLAST searches showed ≥99% nucleotide identity to the sequences of A. alternata (ITS, 100% to KF465761; TEF-1α, 100% to MT133312; Alt a1, 100% to KY923227; and GAPDH, 99% to MK683863). Thus, the fungus was identified as A. alternata based on its morphological and molecular characteristics. To confirm its pathogenicity, 25 healthy leaves of five 2-year-old Y. gloriosa plants were used. Leaves were wounded with one sterile needle and inoculated with 5-mm-diameter fungal agar disks obtained from 5-day-old cultures. Sterile PDA disks of the same size were used as the controls. Treated plants were covered with a plastic bag at 12 to 25℃ for 48 h to ensure a high level of moisture. After 15 days, the inoculated plants developed the symptoms similar to those observed in naturally infected plants, whereas the control plants were symptomless. The fungus was reisolated from the symptomatic leaves with the same morphological and molecular characteristics as the original isolates, fulfilling the Koch's postulates. Leaf spot caused by A. alternata in the Yucca plants has been reported in India (Pandey 2019). To our knowledge, this is the first report of A. alternata causing leaf spot on Y. gloriosa in China. Identification of the cause of the disease is important to developing effective disease management strategies.

Alternaria guilanica sp. nov., a new fungal pathogen causing leaf spot and blight on eggplant in Iran

Phytotaxa ◽  
2021 ◽  
Vol 520 (2) ◽  
pp. 184-194
Author(s):  
ALIREZA POURSAFAR ◽  
ESMAEIL HASHEMLOU ◽  
YOUBERT GHOSTA ◽  
FATEMEH SALIMI ◽  
MOHAMMAD JAVAN-NIKKHAH
Keyword(s):  
New Species ◽  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Phylogenetic Analyses ◽  
Solanum Melongena ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Major Allergen ◽  
Pathogenicity Test ◽  
Internal Transcribed Spacer Region

Eggplant (Solanum melongena L.) is an economically important solanaceous crop in Iran with fruits used for food and traditional medicine. Despite the importance of Alternaria leaf spot and blight disease of solanaceous crops which is commonly seen in the fields, our knowledge about the causal agents on eggplant is limited. In this study, a set of large-spored Alternaria isolates was recovered from eggplant with leaf spot and blight symptoms in Somehsara region, Guilan province, Iran. All recovered isolates shared conspicuous morphological characteristics e.g. production of large, solitary conidia with several transverse disto- and eusepta and long tapering filamentous beak resemble those seen in the members of Alternaria section Porri. Multi-locus phylogenetic analyses based on the internal transcribed spacer region of nrDNA (ITS-rDNA) and parts of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), second largest subunit of RNA Polymerase II (RPB2), translation elongation factor 1-alpha (TEF1-α) and Alternaria major allergen (Alt a 1) gene sequences provided further evidence supporting not only their exact placement in Alternaria sect. Porri, but also in a distinct lineage representing a new species. The new species was named, described and illustrated herein as Alternaria guilanica sp. nov.. The phylogenetic and morphological comaprisions of the new species with other closely related species were also provided. Pathogenicity test conducted for the new strains revealed that they were capable to induce disease symptoms on eggplant leaves under greenhouse conditions, and re-isolation of the inoculated isolates confirmed Koch’s postulates.

scholarly journals First report of Diaporthe ueckerae causing stem canker on soybean (Glycine max L.) in Colombia

Plant Disease ◽  
2021 ◽  
Author(s):  
Nathali López-Cardona ◽  
YUDY ALEJANDRA GUEVARA ◽  
Lederson Gañán-Betancur ◽  
Carol Viviana Amaya Gomez
Keyword(s):  
Management Strategies ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Stem Canker ◽  
Growth Stages ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Glycine Max L ◽  
Soybean Plants

In October 2018, soybean plants displaying elongated black to reddish-brown lesions on stems were observed in a field planted to the cv. BRS Serena in the locality of Puerto López (Meta, Colombia), with 20% incidence of diseased plants. Symptomatic stems were collected from five plants, and small pieces (∼5 mm2) were surface sterilized, plated on potato dextrose agar (PDA) and incubated for 2 weeks at 25°C in darkness. Three fungal isolates with similar morphology were obtained, i.e., by subculturing single hyphal tips, and their colonies on PDA were grayish-white, fluffy, with aerial mycelium, dark colored substrate mycelium, and produced circular black stroma. Pycnidia were globose, black, occurred as clusters, embedded in tissue, erumpent at maturity, with an elongated neck, and often had yellowish conidial cirrus extruding from the ostiole. Alpha conidia were observed for all isolates after 30 days growth on sterile soybean stem pieces (5 cm) on water agar, under 25ºC and 12 h light/12h darkness photoperiod. Alpha conidia (n = 50) measured 6.0 – 7.0 µm (6.4 ± 0.4 µm) × 2.0 – 3.0 µm (2.5± 0.4 µm), were aseptate, hyaline, smooth, ellipsoidal, often biguttulate, with subtruncate base. Beta conidia were not observed. Observed morphological characteristics of these isolates were similar to those reported in Diaporthe spp. by Udayanga et al. (2015). DNA from each fungal isolate was used to sequence the internal transcribed spacer region (ITS), and the translation elongation factor 1-α (TEF1) gene, using the primer pairs ITS5/ITS4 (White et al. 1990) and EF1-728F/EF1- 986R (Carbone & Kohn, 1999), respectively. Results from an NCBI-BLASTn, revealed that the ITS sequences of the three isolates (GenBank accessions MW566593 to MW566595) had 98% (581/584 bp) identity with D. miriciae strain BRIP 54736j (NR_147535.1), whereas the TEF1 sequences (GenBank accessions MW597410 to MW597412) had 97 to 100% (330-339/339 bp) identity with D. ueckerae strain FAU656 (KJ590747). The species Diaporthe miriciae R.G. Shivas, S.M. Thomps. & Y.P. Tan, and Diaporthe ueckerae Udayanga & Castl. are synonymous, with the latter taking the nomenclature priority (Gao et al. 2016). According to a multilocus phylogenetic analysis, by maximum likelihood, the three isolates clustered together in a clade with reference type strains of D. ueckerae (Udayanga et al. 2015). Soybean plants cv. BRS Serena (growth stages V3 to V4) were used to verify the pathogenicity of each isolate using a toothpick inoculation method (Mena et al. 2020). A single toothpick colonized by D. ueckerae was inserted directly into the stem of each plant (10 plants per isolate) approximately 1 cm below the first trifoliate node. Noncolonized sterile toothpicks, inserted in 10 soybean plants served as the non-inoculated control. Plants were arbitrarily distributed inside a glasshouse, and incubated at high relative humidity (>90% HR). After 15 days, inoculated plants showed elongated reddish-brown necrosis at the inoculated sites, that were similar to symptoms observed in the field. Non-inoculated control plants were asymptomatic. Fungal cultures recovered from symptomatic stems were morphologically identical to the original isolates. This is the first report of soybean stem canker caused by D. ueckerae in Colombia. Due to the economic importance of this disease elsewhere (Backman et al. 1985; Mena et al. 2020), further research on disease management strategies to mitigate potential crop losses is warranted.

Molecular and biological characterization of two new species causing peach shoot blight in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Lina Yang ◽  
Lingyun Wang ◽  
Jun Cao ◽  
Yuxin Zhu ◽  
Liang Zhang ◽  
...  
Keyword(s):  
New Species ◽  
Management Strategies ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Colony Growth ◽  
Total Production ◽  
Phenotypic Analysis ◽  
Internal Transcribed Spacer Region ◽  
Two New Species ◽  
Shoot Blight

Peach shoot blight (PSB), which kills shoots, newly sprouted leaf buds and peach fruits, has gradually increased over the last ten years and has resulted in 30-50% of the total production loss of the peach industry in China. Phomopsis amygdali has been identified as the common causal agent of this disease. In this study, two new species, Phomopsis liquidambaris (strain JW18-2) and Diaporthe eres (strain JH18-2), were also pathogens causing PSB, as determined through molecular phylogenetic analysis based on the sequences of the internal transcribed spacer region (ITS), translation elongation factor 1-α (EF1-α) and beta-tubulin (TUB), and colony and conidial morphological characteristics. Biological phenotypic analysis showed that the colony growth rate of strain JW18-2 was faster than that of strains JH18-2 and ZN32 (one of the P. amygdali strains that we previously found and identified). All three strains produced α-conidia; however, JW18-2 could not produce β-conidia on alfalfa decoction and Czapek media, and the β-conidia produced by strain JH18-2 were shorter in length and thicker in width than those produced by strain ZN32. Pathogenicity tests showed that JW18-2 presented the strongest pathogenicity for peach fruits and twigs and was followed by strains JH18-2 and ZN32. The results shed light on the etiology of PSB and provide a warning that P. liquidambaris or D. eres might develop into dominant species after a few years, while also potentially benefitting the development of effective disease control management strategies.

Amanita submelleialba sp. nov. in section Amanita from northern Thailand

Phytotaxa ◽  
2021 ◽  
Vol 513 (2) ◽  
pp. 129-140
Author(s):  
YUAN S. LIU ◽  
JIAN-KUI LIU ◽  
PETER E. MORTIMER ◽  
SAISAMORN LUMYONG
Keyword(s):  
Rna Polymerase Ii ◽  
Phylogenetic Analyses ◽  
Line Drawing ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Nuclear Rdna ◽  
Internal Transcribed Spacer Region ◽  
Northern Thailand ◽  
Extant Species ◽  
Distinct Lineage

Amanita submelleialba sp. nov. in section Amanita, is described from northern Thailand based on both multi-gene phylogenetic analysis and morphological evidences. It is characterized by having small to medium-sized basidiomata; a yellow to yellowish pale pileus covering pyramidal to subconical, white to yellow white volval remnants; globose stipe base covered conical, white to yellow white volval remnants; fugacious subapical annulus; and absent clamps. Multi-gene phylogenetic analyses based on partial nuclear rDNA internal transcribed spacer region (ITS), partial nuclear rDNA larger subunit region (nrLSU), RNA polymerase II second largest subunit (RPB2), partial translation elongation factor 1-alpha (TEF1-α) and beta-tubulin gene (TUB) indicated that A. submelleialba clustered together with A. elata and A. mira, but represented as a distinct lineage from other extant species in section Amanita. The detailed morphological characteristics, line-drawing illustration and comparisons with morphologically similar taxa are provided.

scholarly journals Morphology and Molecular Characteristics of Alternaria sonchi Causing Brown Leaf Spot on Sonchus asper in Korea

2021 ◽  
Vol 27 (3) ◽  
pp. 107-114
Author(s):  
Huan Luo ◽  
Myung Soo Park ◽  
Jun Myoung Yu
Keyword(s):  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Internal Transcribed Spacer Region ◽  
Sonchus Asper ◽  
Brown Leaf Spot ◽  
Brown Leaf

During a disease survey on weeds and minor cultivated crops in Korea, a brown leaf spot disease was observed on Sonchus asper. Leaf lesions were round or irregular in shape, and grayish brown to brown with a purple margin. In severe infection, lesions enlarged and coalesced, resulting in blighting of the leaves. The isolates from these leaf lesions were identified as Alternaira sonchi based on morphological characteristics and phylogenetic analyses of Internal transcribed spacer region, Alternaria allergen a1, glyceraldehyde 3-phosphate dehydrogenase, RNA polymerase II, and translation elongation factor genes. This study provides a comprehensive description of the morphological characteristics and phylogenetical traits of A. sonchi causing brown leaf spot on S. asper in Korea.

scholarly journals First Report of Fusarium ipomoeae Causing Peanut leaf Spot in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Manlin Xu ◽  
Xia Zhang ◽  
Jing Yu ◽  
zhiqing Guo ◽  
Ying Li ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Genomic Dna ◽  
Block Design ◽  
Management Strategies ◽  
Morphological Characteristics ◽  
Ethanol Solution ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
First Report

Peanut (Arachis hypogaea L.) is one of the most economically important crops as an important source of edible oil and protein. In August 2020, circular to oval-shaped brown leaf spots (2-6 mm in diameter) with well-defined borders surrounded by a yellow margin were observed on peanut plant leaves in Laixi City, Shandong Province, China. Symptomatic plants randomly distributed in the field, the incidence was approximately 5%. Leave samples were collected consisted of diseased tissue and the adjacent healthy tissue. The samples were dipped in a 70% (v/v) ethanol solution for 30 s and then soaked in a 0.1% (w/v) mercuric chloride solution for 60 s. The surface-sterilized tissues were then rinsed three times with sterile distilled water, dried and placed on Czapek Dox agar supplemented with 100 μg/ml of chloramphenicol. The cultures were incubated in darkness at 25 °C for 3–5 days. Fungal colonies were initially white and radial, turning to orange-brown in color, with abundant aerial mycelia. Macroconidia were abundant, 4 to 7 septate, with a dorsiventral curvature, and were 3.3–4.5 × 18.5–38.1 μm (n=100) in size; microconidia were absent; chlamydospores were produced in chains or clumps, ellipsoidal to subglobose, and thick walled. The morphological characteristics of the conidia were consistent with those of Fusarium spp. To identify the fungus, an EasyPure Genomic DNA Kit (TransGEN, Beijing, China) was used to extract the total genomic DNA from mycelia. The internal transcribed spacer region (ITS rDNA) and the translation elongation factor 1-α gene (TEF1) were amplified with primers ITS1/ITS4 (White et al. 1990) and EF1/EF2 (O’Donnell et al. 1998), respectively. Based on BLAST analysis, sequences of ITS (MT928727) and TEF1 (MT952337) showed 99.64% and 100% similarity to the ITS (MT939248.1), TEF1 (GQ505636.1) of F. ipomoeae isolates. Sequence analysis confirmed that the fungus isolated from the infected peanut was F. ipomoeae (Xia et al. 2019). The pathogenicity of the fungus was tested in the greenhouse. Twenty two-week-old peanut seedlings (cv. Huayu20) grown in 20-cm pots (containing autoclaved soil) were sprayed with a conidial suspension (105 ml−1) from a 15-day-old culture. Control plants were sprayed with distilled water. The experiment was conducted as a randomized complete block design, and placed at 25 °C under a 12-h photoperiod with 90% humidity. Symptoms similar to those in the field were observed on leaves treated with the conidial suspension ten days after inoculation, but not on control plants. F. ipomoeae was re-isolated from symptomatic leaves but not from the control plants. Reisolation of F. ipomoeae from inoculated plants fulfilled Koch's postulates. To our knowledge, this is the first report of F. ipomoeae causing peanut leaf spot in China. Our report indicates the potential spread of this pathogen in China and a systematic survey is required to develop effective disease management strategies.

scholarly journals Species of Botryosphaeriaceae associated with citrus branch diseases in China

2021 ◽  
Author(s):  
X.E. Xiao ◽  
W. Wang ◽  
P.W. Crous ◽  
H.K. Wang ◽  
C. Jiao ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Dna Sequences ◽  
Fungal Pathogens ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Botryosphaeria Dothidea ◽  
Internal Transcribed Spacer Region

Citrus is an important and widely cultivated fruit crop in South China. Although the species of fungal diseases of leaves and fruits have been extensively studied, the causal organisms of branch diseases remain poorly known in China. Species of Botryosphaeriaceae are known as important fungal pathogens causing branch diseases on citrus in the USA and Europe. To determine the diversity of Botryosphaeriaceae species associated with citrus branch diseases in China, surveys were conducted in the major citrus-producing areas from 2017 to 2020. Diseased tissues were collected from twigs, branches and trunks with a range of symptoms including cankers, cracking, dieback and gummosis. Based on morphological characteristics and phylogenetic comparison of the DNA sequences of the internal transcribed spacer region (ITS), the translation elongation factor 1-alpha gene (tef1), the β-tubulin gene (tub2) and the DNA-directed RNA polymerase II second largest subunit (rpb2), 111 isolates from nine provinces were identified as 18 species of Botryosphaeriaceae, including Botryosphaeria dothidea, B. fabicerciana, Diplodia seriata, Dothiorella alpina, Do. plurivora, Lasiodiplodia citricola, L. iraniensis, L. microconidia, L. pseudotheobromae, L. theobromae, Neodeightonia subglobosa, Neofusicoccum parvum, and six previously undescribed species, namely Do. citrimurcotticola, L. guilinensis, L. huangyanensis, L. linhaiensis, L. ponkanicola and Sphaeropsis linhaiensis spp. nov. Botryosphaeria dothidea (28.8 %) was the most abundant species, followed by L. pseudotheobromae (23.4 %), which was the most widely distributed species on citrus, occurring in six of the nine provinces sampled. Pathogenicity tests indicated that all 18 species of Botryosphaeriaceae obtained from diseased citrus tissues in this study were pathogenic to the tested Citrus reticulata shoots in vitro, while not all species are pathogenic to the tested Cocktail grapefruit (C. paradisi × C. reticulata) shoots in vivo. In addition, Lasiodiplodia was the most aggressive genus both in vitro and in vivo. This is the first study to identify Botryosphaeriaceae species related to citrus branch diseases in China and the results provide a theoretical basis for the implementation of prevention and control measures.

A new pleosporalean fungus isolated from superficial to deep human clinical specimens

2020 ◽  
Author(s):  
Nicomedes Valenzuela-Lopez ◽  
M Teresa Martin-Gomez ◽  
Ibai Los-Arcos ◽  
Alberto M Stchigel ◽  
Josep Guarro ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Rna Polymerase Ii ◽  
Pathogenic Fungus ◽  
Elongation Factor ◽  
Morphological Characterization ◽  
Morphological Description ◽  
Internal Transcribed Spacer Region ◽  
Accurate Identification ◽  
Human Patient ◽  
Opportunistic Fungal Pathogen

Abstract Human infections by pleosporalean fungi (class Dothideomycetes, phylum Ascomycota) are rarely reported. Because their identification is challenging using morphological characterization, several phylogenetic markers must be sequenced for an accurate identification and taxonomical placement of the isolates. Three isolates of clinical origin were phenotypically characterized, but due to the absence of relevant morphological traits, D1-D2 domains of the 28S nrRNA gene (LSU), the internal transcribed spacer region (ITS) of the nrRNA, and fragments of the RNA polymerase II subunit 2 (rpb2) and translation elongation factor 1-alpha (tef1) genes were sequenced to allow a phylogenetic analysis that would solve their phylogenetic placement. That analysis revealed that these isolates did not match any previously known pleosporalean genera, and they are proposed here as the new fungal genus, Gambiomyces. Unfortunately, the isolates remained sterile, which, consequently, made the morphological description of the reproductive structures impossible. Future studies should try to understand the behaviour of this fungus in nature as well as its characteristics as an opportunistic fungal pathogen. Molecular identification is becoming an essential tool for proper identification of Dothideomycetes of clinical origin. Lay Abstract We describe a new pleosporalen pathogenic fungus, Gambiomyces profunda, found in superficial to deep samples from a human patient. Because all strains remained sterile, the fungus was finally identified following a phylogenetic analysis by using four different molecular markers.

scholarly journals First Report of Stemphylium solani as the Causal Agent of a Leaf Spot on Greenhouse Cucumber

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 287-287 ◽  
Author(s):  
D. J. Vakalounakis ◽  
E. A. Markakis
Keyword(s):  
Leaf Spot ◽  
Natural Infection ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
First Report

During the 2011 to 2012 crop season, a severe leaf spot disease of cucumber (Cucumis sativus) cv. Cadiz was noticed on crops in some greenhouses in the Goudouras area, Lasithi, Crete, Greece. Symptoms appeared in late winter, mainly on the leaves of the middle and upper part of the plants. Initially, small necrotic pinpoint lesions with white centers, surrounded by chlorotic halos, 1 to 3 mm in diameter, appeared on the upper leaf surfaces, and these progressively enlarged to spots that could coalesce to form nearly circular lesions up to 2 cm or more in diameter. Stemphylium-like fructifications appeared on necrotic tissue of older lesions. Severely affected leaves became chlorotic and died. No other part of the plant was affected. Small tissue pieces from the edges of lesions were surface disinfected in 0.5% NaClO for 5 min, rinsed in sterile distilled water, plated on acidified potato dextrose agar and incubated at 22 ± 0.5°C with a 12-h photoperiod. Stemphylium sp. was consistently isolated from diseased samples. Colonies showed a typical septate mycelium with the young hyphae subhyaline and gradually became greyish green to dark brown with age. Conidiophores were subhyaline to light brown, 3- to 10-septate, up to 200 μm in length, and 4 to 7 μm in width, with apical cell slightly to distinctly swollen, bearing a single spore at the apex. Conidia were muriform, mostly oblong to ovoid, but occasionally nearly globose, subhyline to variant shades of brown, mostly constricted at the median septum, 22.6 ± 6.22 (11.9 to 36.9) μm in length, and 15.1 ± 2.85 (8.3 to 22.6) μm in width, with 1 to 8 transverse and 0 to 5 longitudinal septa. DNA from a representative single-spore isolate was extracted and the internal transcribed spacer region (ITS) of ribosomal DNA (rDNA) was amplified using the universal primers ITS5 and ITS4. The PCR product was sequenced and deposited in GenBank (Accession No. JX481911). On the basis of morphological characteristics (3) and a BLAST search with 100% identity to the published ITS sequence of a S. solani isolate in GenBank (EF0767501), the fungus was identified as S. solani. Pathogenicity tests were performed by spraying a conidial suspension (105 conidia ml–1) on healthy cucumber (cv. Knossos), melon (C. melo, cv. Galia), watermelon (Citrullus lanatus cv. Crimson sweet), pumpkin (Cucurbita pepo, cv. Rigas), and sponge gourd (Luffa aegyptiaca, local variety) plants, at the 5-true-leaf stage. Disease symptoms appeared on cucumber and melon only, which were similar to those observed under natural infection conditions on cucumber. S. solani was consistently reisolated from artificially infected cucumber and melon tissues, thus confirming Koch's postulates. The pathogenicity test was repeated with similar results. In 1918, a report of a Stemphylium leaf spot of cucumber in Indiana and Ohio was attributed to Stemphylium cucurbitacearum Osner (4), but that pathogen has since been reclassified as Leandria momordicae Rangel (2). That disease was later reported from Florida (1) and net spot was suggested as a common name for that disease. For the disease reported here, we suggest the name Stemphylium leaf spot. This is the first report of a disease of cucumber caused by a species of Stemphylium. References: (1) C. H. Blazquez. Plant Dis. 67:534, 1983. (2) P. Holliday. Page 243 in: A Dictionary of Plant Pathology. Cambridge University Press, Cambridge, UK, 1998. (3) B. S. Kim et al. Plant Pathol. J. 15:348, 1999. (4) G. A. Osner. J. Agric. Res. 13:295, 1918.

Sign in / Sign up

Export Citation Format

Share Document