scholarly journals First Report of Blueberry Leaf Spot Caused by Cylindrocladium colhounii in China

Plant Disease ◽  
2006 ◽  
Vol 90 (12) ◽  
pp. 1553-1553 ◽  
Author(s):  
Y. S. Luan ◽  
L. Feng ◽  
L. J. An
Keyword(s):  
Leaf Spot ◽  
Morphological Traits ◽  
Internal Transcribed Spacers ◽  
Fluorescent Light ◽  
Adaxial Side ◽  
Single Spore ◽  
Tubulin Gene ◽  
First Report ◽  
Plastic Bags ◽  
Β Tubulin

During late July and early August of 2005, leaf spot symptoms were observed in a blueberry nursery at a plantation in Dalian, which to our knowledge, lies within the largest blueberry-production area in China. Symptoms were observed primarily on lowbush species, for example Blomidon, as well as half-highbush cultivars. A slow-growing, white mycelium from the margin of necrotic leaf spots was recovered on potato dextrose agar (PDA). The following morphological traits were observed: erect conidiophores that branch twice and were terminated in a stiped, clavate phialide; hyaline, cylindrical, four-celled conidia; and globose, reddish brown, aggregated chlamydospores. Conidiophores (including stipes and terminal phialides) were 305 to 420 × 5 to 9 μm; primary branches were 9 to 45 × 5 to 6.3 μm; secondary branches were 9 to 17.3 × 3.1 to 4.5 μm; phialides were 7.8 to 17.5 × 2.5 to 6 μm; stipes (from the highest branch area to vesicle) were 150 to 270 μm long; and vesicles were 13 to 30 × 2 to 4.5 μm. Conidia were 50 to 72 × 4 to 5.5 μm. Chlamydospores were 15 to 20 μm in diameter. Koch's postulates were fulfilled by spray inoculating two healthy cultivars with conidiophores homogenized in axenic water. As a control, two healthy plants were sprayed with axenic water. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 26°C under fluorescent light for 14 h and 20°C in darkness for 10 h. After 2 days, the plastic bags were removed and plants were maintained under the same conditions. After 4 days, small-to-medium brown spots with purplish margins were observed on the adaxial side of leaves from inoculated plants, but not from control plants. Fungi isolated from these lesions had the same morphological traits as the ones isolated previously from field plants. The morphological descriptions and measurements were similar to Cylindorocladium colhounii (2). The 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA and the β-tubulin gene were amplified from DNA extracted from single-spore cultures using the ITS1/ITS4 primers and T1/Bt2b primers, respectively, and sequenced (1). The ITS and β-tubulin gene sequences were similar to C. colhounii STE-U 1237 (99%; GenBank Accession No. AF231953) and C. colhounii STE-U 705 (99%; GenBank Accession No. AF231954), respectively. The morphology, secondary conidiation, and sequences of ITS and β-tubulin gene identify the causal fungus as C. colhounii. To our knowledge, this is the first report of C. colhounii on blueberry in China or in the world. References: (1) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (2) T. Watanabe. Page 222 in: Dictorial Atlas of Soil and Seed Fungi. CRC Press, Inc., Boca Raton, Fl, 1994.

scholarly journals First Report of a Pestalotiopsis sp. Causing Leaf Spot of Blueberry in China

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 171-171 ◽  
Author(s):  
Y. S. Luan ◽  
Z. T. Shang ◽  
Q. Su ◽  
L. Feng ◽  
L. J. An
Keyword(s):  
Leaf Spot ◽  
Apical Cell ◽  
Vaccinium Corymbosum ◽  
Internal Transcribed Spacers ◽  
Fluorescent Light ◽  
Tubulin Gene ◽  
First Report ◽  
Plastic Bags ◽  
Plant Nursery ◽  
Β Tubulin

In August 2006, leaf spots were observed on half-high blueberry (Vaccinium corymbosum) in a plant nursery in Dalian, China. The symptomatic potted 1-year-old blueberry plants were located in parts of a plant nursery with poor ventilation. The primary symptom was a leaf spot, 0.4 to 0.8 cm in diameter, with brown margins that enlarged and coalesced. Mycelium grew from symptomatic and green leaf tissue removed from the margin of a necrotic leaf spot. Plant tissues were surface disinfested with 0.1% mercuric chloride for 3 min and 70% ethyl alcohol for 30 s before plating onto potato dextrose agar. The resulting colonies were white with a regular margin and a rough surface. The cultures were covered with black and globular acervuli with a diameter of 100 to 200 μm. The base of each conidiophore was swollen and globose with phialides growing from the apical end. Mature conidia were straight to fusiform, measuring 19.0 to 27.5 × 6.3 to 9.2 μm, and five-celled with the three middle cells brown and darker than the end cells. The apical cell was triangular and hyaline with three simple setulae that were 17.2 to 29.7 μm long. The base cell terminated in a point 4.0 to 8.6 μm long. Koch's postulates were fulfilled for the fungus by spray inoculating two healthy young plants with 2 × 105 conidia per ml of sterile distilled water. As a control, two similar plants were sprayed with sterile water. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 26°C under fluorescent light for 14 h and at 20°C in darkness for 10 h. After 3 days, the plastic bags were removed and plants were maintained under the same conditions. More than 20 days after inoculation, symptoms on inoculated plants were similar to those previously described in the nursery. Control plants did not show any symptoms. Cultures isolated from the lesions were similar to those isolated previously from plants in the nursery. The morphological descriptions and measurements were similar to Pestalotiopsis clavispora (1). The 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA and partial β-tubulin gene were amplified from DNA extracted from single-spore cultures using the ITS1/ITS4 and T1/Bt2b primers (2) respectively, and sequenced (GenBank Accession Nos. EF119336 and EF152585). The ITS sequences were most similar to the ITS regions of P. clavispora TA-8 (98%; GenBank Accession No. AY924264), P. clavispora TA-6 (98%; GenBank Accession No. AY924263), and P. clavispora PSHI 2002 Endo 389 (96%; GenBank Accession No. AY682929). The partial β-tubulin gene sequence was identical to Pestalotiopsis sp. isolate PSHI 2004 Endo 86 (100%; GenBank Accession No. DQ657901). The morphology and sequence data support the identity of the causal fungus as P. clavispora. To our knowledge, this is the first report on the presence of a Pestalotiopsis sp. causing a disease of blueberry in China. References: (1) E. F. Guba. Monograph of Monochaetia and Pestalotia. Harvard University Press, Cambridge, MA, 1961. (2) W. Tao et al. Mol. Cell Biol. 27:689, 2007.

scholarly journals First Report of Alternaria tenuissima Causing Disease on Blueberry in China

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 464-464 ◽  
Author(s):  
Y. S. Luan ◽  
L. Feng ◽  
X. Y. Xia ◽  
L. J. An
Keyword(s):  
Morphological Traits ◽  
Vaccinium Corymbosum ◽  
Histone Gene ◽  
Internal Transcribed Spacers ◽  
Sterile Water ◽  
Single Spore ◽  
Alternaria Tenuissima ◽  
First Report ◽  
Leaf Spots ◽  
Plastic Bags

During September 2006, disease symptoms were observed on mature highbush blueberry (Vaccinium corymbosum L.) cvs. Bluecrop and Covoille in a blueberry commercial field in Dalian, China. The maximum and minimum rainfalls in June to September are 3,111.9 and 1,745.6 ml, respectively. The highest temperature during the summer is 35.3°C and relative humidity may achieve 90%. Circular to irregular, light brown-to-gray leaf spots with brownish red borders, initially 3 to 7 mm in diameter, enlarged and coalesced. Reddish, circular spots appeared on stems, developing small, insignificant cankers. A fungus was recovered on potato dextrose agar (PDA, pH nature) from the margin of necrotic leaf spots. Morphological traits of the strain that developed from a single-spore culture were as follows: colonies were regular and flat, with a rough upper surface that peripherally was olive-green with a black center and dull white spots; short conidiophores arising singly and measuring 81.6 to 163.2 × 4.1 to 8.2 μm; conidia was abundant, ovoid, and obclavate muriformly septate, which horizontal and vertical septations varied from 1 to 6 and 0 to 2, respectively, and its size varied from 26 to 48.8 × 9.7 to 16.3 μm with an average beak length of 9.6 μm, and sporulation pattern is budding. Conidia derived from conidiophores. Koch's postulates were fulfilled for the isolates by spray inoculating two healthy mature plants with 2 × 105 conidia per ml homogenized in sterile water. As a control, two plants were sprayed with sterile water. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 26°C under fluorescent light for 14 h and 20°C in darkness for 10 h. After 2 days, the plastic bags were removed and plants were maintained under the same conditions for 30 days. Symptoms on inoculated plants were similar to those previously observed. Symptoms were not observed on control plants. Cultures isolated from inoculated plants had the same morphological traits as those that were isolated previously from the field plants. The morphological descriptions and measurements were similar to Alternaria tenuissima (2). The 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA and partial cds histone gene were amplified from DNA extracted from single-spore cultures using the ITS1/ITS4 and H3-1a/H3-1b primers, respectively, and sequenced (GenBank Accession No. EF031053) (1,3). The ITS sequence was identical to the ITS regions of A. tenuissima strain EGS34-015 (100%; GenBank Accession No. AY751455), the partial cds histone gene sequence was similar to A. tenuissima isolate MA6 (99%; GenBank Accession No. AF404634). The morphology, secondary conidiation, and sequences of ITS and partial cds histone gene identify the causal fungus as A. tenuissima. To our knowledge, this is the first report on the presence of A. tenuissima affecting blueberry plants in China. References: (1) J. C. Kang et al. Mycol. Res. 106:1151, 2002. (2) E. G. Simmons. Mycotaxon 70:325, 1999. (3) T. J. White et al. Pages 315–322 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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

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

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

scholarly journals First Report of Pestalotiopsis microspora Causing Leaf Spot of Hidcote (Hypericum patulum) in Japan

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1064-1064 ◽  
Author(s):  
M. Zhang ◽  
H. Y. Wu ◽  
T. Tsukiboshi ◽  
I. Okabe
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Its Region ◽  
Basal Cells ◽  
Single Spore ◽  
Management Options ◽  
First Report ◽  
Leaf Spots ◽  
Plastic Bags ◽  
Pestalotiopsis Microspora

Hidcote, Hypericum patulum Thunb. ex Murray, is a deciduous shrub that is cultivated as an ornamental in landscape gardens and courtyards in Japan. In early August 2008, severe leaf spotting was observed on plants growing in a courtyard in Nasushiobara, Tochigi, Japan. More than 30% of the leaves on five shrubs exhibited leaf spot symptoms. Small, round, pale brown lesions were initially observed. Later, they expanded to 5 to 12 mm in diameter, round to irregular-shaped with pale brown centers and dark brown margins. Under continuously wet or humid conditions, black acervuli developed on the leaf lesions. Conidia were straight or slightly curved, fusiform to clavate, and five-celled with constrictions at the septa. Conidia ranged from 17 to 21 × 5 to 8 μm with hyaline apical and basal cells. Fifteen percent of apical cells had two and the rest had three appendages (setulae) ranging from 10 to 21 μm long. The basal hyaline cell tapered into a 2 to 4 μm pedicel. The three median cells ranged from light or dark brown to olive green. These morphological characteristics matched those of Pestalotiopsis microspora (Speg.) G.C. Zhao & N. Li (1,2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. GU908473) from single-spore isolates, which revealed 100% homology with those of other P. microspora isolates (e.g., GenBank Accession Nos. FJ459950 and DQ456865). Koch's postulates were confirmed using leaves of three detached branches of a field-grown asymptomatic plant of H. patulum. Thirty leaves of each branch were inoculated by placing mycelial plugs obtained from the periphery of 7-day-old single-spore cultures on the leaf surface. Potato dextrose agar plugs without mycelium served as controls. Leaves on branches were covered with plastic bags for 24 h to maintain high relative humidity in a greenhouse (approximately 24 to 28°C). After 5 days, all inoculated leaves showed symptoms identical to those described above, whereas control leaves remained symptom free. Reisolation of the fungus from lesions on inoculated leaves confirmed that the causal agent was P. microspora. To our knowledge, this is the first report of leaf spots on H. patulum caused by P. microspora in Japan. Management options may have to be developed and implemented to protect Hidcote plants in areas where leaf spot cannot be tolerated. References: (1) P. A. Saccardo. Sylloge Fungorum III:789, 1884. (2) G. C. Zhao and N. Li. J. Northeast For. Univ. 23(4):21, 1995.

scholarly journals First Report of Leaf Spot Caused by Colletotrichum spaethianum on Peucedanum praeruptorum in China

Plant Disease ◽  
2013 ◽  
Vol 97 (10) ◽  
pp. 1380-1380 ◽  
Author(s):  
M. Guo ◽  
Y. M. Pan ◽  
Y. L. Dai ◽  
Z. M. Gao
Keyword(s):  
Leaf Spot ◽  
Control Strategies ◽  
Pcr Amplification ◽  
Effective Control ◽  
Fluorescent Light ◽  
Actin Gene ◽  
Single Spore ◽  
Chinese Medicinal Herb ◽  
First Report ◽  
Rdna Its

Peucedanum praeruptorum Dunn, a traditional Chinese medicinal herb, is an important crop in Ningguo, China. Since 2010, leaf spot symptoms were observed yearly starting in June. Blighted leaf areas on individual plants ranged from 10 to 25% in many fields, and up to 200 ha were affected each year. Symptoms consisted of small, brown, necrotic spots uniformly distributed on the 1- to 2-week-old leaves. Small tissue pieces from the edges of lesions were disinfected in 2% NaClO for 3 min, rinsed twice in distilled water, plated on potato dextrose agar (PDA), and incubated at 25°C in darkness for 4 days. Single spore isolations were obtained for six strains. When inoculated on SNA media, the six strains produced typical septate mycelium, with the young hyphae hyaline and aged ones white greyish. Setae of the strains on SNA were brown, tip acute, 2- to 3-septate, and 32.5 to 85.6 μm long. Conidiogenous cells were hyaline, cylindrical, 2- to 3-septate, 6.2 to 16.5 μm in length, and 2.8 to 4.3 μm in width. The mature conidia were slightly curved, with round apex and truncate base, 1 to 5 oil globules, and were 13.3 to 23.8 μm in length and 3.0 to 3.9 μm in width, respectively. Appressoria were solitary or in loose groups, dark brown, irregular shapes, and were 6.8 to 9.2 μm in length and 4.3 to 7.1 μm in width. PCR amplification was carried out by utilizing the universal rDNA-ITS primer pair ITS4/ITS5 (1) and the actin gene primer pair ACT-512F and ACT-783R (2). The PCR products of ITS (GenBank Accession No. KC913201) and actin gene (KC913202) from six isolates were identical, respectively, and shared 100% identity to the ITS sequence of strain CBS 167.49 of Colletotrichum spaethianum (GU227807.1) and 99% similarity to the actin gene of strain CBS 167.49 of C. spaethianum (GU227905.1), which was isolated from Hosta sieboldiana in Germany (3). Based on the above, the isolates were identified as C. spaethianum. To confirm pathogenicity, conidial suspensions (105 conidia ml–1) of each of the six isolates were sprayed on four leaves per plant on five 6-month-old P. praeruptorum plants. Control plants were sprayed with water. Plants were maintained at 28°C in a greenhouse with constant humidity (RH 90%) and a 12-h photoperiod of fluorescent light. Symptoms similar to the original ones started to appear after 10 days, while the control plants remained healthy. The tests were repeated three times and the fungus was recovered and identified as C. spaethianum by both morphology and molecular characterization. To our knowledge, this is the first report of C. spaethianum causing leaf spot on P. praeruptorum in China. Since the C. spaethianum infections pose a serious threat to P. praeruptorum production, this disease needs to be considered for developing effective control strategies. References: (1) I. Carbone and L. M. Kohn. Mycologia 91:553, 1999. (2) U. Damm et al. Fung. Divers. 39:45, 2009. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals First Report of Cladosporium Leaf Spot of Spinach Caused by Cladosporium variabile in the Winter Spinach Production Region of California and Arizona

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1071-1071 ◽  
Author(s):  
L. J. du Toit ◽  
M. L. Derie
Keyword(s):  
Leaf Spot ◽  
The United States ◽  
Tween 20 ◽  
Sterile Water ◽  
Single Spore ◽  
Imperial Valley ◽  
First Report ◽  
Production Region ◽  
Plastic Bags ◽  
Seed Crops

In December 2011, symptoms typical of Cladosporium leaf spot caused by Cladosporium variabile (4) were observed in organic “baby leaf” spinach (Spinacia oleracea) crops of the cultivars Amazon, Missouri, Tasman, and Tonga in the Imperial Valley (Imperial County, CA and Yuma County, AZ). Leaves had small, circular lesions (1 to 3 mm in diameter), some of which had progressed to necrotic, bleached lesions surrounded by a thin dark margin. The incidence of symptoms in affected crops was ≤20%. Fungal isolates resembling C. variabile were recovered by surfacesterilizing sections (5 mm2) of symptomatic leaf tissue in 0.6% NaOCl, triple-rinsing the sections in sterile water, and plating the sections onto water agar and potato dextrose agar amended with 100 ppm chloramphenicol (cPDA). Single-spore transfers made onto cPDA were maintained at 24 ± 2°C with a natural day/night cycle. Each isolate produced slow growing cultures consisting of dense masses of dark conidiophores (≤350 μm long) with chains of up to three dematiaceous (olive) conidia, and almost no mycelium. Torulose (coiled) aerial hyphae developed from the apices of conidiophores after 5 to 7 days, and distinguished the isolates as C. variabile, not C. macrocarpum (2,4). Pathogenicity was tested for each of six single-spore isolates using 36-dayold plants of the spinach cultivar Carmel. The plants were enclosed in clear plastic bags overnight and inoculated the next day with the isolates of C. variabile by atomizing approximately 30 ml of a spore suspension (1.0 × 106 conidia/ml in sterile water amended with 0.01% Tween 20) of the appropriate isolate onto the upper and lower leaf surfaces of each of five plants/isolate. Five control plants were inoculated similarly with sterile water + 0.01% Tween 20. The plants were resealed in plastic bags for 72 h and then placed on a greenhouse bench. Pinpoint, sunken lesions developed within 4 to 7 days on the leaves of plants inoculated with each of the six test isolates. Lesions developed into dry, circular spots typical of Cladosporium leaf spot. Symptoms were not observed on control plants. After 20 days, C. variabile was reisolated from lesions caused by all six isolates, but not from control plants. Although Cladosporium leaf spot has been reported in the Salinas Valley of California (4), to our knowledge, this is the first report of the disease on spinach crops in the Imperial Valley of California and Arizona, the primary winter, fresh market spinach production region of the United States. Inoculum of C. variabile may have been introduced to this region on spinach seed lots (3), because even seed infestation levels <0.1% could lead to seed transmission (1) under the dense planting populations (≤9 million seeds/ha) and overhead irrigation typical of “baby leaf” spinach crops in this region. Fungicides can be used to manage Cladosporium leaf spot in conventional spinach crops (1), but management in certified organic crops may be more challenging. References: (1) L. J. du Toit et al. Fung. Nemat. Tests 59:V115, 2004. (2) M. B. Ellis. Page 315 in: Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Surrey, England, 1971. (3) P. Hernandez-Perez. Page 79 in: Management of Seedborne Stemphylium botryosum and Cladosporium variabile Causing Leaf Spot of Spinach Seed Crops in Western Washington, MS thesis, Pullman, WA, 2005. (4) P. Hernandez-Perez and L. J. du Toit. Plant Dis. 90:137, 2006.

scholarly journals First Report of Paramyrothecium breviseta Causing Leaf Spot Disease of Coffea canephora in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Weihuai Wu ◽  
Mengfeng Zhu ◽  
YanQiong Liang ◽  
Xuehui Bai ◽  
Ying Lu ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Coffea Arabica ◽  
Coffea Canephora ◽  
Bootstrap Support ◽  
Leaf Spot Disease ◽  
Single Spore ◽  
First Report ◽  
Spot Disease ◽  
Β Tubulin

Coffee is a tropical plant with two widely cultivated species, namely Coffea arabica and Coffea canephora. A leaf spot disease causing brownish and necrotic lesions was broken out on the C. canephora coffee seedlings in a nursery in Ruili County, Yunnan Province, China, during 2018 to 2019. The incidence of the disease was 15% ~ 20%. Ten diseased leaf samples from five diseased plants were collected for pathogen isolation by tissue separation method. Leaf pieces were cut from the margin of the necrotic lesions (4 × 6 mm), surface-sterilized for 30 s in 75% ethanol, followed by 0.1% arsenic mercury solution for 15 s, then washed 3~4 times with sterilized distilled water and transferred onto potato dextrose agar (PDA) medium in petri plates. Four morphologically similar isolates were obtained from lesions and cultivated on PDA at 25°C. Initial colonies of isolates were round, neat edge, white, floccose mycelium and developed dark green-to-black concentric rings that were sporodochia bearing viscid spore masses after 5~7 days. Conidia were acetates, hyaline and cylindrical with both rounded ends and 4.8 to 6.4 µm long × 1.6 to 2.6 µm wide. Koch's test were conducted on three healthy plants leaves of original source variety C. canephora No.2 and C.arabica Catimor CIFC7963 (control plants) with spore suspension (1 × 106/mL), respectively. Meanwhile, equal numbers of healthy plants were inoculated with water as controls. After inoculation, the plants were transferred into an incubator at 25℃ with saturated humidity. After 10 days of inoculation, all the tested plants presented similar typical symptoms with the diseased leaves under natural conditions; whereas the controls remained healthy. Koch’s postulates were performed by re-isolating the fungus from the inoculated leaves and verifying its colony and morphological characters. Two single spore isolates cultured on PDA medium were selected for DNA extraction. The ribosomal internal transcribed spacer (ITS) was PCR amplified by using primers ITS1 and ITS4 (White et al., 1990), β-tubulin gene by Bt2a and Bt2b (Glass and Donaldson, 1995), the RNA polymerase II second largest subunit (rpb2) by RPB2-5F2 and RPB2-7cR (O’Donnell et al, 2007), calmodulin (cmda) gene by CAL-228F and CAL2Rd (Groenewald et al., 2013). The sequences of ITS (MT853067 ~ MT853068), β-tubulin (MT897899 ~ MT897900), rpb2 (MW256264~ MW286265) and cmda (MT897897~ MT897898) were deposited in GenBank databases. BLAST analysis revealed that the representative isolates sequences shared 99.31%~99.65% similarities to the ITS sequence of Paramyrothecium breviseta (Accession Nos. NR_155670.1), 99.43% similarities to the β-tubulin sequence of P. breviseta (Accession Nos. KU846406.1), 98.98% similarities to the rpb2 sequence of P. breviseta (Accession Nos. KU846351.1), and 98.54%~98.71% similarities to the cmda sequence of P. breviseta (Accession Nos. KU846262.1). As it shown in the phylogenetic tree derived from combined ITS, β-tubulin, rpb2, and cmda gene sequences, the two representative isolates were clustered together with P. breviseta CBS 544.75 with 98% strong bootstrap support, which confirmed that P. breviseta is the causal agent of leaf spot of Coffea canephora. To our knowledge, this is the first report of a leaf spot disease caused by P. breviseta on C. canephora in China, which raised the caution that P. breviseta is also pathogenic to Coffea Arabica.

scholarly journals First Report of Cladosporium Leaf Spot of Spinach Caused by Cladosporium variabile in North Carolina

Plant Disease ◽  
2014 ◽  
Vol 98 (12) ◽  
pp. 1741-1741
Author(s):  
A. C. Scruggs ◽  
S. C. Butler ◽  
L. M. Quesada-Ocampo
Keyword(s):  
North Carolina ◽  
Leaf Spot ◽  
Fungal Growth ◽  
The United States ◽  
Hot Water ◽  
Economic Losses ◽  
Fluorescent Light ◽  
Single Spore ◽  
First Report ◽  
Infected Seed

Cladosporium leaf spot of spinach, caused by Cladosporium variabile, can result in significant economic losses in the United States (2). In March 2014, symptoms consistent with Cladosporium leaf spot (4) appeared on the spinach cultivar Tyee in a greenhouse located in Rowan County, NC. Of 1,080 spinach plants, 90 to 100% were infected. Symptoms consisted of small (1 to 3 mm in diameter), circular, tan lesions each outlined with a dark margin on the adaxial surface of the leaf. On severely infected foliage, lesions coalesced to produce relatively large necrotic regions. Profuse fungal sporulation was observed on the lesion surface with a dissecting microscope at 40× magnification. Using a dissecting microscope, conidia were collected with a sterile needle and transferred to petri plates containing potato dextrose agar. Plates were then incubated at 23 ± 2°C under continuous fluorescent light, and fungal growth was apparent after 24 h. Isolations from leaves of six infected plants produced slow-growing, dark green to brown fungal colonies that reached only 31 mm in diameter after 14 days, which is characteristic of C. variabile (4). Colonies contained dense masses of dematiaceous, septate, unbranched conidiophores with conidial chains, each containing up to five conidia. Conidia were ovate to elongate, with some being septate. The length of individual conidia ranged from 10 to 19 μm. Conidial septa were distinctly dark when observed at 100× magnification, which is a defining feature of C. variabile vs. the conidia of C. macrocarpum (4). The surface of the conidia appeared verrucose at 100× magnification, and conidia were each distinctly darkened toward the base. A single isolate obtained through single-spore transfer was used for DNA extraction, and the histone 3 (H3) gene sequence was amplified using the primers CYLH3F and CYLH3R (1). Sequence analysis of the amplified product using BLAST analysis indicated that the H3 sequences had 100% identity to that of a C. variabile isolate (GenBank Accession No. EF679710.1), and 99% identity to a C. macrocarpum isolate (EF679687.1). The H3 sequence from a representative isolate was deposited in GenBank (KJ769146). To our knowledge, this is the first report of Cladosporium leaf spot on spinach in North Carolina based on morphological evaluation and H3 sequencing results. C. variabile is a seedborne pathogen, so it is possible inoculum was introduced into the greenhouses in North Carolina on infected seed (3). Seeds can be treated with hot water or chlorine to reduce the risk of disease outbreaks caused by infected seed (2). Furthermore, Cladosporium leaf spot may be controlled with the use of fungicides (3). References: (1) P. Crous et al. Stud. Mycol. 50:415, 2004. (2) L. J. du Toit and P. Hernandez-Perez. Plant Dis. 89:1305, 2005. (3) L. J. du Toit et al. Fung. Nemat. Tests 59:V115, 2004. (4) Schubert et al. Stud. Mycol. 58:105, 2007.

scholarly journals First Report of Leaf Spot, Blight, and Stem Lesions Caused by Cylindrocladium pauciramosum on Callistemon in Spain

Plant Disease ◽  
2007 ◽  
Vol 91 (8) ◽  
pp. 1057-1057 ◽  
Author(s):  
A. Pérez-Sierra ◽  
L. A. Álvarez ◽  
M. León ◽  
P. Abad-Campos ◽  
J. Armengol ◽  
...  
Keyword(s):  
Uv Light ◽  
Single Spore ◽  
First Report ◽  
Potted Plants ◽  
Leaf Spots ◽  
Plastic Bags ◽  
The Family ◽  
Stem Lesions ◽  
The Uk ◽  
Β Tubulin

Callistemons (Callistemon citrinus (Curtis) Skeels), evergreen plants of the family Myrtaceae, are commonly grown in Mediterranean gardens for their red bottlebrush-like flowers. During November of 2006, 1-year-old potted plants of callistemon showed leaf spots and blight in commercial nurseries in Valencia, Spain. Symptoms consisted initially of minute brown spots on the leaves, developing into black-gray blotches that finally coalesced. Diseased plants also showed stem lesions and blight of young shoots. Approximately 30% of the plants were affected. A Cylindrocladium sp. was isolated consistently from the infected tissues. Six single conidial isolates were grown on carnation leaf agar (CLA) under near-UV light at 25°C for 7 days (1). The macroconidiophores comprised of a stipe, a sterile elongation, and a penicillated arrangement of primary, secondary, and tertiary branches. The stipes were septate, 110 to 175 (138) μm long, with a terminal obpyriform vesicle measuring 3.75 to 7.5 (5.8) μm wide. Phialides (12.5 × 3.6 μm) were hyaline, doliiform to reniform, with conidia 40 to 55 × 3.7 to 5 μm, cylindrical with rounded ends, aseptate or one septate. Chlamydospores were brown and formed microsclerotia. These features conformed to the description of Cylindrocladium pauciramosum (3). Further confirmation was obtained by sequence analysis. The 5′ end of the β-tubulin gene was amplified using primers T1 and βt2b (2). Comparison with other sequences in GenBank revealed that the isolates described here were identical with C. pauciramosum (Accession No. AY880064) isolated from Ceanothus in the UK. To confirm pathogenicity, 1-year-old plants of callistemon were inoculated with two isolates by spraying with a spore suspension of the fungus (1 × 105 conidia per ml) obtained from 14-day-old single spore colonies on CLA. Control plants were treated with sterile distilled water. After inoculation, all plants were maintained in plastic bags and kept at 22 ± 2°C. Four days after inoculation, the plants developed symptoms similar to those observed in natural infections, and C. pauciramosum was reisolated, successfully completing Koch's postulates. No symptoms were observed on the control plants. C. pauciramosum has been recorded on several hosts, including Callistemon citrinus, in Italy (4). To our knowledge, this is the first report of C. pauciramosum on callistemon in Spain. References: (1) P. W. Crous and M. J. Wingfield. Mycotaxon 51:341, 1994. (2) B. Henricot and A. Culham. Mycologia 94:980, 2002. (3) C. L. Schoch et al. Mycologia 91:286, 1999. (4) C. L. Schoch et al. Plant Dis. 85:941, 2001.

scholarly journals First Report of Pestalotiopsis microspora Causing Leaf Spot on Moyeam in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Si-Qi Yuan ◽  
icai Wang ◽  
Ling Lei ◽  
Ju-Yun Hong ◽  
Tuyong Yi ◽  
...  
Keyword(s):  
Nucleotide Sequence ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Universal Primers ◽  
Molecular Characteristics ◽  
Conidial Suspension ◽  
Tubulin Gene ◽  
First Report ◽  
Wide Range ◽  
Β Tubulin

Ampelopsis grossedentata, commonly known as moyeam, has been widely used as health care herbal tea since it contains natural plant protein cream, 17 amino acids, 14 micronutrients and lots of functional flavonoid and provides a wide range of pharmaceutical functions such as antioxidant, anti-inflammatory, antitumor (Carneiro et al. 2021; Zhang et al. 2020). Moyeam is primarily produced in Zhangjiajie, stretching over the area from between 109’40 to 110’20E to between 28’52 to 29’48N, at 1300 to1890 meter above the sea level, with subtropical humid monsoon climate. Its economic value surpasses $1.25 billion in China (Liang et al. 2020). In July 2020, leaf spots were observed on some moyeam plants in Zhangjiajie. Initial spots were pinhead-sized with a yellow halo margin. The spots developed into light brown necrotic spots 6 to 8 mm in diameter, often with a dark brown margin. After 4 days of development, the spots enlarged and coalesced into irregular shape, frequently falling out and giving the leaves a tattered appearance. The infected plants eventually died with disease incidence ranging from 18 to 23%. This disease resulted in production losses of up to $1.7 million in 2020. One fungal isolate was isolated from the symptomatic leaves based on our previously published methods (Yi et al. 2019). Colonies on potato dextrose agar (PDA) were thick and villous with white at the front of the plate and yellowish at the back. After 1 week, the fungus produced conidia, which were spindle-shaped, straight or slightly curved, with 5 cells, 4-euseptates and 2-3 apical accessory filaments. Morphologically, the fungus was similar to Pestalotiopsis spp. Aerial hyphae with vigorous growth were collected for molecular identification. ITS nucleotide sequence of the rDNA and β-tubulin gene were amplified and sequenced with universal primers ITS1/ITS4 and self-designed primers based on β-tubulin gene conserved motif. BLAST searches against GenBank indicated that the ITS nucleotide sequence shared 99% similarity with that of P. microspora (MG808374.1) and the β-tubulin gene sequence shared 99% similarity with that of P. microspora (AF115396.1). Based on morphological and molecular characteristics, the fungus was identified as P. microspora. ITS and the β-tubulin nucleotide sequences were deposited in GenBank (accession no. MW350011 and MW816914). Pathogenicity tests were carried out with the following procedure. Three healthy moyeam seedlings were sprayed with a conidial suspension of 1 x106 conidia/ml while the other three seedlings were sprayed with distilled water as the controls. Plants were maintained in a greenhouse at 28±1°C. After one day of inoculation, symptoms identical to those in the field developed in the plants inoculated with the fungus. In contrast, no symptoms developed on the control plants. P. microspora has been reported to cause diseases in many crops in China. However, this is the first report of P. microspora causing leaf spot in moyeam in China. Identifying the pathogen causing the disease is important to the development of effective disease management strategies for control of this disease.

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