scholarly journals First Report of Leaf Spot Caused by Diaporthe tulliensis on Boston Ivy (Parthenocissus tricuspidata) in Taiwan

Plant Disease ◽  
2021 ◽  
Author(s):  
Cheng-Chun Huang ◽  
Hsien-Hao Liu ◽  
Ping-Hu Wu ◽  
Hao-Xun Chang
Keyword(s):  
Leaf Spot ◽  
Elongation Factor ◽  
Average Diameter ◽  
Vitis Vinifera L ◽  
Post Inoculation ◽  
Leaf Spots ◽  
Parthenocissus Tricuspidata ◽  
Potential Damage ◽  
Whole Plants ◽  
Β Tubulin

Starting from the May to August 2020 (average humidity 76.6% and temperature 25.2°C in Taipei), Boston ivy (Parthenocissus tricuspidata) plants on the campus of National Taiwan University (25°01'05.4"N 121°32'36.6"E) exhibited leaf rusts caused by Phakopsora ampelopsidis (Tzean et al., 2019) and leaf spots caused by an unknown pathogen. The leaf spots appeared reddish to brown color and mostly irregular to round shape on the simple and trifoliate leaflets (Supplemental Figure 1A-C). The leaf spots were surface-disinfected with 1% NaOCl for 30 seconds, and the margin of healthy and infected tissues was cut and placed onto water agar, which were incubated at room temperature. Hyphae grown out from leaf spots were sub-cultured on potato dextrose agar (PDA), and the majority of isolates exhibited white colony with black pycnidial conidiomata embedded in PDA. The pycnidial conidiomata of two-week-old has an average diameter of 463±193 μm (n=30) and the sizes of α-conidia were 5.71±0.49 μm in length and 2.42±0.32 μm in width (n=50) similar to the previous records (Crous et al. 2015). The α-conidium was one-celled, hyaline, and ovoid with two droplets (Supplemental Figure 1D-G). This putative pathogen was re-inoculated to confirm its pathogenicity on the leaves of Boston ivy plants. A PDA block with actively growing fungal edge was placed on the tiny needle-wounded leaves of detached branches (Supplemental Figure H-I) and the whole plants in pots (Supplemental Figure 1J-M) in a moist chamber at 28°C in dark. Reddish to brown leaf spots were observed by 2 days post-inoculation (dpi) and the leaf spots expanded by 5 dpi. To complete the Koch’s postulates, the pathogen was re-isolated from inoculated leaves and the re-isolated pathogen exhibited identical morphology to the original isolate. The internal transcribed spacer (ITS), translational elongation factor subunit 1-α gene (EF1α), β-tubulin (BT), and calmodulin (CAL) was amplified using the primers ITS1/ITS4 (Martin and Rygiewicz. 2005), EF1-728F/EF1-986R, Bt2a/Bt2b, and CAL-228F/CAL-737R, respectively (Manawasinghe et al. 2019). Using BLAST in the NCBI database, the ITS (MT974186), EF1α (MT982963), and β-tubulin (MT982962) sequences showed 98.57% (NR_147574.1, 553 out of 561 bp), 98.04% (KR936133.1, 350 out of 357 bp), and 99.23% (KR936132.1, 518 out of 522 bp) identity to the Diaporthe tulliensis ex-type BRIP 62248a, respectively (Dissanayake et al. 2017). Phylogenetic analysis using concatenated sequences of ITS, EF1α, and β-tubulin grouped the D. tulliensis isolated from Boston ivy leaf spots with the D. tulliensis ex-type (Supplemental Figure 1N). In summary, the morphological and molecular characterizations supported the causal pathogen of Boston ivy leaf spot as D. tulliensis. While Diaporthe ampelopsidis was reported to infect Parthenocissus quinquefolia and P. tricuspidata (Anonymous, 1960; Wehmeyer, 1933), there is no record for D. tulliensis infecting Boston ivy according to the USDA National Fungus Collections (Farr and Rossman. 2020). Because pathogens of Boston ivy such as P. ampelopsidis may also infect close-related crops like grape (Vitis vinifera L.) and D. tulliensis has been known to infect kiwifruits (Actinidia chinensis) and cocoa (Theobroma cacao) (Bai et al. 2016; Yang et al. 2018), the emergence of D. tulliensis should be aware to avoid potential damage to economic crops.

scholarly journals Molecular Phylogenetic Diversity and Biological Characterization of Diaporthe Species Associated with Leaf Spots of Camellia sinensis in Taiwan

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1434
Author(s):  
Hiran A. Ariyawansa ◽  
Ichen Tsai ◽  
Jian-Yuan Wang ◽  
Patchareeya Withee ◽  
Medsaii Tanjira ◽  
...  
Keyword(s):  
Camellia Sinensis ◽  
Leaf Spot ◽  
Phylogenetic Trees ◽  
Fungal Infections ◽  
Elongation Factor ◽  
Fungal Species ◽  
Tea Leaves ◽  
Phenotypic Characters ◽  
Leaf Spots ◽  
Molecular Phylogenetic

Camellia sinensis is one of the major crops grown in Taiwan and has been widely cultivated around the island. Tea leaves are prone to various fungal infections, and leaf spot is considered one of the major diseases in Taiwan tea fields. As part of a survey on fungal species causing leaf spots on tea leaves in Taiwan, 19 fungal strains morphologically similar to the genus Diaporthe were collected. ITS (internal transcribed spacer), tef1-α (translation elongation factor 1-α), tub2 (beta-tubulin), and cal (calmodulin) gene regions were used to construct phylogenetic trees and determine the evolutionary relationships among the collected strains. In total, six Diaporthe species, including one new species, Diaporthe hsinchuensis, were identified as linked with leaf spot of C. sinensis in Taiwan based on both phenotypic characters and phylogeny. These species were further characterized in terms of their pathogenicity, temperature, and pH requirements under laboratory conditions. Diaporthe tulliensis, D. passiflorae, and D. perseae were isolated from C. sinensis for the first time. Furthermore, pathogenicity tests revealed that, with wound inoculation, only D. hongkongensis was pathogenic on tea leaves. This investigation delivers the first assessment of Diaporthe taxa related to leaf spots on tea in Taiwan.

scholarly journals First Report of Curvularia gladioli Causing a Leaf Spot on Gladiolus grandiflorus in Brazil

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 847-847 ◽  
Author(s):  
D. P. Torres ◽  
M. A. Silva ◽  
D. B. Pinho ◽  
O. L. Pereira ◽  
G. Q. Furtado
Keyword(s):  
Leaf Spot ◽  
Central Cell ◽  
Post Inoculation ◽  
Intermediate Cell ◽  
Conidial Suspension ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
The Third ◽  
Leaf Spots

Gladiolus (Iridaceae) is a popular bulbous plant grown worldwide as an ornamental garden plant or cut flower due to its attractive color, size, and flower shape. In April 2012, leaf spots were observed on plants of Gladiolus grandiflorus varieties T-704 and Amsterdam growing in a production area of cut flowers located in the city of Viçosa, Minas Gerais. The oval to round leaf spots were brown with a dark border surrounded by a halo of yellow tissue. Infected leaf samples were deposited in the herbarium at the Universidade Federal de Viçosa (VIC31897). A fungus was isolated from the leaf spots and a single-spore pure culture was initiated and grown on corn meal carrot agar (CCA) medium in petri dishes incubated at 25°C under a 12-h photoperiod for 4 weeks. A sporulating single-spore culture was deposited at the Coleção de Culturas de fungos fitopatogênicos “Prof. Maria Menezes” (UFRPE, Brazil) code CMM 4055. On CCA medium, the fungal isolate initially appeared white, becoming dark after 14 days. Thirty conidia and conidiophores were measured for identification to species. The septate, smooth to pale brown conidiophores were present singly or in groups. The simple, straight or flexuous conidiophores were 42.5 to 82.5 × 3.5 to 7.5 μm and some had a geniculate growth pattern. The majority of conidia were curved at the third (central) cell from the base, which was usually enlarged compared to the end cells. The cells at each end of the 3-distoseptate conidia were pale brown, the intermediate cell brown or dark brown, and the third (central) cell was often the darkest. The basal cell had a protuberant hilum. Conidia were smooth and 20.0 to 33.5 × 10 to 17.5 μm. These characteristics matched well with the description of Curvularia gladioli (1). To confirm this identification, DNA was extracted using a Wizard Genomic DNA Purification Kit and the internal transcribed spacer region (ITS) of rDNA was amplified using ITS1 and ITS4 primers and the partial 28S rDNA region using primers LR0R and LR5. The sequences were deposited in GenBank as accession nos. JX995106 and JX995107, respectively. The ITS sequence matched sequence AF071337, C. gladioli, with 100% identity. This pathogen was first identified as C. lunata, but based on the characteristic of the hilum, spore size, and pathogenicity testing, the fungus was renamed C. trifolii f. sp. gladioli (3). Due to the explicit curvature of the conidia at the third cell and molecular data, the fungus was reclassified as C. gladioli (1,2). To confirm Koch's postulates, 1-month-old healthy plants of G. grandiflorus var. T-704 and Amsterdam (five plants each) were inoculated with a conidial suspension (2 × 104 conidia mL–1) by spraying the foliage and then placed on a growth chamber at 25°C. The control plants were sprayed with distilled water. Symptoms were consistent with those initially observed and all plants developed leaf spots by 4 days post-inoculation. C. gladioli was consistently recovered from the symptomatic tissue and control plants remained symptomless. To our knowledge, this is the first report of C. gladioli causing leaf spot on G. grandiflorus in Brazil. Due to a lack of chemical fungicides for management of this pathogen, further studies to evaluate the susceptibility of the main varieties of gladiolus grown in Brazil to C. gladioli may be necessary. References: (1) G. H. Boerema and M. E. C. Hamers. Neth. J. Plant Pathol. 95:1, 1989. (2) D. S. Manamgoda et al. Fungal Divers. 56:131, 2012. (3) J. A. Parmelee. Mycologia 48:558, 1956.

scholarly journals First Report of Phomopsis longicolla Causing Leaf Spot on Soybean in China

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 290-290
Author(s):  
C. S. Xue ◽  
Y. Y. Lu ◽  
S. Q. Xiao ◽  
Y. X. Duan
Keyword(s):  
Nucleotide Sequence ◽  
Leaf Spot ◽  
Nucleotide Sequence Identity ◽  
Large Subunit ◽  
Elongation Factor ◽  
Translation Elongation ◽  
Phomopsis Longicolla ◽  
Sequence Identity ◽  
Leaf Spots ◽  
Translation Elongation Factor 1Α

During July 2012, leaf spots affecting 60% of the leaves were observed on soybean cultivar He Feng 60 in fields near Shenyang City, Liaoning Province, leading to 5 to 10% yield loss. The leaf spots were associated with the leaf margins and were irregularly shaped, with brown to black margins and surrounded by a thin, yellow halo. Often, several spots merged to form large necrotic areas, which contained numerous pycnidia on the underside of the leaf. Small pieces (5 mm2) were excised from the margin of diseased and healthy tissue, surface-sterilized in 70% ethanol solution for 30 s and 0.1% mercuric chloride solution for 1 min, washed in three changes of sterile distilled water, and transferred to plates containing potato dextrose agar (PDA). Cultures were maintained in an incubator at 25°C with a 12 h dark/light photoperiod for 5 to 7 days. On PDA, colonies were white with yellow areas, floccose, dense, and moderately fast growing, attaining a diameter of 3.9 mm after 5 days and 9.0 mm after 14 days. Finally, large black stromata appeared after 28 days at 25°C. The conidiomata pycnidia were black, stomatic, globose, length 83.6 to 232 μm, width 37.9 to 146.3 μm and produced α-conidia that were unicellular, hyaline, sometimes two-guttulate, length 4.75 to 8.25 μm, width 1.50 to 3.00 μm. β-Conidia were not observed. To confirm the morphological identification, the ribosomal internal transcribed spacers (ITS1-5.8S-ITS2) from isolates were sequenced (GenBank Accession No. KC460334). The PCR products were cloned into a pMD-19T Cloning Vector (Sangon Biotech, Shanghai, China). The clones were purified with TIANprep Mini Plasmid Kit (Tiangen Biotech, Beijing, China) to get the full-length ITS sequence. BLAST analysis of the isolates showed 100% nucleotide sequence identity with Phomopsis longicolla (AY745021). Four additional primer pairs—large subunit (NL1/NL4), beta-tublin gene (Bt2a/Bt2b), translation elongation factor 1α gene(EF1-728F/EF1-986R), and act gene(ACT-512F/ACT-783R) (1,2)—were amplified and sequenced as described above. The large subunit gene, β-tubulin gene, and translation elongation factor 1α gene from isolates were sequenced (Sangon Biotech). BLAST analysis indicated that the isolates had 100% nucleotide sequence identity with P. longicolla (AB107259, HQ333514, and AF398896). Because the act gene sequence of P. longicolla was not in the NCBI database, this sequence had 94% nucleotide sequence identity with P. cuppatea (JN230389). To fulfill Koch's postulates, five leaves on five healthy soybean plants were inoculated with a conidial suspension (106/ml). Plants inoculated with sterile water served as the noninoculated controls. Plants were incubated in the greenhouse at 25°C. All the inoculated leaves developed pinhead spots on the leaves, gradually increasing to large brown spots. Spots were irregularly shaped, brown and necrotic in the center, and surrounded by a yellow halo. Black pycnidia appeared after 10 days, whereas the noninoculated control plants remained asymptomatic. P. longicolla was consistently recovered from all inoculated plants, except the control. Morphological description of isolates was similar to that of Hobbs (3). However, as described by Hobbs and others, P. longicolla conidiomata pycnidia have prominent necks more than 200 μm long, opening by apical ostioles; locules are uniostiolate or multiostiolate, globose, up to 500 μm wide. The pycnidia size of isolates by frozen section method was smaller than that of Hobbs. Based on morphological and sequence comparisons, the pathogen of leaf spot disease is caused by P. longicolla. This is the first reported leaf spot caused by P. longicolla on soybean in China. References: (1) T. Boekhou et al. Stud. Mycol. 38:75, 1995. (2) P. W. Crous et al. Stud. Mycol. 75:37, 2013. (3) T. W. Hobbs et al. Mycologia 77:535, 1985.

scholarly journals Characterization of Neopestalotiopsis Species Associated with Mango Grey Leaf Spot Disease in Sinaloa, Mexico

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 788
Author(s):  
Saida S. Gerardo-Lugo ◽  
Juan M. Tovar-Pedraza ◽  
Sajeewa S. N. Maharachchikumbura ◽  
Miguel A. Apodaca-Sánchez ◽  
Kamila C. Correia ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Leaf Spot ◽  
Elongation Factor ◽  
Its Region ◽  
Morphological Characterization ◽  
Leaf Spot Disease ◽  
Grey Leaf Spot ◽  
Spot Disease ◽  
Leaf Spots ◽  
Mango Leaves

Mango is one of the most popular and nutritious fruits in the world and Mexico is the world’s largest exporter. There are many diseases that directly affect fruit yield and quality. During the period 2016–2017, leaves with grey leaf spots were collected from 28 commercial mango orchards distributed in two main production areas in Sinaloa State of Mexico, and 50 Neopestalotiopsis isolates were obtained. Fungal identification of 20 representative isolates was performed using morphological characterization and phylogenetic analysis based on the internal transcribed spacer (ITS) region of ribosomal DNA, part of the translation elongation factor 1-alpha (TEF) and the β-tubulin (TUB) genes. Phylogenetic analysis indicated that the 20 isolates from this study formed four consistent groups, however, overall tree topologies do not consistently provide a stable and sufficient resolution. Therefore, even though morphological and phylogenetic separation is evident, these isolates were not assigned to any new taxa and were tentatively placed into four clades (clades A–D). Pathogenicity tests on detached mango leaves of cv. Kent showed that the 20 isolates that belong to the four Neopestalotiopsis clades from this study and induce lesions on mango leaves. This is the first report of species of Neopestalotiopsis causing mango grey leaf spot disease in Mexico.

scholarly journals First Report of Leaf Spot Disease on Cinnamomum camphora (Camphor tree) Caused by Epicoccum poaceicola in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Da Li ◽  
Tianning Zhang ◽  
Qingni Song ◽  
Jun Liu ◽  
Haiyan Zhang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Leaf Growth ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Post Inoculation ◽  
Cinnamomum Camphora ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Camphor Tree

As an important industrial, pharmaceutical and evergreen shade tree (Singh and Jawaid 2012), the camphor tree (Cinnamomum camphora) has been coppiced in Jiangxi Province, China. From 2017 to 2020, we noticed many camphor trees with leaf spots, with an incidence estimated at 50 to 75%, which could severely inhibit leaf growth and reduce their biomass. A dark-green circle with a watery spot appeared on the infected leaves at the initial stage, and necrosis with forming shot-spots surrounded by yellow halos occurred (Figure 1 A). Five leaves with typical symptoms were sampled and washed with tap water for ca. 15 min. Isolation and morphological analysis were performed following the method of Bao et al. (2019). Among 61 fungal isolates, 49 showed the same culture characters. Colonies on PDA were villose and regular, the reverse was scarlet at the edge of the colony, which was ca. 8.75 cm after 7 days of inoculation (Figure 1 I). Chlamydospores were aseptate, dark brown, smooth, in chains or solitary, ellipsoidal to ovoid, 4.8–9.6 × 4.8–11.1 μm (Figure 1 J). The pycnidia were produced on PDA and varied from 47.4 to 85.8 µm (mean 60.2 µm) × 38.6 to 66.8 μm (mean 49.7 μm) (n = 17) (Figure 1 K). Conidia were hyaline, unicellular, elliptical to ovoid, 4.3-6.4 µm (mean 5.1 µm) × 2.3-3.3 µm (mean 2.8 µm) (n = 52) (Figure 1 L). Pathogenicity tests of isolate XW-9 was carried out in the field. Ten leaves were wounded with a sterilized insect needle and inoculated with mycelium plugs (7-mm diameter). Non-colonized PDA plugs served as the negative controlIn addition, conidial suspensions (105 conidia/mL) of isolate XW-9 were sprayed on surface-sterilized leaves with a further ten leaves being sprayed with sterile water as the control. Symptoms described in this study appeared in 100% of the mycelium-inoculated leaves and more than 80% of the conidium-inoculated leaves after 7 days post-inoculation (Figure 1 B-E). No symptoms were seen in the controls (Figure 1 C). Three days after inoculation, brown spots resembling those observed in the field developed on the inoculated leaves, and some lesions turned into shot holes on the infected leaves (Figure 1 G & H). However, no symptoms were observed on the controls (Figure 1 F). The fungus was re-isolated from the margins of the leaf spots and labelled P-XW-9A. The gene regions for ITS, LSU, tub2, RPB2 and ACT of isolates XW-9 and P-XW-9A were amplified and sequenced. The sequences of rDNA-ITS, LSU, tub2, RPB2 and ACT of XW-9 were GenBank MW142397, MW130844, MW165322, MW446945 and MW165324, respectively and those of P-XW-9A were GenBank MW142398, MW130845, MW165323, MW446946 and MW165325, respectively (Lumbsch, et al. 2000; Aveskamp, et al. 2009; Hou et al. 2020). Phylogenetic analysis using concatenated sequences of ITS, LSU, RPB2, and tub2 showed that isolates XW-9 and P-XW-9A formed a single clade with the reference strain of E. poaceicola CBS 987.95 (Figure 2). Thus, XW-9 was identified as E. poaceicola based on its morphological and molecular characteristics. Significantly, the recovered isolate P-XW-9A also aligned with E. poaceicola fulfilling the criteria for Koch's Postulates. E. poaceicola was only reported as a fungal pathogen of Phyllostachys viridis in China (Liu et al. 2020). To our knowledge, this is the first report of leaf spot disease on camphor trees caused by E. poaceicola in China and our findings will be useful for its management.

scholarly journals First Report of Alternaria alternata Causing Black Leaf Spot of Rubber Tree in China

Plant Disease ◽  
2015 ◽  
Vol 99 (2) ◽  
pp. 290-290 ◽  
Author(s):  
Z. Y. Cai ◽  
Y. X. Liu ◽  
G. H. Li ◽  
Y. F. Wang ◽  
M. Zhou
Keyword(s):  
Alternaria Alternata ◽  
Leaf Spot ◽  
Rubber Tree ◽  
Morphological Characteristics ◽  
Correct Identification ◽  
Post Inoculation ◽  
First Report ◽  
Leaf Spots ◽  
Plastic Bags ◽  
Black Leaf Spot

We first reported Alternaria heveae (E.G. Simmons ) to be the pathogen that caused black leaf spot of rubber tree (Hevea brasiliensis Muell. Arg) in Heikou county in July 2014 (1). Black leaf spots that resembled the symptoms caused by A. heveae were observed on the leaves of rubber trees of the whole propagule collection nursery in Jingping County (22°68′ N and 103°05′ E) of Yunnan Province. Black foliar spots (0.1 to 2 mm in diameter) surrounded by a yellow halo with lesions slightly sunken on the leaf surface were observed. To confirm whether the disease was caused by the same pathogen, 5-mm2 sections were removed from the leading edge of the lesion and were surface-sterilized in 75% ethanol, air-dried, plated on potato carrot agar (PCA), and incubated at 28°C in the dark. Colonies of the fungus on PCA had round margins and little aerial mycelia with gray-black coloration after 6 days of growth on PCA (2). Medium brown conidia were found to be in short chains of two to eight spores, ovoid, obclavate, and obpyriform, with or without a short conical or cylindrical-shaped apical beak. Conidia ranged from 22.5 to 67.5 μm long (mean 39.9 μm) × 10 to 15 μm wide (mean 12.5 μm; 100 colodia were measured), with three to six transverse septa and zero to three longitudinal or oblique septa. Morphological characteristics matched the descriptions of A. alternata [(Fries) Keissler] (4).The ITS1-5.8S-ITS2 region of one single-spore isolate, Ah02JP1, was amplified with primers ITS1 and ITS4. The PCR product was sequenced directly and deposited in GenBank (Accession No. KM111289). A BLAST search of the GenBank database revealed 100% similarity with A. alternata isolates KJ829535.1, KJ677246.1, and KF813070.1. Therefore, the pathogen was identified as A. alternata on the basis of its morphological characteristics and ITS sequence. Pathogenicity of a representative isolate, Ah02JP1 was confirmed using a field rubber tree inoculation method. Three rubber plants (the clone of rubber tree Yunyan77-4) were grown to the copper-colored leaf stage. Leaves were spray-inoculated (104 conidia per milliliter spore suspension) until drops were equally distributed using a manual pressure sprayer. Three rubber plants sprayed with sterile distilled water were used as controls. After inoculation, the plants were covered with plastic bags to maintain high relative humidity. The plastic bags were removed 2 days post-inoculation (dpi), and the plants were monitored daily for symptom development. Five days post-inoculation, spots similar to the original ones seen on the field trees developed on all inoculated leaves, while control leaves remained symptomless. A. alternata was re-isolated from spray-inoculated leaves, confirming Koch's postulates. A. alternata has been reported as the causal agent of leaf blight of rubber tree in India, which initially appeared as minute spots on leaves and enlarged with the growth of the leaves (3). However, in the present study, the symptoms (black leaf spots) remained small over time after inoculation. To our knowledge, this is the first report of A. alternata on rubber tree in China. Correct identification of pathogens is essential for disease management strategies. This report will establish a foundation for the further study of Alternaria alternata to address the disease effectively. References: (1) Z. Y. Cai et al. Plant Dis. 98:1011, 2014. (2) E. Mirkova. J. Phytopathol. 151:323, 2003. (3) C. B. Roy et al. J. Plantation Crops 34:499, 2006. (4) T. Y. Zhang. Page 32 in: Flora Fungorum Sinicorum, Vol. 16: Alternaria. Science Press, Beijing, 2003.

scholarly journals First Report of Epicoccum nigrum Causing Brown Leaf Spot in Tea in Guizhou Province, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Qiaoxiu Yin ◽  
Shilong Jiang ◽  
Dongxue Li ◽  
Honglin Huang ◽  
Yong Wang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Guizhou Province ◽  
Post Inoculation ◽  
Conidial Suspension ◽  
Causal Organism ◽  
First Report ◽  
Epicoccum Nigrum ◽  
Leaf Spots ◽  
Brown Leaf ◽  
Tea Plants

Brown leaf spots were observed on tea [Camellia sinensis (L.) Kuntze] in Sinan County (27.74 °N, 108.35 °E) and Kaiyang County (27.96 °N, 107.34 °E), Guizhou Province, China, from 2018 to 2020. For the leaf spots with the typical symptoms, the disease incidence was estimated to range between 56% and 61%, respectively. The disease severity was estimated to range from 39 to 43 across 12 tea plantations, respectively. The disease initially occurred at the margins of leaf tips, and the lesions expanded gradually, being dark brown and irregularly shaped and became necrotic. To identify the causal organism, two leaves from each of 15 tea twigs, one or two per plantation, were detached from 8- or 10-year-old tea plants on each of 12 plantations. Samples taken from the lesion margins were sterilized with 75% ethanol followed by 0.5% NaOCl, placed on potato dextrose agar (PDA), and then incubated at 25oC in darkness for 5 days (Wang et al. 2020). For each sample, hyphal tips from the margin of a growing colony were successively transferred to fresh PDA, and pure cultures were obtained. Three representative strains were grown on PDA, malt extract agar (MEA), and oatmeal agar (OA) plates. The colonies had smooth margins and abundant mycelia on all three media, with the colony colors being from gray to light purple on PDA, white on MEA, and purplish-red on OA at 5 days post-inoculation. At 20 days post-inoculation on MEA, stromata began to gradually form, which were droplet-like, 100 to 2,000 μm in diameter, and semi-immersed on the medium’s surface. Black sporodochia were produced on the surfaces of stromata. Conidiophores were aggregated in sporodochia, densely compacted, and dark brown. Conidia were globose or pyriform, dark, multicellular, and measured 22.95 ± 3.59 × 19.82 ± 3.13 μm (n = 50) in diameter. The morphological characteristics of the mycelia and reproductive structures of the strains were identical to those of Epicoccum nigrum. The internal transcribed spacer (ITS) region of rDNA, and the partial 28S large subunit rDNA (LSU), RNA polymerase II second largest subunit (RPB2), and beta-tubulin (TUB) genes of these strains were amplified using the primers V9G/ITS4 (De Hoog and Gerrits van den Ende 1998; White et al. 1990), LR0R/LR5 (Rehner and Samuels 1994), RPB2-5F2/fRPB2-7cR (Sung et al. 2007), and TUB2Fd/TUB4Rd (Woudenberg et al. 2009), respectively, and deposited in GenBank (accession no. MW646378, MW291537, MW602293, and MW602295 for ITS, LSU, RBP2, and TUB, respectively). A maximum parsimony phylogenetic analysis indicated that the representative strains clustered with E. nigrum CBS 173.73 (Chen et al. 2017). Pathogenicity tests were performed on 5-year-old potted tea and on 10-year-old C. sinensis cv. Fuding-dabaicha in the field. Mycelial plugs (6-mm diam.) and a conidial suspension (106 conidial/mL) were applied on punctured leaves using a sterile needle and non-punctured leaves. Inoculation with only a PDA plug or sterile water served as controls. Brown spots appeared on the wounded sites of tea leaves at 2 days post-inoculation. No symptoms were observed on the non-wounded leaves or wounded leaves inoculated with PDA plugs lacking mycelia. The re-isolated pathogen from diseased plants was identical to the purified strain ACCC39731 used for inoculation, with re-isolation frequency being 85.0%. To our knowledge, this is the first report of E. nigrum causing leaf spot on tea plants in China, and our findings will be useful for its management and further research.

scholarly journals Pseudocercospora and allied genera associated with leaf spots of banana (Musa spp.)

2020 ◽  
Author(s):  
P.W. Crous ◽  
J. Carlier ◽  
V. Roussel ◽  
J.Z. Groenewald
Keyword(s):  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Sequence Data ◽  
Elongation Factor ◽  
Leaf Spot Disease ◽  
Black Sigatoka ◽  
Dna Sequence Data ◽  
Leaf Spots ◽  
Black Leaf Streak ◽  
Close Relatives

The Sigatoka leaf spot complex on Musa spp. includes three major pathogens: Pseudocercospora, namely P. musae (Sigatoka leaf spot or yellow Sigatoka), P. eumusae (eumusae leaf spot disease), and P. fijiensis (black leaf streak disease or black Sigatoka). However, more than 30 species of Mycosphaerellaceae have been associated with Sigatoka leaf spots of banana, and previous reports of P. musae and P. eumusae need to be re-evaluated in light of recently described species. The aim of the present study was thus to investigate a global set of 228 isolates of P. musae, P. eumusae and close relatives on banana using multigene DNA sequence data [internal transcribed spacer regions with intervening 5.8S nrRNA gene (ITS), RNA polymerase II second largest subunit gene (rpb2), translation elongation factor 1-alpha gene (tef1), beta-tubulin gene (tub2), and the actin gene (act)] to confirm if these isolates represent P. musae, or a closely allied species. Based on these data one new species is described, namely P. pseudomusae, which is associated with leaf spot symptoms resembling those of P. musae on Musa in Indonesia. Furthermore, P. eumusae, P. musae and P. fijiensis are shown to be well defined taxa, with some isolates also representing P. longispora. Other genera encountered in the dataset are species of Zasmidium (Taiwan leaf speckle), Metulocladosporiella (Cladosporium leaf speckle) and Scolecobasidium leaf speckle.

scholarly journals First Report of Leaf Spot Disease in Withania coagulans Caused by Alternaria alternata in India

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 420-420
Author(s):  
A. Sharma ◽  
V. Singh ◽  
G. Singh ◽  
P. K. Pati
Keyword(s):  
Medicinal Plant ◽  
Alternaria Alternata ◽  
Leaf Spot ◽  
Management Program ◽  
Leaf Spot Disease ◽  
Post Inoculation ◽  
Isolation Technique ◽  
Leaf Spots ◽  
Withania Coagulans ◽  
Initial Symptoms

Withania coagulans (Paneer doddi) is a medicinal plant in the Solanaceae (1) that grows in northwestern India. An unknown disease appeared in the Amritsar district of Punjab, India on W. coagulans starting in 2009, and was noticed annually in the post-monsoon seasons through 2011. The plants were grown in a net house (74.82323 to 74.82332°E, 31.63678 to 31.63688°N, 221 m elevation), Guru Nanak Dev University, Amritsar. Symptoms first appeared as brown to black spots (2 to 10 mm in diameter) that were sometimes surrounded by a yellow halo, starting on the lower leaves and gradually spreading to the upper leaves. Spots were apparent on both the dorsal and ventral sides of the leaves. In the most severe outbreak of the disease, more than 90% of the leaf area was covered with the leaf spot symptoms. The pathogen was isolated by placing pieces of surface-sterilized leaf spots on potato dextrose agar (PDA), and the hyphae that emerged from the leaf pieces were sub-cultured to PDA. Initially, the fungal colony was white, and gradually turned olive-brown as it matured. Conidiophores were mostly simple, usually becoming geniculate by sympodial elongation. Conidiophores were mostly branched and conidia were arranged in acropetal chains of 6 to 10. Conidia were 15 to 25 μm long and 5 to 10 μm wide, with 3 to 4 transverse septa and 2 to 3 longitudinal septa, muriform, ovoid to ellipsoid, with a broadly rounded base and an apical beak. Based on these morphological characters, the pathogen was identified as Alternaria alternata (Fr.) Keissler (4). The identification of the pathogen was also confirmed by MTCC, Chandigarh, India and deposited in their culture collection with Accession No. MTCC-10939 ( http://mtcc.imtech.res.in ). During preliminary studies, the optimum temperature for its growth was 25 ± 2°C. Pathogenicity of the fungus was demonstrated on three potted W. coagulans plants after spray-inoculating leaves with a spore suspension of 3 × 105 spores per ml. A batch of three plants sprayed with sterile distilled water served as controls. Both inoculated and control plants were incubated at 100% relative humidity for 5 days and transferred to a glasshouse at 25 ± 2°C. Initial symptoms developed on a few plants at 5 to 7 days post-inoculation, and the same leaf symptoms described above from field plants became apparent on all inoculated plants by 10 to 14 days. Control plants did not develop symptoms. The pathogen was recovered from leaf spots using the isolation technique described above, and was identified as A. alternata, thus fulfilling Koch's postulates. Although the leaf spot diseases caused by A. alternata and A. dianthicola were reported on W. somnifera (2,3), to the best of our knowledge, there is no report of either pathogen infecting W. coagulans. Thus, the identification of pathogen will facilitate the disease management program and for enhancing the commercial value of this important endangered medicinal plant. References: (1) S. A. Gilani et al. Afr. J. Biotechnol. 8:2948, 2009. (2) C. K. Maiti et al. Plant Dis. 91:467, 2007. (3) P. K. Pati et al. Indian J Microbiol. 48:432, 2008. (4) E. G. Simmons. Alternaria: An identification manual. American Phytopathological Society, St. Paul, MN, 2007.

First Report of Leaf Spot Caused by Septoria villarsiae on Nymphoides peltata in the United States

2021 ◽  
pp. PHP-12-20-0104-
Author(s):  
Monique De Souza ◽  
Raghuwinder Singh ◽  
Nathan E. Harms ◽  
John McPhedran ◽  
Alicyn N. Smart
Keyword(s):  
United States ◽  
The Netherlands ◽  
Leaf Spot ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
The United States ◽  
Aquatic Weed ◽  
First Report ◽  
Leaf Spots ◽  
Nymphoides Peltata

Nymphoides peltata, commonly known as yellow floating heart, is a freshwater aquatic plant with floating leaves. It is a highly invasive aquatic weed that has been introduced into several countries, including Ireland, New Zealand, Sweden, and the United States. In September 2019, N. peltata plants exhibiting leaf spots were collected from a private pond near Buxton, York County, Maine. Leaf spots were present on a majority of plants, and pycnidia were observed in the center of the spots. Individual pycnidia were aseptically transferred to 1/4-strength potato dextrose agar. Dark gray to black slow-growing colonies were observed between 7 and 14 days. Based on the morphological characteristics, the fungus was identified as Septoria sp. Translation elongation factor 1-alpha gene was amplified, and a 570-bp sequence resulted in 100 and 99.74% homology with Septoria villarsiae strains CBS565.88 and CBS514.78 isolated from N. peltata in the Netherlands, respectively. Previously, S. villarsiae has been reported on Limnanthemum nymphoides from India and on N. peltata from Korea, Poland, Romania, and the Netherlands. To our knowledge, this is the first report of leaf spot caused by S. villarsiae on N. peltata in the United States.

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