Macrophomina vaccinii Causes a Basal Stem and Root Rot of Patchouli (Pogostemon cablin) in China

Patchouli (Pogostemon cablin Benth.) is a perennial herb native to South and South East Asia, which widely used as a traditional herbal medicine against indigestion, diarrhea, cold, fever, vomiting and headache in China (Swamy and Sinniah, 2015). In September 2020, a new basal stem and root rot disease of patchouli was observed in three cultivated fields of Zhanjiang City, Guangdong Province. Symptoms included sudden discoloration, chlorosis and wilting of the leaves and severe rot associated with external and internal browning at the basal part of stems and roots that results in the death of approximately 2 to 5% of plants in each field. To determine the causal agent, symptomatic roots with typical lesions were cut into small pieces, then surface sterilized in 2.5% NaClO for 1 min, rinsed three times in distilled water, and then inoculated on potato dextrose agar (PDA) medium. A fungus with same morphological characteristics was consistently isolated from disease tissue. The mycelia initially white to cream, later turning pale brown to black with age on PDA. To induce the sporulation, the isolated fungi were transferred to synthetic nutrient-poor agar (SNA) with autoclaved pine needles and ten pure cultures were obtained by single spores. Masses of black, hard and oblong microsclerotia (av. 171.2×136.5 µm, n=50) were observed on SNA. Conidia hyaline, ellipsoid to obovoid, smooth, enclosed in a mucous sheath, 15.9~32.5×7.7~11.9 µm (av. 23.9 × 9.6 µm, n=100). The internal transcribed spacer (ITS) regions as well as the partial translation elongation factor (EF-1α) and β-tubulin (TUB) genes of two representative isolates GHX-1 and CHX-2 were sequenced, using primer pairs ITS1/ITS4 (White et al. 1990), EF-688F/EF-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. The obtained sequences were submitted to GenBank under the following accession numbers: ITS, MZ375360 and MZ375361; EF-1α, MZ393804 and MZ393805; and TUB, MZ393806 and MZ393807. BLASTn searches revealed that 100% identity with the existing sequences of ex-type culture CGMCC3.19503 of Macrophomina vaccinii (ITS, MK687450; EF-1α, MK687426; and TUB, MK687434), respectively. Phylogenetic analysis using Neighbour-Joining method in Mega7.0 with concatenated sequences of ITS, EF-1α and TUB showed that the isolates clustered in the clade of M. vaccinii with high bootstrap support values. Based on both of the morphological and molecular results, the isolates were identified as M. vaccinii (Zhao et al., 2019). To confirm the pathogenicity of the two isolates, 5-mm-diameter mycelial agar plus from the margins of 5-day-old PDA cultures were placed on the wounded basal stem of 2-month-old patchouli seedlings in each pot. Five separate pots were used for each isolate and plants inoculated with sterile agar plus were served as controls. All plants were covered with plastic bags to maintain 90% relative humidity and kept at 26°C with a photoperiod of 12 h in a greenhouse conditions. The patchouli plants developed similar necrotic symptoms on basal stem and root to those observed in the field after 3 weeks after inoculation, whereas the control plants were asymptomatic. M. vaccinii was reisolated from inoculated plants and identify by morphological and molecular characteristics, fulfill the Koch’s postulates and identify. Recently, stem blight on blueberry caused by M. vaccinii was reported in China (Zhao et al. 2019). To our knowledge, this is the first report of M. vaccinii causing basal stem and root rot on patchouli in China and worldwide.

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First Report of Phytophthora palmivora Causing Root Rot of Cassava in China

Plant Disease ◽

10.1094/pdis-09-11-0780-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1072-1072 ◽

Cited By ~ 5

Author(s):

H. Guo ◽

C.-P. Li ◽

T. Shi ◽

C.-J. Fan ◽

G.-X. Huang

Keyword(s):

Root Rot ◽

Morphological Characteristics ◽

Its Region ◽

Phytophthora Palmivora ◽

First Report ◽

Tuberous Roots ◽

Whole Plant ◽

Pure Cultures ◽

Short Pedicel ◽

Rot Disease

Cassava (Manihot esculenta) is an economically important crop grown widely in South China. Seventy percent of the cassava grown is used for starch and ethanol production and it has become the foundation of local food and bioenergy systems. In November 2010, a new root rot disease was found on cv. HuaNan205 from a cassava plantation in Danzhou, Hainan Province. Disease occurred on 30% or less of the plants. Initially, the upper leaves wilted at noon and recovered in the evening. Eventually, infected plants no longer recovered and the whole plant wilted and died. Root rot symptoms consisting of irregular brown patches occurred on the tuberous roots. Symptomatic root rot tissue was cut into 1-cm pieces, washed in distilled water, and soaked in a solution of 1% sodium hypochlorite for 3 min. A subsection was cut from each sterilized piece, placed on a plate of V8 agar medium, and incubated at 28°C for 7 days. Pathogenicity was established by following Koch's postulates. In July 2011, 10 plants of cassava cv. HuaNan205 were selected from a disease-free plantation in Danzhou. The pathogen was cultivated on V8 agar at 28°C for 14 days. Four holes were established 15 cm from the base of the cassava plants. Five plants were inoculated with 100 mL of the mycelial suspension in each of the four spots and covered by soil. The other five plants were treated with sterile water as control. Plants were maintained for 4 months. All five of the inoculated plants wilted and two died, while the control plants grew normally. Symptoms similar to the original root lesions were observed on tuberous roots of inoculated plants, while only scars formed on tuberous roots of control plants. The pathogen was reisolated from the lesions of inoculated plants. Microscopic examination showed the sporangia as papillate and ovoid with the widest part close to the base. They were easily washed off and each detached sporangium contained a short pedicel 1.2 to 6.9 μm long, average 2.9 μm. Chlamydospores were readily observed on diseased roots and observed in pure cultures on V8 agar. Morphological characteristics of the specimen were similar to the descriptions for Phytophthora palmivora (2). Genomic DNA of this isolate was extracted with a cetyltrimethylammoniumbromide protocol (3) from mycelium and used as a template for amplification of the internal transcribed spacer (ITS) region of rDNA with primer pair ITS1/ITS4 (1). The sequence (GenBank Accession No. HE580279) exactly matched several sequences (e.g., GenBank Accession Nos. HQ237481.1, AY745750, and AY745751) of P. palmivora. To our knowledge, this is the first report of root rot caused by P. palmivora on cassava in China. References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) J. R. Xu et al. Genetics 143:175, 1996.

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Veronica sibirica Leaf Spots Caused by Phacellium veronicae, a New Disease in China

Plant Disease ◽

10.1094/pdis-11-12-1052-pdn ◽

2013 ◽

Vol 97 (12) ◽

pp. 1662-1662 ◽

Cited By ~ 1

Author(s):

Q. R. Bai ◽

S. Han ◽

Y. Y. Xie ◽

J. Gao ◽

Y. Li

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Control Treatment ◽

Perennial Herb ◽

Conidial Suspension ◽

New Disease ◽

Medical College ◽

Leaf Spots ◽

Plastic Bags ◽

Insect Bites

Veronica sibirica (Veronicastrum sibiricum) is an erect perennial herb, an ornamental, and a traditional Chinese medicine plant distributed mostly in northeastern, northern, and northwestern China. It has dehumidifying and detoxifying properties, and is mainly used for the treatment of cold, sore throat, mumps, rheumatism, and insect bites (4). In June 2008 through 2012, leaf spots of V. sibirica were observed in the Medicinal Herb Garden of Jilin Agricultural University (43°48′N, 125°23′E) and the medicinal plantations of Antu County (43°6′N, 128°53′E), Jilin Province. Leaf spots were amphigenous, subcircular, angular-irregular, brown, and 1 to 10 mm in diameter; they occasionally merged into a larger spot with an indefinite margin or with a pale center and dark border. Pale conidiomata were hypophyllous and scattered on the spots. The conidiophores were 100 to 400 μm high and clustered together to form synnemata 20 to 50 μm in diameter, which splayed out apically and formed loose to dense capitula. Conidiophores occasionally emerged through the stomata individually and produced conidia on the surface of the infected leaves. The conidiogenous cell terminal was geniculate-sinuous with somewhat thickened and darkened conidial scars. Conidia were solitary or catenulate, ellipsoid-ovoid or subcylindric-fusiform, hyaline and spinulose, 4.01 to 7.18 × 11.16 to 20.62 μm with obtuse to somewhat attenuated ends, and slightly thickened, darkened hila. Six isolates were obtained from necrotic tissue of leaf spots and cultured on potato dextrose agar at 25°C. After incubation for 14 days, colony surfaces were white to pinkish. The colony diameter increased by 12 mm after 21 days' incubation. Hyphae were hyaline, septate, and branched. Conidiophores grew individually or fascicularly. The symptoms and morphological characteristics were consistent with previous descriptions (1,2), and the fungus was identified as Phacellium veronicae (Pass.) (U. Braun 1990). The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified using primers ITS4/ITS5 (3). The ITS was identical among all six isolates (HE995799) and 98% identical to that of P. veronicae (JQ920427, HQ690097). Pathogenicity was confirmed by spraying five 1-year-old V. sibirica seedlings with a conidial suspension (106 conidia/ml) of each isolate and five seedlings with sterile water as a control treatment. Plants were grown in the greenhouse at 20 to 25°C and were covered with plastic bags to maintain humidity on the foliage for 72 h. After 15 days, the same symptoms appeared on the leaves as described earlier for the field-grown plants; the control plants remained healthy. The same fungus was reisolated from the leaf spots of inoculated plants. Currently, the economic importance of this disease is limited, but it may become a more significant problem, as the cultivated area of V. sibirica is increasing. To our knowledge, although P. veronicae was recorded on the other species of Veronica (V. austriaca, V. chamaedrys, V. grandis, V. longifolia, V. paniculata, and V. spicata ssp. incana) in Europe (Germany, Denmark, Ireland, Romania) and V. wormskjoldii in North America (Canada) (1), this is the first report of V. sibirica leaf spots caused by P. veronicae in the world, and it is a new disease in China. References: (1) U. Braun. A monograph of Cercosporella, Ramularia and allied genera (phytopathogenic Hyphomycetes) 2, IHW-Verlag, Germany, 1998. (2) U. Braun. Nova Hedwigia 50:499, 1990. (3) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (4) Jiangsu New Medical College. Dictionary of Chinese Materia Medica. Shanghai: Shanghai Scientific and Technical Publishers, China, 1977.

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Identification of Pathogenic Fusarium spp. Responsible for Root Rot of Angelica sinensis and Characterization of their Biological Enemies in Dingxi, China

Plant Disease ◽

10.1094/pdis-06-21-1249-re ◽

2022 ◽

Author(s):

Liu Yang ◽

Tian Yuan ◽

Xia Zhao ◽

Yue Liang ◽

UWAREMWE CONSTANTINE ◽

...

Keyword(s):

Root Rot ◽

Elongation Factor ◽

Its Region ◽

Fungal Species ◽

Cortical Cells ◽

Translation Elongation ◽

Field Samples ◽

Fusarium Pathogens ◽

Rot Disease ◽

Serious Disease

Root rot is a serious disease in plantations of A. sinensis, severely affecting yield and quality and threatening sustainable production. Fusarium isolates (n=32) were obtained from field samples of root rot tissue, leaves and infected soil. Isolates were identified by comparing the sequences of their internal transcribed spacer (ITS) region and translation elongation factor 1-ɑ (TEF-1ɑ) to sequences of known species in the NCBI-database. These Fusarium isolates include F. tricinctum (43.75%), F. equiseti (31.25%), F. solani (9.37%), F. oxysporum (6.25%), F. acuminatum (6.25%), and F. incarnatum (3.12%). For pathogenicity testing under greenhouse conditions, seven isolates were selected based on a phylogenetic analysis, including four strains of F. tricinctum and one strain each of F. solani, F. oxysporum, and F. acuminatum. The seven isolates were all pathogenic but differed in their ability to infect: the four F. tricinctum strains were capable pathogens causing root rot in A. sinensis at 100% incidence and the highly aggressive. Furthermore, the symptoms of root rot induced by those seven isolates were consistent with typical root rot cases in the field, but their disease severity varied. Observed histopathological preparations of F. tricinctum-infected seedlings and tissue-slides results showed this fungal species can penetrate epidermal cells and colonize the cortical cells where it induces necrosis and severe plasmolysis. Plate confrontation experiments showed that isolated rhizosphere bacteria inhibited the Fusarium pathogens that cause root rot in A. sinensis. Our results provide timely information for informing the use of biocontrol agents for suppression of root rot disease.

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Genetic differentiation ofLiparus glabrirostris(Curculionidae: Molytinae) populations from the fragmented habitats of the Alps and Carpathian Mountains

Bulletin of Entomological Research ◽

10.1017/s0007485316000377 ◽

2016 ◽

Vol 106 (5) ◽

pp. 651-662 ◽

Cited By ~ 1

Author(s):

M. Mitrović ◽

Ž. Tomanović ◽

M. Jakovljević ◽

D. Radović ◽

J. Havelka ◽

...

Keyword(s):

Environmental Changes ◽

Elongation Factor ◽

Morphological Characteristics ◽

Genetic Distances ◽

Bootstrap Support ◽

Evolutionary Divergence ◽

Carpathian Mountains ◽

Mitochondrial Haplotypes ◽

Long Time ◽

The Alps

AbstractPopulations ofLiparus glabrirostris(Curculionidae: Molytinae), a weevil inhabiting higher altitudes of Central Europe, were sampled from 24 localities in the Alps and Carpathian Mountains, and the geographical structuring of genetic variation was analyzed. Comparison of the concatenated mitochondrial cytochrome oxidase subunit I and subunit II sequences revealed consistent genetic divergence between the populations ofL. glabrirostrisfrom different mountain ranges. In phylogenetic analysis using maximum parsimony and median-joining networks, concatenated mitochondrial haplotypes from the Alps and Carpathians clustered as separate lineages, with high bootstrap support. Substantial genetic distances determined between the separated groups ranged from 2.6 to 3.0%, with divergence estimated to have initiated approximately 0.85–0.98 million years ago. The nuclear elongation factor 1α gene was additionally amplified and haplotype analysis showed very low evolutionary divergence (0.2%), with separate clustering as well. The observed divergence suggests that the populations have been isolated for a long time, as a consequence of environmental changes resulting in varying fragmentation of habitats in the Alps and Carpathians, interrupting genetic exchange events and altering the genetic structure ofL. glabrirostrispopulations. On the other hand, comparison of morphological characteristics showed no differences to confirm genetically well differentiated groups of populations. A polymerase chain reaction and restriction fragment length polymorphism-based method was therefore developed to discriminate between the Alpine and Carpathian lineages.

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Sclerotium rolfsii, Penyebab Penyakit Busuk Pangkal Batang pada Hippeastrum sp.

Jurnal Fitopatologi Indonesia ◽

10.14692/jfi.15.2.53-58 ◽

2019 ◽

Vol 15 (2) ◽

pp. 53-58

Author(s):

Antok Wahyu Sektiono ◽

Syamsuddin Djauhari ◽

Putri Devinta Pertiwi

Keyword(s):

Host Range ◽

Root Rot ◽

Agar Medium ◽

Sclerotium Rolfsii ◽

Morphological Characteristics ◽

Stem Rot ◽

Potato Dextrose Agar Medium ◽

White Mycelium ◽

Rot Disease ◽

Range Test

Sclerotium rolfsii, a the Causal Agent of Stem Rot Disease on Hippeastrum sp.Symptoms of stem rot that cause Hippeastrum sp. or red lily wither, leaves turn yellow, and eventually die found at Mangliawan Village, District of Pakis, Malang - East Java. The purpose of this study was to identify the pathogens that cause root rot disease on lily plants and find out their host range. Sclerotium from the symptomatic base of the plant was isolated on potato dextrose agar medium. Fungus was identified based on the morphological characteristics of the colonies and mycelium. Host range test of pathogen was carried out by manual inoculation on Rain lily (Zephyranthes) St. Bernard's lily (Chlorophytum) and Beach Spider lily (Hymenocallis). The results of the identification showed that the fungus had white mycelium and formed sclerotium. Sclerotium is irregularly rounded, white when young, and dark brown when ripe, and forms 10 days after incubation. In hyphae, there are branching, septa, and clam connections. Based on the morphological characteristics of the disease the fungus was identified as Sclerotium rolfsii. In the host range test, the fungus was able to infect rain lilies and paris lilies, but not in spider lilies. This is the first report of S. rolfsii infection in lily in Indonesia.

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

Plant Disease ◽

10.1094/pdis-11-20-2471-pdn ◽

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.

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First Report of Sea buckthorn Stem Wilt Caused by Fusarium sporotrichioides in Gansu, China

Plant Disease ◽

10.1094/pdis-03-21-0627-pdn ◽

2021 ◽

Author(s):

Bo Xia ◽

Yue Liang ◽

Jianzhong Hu ◽

Xiaoling Yan ◽

Liqiang Yin ◽

...

Keyword(s):

Elongation Factor ◽

Morphological Characteristics ◽

Gansu Province ◽

Sea Buckthorn ◽

Molecular Characteristics ◽

Ear Rot ◽

Fusarium Sporotrichioides ◽

Tree Roots ◽

Internal Transcribed Spacer Region ◽

First Report

Sea buckthorn (Hippophae rhamnoides) is an important deciduous shrub for fruit and ecological restoration in arid and semi-arid regions of China. Twelve Chinese and Russian cultivars (cv. Shenqiuhong, eshi01, ... eshi11) were planted about 1.6 acre area in a seedling nursery, located in Qingyang City of Gansu province in northwest China, where high mortality (more than 70%) of sea buckthorn was observed in late July 2019. Symptoms consisted of massive chlorosis, drooping leaves and dried-up stems on 5-year-old trees. Pieces of tree roots and stems with irregular light-brown discoloration in the xylem vessels were selected. Small pieces of discolored tissue were surface disinfested (1 min in 1% sodium hypochlorite, followed by three rinses with sterile distilled water), air-dried, and placed on potato dextrose agar (PDA) medium for 5 days at 25°C in the dark. A fungus was consistently isolated from both diseased roots and stems tissues. Colonies on PDA grew rapidly. Dense mycelia were pinky-white initially, and became carmine red color with age on the undersurface of the plate. Macroconidia were moderately curved, 3 to 5 marked septa, hyaline, thick walled, and measuring 27.8± 3.6 µm × 4.8 ± 0.5 µm (n = 30). Microconidia were abundant, pear-shaped, ellipsoid to fusoid, often with a papilla at the base, and 8.4 ± 2.2 µm ×3.1 ± 0.3 µm (n = 30). Genomic DNA was extracted for amplification and sequencing of the internal transcribed spacer region (ITS1 and ITS4 primers) (White et al. 1990) of the ribosomal DNA (Accession Nos. MN160235 to MN160238) and translation elongation factor-1 alpha (EF1 and EF2 primers, accession Nos. MN429075 to MN429078) (O’Donnell et al. 1998). The sequences revealed 99% similarity to the sequences of the ITS (AY188917), and 100% identity with EF1-α (JF740808) regions of Fusarium sporotrichioides. Based on morphological and molecular characteristics, the fungus was identified as F. sporotrichioides (Leslie and Summerell 2006). Koch’s postulates were fulfilled on healthy, potted 1-year-old sea buckthorn seedings using two isolates in a greenhouse at 25 °C, 90% relative humidity, and 12-hour light/dark photoperiod. Ten potted seedings were inoculated on the stems by placing a 5-mm-diameter mycelial plug (5-day-old PDA cultures for each isolate) into the surface of a wound created with a needle, and the inoculation sites were covered with Parafilm to maintain moisture. Ten seedings were inoculated with PDA plugs as controls. Seven to ten days after inoculation, typical symptoms of dark-brown necrotic lesions on chlorotic leaf margins were observed. About 2 weeks after inoculation, the inoculated stems were gradually dry up, accompanied by withering and fallen leaves. Control plants remained asymptomatic. Pathogens were successfully isolated from the inoculated stems again, exhibiting morphological characteristics identical to those of F. sporotrichioides. Previous papers reported F. sporotrichioides as a common pathogen caused lavender wilt (Cosic et al. 2012), foliar spots on forage corn (Moya-Elizondo et al. 2013) and maize ear rot (Wang et al. 2019). To our knowledge, this is the first report of sea buckthorn stem wilt caused by F. sporotrichioides on several Chinese and Russian cultivars in Gansu province of China. In Heilongjiang province, the same disease was reported in 2010 (Song et al. 2010), nearly 30 longitudes away from Gansu province. Therefore, this disease appears to be a serious risk for future sea buckthorn production.

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

Plant Disease ◽

10.1094/pdis-04-21-0857-pdn ◽

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.

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Morphological and Molecular Characteristics of Fungal Species Associated with Crown Rot of Strawberry in South Korea

10.21203/rs.3.rs-713894/v1 ◽

2021 ◽

Author(s):

Oliul Hassan ◽

Taehyun Chang

Keyword(s):

South Korea ◽

Root Rot ◽

Species Complex ◽

Sequence Data ◽

Morphological Characteristics ◽

Fungal Species ◽

Crown Rot ◽

Molecular Characteristics ◽

Pathogenicity Test ◽

Crown And Root Rot

Abstract Crown and root rot is the most important and destructive strawberry diseases in Korea as it causessubstantial economic loss. In August 2020, a severe outbreak of crown and root rot on strawberries (Fragaria×ananassa Duch.) was observed in the greenhouse at Sangju, South Korea. Infected plantlets displayed browning rot within the crown and root, stunted growth, and poor rooting. Thirty fungal isolates were procured from the affected plantlet. Isolates were identified based on morphological characteristics and pathogenicity test as well as sequence data obtained from internal transcribed spacer, large subunit ribosomal ribonucleic acid, translation elongation factor,and RNA polymerase Ⅱ-second largest subunit. Results showed that thecrown and root rot of strawberry in Korea was caused by three distinct fungal species:Fusarium oxysporum species complex, F. solani species complex, andPlectosphaerella cucumerina. To the best of our knowledge,F. solani species complex andP. cucumerinaare reported for the first time as the causal agents of the crown and root rot of strawberryin South Korea.Pathogenicity tests confirmed that these isolates are pathogenic to strawberry.Understanding the composition and biology of the pathogen population will be helpful toprovide effectivecontrol strategies for the disease.

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First Report of Fusarium solani Causing Root Rot of Juglans sigllata Dode in China

Plant Disease ◽

10.1094/pdis-08-14-0801-pdn ◽

2015 ◽

Vol 99 (1) ◽

pp. 159-159 ◽

Cited By ~ 3

Author(s):

L. Zheng ◽

Y. Peng ◽

J. Zhang ◽

W. J. Ma ◽

S. J. Li ◽

...

Keyword(s):

Fusarium Solani ◽

Root Rot ◽

Industrial Development ◽

Elongation Factor ◽

Morphological Characteristics ◽

Colony Growth ◽

Universal Primers ◽

Laboratory Manual ◽

First Report ◽

Stem Cankers

Juglans sigllata Dode, known as the iron walnut, is widely planted in Liangshan prefecture of southwest China for its nuts and wood. Liangshan prefecture is a major traditional growing area of J. sigllata and has unique advantages for walnut industrial development because of its good soil, climate, and availability of water. Currently there are 2.7 million hectares of walnut, contributing important incomes for farmers. In April 2013, numerous J. sigllata were found infected with root rot in the Muli county of Liangshan prefecture. Symptoms included dried leaves, dead branchcs, and even death. Rotted roots were collected and surface-sterilized in 2% NaOCl and 70% ethanol. The junction (1 cm) between infected and healthy regions was removed, plated on rose bengal-glycerin-urea medium, and incubated at 20°C for 12 h. A fungus was found and purified successively by transferring hyphal tips from the margin of a thinly growing colony on 2% water agar (3). Morphological characteristics were identified both on potato dextrose agar (PDA) and carnation leaf-piece agar. Evaluation of pigmentation and colony growth rate were also measured using PDA. Ovoid microconidia (average dimensions 10.6 × 9.1 μm) were observed after 2 to 3 days, and most of them had no septa or only one septum. Macroconidia (average dimensions 47.4 × 5.3 μm), with one to three septate sickle shapes, were found after 3 to 6 days. Single or paired chlamydospores (average dimensions 10.3 × 9.2 μm), which were circular to ovate, smooth or not smooth, were observed after 7 days of incubation in clean water. According to the cultural characteristics, the fungus was primarily identified as Fusarium solani (1). To better determine the species, universal primers ITS1/ITS4 for the ribosomal internal transcribed spacer (ITS) coupled with translation elongation factor (EF-1α) primers EF1/EF2 were used for PCR-based molecular identification. Against GenBank and the FUSARIUM-ID databases, our sequences shared 99 and 98% identities with ITS (FJ459973.1) and EF-1α (JX677562.1) of F. solani, respectively. Both sequences produced in this study have been deposited in GenBank under accession numbers KJ528277 for ITS and KJ528278 for EF-1α. Pathogenicity tests were conducted by drop inoculating 20 ml of microconidia suspension (106 spores/ml) on the roots of 1-year-old healthy potted J.sigllata, Mianyang walnut, and Xinjiang walnut. Controls were not treated with F. solani. Fifteen plants were in each group. All materials, including pots and soil, were disinfected. After 12 days, all J. sigllata inoculated with F. solani exhibited dried leaves, and after 17 days, Mianyang walnut and Xinjiang walnut infected with F. solani also developed the same symptoms. After 24 days, the inoculated J. sigllata died. However, control plants remained asymptomatic. The fungus re-isolated from infected roots showed the same characteristics as described above and was totally identical in appearance to the isolates used to inoculate the plants. No colonies of F. solani were isolated from untreated plants. At present, F. solani has been reported in stem cankers on English walnut in South Africa (2). To our knowledge, this is the first report of root rot caused by F. solani in J. sigllata in China. References: (1) C. Booth. Fusarium Laboratory Guide to the Identification of the Major Species. CMI, Kew, England, 1977. (2) W. Chen and W. J. Swart. Plant Dis. 84:592, 2000. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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