scholarly journals First Report of Penicillium olsonii Bainier & Sartory Causing Postharvest Fruit Rot of Grape (Vitis vinifera L.) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Jian Zou ◽  
Tingfu Zhang ◽  
Guoqin Wen ◽  
Bo Song ◽  
Shijiao Jiang
Keyword(s):  
Vitis Vinifera ◽  
Morphological Characteristics ◽  
Grape Berry ◽  
Fruit Rot ◽  
Vitis Vinifera L ◽  
Grocery Stores ◽  
Conidial Suspension ◽  
Single Spore ◽  
Isolation Technique ◽  
Initial Symptoms

Grapes (Vitis vinifera L.) are very popular in China as fresh fruit. Due to its storability, some grape varieties can be kept fresh until winter, increasing the popularity of fruit grapes. However, in 2019, rot symptoms were observed on cv. Crimson in Wuhan, Hubei (30°52′N, 114°31′E), and Chengdu, Sichuan (30°67′N, 104°06′E). Subsequently, from 2019 to 2021, Liangshan (28°33′N, 102°42′E, cv.Crimson), Ya’an (29°40′N, 102°66′E, cv. Red globe), and Nanchong (30°80′N, 106°06′E, cv. Victoria), Sichuan also experienced the same decay symptoms. Initial symptoms of this disease were slightly sunken lesions on the berries 5 to 7 days in storage at 28℃, and then white mycelial growth on the surface of lesions. The growth became bluish-green following the occurrence of abundant sporulation, along with softening and collapsing the whole berry (Fig. 1a). Twenty symptomatic berries from each city were collected (100 samples in total) and twenty isolates were obtained using the single spore isolation technique developed by Chomnunti et al. (2014). The colony on PDA media initially appeared as white mycelium, and later developed into greenish-gray to grayish-green sporulation with white margins, the colony diameter reached 32.5 to 34.5 mm after ten days of incubation at 28±1℃. The reverse side of the colony was oblive-brown or grayish-yellow. Morphological characteristics of the twenty isolates showed that the conidiophores were broom-shaped and verticillate, the stipes smooth-walled and measured 120 to 300 × 2.5 to 4.0 μm; the ramus (n = 2 to 3) measured 6.0 to 15 × 2.5 to 3.6 μm; the metulas (n = 2 to 4) were verticillate, with sizes ranging from 8.7 to 9.8 × 2.0 to 3.2 μm; the phialides (n = 3 to 7) were elongate and ampulliform, with sizes ranging from 2.0 to 3.5 × 2.0 to 2.4 μm; the conidia (2.0 to 3.5 × 2.0 to 2.4 μm) were sub-globose to ellipsoidal in shape, with thick and finely roughened walls. Based on these cultural and morphological characteristics, the isolates were identified as Penicillium olsonii Bainier & Sartory (Frisvad et al., 1990). A multi-locus approach was performed to accurately identify a representative WHG5 isolate. The internal transcribed spacer regions (ITS), calmodulin (CaM,), beta tubulin (BenA), and 18S ribosomal RNA (18S) of isolate WHG5 were amplified and sequenced as described by Walker et al. (2012). The pairwise alignments of ITS, CaM, BenA, and 18S sequences was nearly 100% identical to Penicillium olsonii with GenBank accession numbers KX056230.1 (524/524 bp, 100%), DQ645807.1 (570/572 bp, 99%), AY674444.1 (472/472 bp, 99%), and FJ717701.1 (1299/1301 bp, 99%), respectively. The resulting sequences were deposited in GenBank (Accession no. ITS: MW192867; CaM: MZ936474; BenA: MZ936475; and 18S: MZ936476). The phylogenetic analysis performed with the Neighbor-Joining method classified WGH5 into the P. olsonii clade with a posterior probability of 100% based on the concatenated sequences of the ITS CaM, BenA, and 18S (Fig. 2). Combined with the above morphological characteristics, we finally confirmed the identity of isolate WGH5 as P. olsonii. To fulfill Koch’s postulates and confirm the pathogenicity of WGH5, a 10 μL conidial suspension (1 × 106 spores/mL) aliquot was inoculated into the healthy grape berry (cv. Crimson) while using sterile distilled water as a control. Thirty berries were surface disinfected with 2% sodium hypochlorite then artificially wounded prior to inoculation with the conidial suspension. The artificial wound was made using a sterilized steel needle with a diameter of 0.5 mm and a depth of 0.3 cm. All the inoculated fruits were placed in sealed and sterilized Petri dishes and incubated at 28±1℃. The experiments were done in triplicate. After five days, the inoculated grape berries showed typical symptoms (Fig. 1b) while the control remained asymptomatic. Using the same protocol as above, the fungus P. olsonii was re-isolated from the symptomatic inoculated berries but not successfully from mock-inoculated berries. Previously, P. olsonii has been reported from Portuguese wine grapes (Serra et al., 2007). This study is the first time that P. olsonii was reported as a plant pathogen in China. Since the grapes were collected from grocery stores, details of post-harvest management that could have affected disease presence and progression of rotting were not available.

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.

scholarly journals Extreme Susceptibility of Primosole Mandarin to Alternaria Fruit Rot in Italy

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1291-1291
Author(s):  
P. Bella ◽  
R. La Rosa ◽  
V. Catara ◽  
G. Polizzi
Keyword(s):  
Morphological Characteristics ◽  
Fruit Rot ◽  
Total Production ◽  
Conidial Suspension ◽  
Single Spore ◽  
The Core ◽  
Fruit Drop ◽  
Plastic Bags ◽  
Citrus Diseases ◽  
Pathogenicity Tests

Primosole mandarin is a promising mandarin-like hybrid of Satsuma Miho and Carvalhais mandarin that ripens very early, at the beginning of October, in southern Italy (2). During August and September 1999 and 2000 in Sicily, widespread fruit rot, affecting from 80 to 95% of the total production, was observed in a 4-year-old Primosole mandarin orchard. The fruits developed color prematurely and light brown-to-black discoloration of the rind at the stylar end. Internal symptoms consisted of a black rot of the fruit core. Sometimes the exterior of the fruits appeared healthy. No premature fruit drop was observed, and infected fruits became mummified and remained attached on the trees. Alternaria citri Ellis & N. Pierce in N. Pierce was consistently isolated from infected tissues, and the identification of the fungus was based on morphological characteristics of the conidia (1). Pathogenicity tests of single-spore isolates were carried out on surface-sterilized Primosole fruits and were repeated twice. Either a conidial suspension (2 × 104 conidia per ml) was injected into the core of fruits, or fruits were pricked at the stylar end near or through growth cracks in poorly formed navels, and the conidial suspension was placed on the wound. Thirty fruits were used per treatment, and thirty noninoculated fruits were used for controls. Following inoculation, the fruits were placed in plastic bags and kept at 30°C for 15 days. No external symptoms were observed on any of the fruits, but when cut in half, decay of the core was observed in all inoculated fruits. A. citri was reisolated from inoculated fruits, fulfilling Koch's postulates. No symptoms were observed on fruits used as controls. We believe that infection is facilitated by growth cracks at the stylar end and the sensitivity to sunburn of Primosole mandarin. To our knowledge, this is the first report of the extreme susceptibility of Primosole mandarin to Alternaria fruit rot. References: (1) G. E. Brown and J. W. Eckert. Postharvest fungal diseases. Page 37 in: Compendium of Citrus Diseases, 2nd ed. L. W. Timmer, S. M. Garnsey, and J. H. Graham, eds. The American Phytopathological Society, St. Paul, MN, 2000. (2) E. Tribulato and G. La Rosa. Italus Hortus 1:21, 1993.

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 Anthracnose of Alocasia macrorrhiza Caused by Colletotrichum karstii in Guangdong, China

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 696-696 ◽  
Author(s):  
Y. He ◽  
C. Shu ◽  
J. Chen ◽  
E. Zhou
Keyword(s):  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Leaf Spot Disease ◽  
Molecular Characteristics ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Leaf Spots ◽  
Purification Technique ◽  
Initial Symptoms

Alocasia macrorrhiza (L.) Schott. (Araceae), native to South America, is a common, herbaceous perennial ornamental plant in tropical and subtropical areas (1). A severe leaf spot disease was observed on this plant in several places on the campus of authors' university in Guangzhou, Guangdong Province, China, in April 2013. Initial symptoms were water-soaked, dark green leaf spots. These small spots gradually expanded to 6- to 11-mm circular lesions. They were grayish-white in color with a yellow halo and many small, black, concentric dots were observed on them. Microscopic examination revealed that these small dots were acervuli, which were 100 to 300 μm in diameter, developing beneath the epidermis and becoming erumpent with age. By using routine tissue-isolation method and single-spore purification technique, four single-conidial isolates were obtained from each of four diseased leaves. These isolates formed a grayish-white colony with numerous pink spore masses on PDA at 28°C. Their mycelial radial growth rate was about 4.5 mm per day. Conidia were single-celled, hyaline, and cylindrical with an obtuse apex and protruding base; they were 12.7 to 14.2 × 4.8 to 5.9 μm in size. Conidial appressoria were irregular in shape, sepia to dark brown, solitary, and 6.9 to 8.5 × 4.6 to 5.9 μm. These morphological characteristics were consistent with the description of Colletotrichum karstii (2). The sequences of beta-tubulin gene (TUB2) and partial actin gene (ACT) of a representative isolate CAM1 were obtained by PCR amplification with primers BT2a/BT2b and ACT512F/ACT783R, respectively. These sequences were deposited in GenBank under the accession numbers of KF444947 and KF460435. BLAST searches showed a 99% homology with the TUB2 and ACT sequences of C. karstii (JX625209, KC843559). Therefore, the fungus isolated from A. macrorrhiza was identified as C. karstii by morphological and molecular characteristics. Pathogenicity tests were performed on 30-day-old plants of A. macrorrhiza grown in plastic pots (0.8 L) by spraying 15 ml conidial suspension (1 × 106 conidia ml–1) of this fungus onto each plant. The control plants were sprayed only with sterile distilled water. These plants then were placed in an intelligent artificial climate incubator with 12-h photoperiod and 100% relative humidity at 24 ± 1°C. Three replicates, each with five plants, were included in a test, and the test was repeated twice. Seven days after inoculation, the inoculated plants showed necrotic lesions on leaves similar to those observed on the campus, but no symptoms were observed on any non-inoculated controls. The same fungus C. karstii was re-isolated from the infected leaves. Although C. karstii is a well-known anthracnose pathogen on some plants belonging to family Orchidaceae (2), this is the first report of the same pathogen causing anthracnose on A. macrorrhiza in Guangdong, China. References: (1) S. Li et al. PLoS ONE 8(6):e66016, 2013. (2) Y. Yang et al. Cryptogr. Mycol. 32:229, 2011.

scholarly journals Landmark-based morphometry reveals phyllometric diversity along the shoot axis of the grapevine (Vitis vinifera L.)

2018 ◽  
Vol 14 (s1) ◽  
pp. 1-9
Author(s):  
Bodor Péter ◽  
Baranyai László ◽  
Szekszárdi Andrea ◽  
Bisztray György Dénes ◽  
Bálo Borbála
Keyword(s):  
Vitis Vinifera ◽  
Leaf Morphology ◽  
Morphological Characteristics ◽  
Morphological Diversity ◽  
Leaf Damage ◽  
Vitis Vinifera L ◽  
Graphic Software ◽  
High Diversity

Leaf morphology of the grapevine (Vitis vinifera L.) cv. ‘Kövidinka’ was evaluated based on 32 landmarks. The aim of this study was to reveal leaf morphological diversity along the shoot axis. For this purpose 10 shoots were collected with 26 to 35 leaves. Altogether 304 leaf samples were digitised and analysed with the GRA.LE.D 2.04. raster graphic software. Leaf damage was estimated based on the missing landmarks on the lamina. Our results showed that the leaves on the 11th and 13th nodes are the most intact, without missing landmarks. Lowest variability (cv = 0,126) of the investigated 54 morphological characteristics were observed among the leaves on the 11th nodes of the shoots, in accordance with the literature. Based on the results length of the veins, angles between the veins and further features such as size of the serrations show high diversity along the shoot axis. These results underline the need of careful sampling during the ampelometric investigations.

scholarly journals First Report of Myrothecium roridum Causing Leaf Spot on Zantedeschia aethiopica in China

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 854-854 ◽  
Author(s):  
B.-J. Li ◽  
H.-Y. Ben ◽  
Y.-X. Shi ◽  
X.-W. Xie ◽  
A.-L. Chai
Keyword(s):  
Leaf Spot ◽  
Morphological Characteristics ◽  
Its Region ◽  
First Record ◽  
Conidial Suspension ◽  
Isolation And Identification ◽  
Zantedeschia Aethiopica ◽  
Calla Lily ◽  
Initial Symptoms ◽  
Myrothecium Roridum

Zantedeschia aethiopica (L.) Spreng. (calla lily), belonging to family Araceae, is a popular ornamental plant in China. In the summer of 2010, leaves of calla lily with typical symptoms of necrotic lesions were observed in a commercial glasshouse in Beijing, China (116°20′ E, 39°44′ N). The initial symptoms were circular to subcircular, 1 to 3 mm, and dark brown lesions on the leaf lamina. Under high humidity, lesions expanded rapidly to 5 to 10 mm with distinct concentric zones and produced black sporodochia, especially on the backs of leaves. Later, the infected leaves were developing a combination of leaf lesions, yellowing, and falling off; as a result, the aesthetic value of the plant was significantly impacted. Leaf samples were used in pathogen isolation. Symptomatic leaf tissues were cut into small pieces and surface sterilized with 70% ethanol for 30 s and then in 0.1% mercuric chloride solution for 1 to 3 min. After being washed in sterile distilled water three times, the pieces were plated on potato dextrose agar (PDA) and incubated at 25°C in darkness for 7 days (5). Initial colonies of isolates were white, floccose mycelium and developed dark green to black concentric rings that were sporodochia bearing viscid spore masses after incubating 5 days. Conidiophores branched repeatedly. Conidiogenous cells were hyaline, clavate, and 10.0 to 16.0 × 1.4 to 2.0 μm. Conidia were hyaline, cylindrical, both rounded ends, and 6.0 to 8.2 × 1.9 to 2.4 μm. Morphological characteristics of the fungus were consistent with the description of Myrothecium roridum Tode ex Fr. (3,4). To confirm the pathogenicity, three healthy plants of calla lily were inoculated with a conidial suspension (1 × 106 conidia per ml) brushed from a 7-day-old culture of the fungus. Control plants were sprayed with sterile water. The inoculated plants were individual with clear plastic bags and placed in a glass cabinet at 25°C. After 7 days, all inoculated leaves developed symptoms similar to the original samples, but control plants remained disease free. Re-isolation and identification confirmed Koch's postulates. For molecular identification, genomic DNA of a representative isolate (MTL07081001) was extracted by modified CTAB method (1), and the rDNA-ITS region was amplified by using primers ITS1 (5-TCCGTAGGTGAACCTGCGG-3) and ITS4 (5-TCCTCCGCTTATTGATATGC-3). The 465-bp amplicon (GenBank Accession No. KF761293) was 100% identity to the sequence of M. roridum (JF724158.1) from GenBank. M. roridum has an extensive host range, covering 294 host plants (2). To our knowledge, this is the first record of leaf spot caused by M. roridum on calla lily in China. References: (1) F. M. Ausubel et al. Current Protocols in Molecular Biology. John Wiley & Sons Inc, New York, 1994. (2) D. F. Farr and A. Y. Rossman, Fungal Databases. Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , October 2013. (3) M. T. Mmbaga et al. Plant Dis. 94:1266, 2010. (4) Y. X. Zhang et al. Plant Dis. 95:1030, 2011. (5) L. Zhu et al. J. Phytopathol. 161:59, 2013.

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 Leaf Spot Caused by Ascochyta marginata on Aralia elata in Korea

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 147-147
Author(s):  
S. H. Lee ◽  
C. K. Lee ◽  
M. J. Park ◽  
H. D. Shin
Keyword(s):  
East Asia ◽  
Leaf Spot ◽  
Morphological Characteristics ◽  
Culture Collection ◽  
Research Report ◽  
Conidial Suspension ◽  
First Report ◽  
Commercial Cultivation ◽  
Aralia Elata ◽  
Initial Symptoms

Aralia elata (Miq.) Seem., known as Japanese angelica tree, is a deciduous shrub belonging to the Araliaceae, which is native to East Asia. The young shoots have long been used in various dishes in East Asia. Commercial cultivation of this shrub, especially in polytunnels, is expanding in Korea. Several diseases including Sclerotinia rot have been known to be present on this plant (1,2). In early September 2007, leaf spot symptoms were first observed on several trees in Hongcheon, Korea. Microscopic observations revealed that the leaf spots were associated with an Ascochyta sp. Further surveys of the Ascochyta leaf spot showed the occurrence of the disease in approximately 5 to 10% of the trees in the 3 ha of commercial fields surveyed in Chuncheon, Gapyeong, Inje, and Jinju, Korea. Initial symptoms on leaves were circular to irregular, brown to dark brown, becoming zonate, and finally fading to grayish brown in the center with a yellow halo. Representative samples were deposited in the herbarium of Korea University. Conidiomata on leaf lesions were pycnidial, amphigenous, but mostly epiphyllous, immersed or semi-immersed in host tissue, light brown to olive brown, and 60 to 200 μm in diameter. Ostioles were papillate, 20 to 35 μm wide, and surrounded by a ring of darker cells. Conidia were hyaline, smooth, cylindrical to clavate, straight to mildly curved, slightly constricted at the septa, medianly one-septate, sometimes aseptate, 8 to 16 × 2.5 to 3.5 μm, and contained small oil drops. These morphological characteristics were consistent with the previous reports of Ascochyta marginata J.J. Davis (3,4). A monoconidial isolate was cultured on potato dextrose agar (PDA) plates and accessioned in the Korea Agricultural Culture Collection (Accession KACC43082). The conidia were readily formed on PDA. Inoculum for the pathogenicity tests was prepared by harvesting conidia from 30-day-old cultures of KACC43082 and a conidial suspension (approximately 2 × 106 conidia/ml) was sprayed onto leaves of three healthy seedlings. Three noninoculated seedlings served as controls. Inoculated and noninoculated plants were covered with plastic bags for 48 h in a glasshouse. After 7 days, typical leaf spot symptoms started to develop on the leaves of the inoculated plants. The fungus, A. marginata, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Japan (4) and China (3). To our knowledge, this is the first report of A. marginata on Japanese angelica trees in Korea. According to our field observations in Korea, the Ascochyta leaf spot mostly occurred on plants growing in a humid environment, especially during the rainy season. The seedlings as well as the trees growing in sunny, well-ventilated plots were nearly free from this disease. Therefore, the growing conditions seemed to be the most important factor for the development and severity of the disease. References: (1) C. K. Lee et al. Plant Pathol. J. 26:426, 2010. (2) S. H. Lee et al. Diseases of Japanese Angelica Tree and Their Control. Research Report 08-10. Korea Forest Research Institute. Seoul, Korea, 2008. (3) J. Sun et al. Acta Mycol. Sin. 14:107, 1995. (4) M. Yoshikawa and T. Yokoyama. Mycoscience 36:67, 1995.

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