scholarly journals First Report of Leaf Spots caused by Nigrospora oryzae on Wild Rice in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Ya Li ◽  
Hong Kai Zhou
Keyword(s):  
Leaf Spot ◽  
Wild Rice ◽  
Morphological Characteristics ◽  
Oryza Rufipogon ◽  
Its Sequences ◽  
Likelihood Method ◽  
Pathogenicity Test ◽  
Sterile Water ◽  
First Report ◽  
Nigrospora Oryzae

In recent years, wild rice (Oryza rufipogon Griff) has been widely cultivated because of its health-promoting effects. In May 2019, leaf spot lesions on cv. Haihong-12 were observed in Zhanjiang (20.93N, 109.79E), China. Leaf symptoms were yellow-to-brown, oval or circular with a very distinctive, large yellow halo. Black spores appeared on the leaves with advanced symptoms. The lesions coalesced, causing the entire leaf to become blighted and die. Disease incidence reached approximately 10% in the fields (8 ha) surveyed. Twenty leaves with symptoms were collected and cut into pieces of 2 ×2 cm in size. They were surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite (NaOCl) for 60 s, rinsed three times with sterile water, blotted dry on sterile paper, plated on potato dextrose agar (PDA) medium, and incubated at 28°C in the dark for 4 days. Ten pure cultures were obtained by transferring hyphal tips to new PDA plates, and monosporic cultures were obtained from three isolates (Nos-1, Nos-2, and Nos-3). Those isolates exhibited very similar morphological characteristics on PDA. Colony of isolate Nos-1 was white at the early stage and became dark gray after 7 days. Conidia were produced from clusters of conidiophores, single celled, black, smooth, spherical, and 9.5 to 14.2 µm (average 10.6 µm ± 0.42) in diameter. Morphological characteristics of the isolates matched the description of Nigrospora oryzae Petch (Wang et al. 2017). The ITS region was amplified using primers ITS1 and ITS4 (White et al. 1990). Nucleotide sequences of isolates Nos-1, Nos-2, and Nos-3 deposited in GenBank under acc. nos. MW042173, MW042174, and MW042175, respectively, were 100% identical to N. oryzae (acc. nos. KX985944, KX985962; and KX986007). A phylogenetic tree generated based on the ITS sequences and using a Maximum Likelihood method with 1,000 bootstraps showed that these three isolates from wild rice were grouped with other N. oryzae isolates downloaded from GenBank (bootstrap = 100%) but away from other Nigrospora spp. Pathogenicity test was performed with these three isolates in a greenhouse at 24 to 30°C. Approximately 50 seedling of wild rice cv. Haihong-12 were grown in each pot. At the 3-leaf stage, plants in three pots were inoculated with each isolate by spraying a spore suspension (105 spores/ml) until runoff. Three pots sprayed with sterile water served as the controls. Each 3-pot treatment was separately covered with a plastic bag. The test was conducted three times. Diseased symptoms were observed on the inoculated leaves after 10 days while no disease was observed in the control plants. Morphological characteristics and the ITS sequences of fungal isolates re-isolated from the diseased leaves were identical to those of N. oryzae. N. oryzae has been reported to cause leaf spot on O. sativa (Wang et al. 2017), but not on O. rufipogon. Thus, this is the first report of N. oryzae causing leaf spot of O. rufipogon in China. The finding provides the information important for further studies to develop management strategies for control of this disease.

scholarly journals First Report of Bipolaris oryzae Causing Leaf Spot on Cultivated Wild Rice (Oryza rufipogon) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Ya Li ◽  
Hong Kai Zhou
Keyword(s):  
Leaf Spot ◽  
Wild Rice ◽  
Morphological Characteristics ◽  
Oryza Rufipogon ◽  
Likelihood Method ◽  
Leaf Spot Disease ◽  
Pathogenicity Test ◽  
Sterile Water ◽  
Bipolaris Oryzae ◽  
First Report

Wild rice (Oryza rufipogon) has been widely studied and cultivated in China in recent years due to its antioxidant activities and health-promoting effects. In December 2018, leaf spot disease on wild rice (O. rufipogon cv. Haihong-12) was observed in Zhanjiang (20.93 N, 109.79 E), China. The early symptom was small purple-brown lesions on the leaves. Then, the once-localized lesions coalesced into a larger lesion with a tan to brown necrotic center surrounded by a chlorotic halo. The diseased leaves eventually died. Disease incidence was higher than 30%. Twenty diseased leaves were collected from the fields. The margin of diseased tissues was cut into 2 × 2 mm2 pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s, and then rinsed three times with sterile water before isolation. The tissues were plated on potato dextrose agar (PDA) medium and incubated at 28 °C in the dark for 4 days. Pure cultures were produced by transferring hyphal tips to new PDA plates. Fifteen isolates were obtained. Two isolates (OrL-1 and OrL-2) were subjected to further morphological and molecular studies. The colonies of OrL-1 and OrL-1 on PDA were initially light gray, but it became dark gray with age. Conidiophores were single, straight to flexuous, multiseptate, and brown. Conidia were oblong, slightly curved, and light brown with four to nine septa, and measured 35.2–120.3 µm × 10.3–22.5 µm (n = 30). The morphological characteristics of OrL-1 and OrL-2 were consistent with the description on Bipolaris oryzae (Breda de Haan) Shoemaker (Manamgoda et al. 2014). The ITS region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and translation elongation factor (EF-1α) were amplified using primers ITS1/ITS4, GDF1gpp1/GDR1 gdp2 (Berbee et al. 1999), and EF-1α-F/EF-1α-R EF-1/EF-2 (O’Donnell 2000), respectively. Amplicons of OrL-1 and OrL-2 were sequenced and submitted to GenBank (accession nos. MN880261 and MN880262, MT027091 and MT027092, and MT027093 and MT027094). The sequences of the two isolates were 99.83%–100% identical to that of B. oryzae (accession nos. MF490854，MF490831，MF490810) in accordance with BLAST analysis. A phylogenetic tree was generated on the basis of concatenated data from the sequences of ITS, GAPDH, and EF-1α via Maximum Likelihood method, which clustered OrL-1 and OrL-2 with B. oryzae. The two isolates were determined as B. oryzae by combining morphological and molecular characteristics. Pathogenicity test was performed on OrL-1 in a greenhouse at 24 °C to 30 °C with 80% relative humidity. Rice (cv. Haihong-12) with 3 leaves was grown in 10 pots, with approximately 50 plants per pot. Five pots were inoculated by spraying a spore suspension (105 spores/mL) onto leaves until runoff occurred, and five pots were sprayed with sterile water and used as controls. The test was conducted three times. Disease symptoms were observed on leaves after 10 days, but the controls remained healthy. The morphological characteristics and ITS sequences of the fungal isolates re-isolated from the diseased leaves were identical to those of B. oryzae. B. oryzae has been confirmed to cause leaf spot on Oryza sativa (Barnwal et al. 2013), but as an endophyte has been reported in O. rufipogon (Wang et al. 2015).. Thus, this study is the first report of B. oryzae causing leaf spot in O. rufipogon in China. This disease has become a risk for cultivated wild rice with the expansion of cultivation areas. Thus, vigilance is required.

scholarly journals First Report of Leaf Blight Caused by Nigrospora oryzae on Poplar in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Huifang Zhang ◽  
Ning Kong ◽  
Shida Ji ◽  
Bin Liu ◽  
Zhen Tian ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Leaf Blight ◽  
Spore Suspension ◽  
Likelihood Method ◽  
Sterile Water ◽  
First Report ◽  
Detached Leaves ◽  
Leaf Test ◽  
Nigrospora Oryzae ◽  
Poplar Seedlings

Populus alba L. × P. berolinensis Dipp. (a hybrid poplar, ‘PaPb poplar’) exhibits fast growth and beautiful tree shape with high drought and cold tolerance, and is widely planted in the cities of Northeast China because of its ornamental and ecological value (Wang et al. 2008). In October 2020, an unknown leaf blight symptom was observed on the seedlings of ‘PaPb poplar’ at Shenyang Agricultural University (41°49′N, 123°34′E) located in Shenyang City, Liaoning Province, China. The disease incidence was 50% in a survey of 200 seedlings on the campus. The typical symptoms were brown-to-black, irregular-shaped lesions (Fig. 1A). To investigate the disease, five symptomatic leaves were collected, and pieces were cut at the margin of diseased and healthy tissue. These pieces were surface sterilized with 2% sodium hypochlorite for 2 min, rinsed three times with sterile distilled water, air dried, placed on potato dextrose agar (PDA) and incubated at 28°C. After 5 days of incubation, three isolates with similar morphological characteristics were observed. Isolate N03 was chosen and used for pathogen identification. The fungal colonies were initially white in color, and later turned gray to black (Fig. 1D). Conidia were single-celled, black, spherical or oblate in shape measuring 9.19 to 12.78 μm × 12.61 to 14.81 μm in diameter (n=40) (Fig. 1E). These were borne on hyaline vesicles at the tip of a conidiophore. Morphologically, the isolate N03 was identified as Nigrospora oryzae (Berk. and Broome) Petch (Wang et al. 2017). The genomic DNA was extracted with a SP Fungal DNA Kit (D5542-01, OMEGA). The internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (TEF1-α), and partial beta-tubulin (TUB) genes were amplified using the primers ITS5/ITS4 (White et al. 1990), EF1-728F/EF-2R (Carbone and Kohn, 1999; O’Donnell et al. 1998), and Bt-2a/Bt-2b (Glass and Donaldson, 1995) primer sets, respectively. The PCR products of ITS, TEF1-α, and TUB were amplified, sequenced, and deposited in GenBank with the following accession numbers MZ148528, MZ182080, and MZ182079, respectively. BLASTn analysis of the ITS, TEF1-α, and TUB sequences had 99.3%, 99.8%, and 99.27% nucleotide identities to MK131325, KY019328, and KY019559, respectively. A phylogenetic tree based on combined ITS, TEF1-α, and TUB sequences was constructed using a Maximum Likelihood method with 1000 bootstraps showing that N03 was grouped with other N. oryzae isolates (Fig. 2). The fungus was identified as N. oryzae based on morphological characteristics and molecular analyses. Koch’s postulates were completed to confirm the pathogenity of N. oryzae on ‘PaPb poplar’. The N03 spore suspension (105 spores/mL) was used to inoculate detached leaves and field leaves in two experiments. The two experiments were repeated three times, respectively. In the detached leaf test, 10 healthy leaves collected from 1-year-old ‘PaPb poplar’ seedlings were inoculated with N03 by spraying with the spore suspension followed by incubation at 28°C on wet filter papers in a petri dish for 7 days. 10 leaves were sprayed with sterile water to save as the controls. For field leaf test, leaves of 5 plants were spray-inoculated with the spore suspension at the 4-week-old growth stage, and an additional 5 plants were sprayed with sterile water. Seven days after inoculation, brown-to-black, irregular-shaped lesions on the margin of leaves were observed on inoculated leaves but not on the controls (Fig. 1B and C). All detached leaves inoculated with N03 were symptomatic. In the field tests, symptom appeared on 20 of the 30 inoculated leaves. N. oryzae was re-isolated from all the inoculated detached leaves and inoculated plants, but not from the controls. N. oryzae is a known pathogen of several hosts, such as Costus speciosus (Koen.) Sm. and Mentha spicata L., but has not been reported on any species of Populus. To our knowledge, this is the first report of leaf blight of ‘PaPb poplar’ caused by N. oryzae in China and the world. This disease could affect growth and development of ‘PaPb poplar’ seedlings, and may cause economic losses in the future. Appropriate strategies should be developed to manage this disease.

scholarly journals First Report of Leaf Spot caused by Curvularia lunata on Wild Rice in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Hong Kai Zhou ◽  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Fei Teng Zhong ◽  
Ya Li
Keyword(s):  
Leaf Spot ◽  
Wild Rice ◽  
Disease Incidence ◽  
Its Region ◽  
Oryza Rufipogon ◽  
Likelihood Method ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Curvularia Lunata ◽  
Sterile Water

Wild rice (Oryza rufipogon), a species only recently cultivated in China, is an invaluable resource for rice breeding and basic research. In June 2019, a leaf spot disease on wild rice (O. rufipogon cv. ‘Haihong-12’) was observed in a 3.3 ha field in Zhanjiang (20.93 N, 109.79 E), China. The early symptoms were the presence of small, brown, and circular to oval spots that eventually turned reddish brown. The size of the spots varied from 1.0–5.0 mm × 1.0–3.0 mm. Disease incidence was higher than 20%. High temperature and high humidity climate were favorable for the disease occurrence. Twenty diseased leaves were collected from the field. The margin of the diseased tissues was cut into 2 mm × 2 mm pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s, then rinsed three times with sterile water before isolation. The tissues were plated onto potato dextrose agar (PDA) medium and incubated at 28 °C in the dark for 4 days. Pure cultures were produced by transferring hyphal tips to new PDA plates. Three isolates, namely, Cls-1, Cls-2, and Cls-3, were subjected to further morphological and molecular studies. The colonies of the three isolates on PDA were initially light gray later becoming dark green. Conidiophores were erect, dark brown, geniculate, and unbranched. Conidia were fusiform, geniculate or hook-shaped, smooth-walled, dark-brown, 3-septate, with the second curved cell about 13.4–18.2 μm × 6.5–8.6 μm in size (n = 30). These morphological features agreed with previous descriptions of Curvularia lunata (Wakker) Boed (Macri and Lenna 1974). The ITS region, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and translation elongation factor (EF-1α) were amplified using primers ITS1/ITS4, gpp1/gdp2 (Berbee et al. 1999), and EF-1/EF-2 (O’Donnell 1997), respectively. Amplicons of the three isolates were sequenced and submitted to GenBank (accession nos. MW042182, MW042183, and MW042184; MW091453, MW091454, and MW091455; MW090049, MW090050, and MW090051). The sequences of the two isolates were 100% identical to those of C. lunata (accession nos. MG971304, MG979801, MG979800) according to the results of BLAST analysis. A phylogenetic tree was built on the basis of concatenated data from the sequences of ITS, GAPDH, and EF-1α via the maximum likelihood method. The tree clustered Cls-1, Cls-2, and Cls-3 with C. lunata. The three isolates were determined as C. lunata by combining morphological and molecular characteristics. Pathogenicity tests were performed on Cls-1 in a greenhouse at 24 °C–30 °C with 80% relative humidity. Individual rice plants (cv. ‘Haihong-12’) with three leaves were grown in 10 pots, with approximately 50 plants per pot. Five pots were inoculated by spraying a spore suspension (105 spores/mL) onto leaves until runoff occurred, and another five pots were sprayed with sterile water and used as controls. The test was conducted three times. Disease symptoms were observed on the leaves after 10 days, but the controls remained healthy. C. lunata occurs on O. sativa (rice) (Liu et al. 2014; Majeed et al. 2016), but it has not been reported on O. rufipogon until now. To the best of our knowledge, this study is the first to report that C. lunata causes leaf spots on O. rufipogon in China. Thus, vigilance is required for breeding O. rufipogon.

scholarly journals First Report of Leaf Spot of Weigela florida Caused by Epicoccum layuense in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yue Tian ◽  
Yingying Zhang ◽  
Chaodong Qiu ◽  
Zhenyu Liu
Keyword(s):  
Leaf Spot ◽  
Large Subunit ◽  
Morphological Characteristics ◽  
Likelihood Method ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
Beta Tubulin ◽  
First Report ◽  
Leaf Spots ◽  
Weigela Florida

Weigela florida (Bunge) A. DC. is a dense, rounded, deciduous shrub commonly planted in landscapes. It is also used in Chinese medicine to treat sore throat, erysipelas, cold, and fever (Zheng et al. 2019). In May 2019, leaf spots were observed on approximately 50% of W. florida plants grown in the Wisdom Plaza Park of Anhui Agricultural University in Hefei, Anhui Province, China. Leaf spots begun as small light brown and irregular lesions, enlarged, turned reddish brown, coalesced to form large blighted areas, and eventually covered the entire leaf surface. Five pieces of tissues were removed from the lesion margins of each diseased leaf (five leaves from five different plants), chopped into several 3-4 mm2 pieces, disinfected with 1.5% NaOCl for 2 min, rinsed 3 times with sterile distilled water for 1 min, plated onto Potato Dextrose Agar (PDA) medium containing 50 μg/ml of ampicillin and kanamycin, and incubated at 25°C with a 12-hour photoperiod for 5 days. One segment of the fungal growth from the growing edge of the colony was transferred onto a fresh PDA plate for purification and incubated under the same conditions for another 5 days. The colony morphology of one representative isolate (AAU0519) was characterized by a pale orange cushion in the center surrounded by irregular pink margin, diffusing red orange pigments into the PDA medium. Isolate AAU0519 was cultured on PDA medium for 7 days at 25°C in the dark to induce sporulation. The produced conidia were globose, subglobose to pyriform, golden brown to brown, and with a diameter of 7.7 - 23.8 μm. Both cultural and morphological characteristics suggested that isolate AAU0519 was an Epicoccum species, according to the description by Chen et al. 2017. Amplification and sequencing of the internal transcribed spacer (ITS), beta-tubulin, and 28S large subunit ribosomal RNA (LSU) gene fragments from the extracted genomic DNA of AAU0519 were performed using primer sets ITS1/ITS4 (White et al. 1990), Bt2a/Bt2b (Glass and Donaldson 1995), and LSU1Fd/LR5 (Crous et al. 2009; Vilgalys and Hester 1990), respectively. A phylogenetic tree was constructed by the maximum-likelihood method with 1,000 bootstrapping replications based on the concatenated ITS, beta-tubulin, and LSU sequences from isolate AAU0519 and representative strains of 22 species of the genus Epicoccum (Chen et al. 2017). Isolate AAU0519 clustered with ex-holotype CGMCC 3.18362 of Epicoccum layuense Qian Chen, Crous & L. Cai (Chen et al. 2017). All obtained sequences were deposited into GenBank under accession numbers MK983497 (ITS), MN328723 (beta-tubulin), and MN328724 (LSU). A pathogenicity test was conducted on leaves of five 3-year-old W. florida cultivar “Red Prince” planted in the field (five leaves for each treatment and control per plant) by spraying 30 ml of a spore suspension (106 spores/ml) of isolate AAU0519 as treatment or sterilized distilled water as control. Before the inoculation, the leaves were disinfected with 70% ethanol. After inoculation, the leaves were wrapped with a plastic bag to keep high relative humidity. The average air temperature was about 28°C during the period of pathogenicity test. The experiment was repeated once. Ten days after inoculation, the fungal-inoculated leaves developed light brown lesions resembling those of naturally infected leaves, control leaves did not develop any symptoms. E. layuense was recovered from leaf lesions and its identity was confirmed by morphological and sequence analyses as described above. To our knowledge, E. layuense has been previously reported as a pathogen of Perilla sp. (Chen et al. 2017), oat (Avena sativa) (Chen et al. 2019), and tea (Camellia sinensis) plants (Chen et al. 2020), but this is the first report of E. layuense causing leaf spot on W. florida in China. This pathogen could pose a threat to the ornamental value of W. florida plants. Thus, it is necessary to adopt effective management strategies against leaf spot on W. florida.

scholarly journals First report of Alternaria alternata causing brown leaf spot on wild rice (Oryza rufipogon) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Fei Teng Zhong ◽  
Yue Lian Liu ◽  
Dianfeng Zheng ◽  
Shili Lu
Keyword(s):  
Rna Polymerase Ii ◽  
Alternaria Alternata ◽  
Leaf Spot ◽  
Wild Rice ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Oryza Rufipogon ◽  
Sterile Water ◽  
Brown Leaf Spot ◽  
Brown Leaf

Oryza rufipogon Griff is a wild rice germplasm that might contain genes valuable for rice breeding. In May to June 2019, a leaf disease on wild rice (O. rufipogon cv. ‘Haihong-12’) was observed in a 3.3 ha field in Zhanjiang (20.93° N, 109.79° E), Guangdong, China. Early symptoms were yellow spots from the tip of leaves. Later, the spots gradually expanded downward the entire leaf to turn brown in turn. Symptoms were found in the tillering to the grain-filling stages (Supplementary Figure 1). The disease incidence on plants was between 10% and 40%. Twenty diseased leaves were collected from the field. The margin of the diseased tissues was cut into 2 mm × 2 mm pieces, surface-disinfected with 75% ethanol and 2% sodium hypochlorite for 30 s and 60 s, respectively, and rinsed three times with sterile water before isolation. The tissues were plated onto potato dextrose agar (PDA) medium and incubated at 28 °C. After 5-day incubation, grayish fungal colonies appeared on PDA. Single-spore isolation method was used to recover pure cultures for three isolates (Aas-1, Aas-2, and Aas-3). The colonies first produced light-grayish aerial mycelia, which turned dark grayish upon maturity. Conidiophores were branched. Conidia were two to four in chains, dark brown, ovoid or ellipsoid, and mostly beakless; had one to four transverse and zero to three longitudinal septa; and measured within 7.0–18.5 (average = 12.5) × 3.0–8.8 (average = 4.5) μm (n = 30). Morphological characteristics of the isolates were consistent with the description of Alternaria alternata (Fr.) Keissler (Simmons 2007). The internal transcribed spacer (ITS) region, partial RNA polymerase II largest subunit (RPB2) gene, translation elongation factor, and glyceraldehyde-3-phosphate dehydrogenase were amplified with primers ITS1/ITS4, RPB2-6F/RPB2-7R, EF-1α-F/EF-1α-R, and GDF1/GDR1, respectively (Woudenberg et al. 2015). Amplicons were sequenced and submitted to GenBank (accession nos. MW042179 to MW042181, MW090034 to MW090036, MW090046 to MW090048, and MW091450 to MW091452, respectively). The sequences of the three isolates were 100% identical (ITS, 570/570 bp; RPB2, 1006/1006 bp; TEF, 254/254 bp and GADPH, 587/587 bp) with those of CBS 479.90 (accession nos. KP124319, KP124787, KP125095, and KP124174) through BLAST analysis. The sequences were also concatenated for phylogenetic analysis by maximum likelihood. The isolates clustered with A. alternata CBS 479.90 (Supplementary Figure 2). The fungus associated with brown leaf spot on wild rice was thus identified as A. alternata. Pathogenicity tests were done in a greenhouse at 24 °C–30 °C with 80% relative humidity. Individual rice plants (cv. ‘Haihong-12’) with three leaves were grown in 10 pots, with around 50 plants per pot. Five pots were inoculated by spraying a spore suspension (105 spores/mL) onto leaves until runoff occurred, and another five pots were sprayed with sterile water to serve as controls. The test was done three times. Disease symptoms were found on the leaves after 7 days. The tips of the leaves turned yellow and spread downward. Then, the whole leaf turned brown and dried out, but the controls stayed healthy. The pathogen was re-isolated from infected leaves and phenotypically identical to the original isolate Aas-1 to fulfill Koch’s postulates. To our knowledge, this report is the first one on A. alternata causing brown leaf spot on wild rice (O. rufipogon). The pathogen has the potential to reduce wild rice yields and future breeding should consider resistance to this pathogen.

scholarly journals First Report of Nigrospora oryzae Causing Leaf Spot of Cotton in China

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1379-1379 ◽  
Author(s):  
L. X. Zhang ◽  
S. S. Li ◽  
G. J. Tan ◽  
J. T. Shen ◽  
T. He
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Morphological Data ◽  
Its Sequence ◽  
Pathogenicity Test ◽  
First Report ◽  
Wide Range ◽  
Cotton Plants ◽  
Symptomatic Leaf ◽  
Nigrospora Oryzae

Cotton (Gossypium hirsutum L.) is widely cultivated for the important economic value of the fiber. In the summer of 2011, a leaf spot of cotton plants cv. Wanza40 was observed in 11 fields (total of about 4 ha) in Qianshan County in southwest Anhui Province, China. Approximately 30% of the plants in each field were symptomatic. Affected plants exhibited brown to reddish, irregular foliar lesions, each with a brown border near the vein of the leaves. A sign of fungal infection was a dark leaf mold observed on lesions on the abaxial surface of leaves. Sections of symptomatic leaf tissues were surface-sterilized (in 75% ethanol for 30 s, then 1% NaOCl for 1 min), rinsed three times in sterile distilled water, and plated onto potato dextrose agar (PDA). A fungus consistently recovered from symptomatic leaf samples produced colonies that were initially white and then became grayish brown with the onset of sporulation. Black, spherical to subspherical, single-celled conidia (10 to 12 × 14 to 16 μm) were borne on a hyaline vesicle at the tip of each conidiophore. Morphological characteristics of the fungus were similar to that of Nigrospora oryzae (2). The internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) from a representative strain of the fungus, AHC-1, was amplified using the primers ITS1/ITS4 (4) and sequenced (GenBank Accession No. JQ864579). The ITS sequence had 99% identity with >553 bp of the ITS sequence of an N. oryzae isolate (GenBank Accession No. EU918714.1). On the basis of morphological data and ITS rDNA sequence, the isolate was determined to be N. oryzae. A pathogenicity test was performed on detached, young leaves of 4-month-old healthy cotton plants of cv. Wanza40. Six leaves were inoculated by placing a colonized agar piece (5 mm in diameter) from 7-day-old cultures of the fungus on pushpin-wounded leaves. Another six leaves treated with sterile PDA plugs served as a negative control treatment. Leaves were incubated in petri dishes and maintained at 25°C in a growth chamber programmed for 12 hours of fluorescent white light/day. After 5 days, brown to black lesions were observed on all inoculated leaves, whereas no symptoms developed on control leaves. N. oryzae was consistently reisolated from symptomatic leaves but not from the control leaves. N. oryzae is a weak pathogen on a wide range of plants, and has been described as the causal agent of lint rot on cotton (1,3), but to our knowledge this is the first report of N. oryzae causing a leaf spot of cotton in China. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA, Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , April 8, 2012. (2) H. J. Hudson. Trans. Br. Mycol. Soc. 46:355, 1963. (3) A. J. Palmatter et al. Plant Dis. 87:873, 2003. (4) T. J. White et al. In: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Leaf Spot Caused by Pseudocercospora pruni-persicicola on Sweet Cherry in Korea

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 693-693
Author(s):  
I. Y. Choi ◽  
U. Braun ◽  
J. H. Park ◽  
H. D. Shin
Keyword(s):  
Leaf Spot ◽  
Sweet Cherry ◽  
Prunus Persica ◽  
Morphological Characteristics ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Voucher Specimen ◽  
First Report ◽  
Close Phylogenetic Relationship

Sweet cherry, Prunus avium (L.) L., is not much cultivated in Korea, with only 150 ha planted for domestic consumption. In September 2012, a previously unknown leaf spot was observed with nearly 100% incidence on trees (cv. Seneca) planted in a plastic greenhouse in Iksan City of Korea. Interestingly, the same cultivar as well as other cultivars planted outdoors did not show these symptoms. Leaf spots were irregular to subcircular, dark brown with or without a yellow halo, and becoming coalesced to cause leaf blight and premature defoliation. A cercosporoid fungus was consistently associated with disease symptoms. Fungal structures within the lesion developed on both leaf sides but mostly on the upper side. Stromata were well-developed, globular, dark brown, composed of textura angularis-globosa, and 30 to 80 μm in diameter. Conidiophores were densely fasciculate, pale olivaceous to pale brown, subcylindrical, geniculate-sinuous, 8 to 24 × 3 to 4 μm, and aseptate to 2-septate. Conidiogenous loci were inconspicuous, neither thickened nor darkened. Conidia were olivaceous, generally darker than conidiophores, cylindrical to obclavate, almost straight to mildly curved, short obconically truncate at the base, obtuse at the apex, 1- to 10-septate, constricted at the septa, 12 to 86 × 3.5 to 5 μm, guttulate, and had unthickened, not darkened hila. Morphological characteristics of the fungus were consistent with previous descriptions of Pseudocercospora pruni-persicicola (J.M. Yen) J.M. Yen (1,3). A voucher specimen was deposited in the Korea University herbarium (Accession No. KUS-F27264) and a monoconidial isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC47019). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 (4) and sequenced. The resulting 505-bp sequence was deposited in GenBank (Accession No. KF670713). A BLAST search in GenBank revealed that the sequence showed >99% similarity with sequences of many Pseudocercospora species, indicating the close phylogenetic relationship of species in this genus. To conduct a pathogenicity test, a conidial suspension (~1 × 104 conidia/ml) was prepared in sterile water by harvesting conidia from 2-week-old cultures on V8 juice agar, and the suspension was sprayed until runoff onto the leaves of five healthy seedlings. Control plants were sprayed with sterile water. The plants were covered with plastic bags to maintain a relative humidity of 100% for 48 h and then transferred to a greenhouse. Necrotic spots appeared on the inoculated leaves 20 days after inoculation, and were identical to the ones observed in the field. P. pruni-persicicola was re-isolated from symptomatic leaf tissues, fulfilling Koch's postulates. Control plants remained symptomless. The fungus has previously been recorded on Prunus persica (L.) Stokes in Taiwan (2,3). To our knowledge, this is the first report of this fungus on P. avium globally as well as in Korea. The disease poses a new threat to the sweet cherry industry in Korea. References: (1) U. Braun and V. A. Melnik. Cercosporoid Fungi from Russia and Adjacent Countries. Rus. Acad. Sci., St.-Petersburg, 1997. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved August 24, 2013. (3) J. M. Yen. Rev. Mycol. 42:57, 1978. (4) T. J. White et al. PCR Protocols. Academic Press, San Diego, CA, 1990.

scholarly journals First Report of a Leaf Spot on Goldthread (Coptis chinensis) Caused by Phoma aquilegiicola in China

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1428-1428 ◽  
Author(s):  
Y. Yu ◽  
Z. C. Su ◽  
W. Z. Tan ◽  
C. W. Bi
Keyword(s):  
Leaf Spot ◽  
Pathogenic Fungus ◽  
Morphological Characteristics ◽  
Its Sequences ◽  
Leaf Margin ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Coptis Chinensis ◽  
First Report ◽  
And Control

Goldthread (Coptis chinensis) is an important herbaceous plant in traditional Chinese medicine (3). Annual production of goldthread root is ~3,000 tons (dry weight) in China. The plant is cultivated extensively in Shizhu Co., Chongqing (29.98°E, 108.13°N), where goldthread yields account for more than 60% of total world production. A foliar disease was first observed on goldthread plants in 2008 in Shizhu County (5). In 2011 and 2012, about 10 ha of goldthread fields in different townships of Shizhu Co. were surveyed. The results demonstrated that the disease present in the fields was widespread at incidences of 30 to 100%, with yield losses of 15 to 75%. Typical symptoms included irregular, purple brown lesions on leaves, beginning usually at the leaf margin and extending to the central leaf blade. The lesions coalesced and turned deep purple. Black pycnidia were visible on the lesions, and severely diseased plants were usually wholly blighted. To identify the pathogen, infected leaves were collected from goldthread fields in different townships of Shizhu Co. and small pieces of symptomatic tissue were cut from each leaf. The leaf pieces were surface-disinfected for 1 min in 1.5% sodium hypochlorite, rinsed in sterilized water, air-dried, and transferred onto potato dextrose agar (PDA) plates with 0.5 g/liter of streptomycin sulfate. Thirty-three fungal isolates with similar colony morphology were obtained. On oatmeal agar plates, each colony was circular with a smooth edge, initially cream, and then pale-brown. Pycnidia were dark brown, spherical, with or without papillae, and 100 to 112 × 189 to 222 μm. Conidia were produced on short, straight, and aseptate conidiophores in the pycnidia; they were monocellular, hyaline, ellipsoidal or clavate, and 2.01 to 2.50 × 4.20 to 5.55 μm. Three isolates (SZ-9, SZ-10, and SZ-13) were selected randomly from all 33 isolates, and genomic DNA of each isolate was extracted following the CTAB method (4). The rDNA ITS region of each isolate was amplified with V9G/ITS4 primers and sequenced (1). The ITS sequences of the three isolates (GenBank Accession Nos. KF692355.2 [SZ-9], KF985236.1 [SZ-10], and KF985237.1 [SZ-13]) were identical, and BLAST revealed 100% identity with the ITS sequence of an isolate of Phoma aquilegiicola (CBS 107.96, GU237735.1). Based on the morphological characteristics and ITS sequences, all three isolates were identified as P. aquilegiicola. Pathogenicity test of 10 isolates was conducted by placing a 5-mm-diameter mycelial agar plug (from the margin of a 5-day-old PDA culture) on each of 10 fully-expanded leaves of healthy goldthread plants/isolate. Ten leaves were treated similarly with sterilized PDA plugs as a control. Inoculated and control plants were incubated in the dark for 24 h at 25 ± 2°C and >90% RH, and then maintained in a growth chamber at 25 ± 2°C, 3,100 lux, and >90% RH. The pathogenicity test was carried out three times. Symptoms developed on all inoculated leaves for all 10 isolates, but not on the control plants. Lesions were first visible 48 h after inoculation, and typical irregular lesions similar to those observed on field plants were seen after 6 days. The same pathogenic fungus was re-isolated from the infected leaves but not from the non-inoculated leaves. A disease caused by P. aquilegiicola was first reported on Aquilegia flabellata plants of the cv. Fan Columbine in a perennial garden in Italy (2). This is the first report of leaf spot on goldthread caused by P. aquilegiicola in China. Studies on the epidemiology and control of the disease are necessary owing to the economic significance of the host and destructiveness of the disease. References: (1) M. M. Aveskamp et al. Mycologia 101:363, 2009. (2) A. Garibaldi et al. Plant Dis. 95:880, 2011. (3) B. Liu et al. J. Pharmaceut. Biomed. 41:1056, 2006. (4) M. A. Saghai-Maaroof et al. Proc. Natl. Acad. Sci. USA. 81:8014, 1984. (5) X. R. Zhou et al. J. Shizhen Medicine Res. 23:471, 2012.

scholarly journals First Report of Nigrospora oryzae Causing Leaf Spot on Ginger in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zeng-Liang LIU ◽  
Shuangyun Zhou ◽  
Liangliang Qi ◽  
Xiaoguo Wang ◽  
Juan Song ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Likelihood Method ◽  
Effective Control ◽  
Economic Losses ◽  
Leaf Spot Disease ◽  
First Report ◽  
Nigrospora Oryzae

Ginger (Zingiber officinale Rosc.) is an herbal crop widely grown in China for its medicinal and savory qualities of rhizomes. In August 2018, leaf spot symptoms were observed on ginger plants grown in a field in Nanning, Guangxi Province (E108°3'54", N23°14'48"). Disease incidence was above 50%, and in a Nanning field, rhizome yield loss was almost 30%. Early symptoms appeared as circular, necrotic areas that later developed into circular or irregular spots. The centers of the lesions were white and often surrounded by chlorotic halos (Figure S1A). In severe infections, the spots frequently coalesced, causing the entire leaf to become withered and curved. Small pieces (3 to 4 mm2) from the margin of infected lesions were surface sterilized in 75% ethanol for 40 s followed by 1% NaOCl for 90 s, placed on potato dextrose agar (PDA) and incubated at 28°C in the dark for 4 days. Hyphal tips from the leading edge of colonies were transferred to fresh PDA plates to obtain pure cultures. Fungal colonies were initially white, then turned black/grayish brown when maintained in the dark at 28°C after 5 days (Figure S1B). Conidia were single-celled, brown, or black, smooth, spherical, or subspherical with diameters varying from 9.5 to 15 μm (mean = 13.5 ± 0.72 µm, n = 50) (Figure S1C). Based on these morphological characteristics, the isolates were provisionally identified as Nigrospora oryzae (Ellis 1971; Hudson 1963). Genomic DNA was extracted from a representative isolate Sjb-2. The internal transcribed spacer (ITS) region, beta-tubulin (TUB2), and the translation elongation factor 1-alpha (TEF1-α) were amplified using primer pairs including ITS1/ITS4 (White et al. 1990), Bt-2a/Bt-2b (Glass and Donaldson 1995), and EF1-728F/EF1-986R (Carbone et al. 1999), respectively. The obtained ITS sequence (GenBank accession no. MW555242), TUB2 sequence (MZ048644), and TEF1-α sequence (MZ048645) showed >99% similarity with several GenBank sequences of N. oryzae (KF516962 for ITS; MK550707 for TUB2; and KY019425 for TEF1-α, respectively). Based on the combined sequences of ITS, TUB2 and TEF1-α sequences, a phylogenetic tree was constructed using the maximum likelihood method and confirmed that the isolates were N. oryzae (Figure S2). Pathogenicity of the isolate was confirmed by fulfilling Koch’s postulates. Agar blocks (3 mm diameter) containing a fungal mycelium were placed on detached healthy leaves of ginger. The leaves were then wrapped with sterile polyethylene and incubated in a greenhouse at 25°C with 60% RH. Within 7 days, symptoms appeared on inoculated leaves similar to spots observed in the field, whereas controls remained symptomless. The same pathogen was reisolated from the spots. Pathogenicity tests were performed twice with three replications, indicating that N. oryzae is responsible for leaf spot disease on ginger. The disease in ginger caused by N. oryzae had been reported in Southern Africa (Grech et al. 1989). To our knowledge, this is the first report of N. oryzae causing leaf spot of ginger in China. In the field, this pathogen can substantially affect ginger's health and rhizome yield if no effective control measures are implemented. Therefore, management of the disease should be further investigated to avoid major economic losses.

scholarly journals First Report of Leaf Spot caused by Bipolaris oryzae on Switchgrass in Tennessee

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1654-1654 ◽  
Author(s):  
A. L. Vu ◽  
M. M. Dee ◽  
J. Zale ◽  
K. D. Gwinn ◽  
B. H. Ownley
Keyword(s):  
Leaf Spot ◽  
Panicum Virgatum ◽  
Morphological Characteristics ◽  
Its Region ◽  
Spore Production ◽  
Post Inoculation ◽  
Sterile Water ◽  
Bipolaris Oryzae ◽  
First Report ◽  
Symptomatic Leaf

Knowledge of pathogens in switchgrass, a potential biofuels crop, is limited. In December 2007, dark brown to black irregularly shaped foliar spots were observed on ‘Alamo’ switchgrass (Panicum virgatum L.) on the campus of the University of Tennessee. Symptomatic leaf samples were surface-sterilized (95% ethanol, 1 min; 20% commercial bleach, 3 min; 95% ethanol, 1 min), rinsed in sterile water, air-dried, and plated on 2% water agar amended with 3.45 mg fenpropathrin/liter (Danitol 2.4 EC, Valent Chemical, Walnut Creek, CA) and 10 mg/liter rifampicin (Sigma-Aldrich, St. Louis, MO). A sparsely sporulating, dematiaceous mitosporic fungus was observed. Fungal plugs were transferred to surface-sterilized detached ‘Alamo’ leaves on sterile filter paper in a moist chamber to increase spore production. Conidia were ovate, oblong, mostly straight to slightly curved, and light to olive-brown with 3 to 10 septa. Conidial dimensions were 12.5 to 17 × 27.5 to 95 (average 14.5 × 72) μm. Conidiophores were light brown, single, multiseptate, and geniculate. Conidial production was polytretic. Morphological characteristics and disease symptoms were similar to those described for Bipolaris oryzae (Breda de Haan) Shoemaker (2). Disease assays were done with 6-week-old ‘Alamo’ switchgrass grown from seed scarified with 60% sulfuric acid and surface-sterilized in 50% bleach. Nine 9 × 9-cm square pots with approximately 20 plants per pot were inoculated with a mycelial slurry (due to low spore production) prepared from cultures grown on potato dextrose agar for 7 days. Cultures were flooded with sterile water and rubbed gently to loosen mycelium. Two additional pots were inoculated with sterile water and subjected to the same conditions to serve as controls. Plants were exposed to high humidity by enclosure in a plastic bag for 72 h. Bags were removed, and plants were incubated at 25/20°C with 50 to 60% relative humidity. During the disease assay, plants were kept in a growth chamber with a 12-h photoperiod of fluorescent and incandescent lighting. Foliar leaf spot symptoms appeared 5 to 14 days post-inoculation for eight of nine replicates. Control plants had no symptoms. Symptomatic leaf tissue was processed and plated as described above. The original fungal isolate and the pathogen recovered in the disease assay were identified using internal transcribed spacer (ITS) region sequences. The ITS region of rDNA was amplified with PCR and primer pairs ITS4 and ITS5 (4). PCR amplicons of 553 bp were sequenced, and sequences from the original isolate and the reisolated pathogen were identical (GenBank Accession No. JQ237248). The sequence had 100% nucleotide identity to B. oryzae from switchgrass in Mississippi (GU222690, GU222691, GU222692, and GU222693) and New York (JF693908). Leaf spot caused by B. oryzae on switchgrass has also been described in North Dakota (1) and was seedborne in Mississippi (3). To our knowledge, this is the first report of B. oryzae from switchgrass in Tennessee. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/, 28 June 2012. (2) J. M. Krupinsky et al. Can. J. Plant Pathol. 26:371, 2004. (3) M. Tomaso-Peterson and C. J. Balbalian. Plant Dis. 94:643, 2010. (4) T. J. White et al. Pages 315-322 in: PCR Protocols: a Guide to Methods and Applications. M. A. Innis et al. (eds), Acad. Press, San Diego, 1990.

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