scholarly journals First Report of Lasiodiplodia theobromae and L. pseudotheobromae Causing Canker Disease of Sacha Inchi in Hainan, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Weiwei Wang ◽  
Xiqiang Song
Keyword(s):  
Phylogenetic Analysis ◽  
Tap Water ◽  
Disease Incidence ◽  
Gene Bank ◽  
Sodium Hypochlorite Solution ◽  
Pathogenicity Test ◽  
Oilseed Crop ◽  
Canker Disease ◽  
First Report ◽  
Sacha Inchi

Sacha inchi (Plukenetia volubilis L.) belongs to the family Euphorbiaceae. It is a perennial wooden oilseed crop, and also exhibits a good source of polyunsaturated fatty acids, protein and other bioactive compounds, such as tocopherols, carotenes and phytosterols (Chirinos et al. 2013). During 2017-2018 survey, canker disease showing greyish-brown sunken lesions was observed on the branches of sacha inchi in Danzhou campus, Hainan University, China. The disease incidence is less than 5%. However, it can lead to leaf yellowing, wilt, and eventually the whole plant death. In Nov. 2017, twelve branches showing the typical canker symptoms were collected and covered with parafilm at both ends of all samples to prevent desiccation and placed in black plastic bags keeping at 4°C until isolations were made. Samples were rinsed with tap water and dried with paper towels. Fragments, 5mm in length and cut from the junction of diseased and healthy parts of branches, were surface-sterilized with 2% sodium hypochlorite solution for 2 min, rinsed with sterilized distilled water for 5 times, dried by sterilized filter paper, plated on PDA medium amended with 100 μg/mL streptomycin (PDA-str) and incubated in the dark for 4 days at 28°C. Pure cultures of fungal isolates were obtained by transferring mycelial fragments from colony margins onto fresh PDA plates and incubated as described before. The colonies of cultures were initially white, and eventually turned black after 4 days on PDA medium (Fig S1A). The morphology characterization of conidia produced by the isolates was initially hyaline and aseptate (Fig S1B), and a single median septum formed in the mature conidia (Fig S1B). The average size of 50 conidia was 16.39±1.46ⅹ 8.52±0.92μm for J6, and 15.64±1.73ⅹ 8.94±0.86μm for J3. Three genes were used for phylogenetic analysis (Alves et al. 2006). ITS regions and the partial of TUB (β-tubulin gene) were amplified using the primer pairs ITS1 and ITS4 (White et al. 1990), Bt2a and Bt2b (Glass and Donaldson 1995), respectively, and EF1-688F/EF1-1251R for J3 and EF1-728F/EF1-986R for J6 were used to amplify TEF (translation elongation factor 1-alpha) (Alves et al. 2008). The sequences of ITS, TUB and TEF from J3 and J6 were deposited in Gene-Bank (Table S1). The blast searches in Gene-Bank with ITS, TUB and TEF amplified from isolates J3, respectively, revealed 100, 99, and 100% identities with L. pseudotheobromae, and isolate J6 showed 100, 100 and 99% of identity with L. theobromae. The phylogenetic analysis of the combined ITS, TUB and TEF sequences of J3, J6 and 28 reference strains retrieved from Gene-Bank was performed using the program MEGA 6.0 evaluated by 1000 bootstrap replications, and the result was consistent with the conclusion above (Fig S2). With the phylogenic studies supported by morphological characters, J3 was identified as L. pseudotheobromae and J6 was L. theobromae. For the pathogenicity test, J3 and J6 were used to inoculate 4-week-old healthy sacha inchi potted seedlings. One wound about 5 mm in depth per seedling stem was made using a sterile blade. A 5-mm-diameter mycelium plug of each isolate taken from the edge of 4-day-old culture growing on PDA was placed to the freshly wound of each plant stem and the inoculated area was wrapped with Parafilm. Sterile PDA plugs were placed onto the wounds of control seedlings. Nine healthy seedlings were inoculated with each isolate or PDA plugs in a completely randomized design. After inoculation, plants were placed in a greenhouse at room temperature (26 to 30°C, 80% RH) and were irrigated when needed. The experiment was conducted twice. Five days later, black or dark-brown canker lesions formed on the stems of inoculated plants, and expended upward and downward from the inoculation points. Pycnidia produced on the necrotic regions and were used to to observe the morphology of conidia (Fig S3). The fungus L. pseudotheobromae or L. theobromae can be re-isolated from the inoculated plants, but not from the control ones. L. pseudotheobromae was recorded to be collected from dead leaves of P. volubilis in Yunnan Province, China, but did not prove this fungus to be pathogenic (Tennakoon et al. 2016). This is the first report that L. theobromae and L. pseudotheobromae causing stem canker in sacha inchi in Hainan, China. The results pave the way for the development of management strategies for canker disease in sacha inchi.

scholarly journals First Report of Fusarium culmorum and Microdochium bolleyi Causing Root Rot on Triticale in Kazakhstan

Plant Disease ◽  
2021 ◽  
Author(s):  
Mehtap Alkan ◽  
Göksel Özer ◽  
İmren Mustafa ◽  
Fatih OZDEMIR ◽  
Alexei Morgounov ◽  
...  
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Fusarium Culmorum ◽  
Gaeumannomyces Graminis ◽  
Control Treatment ◽  
Sodium Hypochlorite Solution ◽  
Pathogenicity Test ◽  
First Report ◽  
Agar Plug ◽  
Microdochium Bolleyi

Triticale (×Triticosecale Wittmack) is obtained from wheat × rye crossing. It is positioned between wheat and rye in terms of resistance to soilborne pathogens including Gaeumannomyces graminis var. tritici, Fusarium culmorum, F. avenaceum, and Bipolaris sorokiniana (Arseniuk and Góral 2015). In 2019, seven triticale fields were surveyed in Almaty Province, Kazakhstan to examine soil-borne fungal pathogens. A total of 28 symptomatic plants with stunting, rot or discolored root were collected to identify causal agents. The overall disease incidence was approximately 8 to 10% in the fields. Fungi were isolated from 3-5 mm pieces excised from symptomatic tissues. The pieces were exposed to surface disinfection in 1% sodium hypochlorite solution for 2 min, rinsed three times with sterile distilled water, blotted dry, and plated on 1/5 strength potato dextrose agar (PDA) amended with 0.01% streptomycin. Plates were left in the dark at 23°C for 7 days. A total of 34 fungal colonies were isolated of which nineteen isolates, originally from six fields showed the cultural characteristics of B. sorokiniana. This species was previously reported to cause common root rot on triticale in Kazakhstan (Özer et al. 2020). Ten isolates from four fields produced pale orange and cottony mycelium with red pigmentation on the agar, which is typical of Fusarium-like growth. The remaining isolates (n=5) from two fields produced salmon-colored and scarce aerial mycelium with no soluble pigmentation, similar to Microdochium spp. Fusarium isolates produced thick-walled and curved macroconidia with 3-4 septa (n=50, 25.7 to 37.6 × 4.1 to 7.3 μm in size) and notched basal cell on PDA, but microconidia were absent, which matches the description of F. culmorum (Wm.G. Sm.) Sacc. (Leslie and Summerell 2006). Microdochium isolates produced swollen, brown, and thick-walled chlamydospores and hyaline, one-celled, and thin-walled conidia (n=50, 5.4 to 9.3 × 1.5 to 3.0 μm in size) formed on ampullate and cylindrical conidiogenous cells on oatmeal agar (OA). These morphological features are consistent with previous observations for Microdochium bolleyi (R. Sprague) de Hoog & Herm.-Nijh. (Hong et al. 2008). To confirm morphological preliminary identifications, the portion of the translation elongation factor 1-alpha (EF1-α) gene was amplified with EF1/EF2 primers (O’Donnell et al. 1998) for representative Fusarium isolates (n=4) for each field. Additionally, the internal transcribed spacer (ITS) of ribosomal DNA was amplified with ITS1/ITS4 primers (White et al. 1990) for representative Microdochium isolates (n=2) for each field. BLASTn queries against NCBI GenBank revealed that the EF1-α sequences of Fusarium isolates (MW311081-MW311084) shared 100% identity with F. culmorum strain CBS 110262 (KT008433). The ITS sequences of M. bolleyi isolates (MW301448-MW301449) matched that of M. bolleyi strain CBS 137.64 (AM502264) with 100% sequence similarity. Pathogenicity test was conducted on pregerminated seeds of triticale cv. Balausa. A plastic pot (17 cm height, 9 cm in diam) was filled with a sterile mixture of vermiculite, peat, and soil (1:1:1, v/v/v). Mycelial plugs (1 cm in diam) were cut from the margin of a growing culture of representative isolates (Kaz_Fus123 and Kaz_Mb01) and placed onto the mixture in the pot. A sterile agar plug was employed as a control treatment. One pregerminated seed was put on the plug and covered with the mixture. The pots were transferred to a growth chamber set at 23 ± 2°C and a photoperiod of 14 hours. The experiment was performed twice using 5 replication pots per isolate. Four weeks after inoculation, discoloration of the crown was observed on all the inoculated roots, whereas no symptoms were observed on the control plants. Koch’s postulates were fulfilled by reisolating and identifying the pathogen based on the morphology described above. This is the first report of M. bolleyi and F. culmorum causing root rot on triticale in Kazakhstan. Although B. sorokiniana is the most primary pathogen that may limit yield in the production of triticale in Kazakhstan, F. culmorum and M. bolleyi have been found to be less frequent and less aggressive pathogens, respectively. Further studies are needed to better understand the potential distribution and impact of these pathogens on triticale.

scholarly journals First report of leaf spot disease caused by Colletotrichum siamense on Cornus hongkongensis (Hemsl.) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Qing-Hai Wang ◽  
Yang Zhang ◽  
Yu-tong Zhang ◽  
Dong Li ◽  
Xiao-li Lin ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Bootstrap Support ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Accurate Identification ◽  
First Report ◽  
Colletotrichum Siamense

Cornus hongkongensis (Hemsl.) is an excellent ornamental tree species in China and elsewhere. In 2019, C. hongkongensis anthracnose was firstly observed at the campus of Jiangxi Agricultural University (JXAU) (28°45′56″N, 115°50′21″E), then found in parks, Nanchang, China. In early August, the disease appeared and lasted until the leaves dropped (November). The disease incidence was above 60%, and the diseased leaf rate was above 70%. The lesions mostly appeared along the leaf edges. Some small round to irregular lesions also developed in other parts of the leaves. These diseased leaves had circular or irregularly shaped spots with gray-white color in the center and dark brown on the edge of the lesions. Later, the lesions became necrotic and shriveled. As the disease progressed, the spots coalesced so that affected leaves appeared blighted (Supplementary Figure 1 A-C). To identify the pathogen, leaves with typical symptoms from the campus of JXAU were collected and small pieces (5 × 5 mm) from the lesion borders were surfaced sterilized in 70% ethanol for 30 s, followed by 1 min in 3% NaOCl, and then rinsed with sterile distilled water three times. Leaf pieces were placed on potato dextrose agar (PDA) and incubated at 25 °C under a 12-h light/dark cycle (3000 lx). Pure cultures were obtained from individual conidia by single spore isolates. For studies of microscopic morphology, a representative isolate JX-S4 was subcultured on PDA. The colony of JX-S4 was white and turning gray and light gray on the reverse side, producing dark-green pigmentation near the center (Supplementary Figure 1 D). The conidia were one-celled, straight, hyaline, subcylindrical with rounded ends and 16.9 ± 1.6 × 6.0 ± 0.6 µm (n = 50) in size. Appressoria were one-celled, pale brown, thick-walled, ellipsoidal, and measured 8.7 ± 1.7 × 6.4 ± 0.8 µm (n = 50) (Supplementary Figure 1 E, F). The morphological characteristics of JX-S4 matched those of the Colletotrichum siamense species (Weir et al. 2012). For accurate identification, the internal transcribed spacer (ITS) and the genes encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase (CHS-I), beta-tubulin 2 (TUB2), and calmodulin (CAL) were respectively amplified with primers ITS1/ITS4, GDF/GDR, CHS-79F/CHS-345R, βt2a/βt2b, and CL1/CL2. The sequences were deposited in GenBank (Accession nos. MT587807, MT628710, MT628709, MT628711, and MT628708). Phylogenetic analysis was calculated with concatenated sequences (ITS, GAPDH, CHS-I, CAL, and TUB2) using MEGA 7. In the maximum likelihood phylogenetic tree, Isolate JX-S4 was clustered with C. siamense with 93% bootstrap support (Supplementary Figure 2). Based on the morphological characteristics and phylogenetic analysis, JX-S4 was identified as C. siamense. Pathogenicity test of JX-S4 was verified on 45 attached healthy leaves from three C. hongkongensis plants (10-year-old) at the campus of JXAU inoculated with mycelial plugs (φ=5 mm) from the culture edge (6-day-old) on PDA. And an additional 45 healthy leaves were inoculated with PDA plugs as controls. The leaves were wounded with a red-hot needle (φ=0.5 mm). All treatment and control leaves were wrapped up with black plastic bags to keep them moist for 2 days. The pathogenicity tests were repeated twice. Within 7 days, all the inoculated leaves developed the lesions, which were similar to those observed in the field. Control leaves were asymptomatic (Supplementary Figure 1 G, H). The same fungus was re-isolated from the symptomatic tissues, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. siamense causing C. hongkongensis anthracnose. This finding provides crucial information for managing this disease. For example, when diagnosing Cornus anthracnose, C. siamense needs to be looked out for and appropriate control measures implemented.

scholarly journals First Report of Phytophthora drechsleri Associated with Stem and Foliar Blight of Gynura bicolor in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 874-874 ◽  
Author(s):  
Y. M. Shen ◽  
C. H. Chao ◽  
H. L. Liu
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Hyphal Growth ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
First Report ◽  
Foliar Blight ◽  
Dual Cultures ◽  
Phytophthora Drechsleri ◽  
Gynura Bicolor

Gynura bicolor (Roxb. ex Willd.) DC., known as Okinawa spinach or hong-feng-cai, is a commonly consumed vegetable in Asian countries. In May 2010, plants with blight and wilt symptoms were observed in commercial vegetable farms in Changhua, Taiwan. Light brown-to-black blight lesions developed from the top of the stems to the petioles and extended to the base of the leaves. Severely infected plants declined and eventually died. Disease incidence was approximately 20%. Samples of symptomatic tissues were surface sterilized in 0.6% NaOCl and plated on water agar. A Phytophthora sp. was consistently isolated and further plated on 10% unclarified V8 juice agar, with daily radial growths of 7.6, 8.6, 5.7, and 2.4 mm at 25, 30, 35, and 37°C, respectively. Four replicates were measured for each temperature. No hyphal growth was observed at 39°C. Intercalary hyphal swellings and proliferating sporangia were produced in culture plates flooded with sterile distilled water. Sporangia were nonpapillate, obpyriform to ellipsoid, base tapered or rounded, and 43.3 (27.5 to 59.3) × 27.6 (18.5 to 36.3) μm. Clamydospores and oospores were not observed. Oospores were present in dual cultures with an isolate of P. nicotianae (p731) (1) A2 mating type, indicating that the isolate was heterothallic. A portion of the internal transcribed spacer sequence was deposited in GenBank (Accession No. HQ717146). The sequence was 99% identical to that of P. drechsleri SCRP232 (ATCC46724) (3), a type isolate of the species. The pathogen was identified as P. drechsleri Tucker based on temperature growth, morphological characteristics, and ITS sequence homology (3). To evaluate pathogenicity, the isolated P. drechsleri was inoculated on greenhouse-potted G. bicolor plants. Inoculum was obtained by grinding two dishes of the pathogen cultured on potato dextrose agar (PDA) with sterile distilled water in a blender. After filtering through a gauze layer, the filtrate was aliquoted to 240 ml. The inoculum (approximately 180 sporangia/ml) was sprayed on 24 plants of G. bicolor. An equal number of plants treated with sterile PDA processed in the same way served as controls. After 1 week, incubation at an average temperature of 29°C, blight and wilt symptoms similar to those observed in the fields appeared on 12 inoculated plants. The pathogen was reisolated from the lesions of diseased stems and leaves, fulfilling Koch's postulates. The controls remained symptomless. The pathogenicity test was repeated once with similar results. G. bicolor in Taiwan has been recorded to be infected by P. cryptogea (1,2), a species that resembles P. drechsleri. The recorded isolates of P. cryptogea did not have a maximal growth temperature at or above 35°C (1,2), a distinctive characteristic to discriminate between the two species (3). To our knowledge, this is the first report of P. drechsleri being associated with stem and foliar blight of G. bicolor. References: (1) P. J. Ann. Plant Pathol. Bull. 5:146, 1996. (2) H. H. Ho et al. The Genus Phytophthora in Taiwan. Institute of Botany, Academia Sinica, Taipei, 1995. (3) R. Mostowfizadeh-Ghalamfarsa et al. Fungal Biol. 114:325, 2010.

scholarly journals First Report of Curvularia aeria on Etlingera linguiformis from Nagaland, India

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1580-1580 ◽  
Author(s):  
C. Kithan ◽  
L. Daiho
Keyword(s):  
Leaf Surface ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Indian Agricultural Research Institute ◽  
Mountain Range ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Conidial Suspension ◽  
First Report ◽  
Initial Symptoms

Etlingera linguiformis (Roxb.) R.M.Sm. of Zingiberaceae family is an important indigenous medicinal and aromatic plant of Nagaland, India, that grows well in warm climates with loamy soil rich in humus (1). The plant rhizome has medicinal benefits in treating sore throats, stomachache, rheumatism, and respiratory complaints, while its essential oil is used in perfumery. A severe disease incidence of leaf blight was observed on the foliar portion of E. linguiformis at the Patkai mountain range of northeast India in September 2012. Initial symptoms of the disease are small brown water soaked flecks appearing on the upper leaf surface with diameter ranging from 0.5 to 3 cm, which later coalesced to form dark brown lesions with a well-defined border. Lesions often merged to form large necrotic areas, covering more than 90% of the leaf surface, which contributed to plant death. The disease significantly reduces the number of functional leaves. As disease progresses, stems and rhizomes were also affected, reducing quality and yield. The diseased leaf tissues were surface sterilized with 0.2% sodium hypochlorite for 2 min followed by rinsing in sterile distilled water and transferred into potato dextrose agar (PDA) medium. After 3 days, the growing tips of the mycelium were transferred to PDA slants and incubated at 25 ± 2°C until conidia formation. Fungal colonies on PDA were dark gray to dark brown, usually zonate; stromata regularly and abundantly formed in culture. Conidia were straight to curved, ellipsoidal, 3-septate, rarely 4-septate, middle cells broad and darker than other two end cells, middle septum not median, smooth, 18 to 32 × 8 to 16 μm (mean 25.15 × 12.10 μm). Conidiophores were terminal and lateral on hyphae and stromata, simple or branched, straight or flexuous, often geniculate, septate, pale brown to brown, smooth, and up to 800 μm thick (2,3). Pathogen identification was performed by the Indian Type Culture Collection, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi (ITCC Accession No. 7895.10). Further molecular identity of the pathogen was confirmed as Curvularia aeria by PCR amplification and sequencing of the internal transcribed spacer (ITS) regions of the ribosomal DNA by using primers ITS4 and ITS5 (4). The sequence was submitted to GenBank (Accession No. MTCC11875). BLAST analysis of the fungal sequence showed 100% nucleotide similarity with Cochliobolus lunatus and Curvularia aeria. Pathogenicity tests were performed by spraying with an aqueous conidial suspension (1 × 106 conidia /ml) on leaves of three healthy Etlingera plants. Three plants sprayed with sterile distilled water served as controls. The first foliar lesions developed on leaves 7 days after inoculation and after 10 to 12 days, 80% of the leaves were severely infected. Control plants remained healthy. The inoculated leaves developed similar blight symptoms to those observed on naturally infected leaves. C. aeria was re-isolated from the inoculated leaves, thus fulfilling Koch's postulates. The pathogenicity test was repeated twice. To our knowledge, this is the first report of the presence of C. aeria on E. linguiformis. References: (1) M. H. Arafat et al. Pharm. J. 16:33, 2013. (2) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (3) K. J. Martin and P. T. Rygiewicz. BMC Microbiol. 5:28, 2005. (4) C. V. Suberamanian. Proc. Indian Acad. Sci. 38:27, 1955.

scholarly journals First report of Alternaria alternata causing leaf blight on little millet (Panicum sumatrense) in India.

Plant Disease ◽  
2020 ◽  
Author(s):  
Boda Praveen ◽  
A. Nagaraja ◽  
M. K. Prasanna Kumar ◽  
Devanna Pramesh ◽  
K. B. Palanna ◽  
...  
Keyword(s):  
Crop Yields ◽  
Disease Incidence ◽  
Leaf Blight ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Pcr Assay ◽  
Causal Organism ◽  
First Report ◽  
Little Millet

Little millet (LM) is a minor cereal crop grown in the Indian sub-continent. During October 2018, dark brown, circular to oval necrotic spots surrounded by concentric rings were observed on the upper leaf surface of the LM (cv. VS-13) grown in the fields of the University of Agricultural Sciences, Bengaluru, India (13.0784oN, 77.5793oE). As the disease progressed, infected leaves became blighted. Disease incidence up to 53% was recorded in 3 fields of 0.4-hectare area each. Thirty symptomatic leaves were collected to isolate the associated causal organism. The margins of diseased tissue were cut into 5 × 5-mm pieces, surface-sterilized in 75% ethanol for 45 seconds followed by 1% sodium hypochlorite for 1 min, finally rinsed in sterile distilled water five times and placed on PDA. After 7 days of incubation at 25°C, greyish fungal colonies appeared on PDA. Single-spore isolations were performed to obtain ten isolates. Pure cultures of the fungus initially produced light gray aerial mycelia that later turned to dark grey. All isolates formed obclavate to pyriform conidia measured 22.66-48.97μm long and 6.55-13.79µm wide with 1-3 longitudinal and 2-7 transverse septa with a short beak (2.55-13.26µm) (n=50). Based on the conidial morphology, the fungus was identified as Alternaria sp. Further, the taxonomic identity of all ten isolates was confirmed as A. alternata using species-specific primers (AAF2/AAR3, Konstantinova et al. 2002) in a PCR assay. Later, one of the isolate UASB1 was selected, and its internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh), major allergen Alt a 1 (Alt a 1), major endo-polygalacturonase (endoPG), OPA10-2, and KOG1058 genes were amplified in PCR (White et al. 1990; Berbee et al. 1999; Woudenberg et al. 2015), and the resultant products were sequenced and deposited in the NCBI GenBank (ITS, MN919390; gapdh, MT637185; Alt a 1, MT882339; endoPG, MT882340; OPA10-2, MT882341; KOG1058, MT882342). Blastn analysis of ITS, gapdh, Alt a 1, endoPG, OPA10-2, KOG1058 gene sequences showed 99.62% (with AF347031), 97.36% (with AY278808), 99.58% (with AY563301), 99.10% (with JQ811978), 99.05% (with KP124632) and 99.23% (with KP125233) respectively, identity with reference strain CBS916.96 of A. alternata, confirming UASB1 isolate to be A. alternata. For pathogenicity assay, conidial suspension of UASB1 isolate was spray inoculated to ten healthy LM (cv. VS-13) plants (45 days old) maintained under protected conditions. The spore suspension was sprayed until runoff on healthy leaves, and ten healthy plants sprayed with sterile water served as controls. Later, all inoculated and control plants were covered with transparent polyethylene bags and were maintained in a greenhouse at 28±2 ◦C and 90% RH. The pathogenicity test was repeated three times. After 8 days post-inoculation, inoculated plants showed leaf blight symptoms as observed in the field, whereas no disease symptoms were observed on non-inoculated plants. Re-isolations were performed from inoculated plants, and the re-isolated pathogen was confirmed as A. alternata based on morphological and PCR assay (Konstantinova et al. 2002). No pathogens were isolated from control plants. There is an increasing acreage of LM crop in India, and this first report indicates the need for further studies on leaf blight management and the disease impacts on crop yields.

scholarly journals First Report of Colletotrichum siamense Causing Anthracnose of Monstera deliciosa in Zhanjiang, China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Yu Han Zhou
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Pathogenicity Test ◽  
Sterile Water ◽  
Single Spore ◽  
First Report ◽  
Rdna Its ◽  
Colletotrichum Siamense ◽  
Monstera Deliciosa ◽  
Pure Cultures

Monstera deliciosa Liebm is an ornamental foliage plant (Zhen et al. 2020De Lojo and De Benedetto 2014). In July of 2019, anthracnose lesions were observed on leaves of M. deliciosa cv. Duokong with 20% disease incidence of 100 plants at Guangdong Ocean University campus (21.17N,110.18E), Guangdong Province, China. Initially affected leaves showed chlorotic spots, which coalesced into larger irregular or circular lesions. The centers of spots were gray with a brown border surrounded by a yellow halo (Supplementary figure 1). Twenty diseased leaves were collected for pathogen isolation. Margins of diseased tissue was cut into 2 × 2 mm pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite (NaOCl) for 60 s, rinsed three times with sterile water before isolation. Potato dextrose agar (PDA) was used to culture pathogens at 28℃ in dark. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. Fourteen isolates were obtained from 20 leaves. Three single-spore isolates (PSC-1, PSC-2, and PSC-3) were obtained ,obtained, which were identical in morphology and molecular analysis (ITS). Therefore, the representative isolate PSC-1 was used for further study. The culture of isolate PSC-1 on PDA was initially white and later became cottony, light gray in 4 days, at 28 °C. Conidia were single celled, hyaline, cylindrical, clavate, and measured 13.2 to 18.3 µm × 3.3 to 6.5 µm (n = 30). Appressoria were elliptical or subglobose, dark brown, and ranged from 6.3 to 9.5 µm × 5.7 to 6.5 µm (n = 30). Morphological characteristics of isolate PSC-1 were consistent with the description of Colletotrichum siamense (Prihastuti et al. 2009; Sharma et al. 2013). DNA of the isolate PSC-1 was extracted for PCR sequencing using primers for the rDNA ITS (ITS1/ITS4), GAPDH (GDF1/GDR1), ACT (ACT-512F/ACT-783R), CAL (CL1C/CL2C), and TUB2 (βT2a/βT2b) (Weir et al. 2012). Analysis of the ITS (accession no. MN243535), GAPDH (MN243538), ACT (MN512640), CAL (MT163731), and TUB2 (MN512643) sequences revealed a 97-100% identity with the corresponding ITS (JX010161), GAPDH (JX010002), ACT (FJ907423), CAL (JX009714) and TUB2 (KP703502) sequences of C. siamense in GenBank. A phylogenetic tree was generated based on the concatenated sequences of ITS, GAPDH, ACT, CAL, and TUB2 which clustered the isolate PSC-1 with C. siamense the type strain ICMP 18578 (Supplementary figure 2). Based on morphological characteristics and phylogenetic analysis, the isolate PSC-1 associated with anthracnose of M. deliciosa was identified as C. siamense. Pathogenicity test was performed in a greenhouse at 24 to 30oC with 80% relative humidity. Ten healthy plants of cv. Duokong (3-month-old) were grown in pots with one plant in each pot. Five plants were inoculated by spraying a spore suspension (105 spores ml-1) of the isolate PSC-1 onto leaves until runoff, and five plants were sprayed with sterile water as controls. The test was conducted three times. Anthracnose lesions as earlier were observed on the leaves after two weeks, whereas control plants remained symptomless. The pathogen re-isolated from all inoculated leaves was identical to the isolate PSC-1 by morphology and ITS analysis, but not from control plants. C. gloeosporioides has been reported to cause anthracnose of M. deliciosa (Katakam, et al. 2017). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa in ChinaC. siamense causes anthracnose on a variety of plant hosts, but not including M. deliciosa (Yanan, et al. 2019). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa, which provides a basis for focusing on the management of the disease in future.

scholarly journals First Report of Clubroot on Capsella bursa-pastoris Caused by Plasmodiophora brassicae in Sichuan Province of China

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 687-687 ◽  
Author(s):  
L. Ren ◽  
X. P. Fang ◽  
C. C. Sun ◽  
K. R. Chen ◽  
F. Liu ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Tap Water ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Sichuan Province ◽  
Clubroot Disease ◽  
Cruciferous Vegetable ◽  
First Report ◽  
Resting Spores

Shepherd's purse (Capsella bursa-pastoris (L.) Medicus) is an edible and wild medicinal plant widely distributed in China. This plant has been cultivated in Shanghai, China, since the end of the 19th century. Infection of C. bursa-pastoris by Plasmodiophora brassicae, the causal agent of clubroot disease on Brassica spp. has been reported in Korea (2), but is not known to occur in China. In February of 2011, stunted and wilted shepherd's purse (SP) plants were observed in a field planted to oilseed rapes (B. napus) in Sichuan Province of China. Symptomatic SP plants also exhibited root galls. Disease incidence was 6.2% and 100% for SP and B. napus, respectively. Root galls on diseased SP plants were collected for pathogen identification. Many resting spores were observed when the root galls were examined under a light microscope. The resting spores were circular in shape, measuring 2.0 to 3.1 μm in diameter (average 2.6 μm). PCR amplification was conducted to confirm the pathogen. DNA was extracted from root galls and healthy roots (control) of SP. Two primers, TC2F (5′-AAACAACGAGTCAGCTTGAATGCTAGTGTG-3′) and TC2R (5′-CTTTAGTTGTGTTTCGGCTAGGATGGTTCG-3′) were used to detect P. brassicae (1). No PCR amplifications were observed with the control DNA as template. A fragment of the expected size (approximately 520 bp) was obtained when DNA was amplified from diseased roots of SP. These results suggest that the pathogen in the galled roots of SP is P. brassicae. Pathogenicity of P. brassicae in SP was tested on plants of both SP and Chinese cabbage (CC) (B. campestris ssp. pekinensis). A resting spore suspension prepared from naturally infected SP roots was mixed with a sterilized soil in two plastic pots, resulting in a final concentration of 5 × 106 spores/g soil. Soil treated with the same volume of sterile water was used as a control. Seeds of SP and CC were pre-germinated on moist filter paper for 2 days (20°C) and seeded into the infested and control pots, one seed per pot for planted for CC and four seeds per pot for SP. The pots were placed in a chamber at 15 to 25°C under 12 h light and 12 h dark. Plants in each pot were uprooted after 4 weeks and the roots of each plant were washed under tap water and rated for clubroot disease. No disease symptoms were observed in the control treatments of SP or CC. Plants of both species showed symptoms of clubroot, with the disease incidence of 62.5% and 100% on SP and CC, respectively. The pathogen was isolated from diseased roots of each plant and confirmed as P. brassicae based on morphological characteristics and PCR detection. To our knowledge, this is the first report of clubroot disease on C. bursa-pastoris in Sichuan Province of China. This finding suggests that it may be necessary to manage C. bursa-pastoris in cruciferous vegetable (cabbage, turnip) and oilseed rape production fields. References: (1) T. Cao et al. Plant Dis. 91:80, 2007. (2) W. G. Kim et al. Microbiology 39:233, 2011.

scholarly journals First Report of Fire Blight on Pear Trees Caused by Erwinia amylovora in Kurdistan Province, Iran

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1111-1111 ◽  
Author(s):  
S. N. Mollaei ◽  
B. Harighi
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Reca Gene ◽  
Phylogenetic Position ◽  
Bacterial Suspension ◽  
Sodium Hypochlorite Solution ◽  
Pathogenicity Test ◽  
First Report ◽  
Appl Environ ◽  
Pear Trees

Pear (Pyrus L.) is one of the most widely grown crops in western Iran. Since 2010, an outbreak of a disease with symptoms similar to fire blight has been observed on pear trees in various locations of Kurdistan Province. Initial flower symptoms include water-soaking and rapidly shriveling, infected flowers that remained hanging on the trees. Immature fruits become water-soaked, turned brown, and shriveled. Infected flowers and immature fruits were collected from different locations in the province. Small pieces (about 1 mm2) were excised from infected tissues, surface sterilized with 0.5% sodium hypochlorite solution, followed by rinsing in sterile-distilled water (SDW). Each piece was macerated in 2 to 3 ml of SDW, streaked onto nutrient agar sucrose or eosin methylene blue agar media, and incubated at 27 to 29°C. After 48 to 72 h, single colonies were subcultured onto the same media and stored at 4°C. In total, 74 bacteria were isolated from infected tissues. All isolates were gram-negative and rod-shaped. Based on other phenotypic properties, strains were grouped into three clusters at a similarity level of 65% (data not shown). Forty-one and 23 strains showed properties as expected for Erwinia amylovora and Enterobacter sp., respectively. Other strains showed properties resembling Pantoea agglomerans. All strains identified as E. amylovora produced an expected DNA fragment of about 900 bp by PCR using primers PE29A and PE29B corresponding to plasmid pEA29 (1). The result was confirmed by using primers AMSbL and AMSbR derived from the ams region required for amylovoran synthesis of E. amylovora. E. amylovora strains produced an expected 1,600-bp fragment (2). For the pathogenicity test, a bacterial suspension was adjusted to approximately 1 × 107 CFU/ml from cell cultures grown in nutrient broth at 27°C for 48 h. Immature pear fruits sterilized with 70% ethanol and rinsed with SDW were injected with the bacterial suspension using a 25-gauge sterile needle. Fruits injected with sterile water were used as controls. Pear fruits were kept in a mist chamber at 27 to 29°C. Symptoms were assessed up to 2 weeks after inoculation. All E. amylovora strains produced typical symptoms on inoculated immature pear fruits. Necrosis and oozing of bacterial exudates were observed after 3 to 7 days. The phylogenetic position of two selected strains was analyzed by sequence comparison of recA gene among other species in the genus Erwinia and related bacteria. The recA sequence of bacterial strains identified as E. amylovora revealed high similarity (99%) to the E. amylovora type strain (CFBP 1430). Genetic diversity of selected strains was assessed and compared with E. amylovora reference strain CFBP 1430 using ERIC and REP primers in rep-PCR analysis. (3). UPGMA cluster analysis of the combined data obtained in the rep-PCR experiments using Dice's coefficient revealed that the majority of E. amylovora strains showed the same fingerprint patterns at a similarity level of 93%, indicating genetic homogeneity among strains but clearly separated from Enterobacter sp. and P. agglomerans strains. To our knowledge, this is the first report that characterizes the phenotypic and genetic properties of E. amylovora in western part of Iran. References: (1) S. Bereswill et al. Appl. Environ. Microbiol. 58:3522, 1992. (2) S. Bereswill et al. Appl. Environ. Microbiol. 61:2636, 1995. (3) J. Versalovic et al. Mol. Cell Biol. 5:25, 1994.

scholarly journals First Report of Root Rot of Bean and Soybean Caused by Rhizoctonia zeae in Turkey

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 203-203 ◽  
Author(s):  
I. Erper ◽  
G. Karaca ◽  
I. Özkoç
Keyword(s):  
Tap Water ◽  
Pathogenicity Test ◽  
First Report ◽  
Rhizosphere Soils ◽  
Soybean Seedlings ◽  
Oat Seeds ◽  
Soybean Plants ◽  
Waitea Circinata ◽  
Rhizoctonia Zeae ◽  
Corn Kernels

To determine the species of Rhizoctonia on bean and soybean plants grown in Samsun (Turkey), field surveys were performed at 104 locations during 2001 and 2002. Rhizoctonia spp. were obtained from isolations from the necrotic lesions on the hypocotyl and rhizosphere soils. Species were identified according to Ogoshi (3) on the basis of hyphal and colony morphology and anastomosis reaction with known tester isolates (provided by M. Hyakumachi, Gifu University, Japan). Fifty Rhizoctonia spp. isolates obtained from these locations were identified as Rhizoctonia zeae (teleomorph Waitea circinata var. zeae). Nine of the 27 bean isolates and 8 of the 23 soybean isolates were recovered from plant tissues. These isolates had optimum temperature (32°C) for growth. Colonies were orange when young, becoming salmon colored with age. Sclerotia formed both on the agar surface or submerged in the medium. Superficial sclerotia were more uniform and nearly spherical, mostly 0.2 to 0.5 mm in diameter, and they were first orange and then turned brown. Pathogenicity was tested with three R. zeae isolates grown on sterile oat seeds at 25°C for 10 days. Bean and soybean seedlings grown in 1-liter plastic pots containing sterile potting mix (field soil/composted manure/sand 2:2:1 [v/v]) at true-leaf stage were inoculated by placing five infested oat seeds adjacent to the roots. Sterile oat seeds were used for controls. After 3 to 4 weeks of incubation at 17 to 25°C in a glasshouse, roots of the plants were cleaned with tap water and evaluated for disease severity. Four replicate pots were used for each isolate/plant combination. All isolates produced superficial brown lesions on roots and hypocotyls similar to those observed on plants used for isolations and root growth declined. R. zeae was reisolated from the lesions on all bean and soybean plants used for the pathogenicity test. While R. zeae was previously reported from Johnsongrass roots (1) and corn kernels (2), to our knowledge, this is the first report of R. zeae isolated from bean and soybean plants and rhizosphere soils in Turkey. References: (1) E. Demirci, and C. Eken. Plant Dis. 83:200, 1999. (2) E. Demirci and S. Kordali. Plant Dis. 83:879, 1999. (3) A. Ogoshi. Rev. Plant. Prot. Res. 8:93, 1975.

scholarly journals First Report of Fusarium asiaticum Causing Stem Rot of Ligusticum chuanxiong in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Tingting Zhu ◽  
Linxuan Li ◽  
Antonios Petridis ◽  
George Xydis ◽  
Maozhi Ren
Keyword(s):  
Disease Incidence ◽  
Elongation Factor ◽  
Stem Rot ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
First Report ◽  
Ligusticum Chuanxiong ◽  
Fusarium Asiaticum ◽  
Sterile Needle ◽  
Yellow Pigments

Ligusticum chuanxiong (known as Chuanxiong in China) is a traditional edible-medicinal herb, which has been playing important roles in fighting against COVID-19 (Ma et al. 2020). In March 2021, we investigated stem rot of Chuanxiong in six adjacent fields (~100 ha) in Chengdu, Sichuan Province, China. The disease incidence was above 5% in each field. Symptomatic plants showed stem rot, watersoaked lesions, and blackening with white hyphae present on the stems. Twelve symptomatic Chuanxiong plants (2 plants/field) were sampled. Diseased tissues from the margins of necrotic lesions were surface sterilized in 75% ethanol for 45 s, and 2% NaClO for 5 min. Samples were then rinsed three times in sterile distilled water and cultured on potato dextrose agar (PDA) at 25ºC for 72 h. Fourteen fungal cultures were isolated from 18 diseased tissues, of which eight monosporic isolates showed uniform characteristics. The eight fungal isolates showed fluffy white aerial mycelia and produced yellow pigments with age. Mung bean broth was used to induce sporulation. Macroconidia were sickle-shaped, slender, 3- to 5-septate, and averaged 50 to 70 μm in length. Based on morphological features of colonies and conidia, the isolates were tentatively identified as Fusarium spp. (Leslie and Summerell 2006). To identify the species, the partial translation elongation factor 1 alpha (TEF1-α) gene was amplified and sequenced (O’Donnell et al. 1998). TEF1-α sequences of LCSR01, LCSR02 and LCSR05 isolates (GenBank nos. MZ169386, MZ169388 and MZ169387) were 100%, 99.72% and 99.86% identical to that of F. asiaticum strain NRRL 26156, respectively. The phylogenetic tree based on TEF1-α sequences showed these isolates clustered with F. asiaticum using Neighbor-Joining algorithm. Furthermore, these isolates were identified using the specific primer pair Fg16 F/R (Nicholson et al. 1998). The results showed these isolates (GenBank nos. MZ164938, MZ164939 and MZ164940) were 100% identical to F. asiaticum NRRL 26156. Pathogenicity test of the isolate LCSR01 was conducted on Chuanxiong. After wounding Chuanxiong stalks and rhizomes with a sterile needle, the wounds were inoculated with mycelia PDA plugs. A total of 30 Chuanxiong rhizomes and stalks were inoculated with mycelia PDA plugs, and five mock-inoculated Chuanxiong rhizomes and stalks served as controls. After inoculation, the stalks and rhizomes were kept in a moist chamber at 25°C in the dark. At 8 days post inoculation (dpi), all inoculated stalks and rhizomes exhibited water-soaked and blackened lesions. At 10 dpi, the stalks turned soft and decayed, and abundant hyphae grew on the exterior of infected plants, similar to those observed in the field. No disease symptoms were observed on the control plants. The pathogen was re-isolated from the inoculated tissues and the identity was confirmed as described above. Ten fungal cultures were re-isolated from the 10 inoculated tissues, of which nine fungal cultures were F. asiaticum, fulfilling Koch’s postulates. To our knowledge, this is the first report of F. asiaticum causing stem rot of Chuanxiong in China. Chuanxiong has been cultivated in rotation with rice over multiple years. This rotation may have played a role in the increase in inoculum density in soil and stem rot epidemics in Chuanxiong. Diseased Chuanxiong may be contaminated with the mycotoxins produced by F. asciaticum, 3-acetyldeoxynivalenol or nivalenol, which may deleteriously affect human health. Therefore, crop rotations should be considered carefully to reduce disease impacts.

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