scholarly journals First Report of Anthracnose Caused by Colletotrichum fructicola on Hybrid Pear Fruit in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Eu Ddeum Choi ◽  
Sook-Young Park
Keyword(s):  
Control Strategies ◽  
Morphological Characteristics ◽  
Likelihood Method ◽  
Pyrus Pyrifolia ◽  
Post Inoculation ◽  
Conidial Suspension ◽  
Pear Fruit ◽  
Single Spore ◽  
First Report ◽  
Other Information

In August 2020, anthracnose-like symptoms was observed on pear fruit (Pyrus pyrifolia  P. communis) cultivated at 0.2 ha by the National Institute of Horticultural and Herbal Science Pear Research Institute at the Rural Development Administration (Naju, Jeonnam Province in Korea). Symptoms were observed only on fruit (112 days after full bloom (DAFB)), and disease incidences was at least 90%. Initial black specks developed into larger brown or black lesions on fruit after 3 days. Later, sunken lesions with orange conidial masses were observed. Finally, infected fruit dropped prematurely. To isolate and identify the pathogen, small pieces (5  5 mm) from the margin of lesions on fruit were surface sterilized by immersing in 70% ethanol for 1 minute, washed three times with sterile water, dried, and placed on water agar amended with 100 ppm streptomycin, then incubated in the dark at 25°C. Hyphae emerging from the three independent tissues were subcultured on Potato Dextrose Agar (PDA), resulting in three independent isolates (CP-1, CP-2, CP-3) after single spore isolation. Colonies were pale gray on PDA, but the colony edges were white. Conidia were transparent, cylindrical with rounded ends, and 13.8 to 20.1 μm  4.8 to 6.2 μm (avg. 18.3 μm  5.4 μm, n = 100) in size. Appressoria were dark brown, globose or subcylindrical, and 6.3 to 9.5 μm  5.2 to 6.9 μm in size (8.1  6.1 μm, n = 100). The morphological characteristics were similar to the descriptions of C. gloeosporioides species complex (Weir et al. 2012). Sequences of ITS (MT921589-91), GAPDH (MT921987-89), CAL (MT921990-92), ACT (MT921993-95), CHS-1 (MT921996-98), TUB2 (921999-01), and ApMAT (MT922002-04) sequences from CP-1, CP-2, and CP-3 matched with C. fruiticola strain BRIP 62871 (100%; MK298285), HXQT-2 (100%; MN52588), HXQT-2 (100%; MN52839), HXQT-2 (99.65; MN525801), ICKP18B4 (99.34%; LC494275), HB5 (100%; MH985245), and GQHZJ23 (100%; MN338294), respectively. Concatenated gene sequences were used for a phylogenetic analysis based on the maximum likelihood method. The reference gene accessions and other information are presented in Weir et al. (2012). The analysis placed the isolates within a clade comprising C. fructicola. Pathogenicity of CP-1 was tested using 120 healthy pear fruits. The fruit surfaces were sterilized with 70% ethyl alcohol for 2 min and washed twice with sterilized water. Three 120 DAFB fruits were inoculated with 10 l of a conidial suspension (1×106 conidia/ml) with and without wounding. Another three control fruits were inoculated with sterile distilled with and without wounding. The inoculated fruit were placed in a plastic box to maintain high humidity and incubated in the dark at 25°C. Symptoms were observed on both wounded fruits after 3 days post inoculation (dpi) and 5 dpi on the unwounded fruits. No symptoms were observed in the control on both the wounded fruits. Pathogenicity tests was performed in duplicate. The pathogen was re-isolated from symptomatic tissues (100%) on treatments on both the wounded and unwounded fruits, but not control. The identity of the both re-isolated pathogen from the wounded and unwounded fruits was confirmed via analysis of seven genes and morphological characteristics, thus fulfilling Koch’s postulates. Although C. fructicola has been reported on apples and peaches in Korea (Kim et al. 2018; Lee et al. 2020), this is the first report of anthracnose caused by C. fructicola on pear fruit in Korea, highlighting the need for systematically investigating the diversity and incidence of pear anthracnose in Korea. This study will contribute to the development of control strategies for anthracnose disease on pear fruit in Korea.

scholarly journals First Report of Crown Rot of Banana Caused by Fusarium porliferatum in Georgia, USA

Plant Disease ◽  
2021 ◽  
Author(s):  
Sumyya Waliullah ◽  
Greg E. Fonsah ◽  
Jason Brock ◽  
Yonggang Li ◽  
Emran Ali
Keyword(s):  
Sequence Similarity ◽  
Morphological Characteristics ◽  
Fusarium Proliferatum ◽  
Crown Rot ◽  
Post Inoculation ◽  
Conidial Suspension ◽  
Banana Fruit ◽  
Single Spore ◽  
First Report ◽  
Initial Symptoms

Crown rot is one of the most damaging disease of banana fruit characterized by rot and necrosis of crown tissues. In severe cases, the disease can spread to the pedicel and banana pulp. Crown rot can be infected by several common fungi, including Lasiodiplodia theobromae, Musicillium theobromae, Colletotrichum musae, and a complex of Fusarium spp. and lead to softening and blackening of tissues (Lassois et al., 2010; Kamel et al., 2016; Triest et al., 2016; Snowdon, 1990). In November 2020, typical crown rot of banana fruits (cv. Pisang Awak, belonging to the tetraploid AABB genome) were observed from UGA Banana Research 12 Plots, Tifton, GA, with incidence rates of 15%. Initial symptoms appeared in the infected crown of green banana fruits. As the infection progressed, the crown tissues became blackened and softened, followed by an internal development of infection affecting the peduncle and the fruit, triggered early ripening of bananas. At last, the development of necrosis on the pedicels and fruits appeared and caused the fingers to fall off. To identify the pathogen, tissue pieces (~0.25 cm2) from the infected crown and pedicles were surface-sterilized in a 10% bleach solution for 1 min, followed by 30 s in 70% EtOH. The disinfected tissues were rinsed in sterile water 3 times and cultured on potato dextrose agar (PDA) amended with 50 µg/ml streptomycin at 25°C in the dark for 5–10 days. Isolates of the pathogen were purified using the single-spore isolation method (Leslie and Summerell 2006). Colonies on PDA produced fluffy aerial mycelium and developed an intense purple pigment when viewed from the underside. A range of colony pigmentation and growth rates were observed among the isolates. The microconidia were ovoid, hyaline, or ellipse in shape. The morphological features of the isolates were identified as Fusarium proliferatum (Leslie and Summerell, 2006). To further identify the isolates, genomic DNA was extracted from a representative isolate. And the internal transcribed spacer (ITS) region, the partial elongation factor (TEF1-α) gene and the β-tubulin gene (TUB2)were amplified and sequenced using the primers ITS1/ITS4 (Yin et al. 2012), EF-1 /EF-2 (O’Donnell et al. 1998) and B-tub1 /B-tub2 (O’Donnell and Cigelnik, 1997), respectively. The amplicons were sequenced and deposited in NCBI (accessions no. MZ292989, MZ293071 for ITS: MZ346602, MZ346603 for TEF1-α and MZ346600 and MZ346601 for B-tub). The ITS, TEF1-α, and B-tub sequences of the isolates showed 100% sequence similarity with Fusarium proliferatum isolates (accessions no. MT560212, LS42312, and LT575130, respectively) using BLASTn in Genbank. For pathogenicity testing, three whole bunched bananas sterilized with 10% bleach solutions and washed by sterilized water, were cut into 5 bananas per brunch. The cut surface of the banana crown was inoculated with conidial suspension (1.0 × 107 cfu/ml) of the pathogen with pipette tips. Equal number of bananas were treated with sterilized water in the same volume as a control. All bananas were sealed in a plastic bag and incubated at 25°C. After 7 days post inoculation, all inoculated bananas showed initial crown rot symptoms while no symptoms were observed on the control bananas. The fungus was re-isolated from the symptomatic tissues of infected bananas and confirmed to be genetically identical to F. proliferatum of the original inoculated strains according to morphological characteristics and molecular identification, fulfilling Koch’s postulates. To the best of our knowledge, this is the first report of F. proliferatum causing crown rot on bananas in Georgia, USA.

scholarly journals First Report of Colletotrichum cereale Causing Anthracnose on Avena nuda in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Na Zhao ◽  
Junyu Yang ◽  
Xiaoli Fang ◽  
lingrui Li ◽  
Hongfei Yan ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Causal Agent ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Fungal Isolates ◽  
Colletotrichum Cereale ◽  
Avena Nuda

Naked oats (Avena nuda L.) is rich in protein, fat, vitamin, mineral elements and so on, and is one of the world's recognized cereal crops with the highest nutritional and healthcare value. In July 2019, leaf spot was detected on A. nuda in Zhangbei experimental station of Hebei Agricultural University. The incidence of disease is 10% to 20%. The symptoms were similar to anthracnose disease, the infected leaves had fusiform or nearly fusiform yellowish-brown spots, yellow halo around the spots. Numerous acervuli with black setae diagnostic of fungi in the genus Colletotrichum were present on necrotic lesions. To identify the pathogen, ten symptomatic leaves were collected, and only one disease spot was isolated from each leaf. Small square leaf pieces (3 to 5 mm) were excised from the junction of diseased and healthy tissues with a sterile scalpel and surface disinfested with 75% alcohol for 30s, 0.1% corrosive sublimate for 1 min, rinsed three times in sterile water. Plant tissues were then transferred on potato dextrose agar (PDA), and incubated at 25°C for 7 days. Two fungal isolates were obtained and purified by single-spore isolation method. All fungi have the same morphology and no other fungi were isolated. The aerial mycelium was gray black. The conidia were colorless and transparent, falcate, slightly curved, tapered toward the tips, and produced in acervuli with brown setae. The length and width of 100 conidia were measured and size ranged from 1.86 to 3.84 × 8.62 to 29.81 μm. These morphological characteristics were consistent with the description of Colletotrichum cereale (Crouch et al. 2006). To further assess the identity of the species, the genomic DNA of two fungal isolates (LYM19-4 and LYM19-10) was extracted by a CTAB protocol. The ribosomal DNA internal transcribed spacer (ITS) region as well as, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and the beta-tubulin 2 (Tub2) partial genes were amplified and sequenced with primers ITS4/5, GDF/GDR, ACT-512F/ACT-783R, and T1/Bt2b, respectively (Carbone et al. 1999; Templeton et al. 1992; O'Donnell et al. 1997; Glass et al. 1995). The sequences of the ITS-rDNA region (MW040121, MW040122), the GAPDH sequences (MW052554, MW052555), the ACT sequences (MW052556, MW052551) and the Tub2 sequences (MW052552, MW052553) of the two single-spore isolates were more than 99% identical to C. cereale isolate CGMCC3.15110 (JX625159, KC843517, KC843534 and JX625186). Maximum likelihood tree based on concatenated sequences of the four genes were constructed using MEGA7. The results showed the strains isolated from A. nuda were closely related to C. cereale, as supported by high bootstrap values. A pathogenicity test of the C. cereale isolates was performed on first unfolding leaves of A. nuda. Koch's postulates were carried out with isolates by spraying a conidial suspension of 106 conidia/mL on leaves of healthy A. nuda. Four replicated pots were inoculated at a time, 10 leaves each pot, while sterile distilled water was used as the control. All treated plants were placed in a moist chamber (25°C, 16-h light and 8-h dark period). Anthracnose symptoms developed on the inoculated plants 7 days post inoculation while all control plants remained healthy. Microscopic examination showed the surface of infected leaves had the same acervuli, setae, and conidia as the original isolate. The pathogenicity test was repeated three times. C. cereale was previously reported as the causal agent of anthracnose on feather reed grass in US (Crouch et al. 2009). To our knowledge, this is the first report of C. cereale as the causal agent of A. nuda anthracnose in China.

scholarly journals First Report of Ergot (Claviceps purpurea) on Drunken Horse Grass (Achnatherum inebrians) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Haijuan Zhang ◽  
Taixiang Chen ◽  
Yali He ◽  
Chunjie Li
Keyword(s):  
Molecular Characterization ◽  
Morphological Characteristics ◽  
Post Inoculation ◽  
Conidial Suspension ◽  
Claviceps Purpurea ◽  
Large Area ◽  
Single Spore ◽  
First Report ◽  
Achnatherum Inebrians ◽  
Natural Grasslands

Drunken horse grass (Achnatherum inebrians) belongs to the family Poaceae: it is mainly distributed in the natural grasslands of northern and northwestern in China. Ergot is a disease that can not only affect the growth of the grass, but also cause livestock poisoning (Coufal-Majewski et al. 2016). In September 2018, ergot was observed in a large area (about 15 ha) in Xinghai county, Qinghai province, China (35° 47′ N, 99° 53′ E, Altitude 3559 m). Around 65% of the plants of Achnatherum inebrians were affected. Symptoms initially showed drop-like honeydew on the ears of drunken horse grass, and later brown to dark brown sclerotia were observed. These were straight to slightly curved, measured 6.7 to 13.5 × 1.5 to 2.1 mm, which was approximately 1 to 4 times the size of healthy seeds. Sixteen spikes with typical symptoms were collected from eight different fields. Sclerotia were disinfested by immersion in 75% ethanol for 30 s and 1% NaClO for 90 s, rinsed three times in sterilized water, plated on potato dextrose agar (PDA) medium, incubated at 24°C in the dark and isolates purified by culturing from single spores. Finally, 16 single-spore cultures with similar phenotypes were obtained from these sclerotia. Colonies produced on PDA for 15 days at 24 ℃ were grayish white with fluffy aerial mycelium, about 60 mm in diameter. Conidia were hyaline, ovoid to cylindrical, 5.42 to 7.69 × 2.85 to 3.75 μm (avg. 5.67 × 3.2; n = 50). These morphological characteristics were consistent with the descriptions of Claviceps species in general (PíchovÁ et al. 2018). To further identify the Claviceps spp., isolate NSZJ (=MHLZU-AI20201012) was selected as a representative for molecular characterization. Two nuclear protein-coding genes TUB2 and MCM7 were amplified by T2/T12 (O’Donnell and Cigelnik 1997) and CARCA-F/M456-5R (Rehner and Buckley 2005), respectively, and sequenced. Sequences were deposited in GenBank (accession nos. MW115640 for TUB2 and MW115641 for MCM7). A BLAST analysis of these two segments showed >99% identity with those sequences of isolate W3 of C. purpurea (Pazoutová et al. 2014). To confirm the pathogenicity on drunken horse grass, 20 healthy plants (2-year-old) grown in an experimental field at the College of Pasture Agriculture Science and Technology, Yuzhong Campus of Lanzhou University in China (104° 39′ E, 35° 89′ N, altitude1653m) were spray-inoculated with conidial suspension (1 × 106 conidia/ml) during the flowering period. Another 20 plants in the field were sprayed with sterilized distilled water as controls. All plants were individually covered with transparent polyethylene bags for 24 h to maintain high relative humidity. After 7 to 10 days, small yellowish-white drops of honeydew were observed in some florets. At 22 days post inoculation, all the inoculated panicles developed three to six sclerotia per head, ranging in size from 6.7 to 13.5 mm, while control plants remained healthy. The same pathogen was consistently re-isolated from inoculated spikes and confirmed by morphological and molecular characterization as described above. Claviceps purpurea was reported to be associated with ergot in A. lemmonii in Idaho and A. robustum in Montana (Alderman et al. 2004). To our knowledge, this is the first report of C. purpurea causing ergot in A. inebrians in China.

scholarly journals First Report of Ramularia coleosporii causing Leaf Spot on Perilla frutescens in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Md Aktaruzzaman ◽  
Tania Afroz ◽  
Hyo-Won Choi ◽  
Byung Sup Kim
Keyword(s):  
Leaf Spot ◽  
Ipomoea Batatas ◽  
Rust Fungus ◽  
Morphological Characteristics ◽  
Perilla Frutescens ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Perilla (Perilla frutescens var. japonica), a member of the family Labiatae, is an annual herbaceous plant native to Asia. Its fresh leaves are directly consumed and its seeds are used for cooking oil. In July 2018, leaf spots symptoms were observed in an experimental field at Gangneung-Wonju National University, Gangneung, Gangwon province, Korea. Approximately 30% of the perilla plants growing in an area of about 0.1 ha were affected. Small, circular to oval, necrotic spots with yellow borders were scattered across upper leaves. Masses of white spores were observed on the leaf underside. Ten small pieces of tissue were removed from the lesion margins of the lesions, surface disinfected with NaOCl (1% v/v) for 30 s, and then rinsed three times with distilled water for 60 s. The tissue pieces were then placed on potato dextrose agar (PDA) and incubated at 25°C for 7 days. Five single spore isolates were obtained and cultured on PDA. The fungus was slow-growing and produced 30-50 mm diameter, whitish colonies on PDA when incubated at 25ºC for 15 days. Conidia (n= 50) ranged from 5.5 to 21.3 × 3.5 to 5.8 μm, were catenate, in simple or branched chains, ellipsoid-ovoid, fusiform, and old conidia sometimes had 1 to 3 conspicuous hila. Conidiophores (n= 10) were 21.3 to 125.8 × 1.3 to 3.6 μm in size, unbranched, straight or flexuous, and hyaline. The morphological characteristics of five isolates were similar. Morphological characteristics were consistent with those described for Ramularia coleosporii (Braun, 1998). Two representative isolates (PLS 001 & PLS003) were deposited in the Korean Agricultural Culture Collection (KACC48670 & KACC 48671). For molecular identification, a multi-locus sequence analysis was conducted. The internal transcribed spacer (ITS) regions of the rDNA, partial actin (ACT) gene and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene were amplified using primer sets ITS1/4, ACT-512F/ACT-783R and gpd1/gpd2, respectively (Videira et al. 2016). Sequences obtained from each of the three loci for isolate PLS001 and PLS003 were deposited in GenBank with accession numbers MH974744, MW470869 (ITS); MW470867, MW470870 (ACT); and MW470868, MW470871 (GAPDH), respectively. Sequences for all three genes exhibited 100% identity with R. coleosporii, GenBank accession nos. GU214692 (ITS), KX287643 (ACT), and 288200 (GAPDH) for both isolates. A multi-locus phylogenetic tree, constructed by the neighbor-joining method with closely related reference sequences downloaded from the GenBank database and these two isolates demonstrated alignment with R. coleosporii. To confirm pathogenicity, 150 mL of a conidial suspension (2 × 105 spores per mL) was sprayed on five, 45 days old perilla plants. An additional five plants, to serve as controls, were sprayed with sterile water. All plants were placed in a humidity chamber (>90% relative humidity) at 25°C for 48 h after inoculation and then placed in a greenhouse at 22/28°C (night/day). After 15 days leaf spot symptoms, similar to the original symptoms, developed on the leaves of the inoculated plants, whereas the control plants remained symptomless. The pathogenicity test was repeated twice with similar results. A fungus was re-isolated from the leaf lesions on the inoculated plants which exhibited the same morphological characteristics as the original isolates, fulfilling Koch’s postulates. R. coleosporii has been reported as a hyperparasite on the rust fungus Coleosporium plumeriae in India & Thailand and also as a pathogen infecting leaves of Campanula rapunculoides in Armenia, Clematis gouriana in Taiwan, Ipomoea batatas in Puerto Rico, and Perilla frutescens var. acuta in China (Baiswar et al. 2015; Farr and Rossman 2021). To the best of our knowledge, this is the first report of R. coleosporii causing leaf spot on P. frutescens var. japonica in Korea. This disease poses a threat to production and management strategies to minimize leaf spot should be developed.

scholarly journals First Report of Leaf Spot Caused by Botrytis cinerea on Cardamine hupingshanensis in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Jun Guo ◽  
Jin Chen ◽  
Zhao Hu ◽  
Jie Zhong ◽  
Jun Zi Zhu
Keyword(s):  
Botrytis Cinerea ◽  
Morphological Characteristics ◽  
Gray Mold ◽  
Hunan Province ◽  
Conidial Suspension ◽  
Heat Shock Protein 60 ◽  
Basal Cells ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
First Report

Cardamine hupingshanensis is a selenium (Se) and cadmium (Cd) hyperaccumulator plant distributed in wetlands along the Wuling Mountains of China (Zhou et al. 2018). In March of 2020, a disease with symptoms similar to gray mold was observed on leaves of C. hupingshanensis in a nursery located in Changsha, Hunan Province, China. Almost 40% of the C. hupingshanensis (200 plants) were infected. Initially, small spots were scattered across the leaf surface or margin. As disease progressed, small spots enlarged to dark brown lesions, with green-gray, conidia containing mold layer under humid conditions. Small leaf pieces were cut from the lesion margins and were sterilized with 70% ethanol for 10 s, 2% NaOCl for 2 min, rinsed with sterilized distilled water for three times, and then placed on potato dextrose agar (PDA) medium at 22°C in the dark. Seven similar colonies were consistently isolated from seven samples and further purified by single-spore isolation. Strains cultured on PDA were initially white, forming gray-white aerial mycelia, then turned gray and produced sclerotia after incubation for 2 weeks, which were brown to blackish, irregular, 0.8 to 3.0 × 1.2 to 3.5 mm (n=50). Conidia were unicellular, globose or oval, colourless, 7.5 to 12.0 × 5.5 to 8.3 μm (n=50). Conidiophores arose singly or in group, straight or flexuous, septate, brownish to light brown, with enlarged basal cells, 12.5 to 22.1 × 120.7 to 310.3 μm. Based on their morphological characteristics in culture, the isolates were putatively identified as Botrytis cinerea (Ellis 1971). Genomic DNA of four representative isolates, HNSMJ-1 to HNSMJ-4, were extracted by CTAB method. The internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate dehydrogenase gene (G3PDH), heat-shock protein 60 gene (HSP60), ATP-dependent RNA helicaseDBP7 gene (MS547) and DNA-dependent RNA polymerase subunit II gene (RPB2) were amplified and sequenced using the primers described previously (Aktaruzzaman et al. 2018) (MW820311, MW831620, MW831628, MW831623 and MW831629 for HNSMJ-1; MW314722, MW316616, MW316617, MW316618 and MW316619 for HNSMJ-2; MW820519, MW831621, MW831627, MW831624 and MW831631 for HNSMJ-3; MW820601, MW831622, MW831626, MW831625 and MW831630 for HNSMJ-4). BLAST searches showed 99.43 to 99.90% identity to the corresponding sequences of B. cinerea strains, such as HJ-5 (MF426032.1, MN448500.1, MK791187.1, MH727700.1 and KX867998.1). A combined phylogenetic tree using the ITS, G3PDH, HSP60 and RPB2 sequences was constructed by neighbor-joining method in MEGA 6. It revealed that HNSMJ-1 to HNSMJ-4 clustered in the B. cinerea clade. Pathogenicity tests were performed on healthy pot-grown C. hupingshanensis plants. Leaves were surface-sterilized and sprayed with conidial suspension (106 conidia/ mL), with sterile water served as controls. All plants were kept in growth chamber with 85% humidity at 25℃ following a 16 h day-8 h night cycle. The experiment was repeated twice, with each three replications. After 4 to 7 days, symptoms similar to those observed in the field developed on the inoculated leaves, whereas controls remained healthy. The pathogen was reisolated from symptomatic tissues and identified using molecular methods, confirming Koch’s postulates. B. cinerea has already been reported from China on C. lyrate (Zhang 2006), a different species of C. hupingshanensis. To the best of our knowledge, this is the first report of B. cinerea causing gray mold on C. hupingshanensis in China and worldwide. Based on the widespread damage in the nursery, appropriate control strategies should be adopted. This study provides a basis for studying the epidemic and management of the disease.

scholarly journals First Report of Dieback of Camellia azalea Caused by Glomerella cingulata f. sp. camelliae in Guangdong, China

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1583-1583 ◽  
Author(s):  
S. Sun ◽  
J. Wang ◽  
H. Zhao ◽  
M. Zhang ◽  
C. Shu ◽  
...  
Keyword(s):  
Average Rate ◽  
Morphological Characteristics ◽  
Guangdong Province ◽  
Middle Part ◽  
Individual Plant ◽  
Conidial Suspension ◽  
Glomerella Cingulata ◽  
Single Spore ◽  
First Report ◽  
Necrotic Spots

Camellia azalea Wei (Theaceae) is a critically endangered species with high ornamental value in China. Its wild individual plants, less than 1,000, are only found in Yangchun, Guangdong Province, China. Since 2010, a severe dieback on C. azalea has been observed in several commercial plantations in Foshan, Guangdong Province, during the process of artificial propagation. The infection started from the middle portion of the new shoots, where necrosis spots developed and expanded to girdle the stems. Consequently, the shoots died and became brown in color. Later, the necrotic spots turned pale gray, and many small, black fruiting bodies emerged. In the end, more than half of the dead shoots broke off from the necrotic spots. Generally, about 10 to 20% new shoots were infected for one individual plant. Although the older branches with leaves were not infected and showed no symptoms, the dieback of crown outer layer greatly reduced the ornamental value of the plants and the sale price went down. Another part of the plants that is often infected is the stalk, resulting in the drop of fruits. By using routine isolation methods and single-spore purification technique, 18 single-conidial isolates with similar colony morphology were obtained from five diseased plants. The cultures of single-conidial isolates grew at an average rate of 6.8 mm per day on PDA at 28°C. The central part of colony became gray-green with age, and acervuli formed on the medium after incubation for 7 to 10 days. Conidia, round at both ends, were 13.65 to 18.3 × 3.61 to 5.92 μm (avg. = 16.1 ± 1.6 × 4.8 ± 0.8 μm, n = 50) in size. After culturing for 50 to 60 days, perithecia matured. Ascopores were hyaline, straight, aseptate, and 10.02 to 13.77 × 3.27 to 4.45 μm (avg. = 12.2 ± 1.1 × 3.9 ± 0.4 μm, n = 50) in size. The cultural and morphological characteristics of these isolates are consistent with the description of Glomerella cingulata f. sp. camelliae (1). The sequences (GenBank Accession Nos. KJ668576, KJ668577, KJ676642, KJ689374, KJ689375, and KJ689376) of ITS, GPDH, GS, actin, β-tubulin, and CAL regions of three representative isolates are identical and share 99, 99, 100, 99, 100, and 100% identity with those of the type specimen of G. cingulata f. sp. camelliae ICMP 10643 (JX010224, JX009908, JX010119, JX009540, JX010436, and JX009630), respectively (2). Twenty randomly selected shoots with young leaves on the top of them, detached from different trees, were scratched in the middle part with a fine scalpel to generate a 5-mm-long wound, 50 μl conidial suspension (1 × 105 conidia ml−1) was then dropped onto the wound for inoculation. The control shoots were inoculated with the same volume of sterile distilled water. All inoculated shoots were placed into an intelligent artificial climate incubator with 12-h photoperiod and 100% relative humidity at 28 ± 1°C. Each treatment replicated on five shoots, and the tests were repeated twice. Symptoms resembling those in the field were observed on all conidia-inoculated shoots after 10 to 14 days, and control shoots were asymptomatic. The same fungus G. cingulata f. sp. camelliae was consistently re-isolated from the diseased shoots, fulfilling Koch's postulates. G. cingulata f. sp. camelliae has been reported on other species of Camellia outside China, but this is the first report in China where the species is endemic and endangered (1,2). References: (1) J. S. W. Dickens et al. Plant Pathol. 38:75, 1989. (2) B. Weir et al. Stud Mycol. 73:115, 2012.

scholarly journals First report of Nigrospora sphaerica causing fruit dried-shrink disease in Akebia trifoliata from China

Plant Disease ◽  
2021 ◽  
Author(s):  
Xiujing Hong ◽  
Shijia Chen ◽  
linchao Wang ◽  
Bo Liu ◽  
Yuruo Yang ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Morphological Characteristics ◽  
Its Region ◽  
Average Diameter ◽  
Ethanol Solution ◽  
Likelihood Method ◽  
Conidial Suspension ◽  
Multiple Sequence ◽  
First Report ◽  
Pure Cultures

Akebia trifoliata, a recently domesticated horticultural crop, produces delicious fruits containing multiple nutritional metabolites and has been widely used as medicinal herb in China. In June 2020, symptoms of dried-shrink disease were first observed on fruits of A. trifoliata grown in Zhangjiajie, China (110.2°E, 29.4°N) with an incidence about 10%. The infected fruits were shrunken, colored in dark brown, and withered to death (Figure S1A, B). The symptomatic fruits tissues (6 × 6 mm) were excised from three individual plants, surface-disinfested in 1% NaOCl for 30s and 70% ethanol solution for 45s, washed, dried, and plated on potato dextrose agar (PDA) containing 50 mg/L streptomycin sulfate in the dark, and incubated at 25℃ for 3 days. Subsequently, hyphal tips were transferred to PDA to obtain pure cultures. After 7 days, five pure cultures were obtained, including two identical to previously reported Colletotrichum gloeosporioides causing leaf anthracnose in A. trifoliata (Pan et al. 2020) and three unknown isolates (ZJJ-C1-1, ZJJ-C1-2, and ZJJ-C1-3). The mycelia of ZJJ-C1-1, ZJJ-C1-2 and ZJJ-C1-3 were white, and formed colonies of approximate 70 mm (diameter) in size at 25℃ after 7 days on potato sucrose agar (PSA) plates (Figure S1C). After 25 days, conidia were formed, solitary, globose, black, shiny, smooth, and 16-21 μm in size (average diameter = 18.22 ± 1.00 μm, n = 20) (Figure S1D). These morphological characteristics were similar to those of N. sphaerica previously reported (Li et al. 2018). To identify species of ZJJ-C1-1, ZJJ-C1-2 and ZJJ-C1-3, the internal transcribed spacer (ITS) region, β-tubulin (TUB2), and the translation elongation factor 1-alpha (TEF1-α) were amplified using primer pairs including ITS1/ITS4 (Vilgalys and Hester 1990), Bt-2a/Bt-2b (Glass and Donaldson 1995), and EF1-728F/EF-2 (Zhou et al. 2015), respectively. Multiple sequence analyses showed no nucleotide difference was detected among genes tested except ITS that placed three isolates into two groups (Figure S2). BLAST analyses determined that ZJJ-C1-1, ZJJ-C1-2 and ZJJ-C1-3 had 99.73% to N. sphaerica strains LC2705 (KY019479), 100% to LC7294 (KY019397), and 99.79-100% to LC7294 (KX985932) or LC7294 (KX985932) based on sequences of TUB2 (MW252168, MW269660, MW269661), TEF-1α (MW252169, MW269662, MW269663), and ITS (MW250235, MW250236, MW192897), respectively. These indicated three isolates belong to the same species of N. sphaerica. Based on a combined dataset of ITS, TUB2 and TEF-1α sequences, a phylogenetic tree was constructed using Maximum likelihood method through IQ-TREE (Minh et al. 2020) and confirmed that three isolates were N. sphaerica (Figure S2). Further, pathogenicity tests were performed. Briefly, healthy unwounded fruits were surface-disinfected in 0.1% NaOCl for 30s, washed, dried and needling-wounded. Then, three fruits were inoculated with 10 μl of conidial suspension (1 × 106 conidia/ml) derived from three individual isolates, with another three fruits sprayed with 10 μl sterilized water as control. The treated fruits were incubated at 25℃ in 90% humidity. After 15 days, all the three fruits inoculated with conidia displayed typical dried-shrink symptoms as those observed in the farm field (Figure S1E). The decayed tissues with mycelium and spores could be observed on the skin or vertical split of the infected fruits after 15 days’ inoculation (Figure S1F-H). Comparably, in the three control fruits, there were no dried-shrink-related symptoms displayed. The experiment was repeated twice. The re-isolated pathogens were identical to N. sphaerica determined by sequencing the ITS, TUB2 and TEF-1α. Previous reports showed N. sphaerica could cause postharvest rot disease in kiwifruits (Li et al. 2018). To our knowledge, this is the first report of N. sphaerica causing fruits dried-shrink disease in A. trifoliata in China.

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

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

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

scholarly journals First Report of Passalora Leaf Spot Caused by Passalora bougainvilleae on Bougainvillea in Mexico

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 775-775 ◽  
Author(s):  
V. Ayala-Escobar ◽  
V. Santiago-Santiago ◽  
A. Madariaga-Navarrete ◽  
A. Castañeda-Vildozola ◽  
C. Nava-Diaz
Keyword(s):  
Uv Light ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
The United States ◽  
Pathogenicity Test ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Bougainvillea Spectabilis

Bougainvillea (Bougainvillea spectabilis Willd) growing in 28 gardens during 2009 showed 100% disease incidence and 3 to 7% disease severity. Bougainvilleas with white flowers were the most affected. Symptoms consisted of light brown spots with dark brown margins visible on adaxial and abaxial sides of the leaves. Spots were circular, 2 to 7 mm in diameter, often surrounded by a chlorotic halo, and delimited by major leaf veins. Single-spore cultures were incubated at 24°C under near UV light for 7 days to obtain conidia. Pathogenicity was confirmed by spraying a conidial suspension (1 × 104 spores/ml) on leaves of potted bougainvillea plants (white, red, yellow, and purple flowers), incubating the plants in a dew chamber for 48 h and maintaining them in a greenhouse (20 to 24°C). Identical symptoms to those observed at the residential gardens appeared on inoculated plants after 45 to 60 days. The fungus was reisolated from inoculated plants that showed typical symptoms. No symptoms developed on control plants treated with sterile distilled water. The fungus produced distinct stromata that were dark brown, spherical to irregular, and 20 to 24 μm in diameter. Conidiophores were simple, born from the stromata, loose to dense fascicles, brown, straight to curved, not branched, zero to two septate, 14 × 2 μm, with two to four conspicuous and darkened scars. The conidia formed singly, were brown, broad, ellipsoid, obclavate, straight to curved with three to four septa, 40 × 4 μm, and finely verrucous with thick hilum at the end. Fungal DNA from the single-spore cultures was obtained using a commercial DNA Extraction Kit (Qiagen, Valencia, CA); ribosomal DNA was amplified with ITS5 and ITS4 primers and sequenced. The sequence was deposited at the National Center for Biotechnology Information Database (GenBank Accession Nos. HQ231216 and HQ231217). The symptoms (4), morphological characteristics (1,2,4), and pathogenicity test confirm the identity of the fungus as Passalora bougainvilleae (Muntañola) Castañeda & Braun (= Cercosporidium bougainvilleae Muntañola). This pathogen has been reported from Argentina, Brazil, Brunei, China, Cuba, El Salvador, India, Indonesia, Jamaica, Japan, Thailand, the United States, and Venezuela (3). To our knowledge, this is the first report of this disease on B. spectabilis Willd in Mexico. P. bougainvilleae may become an important disease of bougainvillea plants in tropical and subtropical areas of Mexico. References: (1) U. Braun and R. R. Castañeda. Cryptogam. Bot. 2/3:289, 1991. (2) M. B. Ellis. More Dematiaceous Hypomycetes. Commonwealth Mycological Institute, Kew, Surrey, UK, 1976. (3) C. Nakashima et al. Fungal Divers. 26:257, 2007. (4) K. L. Nechet and B. A. Halfeld-Vieira. Acta Amazonica 38:585, 2008.

scholarly journals First report of Fusarium incarnatum causing fruit rot of litchi in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zhaoyin Gao ◽  
Jiaobao Wang ◽  
Zhengke Zhang ◽  
Min Li ◽  
Deqiang Gong ◽  
...  
Keyword(s):  
Southern China ◽  
Fusarium Species ◽  
Morphological Characteristics ◽  
Fruit Rot ◽  
Conidial Suspension ◽  
Single Spore ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Litchi Fruit ◽  
His3 Gene

Litchi (Litchi chinensis Sonn.) is an indigenous tropical and subtropical fruit in Southern China with an attractive appearance, delicious taste, and good nutritional value (Jiang et al. 2003). In March 2020, brown rots were observed on nearly ripe litchi fruits (cv. Guihuaxiang) in an orchard of Lingshui county, Hainan province of China (18.615877° N, 109.948871° E). About 5% fruits were symptomatic in the field, and the disease caused postharvest losses during storage. The initial infected fruits had no obvious symptoms on the outer pericarp surfaces, but appeared irregular, brown to black-brown lesions in the inner pericarps around the pedicels. Then lesions expanded and became brown rots. Small tissues (4 mm × 4 mm) of fruit pericarps were cut from symptomatic fruits, surface-sterilized in 1% sodium hypochlorite for 3 min, rinsed in sterilized water three times, plated on potato dextrose agar (PDA) and incubated at 28℃ in the darkness. Morphologically similar colonies were isolated from 85% of 20 samples after 4 days of incubation. Ten isolates were purified using a single-spore isolation method. The isolates grown on PDA had abundant, fluffy, whitish to yellowish aerial mycelia, and the reverse side of the Petri dish was pale brown. Morphological characteristics of conidia were further determined on carnation leaf-piece agar (CLA) (Leslie et al. 2006). Macroconidia were straight to slightly curved, 3- to 5-septates with a foot-shaped basal cell, tapered at the apex, 2.70 to 4.43 µm × 18.63 to 37.58 µm (3.56 ± 0.36 × 28.68 ± 4.34 µm) (n = 100). Microconidia were fusoid to ovoid, 0- to 1-septate, 2.10 to 3.57 µm × 8.18 to 18.20 µm (2.88 ± 0.34 × 11.71 ± 1.97 µm) (n = 100). Chlamydospores on hyphae singly or in chains were globose, subglobose, or ellipsoidal. Based on cultural features and morphological characteristics, the fungus was identified as a Fusarium species (Leslie et al. 2006). To further confirm the pathogen, DNA was extracted from the 7-day-old aerial mycelia of three isolates (LZ-1, LZ-3, and LZ-5) following Chohan et al. (2019). The sequences of the internal transcribed spacer region of rDNA (ITS), translation elongation factor-1 alpha (tef1) gene, and histone H3 (his3) gene were partially amplified using primers ITS1/ITS4, EF1-728F/EF1-986R, and CYLH3F/CYLH3R, respectively (Funnell-Harris et al. 2017). The nucleotide sequences were deposited in GenBank (ITS: 515 bp, MW029882, 533 bp, MW092186, and 465 bp, MW092187; tef1: 292 bp, MW034437, 262 bp, MW159143, and 292 bp, MW159141; his3: 489 bp, MW034438, 477 bp, MW159142, and 474 bp, MW159140). The ITS, tef1, and his3 genes showed 99-100% similarity with the ITS (MH979697), tef1 (MH979698), and his3 (MH979696) genes, respectively of Fusarium incarnatum (TG0520) from muskmelon fruit. The phylogenetic analysis of the tef1 and his3 gene sequences showed that the three isolates clustered with F. incarnatum. Pathogenicity tests were conducted by spraying conidial suspension (1×106 conidia/ml) on wounded young fruits in the orchid. Negative controls were sprayed with sterilized water. Fruits were bagged with polythene bags for 24 hours and then unbagged for 10 days. Each treatment had 30 fruits. The inoculated fruits developed symptoms similar to those observed in the orchard and showed light brown lesions on the outer pericarp surfaces and irregular, brown to black-brown lesions in the inner pericarps, while the fruits of negative control remained symptomless. The same fungus was successfully recovered from symptomatic fruits, and thus, the test for the Koch’s postulates was completed. F. semitectum (synonym: F. incarnatum) (Saha et al. 2005), F. oxysporum (Bashar et al. 2012), and F. moniliforme (Rashid et al. 2015) have been previously reported as pathogens causing litchi fruit rots in India and Bangladesh. To our knowledge, this is the first report of Fusarium incarnatum causing litchi fruit rot in China.

Sign in / Sign up

Export Citation Format

Share Document