First Report of Lotus Seedpod Withering Caused by Fusarium proliferatum on Nelumbo nucifera Plants in China

Nelumbo nucifera (Nymphaeaceae family) is a well-known plant in China and with the increasing value of this crop, the planting area of lotus is expanding. In May 2019, an unknown withering lotus seedpod was obtained in Guangchang County of Jiangxi Province (26.79°N, 116.31°E). The disease arose between May and July of each year, resulted in the withering and consequent death of ~10% of lotus seedpods, with the disease being most serious during the rainy season. The initial symptoms of this disease include the shrinking of young lotus seedpods with concomitant yellowing of the epidermal tissue layer. These pods failed to grow normally and could to wither and die within one week, with the withering symptoms gradually spreading to associated stem tissues. To characterize the pathogens responsible for this disease, ten diseases seedpods were collected and cut into pieces of ~5×5 mm, then sterilized with 75% ethanol for 30 s, and treated with 0.1% mercuric chloride for 5 min. After being washed four times under sterilized water, samples were then transferred onto potato dextrose agar (PDA) and incubated for 7 d at 28℃ in the dark. Eight purified isolates yielded large numbers of aerial mycelium that were initially white in color, but then changed to a purple-red color over the course of this incubation period. The average mycelial growth rate was 6.3 mm per day (n=5). On PDA, macroconidia exhibited 3-5 septa and were straight or slightly curved, with a size of 21.6-47.4×2.5-4.6 µm (average: 31.9×3.5 µm, n=50). The microconidia were hyaline, ovoid or ellipse and 4.6-13.5×2.2-4.3 µm in size (average: 8.7×3.1 µm, n=50). The morphological features of these fungi were noted to be in line with those of Fusarium proliferatum (Leslie and Summerell, 2006; Zhao et al., 2019). To confirm the identity of this putative pathogen at the molecular level, the universal ITS4/ITS5 primers (White et al., 1990), the Fusarium specific pair PRO1/PRO2 (Mulè et al., 2004), EF1T/EF2T (O'Donnell et a., 1998) and RPB2F/R (O'Donnell et al., 2010) primers were utilized to amplify the internal transcribed spacer 1 (ITS1)-5.8S rRNA gene-internal transcribed spacer 2 (ITS2), calmodulin, alpha elongation factor genes, and RNA-dependent DNA polymerase II subunit from these isolates. Following alignment of the resultant sequences with GenBank via a BLAST analysis, the sequences (GenBank accession numbers: MW862499, MW762531, MW767988, MW831311, respectively.) showed 100% identities to the corresponding DNA sequences in F. proliferatum (GenBank accession numbers: MW817705, LS423443, MH153750, and MW091308, respectively.). Based upon these morphological and molecular findings, this pathogen was identified as F. proliferatum. Pathogenicity testing was then performed using five plump healthy lotus seedpods. Sterile needles were used to generate wounds (2 mm deep, 1 mm in diameter) a 10 µL suspension of prepared spores (1.0×106 spores/mL) derived from a 7-day-old culture grown on PDA was injected into the wound sites of the lotus seedpod. As a control, give seedpods were additionally wounded and injected as the same as treated with 10 µL of sterile water. The experiments were repeated three times with five biological replicates. All seedpods were then incubated at 28℃ in a growth chamber (12 h light/dark) with 80% relative humidity. After a 3-day incubation period, wounded sites injected with spore suspensions exhibited browning. Following a 5-day incubation period, a mean lesion diameter of 9.8 mm was observed, with white mycelia growing on the wound surface and with evident withering of the internal and external tissues near the wounded site. In contrast, blank control wound sites remained healthy. We were again able to isolate F. proliferatum from the infected lotus seedpods. Finally, eight isolates were obtained were identified as the pathogen based on these morphological and molecular analyses, thus fulfilling Koch's postulates. This is the first report to our knowledge to have described a case of F. proliferatum causing lotus seedpod withering in China, providing a foundation for future research efforts aimed at presenting diseases caused by this pathogen.

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Pseudohydnum brunneiceps (Auriculariales, Basidiomycota), a new species from Central China

Phytotaxa ◽

10.11646/phytotaxa.441.1.8 ◽

2020 ◽

Vol 441 (1) ◽

pp. 87-94

Author(s):

YAN-LIU CHEN ◽

MING-SHENG SU ◽

LIN-PING ZHANG ◽

QIN ZOU ◽

FEI WU ◽

...

Keyword(s):

New Species ◽

Molecular Phylogeny ◽

Dna Sequences ◽

Internal Transcribed Spacer ◽

Phylogenetic Analyses ◽

Central China ◽

Jiangxi Province ◽

Line Drawings ◽

A New Species ◽

Representative Samples

Pseudohydnum brunneiceps is described as a new species from Jiangxi Province, central China. Morphologically, it is characterized by a gelatinous basidiocarps, pilei pale yellowish brown, dark reddish brown to blackish velutinate, spines conical and white, and basidiospores globose to broadly ellipsoidal. Phylogenetic analyses of DNA sequences from partial 28S region and internal transcribed spacer (ITS) also confirm that P. brunneiceps forms an independent lineage within Pseudohydnum. A description, photographs of the fresh basidiomata and line-drawings of the microstructures are provided. In addition, the previous records of P. gelatinosum in China should be re-evaluated by more representative samples by molecular phylogeny.

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First Report of Clover Proliferation Phytoplasma in Strawberry

Plant Disease ◽

10.1094/pdis.1999.83.10.967c ◽

1999 ◽

Vol 83 (10) ◽

pp. 967-967 ◽

Cited By ~ 4

Author(s):

R. Jomantiene ◽

J. L. Maas ◽

E. L. Dally ◽

R. E. Davis ◽

J. D. Postman

Keyword(s):

Dna Sequences ◽

Rrna Gene ◽

Universal Primer ◽

Disease Symptoms ◽

First Report ◽

Chain Reactions ◽

Polymerase Chain Reactions ◽

Fragaria Virginiana ◽

Phytoplasma Infection ◽

Group 2

In 1996, diseased plants of Fragaria virginiana Duchesne were collected from a native population in Quebec, Canada, and sent to the National Clonal Germplasm Repository in Corvallis, OR, where grafting onto disease-free plants of F. chiloensis (L.) Duchesne (4) was performed. Plants of both species were sent to Beltsville, MD, for identification of a phytoplasma possibly associated with the disease symptoms of dwarfing and multibranching crowns. A phytoplasma was found in both species and characterized as the strawberry “multicipita” (SM) phytoplasma, which is representative of subgroup 16SrVI-B, a new subgroup of the clover proliferation (CP) group (2). In 1999, we observed commercial strawberry (Fragaria × ananassa Duchesne) plants collected in California and Maryland that were stunted and chlorotic or exhibited these symptoms in addition to small, distorted leaves. Infected F. × ananassa plants, as well as diseased F. virginiana and grafted F. chiloensis plants previously infected by the SM phytoplasma, were assessed for phytoplasma infection by nested polymerase chain reactions primed by phytoplasma universal primer pairs R16mF2/R1 and F2n/R2 (1) or P1/P7 (3) and F2n/R2 for amplification of phytoplasma 16S rDNA (16S rRNA gene) sequences. Phytoplasma-characteristic 1.2-kbp DNA sequences were amplified from all diseased plants. No DNA sequences were amplified from healthy plants. Restriction fragment length polymorphism patterns of rDNA digested with AluI, KpnI, HhaI, HaeIII, HinfI, HpaII, MseI, RsaI, and Sau3A1 endonucleases indicated that all plants were infected by a phytoplasma that belonged to subgroup 16SrVI-A (CP phytoplasma subgroup) and that diseased F. virginiana and grafted F. chiloensis plants were infected by both SM and CP. This is the first report of the CP phytoplasma, subgroup 16SrVI-A, infecting strawberry. This report also indicates that the occurrence of the CP phytoplasma in strawberry may be widespread in North America and that F. chiloensis, F. virginiana, and F. × ananassa plants are susceptible to infection by the CP phytoplasma. References: (1) D. E. Gunderson and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) R. Jomantiene et al. HortScience 33:1069, 1998. (3) R. Jomantiene et al. Int. J. Syst. Bacteriol. 48:269, 1998. (4) J. D. Postman et al. Acta Hortic. 471:25, 1998.

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First Report of Fusarium Blight on Majesty Palm Caused by Fusarium proliferatum in Italy

Plant Disease ◽

10.1094/pdis.2003.87.9.1149a ◽

2003 ◽

Vol 87 (9) ◽

pp. 1149-1149 ◽

Cited By ~ 6

Author(s):

G. Polizzi ◽

A. Vitale

Keyword(s):

Fusarium Proliferatum ◽

Conidial Suspension ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms ◽

Mt Etna ◽

Young Leaves ◽

Pure Cultures ◽

Severe Infections ◽

Fusarium Sp

During spring 2002, a new disease of majesty palm (Ravenea rivularis Jumelle & H. Perrier) was observed on young, container-grown plants (3 to 4 years old with five to seven expanded leaves) in a nursery in eastern Sicily. Initial symptoms on the youngest, expanded leaves and especially on the unopened, spear leaves were small, reddish-brown necrotic lesions (2 to 4 mm in diameter) with a yellow halo. In high humidity, lesions increased in size and number, coalescing into large, irregular dead areas. These symptoms developed into blights of the youngest, unopened leaves. As a consequence, infected leaves would dieback and only a few plants recovered from these severe infections. On the surviving plants, reddish-brown necrotic lesions appeared on the rachis. From these lesions, 30 pieces of tissue were cut, surface sterilized (30 s in 1.2% wt/vol of NaOCl), washed with sterile water, and plated on potato dextrose agar supplemented with 1.1 μl/ml of lactic acid (stock 88 to 92%) (A-PDA). Conidia and conidiophores were collected directly from the tissue with a flamed needle and placed on A-PDA. Fusarium sp. was consistently isolated from the necrotic tissue, and after 3 days, single hyphal tips were transferred to pure cultures from which were obtained two single, conidial isolates. These fungal isolates were forwarded to the CABI Bioscience U.K. Centre, Bakeham Lane (Egham), Surrey, U.K., where both isolates were identified as Fusarium proliferatum (T. Matsushima) Nirenberg. A morpho-biometrical characterization was performed on carnation leaf agar with a photoperiod of 10 h. Macroconidia were slender, lightly falcate to almost straight, 3- to 5-septate, and ranged from 37 to 53 × 2.5 to 3 μm (average 44.1 × 2.8 μm). Microconidia, clavate or oval with a truncated base, were formed in chains from mono- or polyphialides. Chlamydospores were absent. Eight 2-year-old seedlings (three to five expanded leaves) of majesty palm had the unopened spear leaves needle-wounded and another eight were unwounded. All were sprayed with a conidial suspension (1.5 × 106 CFU/ml). An equal number of noninoculated plants were used as a control. All plants were covered with polyethylene bags and incubated in a greenhouse at 25 ± 2°C for 72 h. All wounded majesty palms showed brown areas on unopened spear leaves. When natural injures were present, reddish leaf spots appeared as early as 4 days after inoculation. Macroscopic observations revealed the presence of white mycelium on the necrotic areas and reddish spots. Koch's postulates were satisfied by reisolation of the fungus on A-PDA from artificially infected tissues. On the basis of 3 months of field observations in Sicily, spread of Fusarium blight on majesty palm was always greater when plants were injured on the tender and unopened leaves by volcanic cinders from Mt. Etna, which caused bruises on young leaves. The disease does not represent a major threat to nurseries, but it could cause loss in the cultivation of the majesty palm. F. proliferatum was previously recorded in Saudi Arabia as the causal agent of wilt and dieback of date palm (1). To our knowledge, this is the first report of F. proliferatum on palms in Italy and the first outbreak of the disease on majesty palm. Reference: (1)M. Y. Abdalla et al. Plant Dis. 84:321, 2000.

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First Report of Alternaria tenuissimain Causing Leaf Spot of Celery (Apium graveolens) in China

Plant Disease ◽

10.1094/pdis-09-20-2083-pdn ◽

2020 ◽

Author(s):

Jianqiang Zhang ◽

Kangli Wu ◽

Xiaomeng Zhang ◽

Jiajia Li ◽

Abdramane salah zene ◽

...

Keyword(s):

Dna Sequences ◽

Leaf Spot ◽

Leaf Age ◽

Apium Graveolens ◽

Control Group ◽

Sterile Water ◽

Internal Transcribed Spacer Region ◽

Data Set ◽

First Report ◽

Initial Symptoms

Celery (Apium graveolens) is one of the most widely grown vegetables in the world. A survey in Anding District of Gansu Province in 2019 showed that the incidence of celery leaf spot was 25%-45%. The disease mainly occurs in late June and July. The leaf spot is conducive to the onset at high temperature and humidity environment. The initial symptoms were many small light brown, irregular-shaped on the leaves. The lesions gradually enlarged in the later stage of the disease, and multiple lesions coalesced to form large irregular brown spots, eventually the whole leaves died. A 3~4mm leaf tissue was cut from the junction of the diseased leaf and the healthy area, the leaf tisse was surface-sterilized in 1.5% NaClO for 1 min and washed with sterile water. Then, it was incubated on potato dextrose agar (PDA) and obtained the pure culture (Q1). After 5 days of cultivation at 25°C, the fungal colonies were olivaceous to dark olive with white margins and abundant aerial mycelia. The conidia were obclavate or ellipsoid, pale brown, with 3~4 longitudinal septa and 2~7 transverse septa, and measured 20.0 to 50.0 × 3.5 to 14.0μm (n=50). Conidiophores were septate, arising singly, and measured 3.5 to 40.0 × 2.5 to 4.5 μm (n=50). Based on morphological characteristics, the fungus was preliminarily identified as A.tenuissima (Simmons 2007). To further confirm the identification, the internal transcribed spacer region (ITS), translation elongation factor 1-α gene (TEF), RNA polymerase II second largest subunit (RPB2), major allergen Alt a 1 gene (Alt a 1), endopolygalacturonase gene (endoPG), anonymous gene region (OPA10-2) and glyceraldehyde 3-phos-phatedehydrogenase (GAPDH) were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004), EF1-728F/EF1-986R (Carbone et al. 1999), RPB2-5F2/RPB2-5R (Sung et al. 2007), Alt-for/Alt-rev (Hong et al. 2005), EPG-specific/EPG-3b (Peever et al. 2004), OPA10-2R/OPA10-2L (Peever et al. 2004) and Gpd1/Gpd2 (Berbee et al. 1999) (GenBank accession no.MN046364, MW016001, MW016002, MW016003, MW016004, MW016005, MW016006). DNA sequences of TEF, RPB2, endoPG, OPA10-2 and GAPDH were 100% identical to those of A. tenuissima (MN256108, MK605866, KP789503, JQ859829 and MK683802), but ITS and Alt a 1 were 100% similarity with A. tenuissima (MN615420, JQ282277) and A. alternate (MT626589, KP123847). The ITS and Alt a 1 sequence did not distinguish A. tenuissima from the A. alternate complex. Maximum likelihood phylogenetic analyses were performed for the combined data set with TEF, RPB2, and endoPG using MEGA6 under the Tamura-Nei model (Kumar et al. 2016). The isolate Q1 clustered with type strain A. tenuissima CBS 918.96. The 20 celery plants of 4-7 leaf age were used test the pathogenicity of Q1, the ten plants were sprayed with 20ml of spore suspension (1×105 spores/ml), the control was sprayed with 20mL sterile water, which were placed in a growth chamber (25℃, a 14h light and 10h dark period, RH > 80%). Eight days after inoculation, 40% of the leaves formed lesions, which were consistent with the field observation，the control group was asymptomatic. The pathogen was reisolated from infected leaves to fulfill Koch’s postulates. To our knowledge, this is the first report of A. tenuissima causing leaf spot on celery in China.

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First Report of Curvularia lunata Causing Leaf Spot on Lotus in China

Plant Disease ◽

10.1094/pdis-03-12-0234-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1068-1068 ◽

Cited By ~ 6

Author(s):

R. Q. Cui ◽

X. T. Sun

Keyword(s):

Leaf Spot ◽

Ethanol Solution ◽

Jiangxi Province ◽

Its2 Region ◽

Curvularia Lunata ◽

Commonwealth Mycological Institute ◽

Conidial Suspension ◽

First Report ◽

Conidial State ◽

Initial Symptoms

Lotus (Nelumbo nucifera Gaertn.) is a flowering aquatic plant, and is widely planted as a vegetable and ornamental plant in China. In June 2011, a leaf spot was observed on lotus in Pingxiang City of Jiangxi Province, causing approximately 60% of leaves to die and leading to 10 to 15% yield loss. Initial symptoms were purple-brown spots emerging on the leaf surfaces with diameters ranging from 0.5 to 3 cm, which later developed grayish white centers and a black-brown banding pattern on the edges. Lesions often merged to form large necrotic areas, covering more than 70% of the leaf surface, which may have contributed to plant death. Small pieces (5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface sterilized in 70% ethanol solution for 1 min and 0.1% mercuric chloride solution for 5 min, washed in three changes of sterile distilled water, and transferred to potato dextrose agar plates. Cultures were maintained in an incubator at 25°C for 5 to 7 days. After 7 days, six black-brown colonies were isolated, which developed dark brown septate conidiophores. Conidia were 20 to 25 × 9 to 13 μm, with three-horizontal septa, and curved at the third cell from the base that was longer and darker than the others. Cells at each end were subhyaline and intermediate cells were medium brown. These characteristics were consistent with Curvularia lunata (Wakker) Boedijng (1,2,4). Molecular characterization was based on rDNA sequence. For two isolates, DNA was extracted using a CTAB protocol with 0.8% mercaptoethanol, then the ITS1-5.8S-ITS2 region was amplified with primers ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (3). PCR products were cloned and sequencing reactions were run on an AB3730 Stretch DNA sequencing system. On the basis of a comparison of 598 base pairs, both isolates had the same sequence (GenBank Accession No. JQ701798), which differed by one base pair from Cochliobolus lunatus NBRC 100173 (GenBank Accession No. JN943426) (conidial state: Curvularia lunata). Pathogenicity experiments were conducted by inoculating a conidial suspension (106 CFU/ml) on five newly matured leaves of healthy lotus. Plants inoculated with sterile water served as the noninoculated controls. Plants were incubated in the greenhouse at 20 to 25°C. All the inoculated leaves started showing disease symptoms (purple flecks) after 7 days and the noninoculated control plants remained asymptomatic. C. lunata was consistently recovered from all inoculated plants, except the control, thus fulfilling Koch's postulates. To our knowledge, this is the first report of leaf spot caused by C. lunata on lotus in China. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1971. (2) M. M. Hawa, et al. Plant Dis. 93: 971, 2009. (3) K. J. Martin and P. T. Rygiewicz. BMC Microbiol. 5:28, 2005. (4) F. B. Rocha et al. Austral. Plant Pathol. 33: 601, 2004.

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First report of Fusarium proliferatum causing stem and root rot on lucky bamboo (Dracaena braunii) in Iraq

Hellenic Plant Protection Journal ◽

10.2478/hppj-2019-0001 ◽

2019 ◽

Vol 12 (1) ◽

pp. 1-5

Author(s):

A.A. Lahuf

Keyword(s):

Ribosomal Dna ◽

Root Rot ◽

Internal Transcribed Spacer ◽

Morphological Characteristics ◽

Its Region ◽

Fusarium Proliferatum ◽

Ornamental Plant ◽

Sequence Analyses ◽

First Report

Summary Lucky bamboo (Dracaena braunii) is a popular ornamental plant in Iraq. Individuals of this plant showing stem and root rot symptoms were observed during a survey conducted from November 2015 to February 2016 in several nurseries in Kerbala province, Iraq. Based on morphological characteristics and sequence analyses of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA), the pathogen was identified as Fusarium proliferatum. This is the first report of stem and root rot caused by F. proliferatum on lucky bamboo (D. braunii) in Iraq.

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

Plant Disease ◽

10.1094/pdis-08-21-1809-pdn ◽

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.

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First Report of Clover Yellow Edge and STRAWB2 Phytoplasmas in Strawberry in Maryland

Plant Disease ◽

10.1094/pdis.1999.83.11.1072c ◽

1999 ◽

Vol 83 (11) ◽

pp. 1072-1072 ◽

Cited By ~ 8

Author(s):

R. Jomantiene ◽

J. L. Maas ◽

E. L. Dally ◽

R. E. Davis

Keyword(s):

Dna Sequences ◽

Infected Plant ◽

Rrna Gene ◽

16S Rrna Gene Sequences ◽

Universal Primer ◽

First Report ◽

Chain Reactions ◽

Polymerase Chain Reactions ◽

Phytoplasma Infection ◽

Polymerase Chain

Commercial strawberry (Fragaria × ananassa Duchesne) plants that were either chlorotic and severely stunted or exhibiting fruit phyllody were collected in Maryland. The plants were assessed for phytoplasma infection by nested polymerase chain reactions primed by phytoplasma universal primer pairs R16mF2/R1 and F2n/R2 (2) or P1/P7 (3) and F2n/R2 for amplification of phytoplasma 16S ribosomal (r) DNA (16S rRNA gene) sequences. Phytoplasma-characteristic 1.2-kbp DNA sequences were amplified from all diseased plants. No phytoplasma-characteristic DNAs were amplified from healthy plants. Restriction fragment length polymorphism patterns of rDNA digested with AluI, KpnI, HhaI, HaeIII, HpaII, MseI, RsaI, and Sau3A1 endonucleases indicated that chlorotic and stunted plants were infected by a phytoplasma that belonged to subgroup 16SrIII-B (clover yellow edge [CYE] subgroup) and that the plant exhibiting fruit phyllody was infected by a phytoplasma that belonged to subgroup 16SrI-K (STRAWB2 subgroup). The STRAWB2 phytoplasma was first reported from strawberry plants grown in Florida and characterized as representative of a new subgroup of the aster yellows group, 16SrI (3); this is the first report of this phytoplasma occurring in strawberry outside of Florida. A STRAWB2-infected plant produced phylloid fruits in two consecutive years of observation in the greenhouse; the plant previously had been field-grown in a breeder's evaluation plots in Beltsville, MD. The CYE phytoplasma was first experimentally transmitted by leafhopper to commercial strawberry and F. virginiana Duchesne in Ontario Canada (1); this is the first report of natural CYE phytoplasma infection of strawberry in Maryland. CYE phytoplasma-infected plants, representing ≈5% of the total number of plants of one advanced sselection, were located in a breeder's evaluation plots in Beltsville. References: (1) L. N. Chiykowski. Can. J. Bot. 54:1171, 1976. (2) D. E. Gunderson and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) R. Jomantiene et al. Int. J. Syst. Bacteriol. 48:269, 1998.

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First Report of Target Spot Caused by Corynespora cassiicola on Cotton in Georgia

Plant Disease ◽

10.1094/pdis-01-12-0035-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1066-1066 ◽

Cited By ~ 14

Author(s):

A. M. Fulmer ◽

J. T. Walls ◽

B. Dutta ◽

V. Parkunan ◽

J. Brock ◽

...

Keyword(s):

Dna Sequences ◽

Leaf Spot ◽

Pure Culture ◽

Pathogenic Fungi ◽

Fluorescent Light ◽

Corynespora Cassiicola ◽

Sterile Water ◽

First Report ◽

Target Spot ◽

Initial Symptoms

In 2005, crop consultants in southwestern Georgia reported an unusual occurrence of leaf spot in cotton (Gossypium hirsutum L.). Initial symptoms first developed as brick red dots that led to the formation of irregular to circular lesions with tan-to-light brown centers. Lesions further enlarged and often demonstrated a targetlike appearance formed from concentric rings within the spot. Observations included estimates of premature defoliation up to 70%, abundant characteristic spots on the leaves and bracts, and losses of several hundred kg of lint/ha. When symptomatic leaves were submitted to the University of Georgia Tifton Plant Disease Clinic in Tifton, GA, for identification in 2008, the causal agent was tentatively diagnosed as Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei on the basis of similar symptoms and signs previously reported on cotton (3). In September 2011, symptomatic leaves were obtained from diseased cotton within a field (var. DP 1048B2RF) near Attapulgus, GA. Symptomatic tissue from diseased leaves was surface disinfested in 0.5% sodium hypochlorite for 1 min and plated on potato dextrose agar (PDA). Ten isolates were incubated at 21.1°C for 2 weeks with a 12/12 h light/dark cycle using fluorescent light located approximately 70 cm above the cultures. After 1 week, two isolates were transferred to quarter strength PDA for enhanced sporulation and were grown under the same conditions. Conidiophores from the isolated fungus were simple, erect, intermittently branching and septate, and gave rise to single, subhyaline conidia. Conidia had 4 to 17 pseudosepta and were 50 to 197 μm long and 7 to 16 μm wide, straight to curved, and obclavate to cylindrical. Pathogenicity tests were conducted by spraying 10 cotton seedlings (DP 555BR and DP 1048B2RF, two to four true leaf stage) until runoff with a blended suspension from a 2-week-old pure culture of the fungus diluted with 100 mL of sterile water. Five plants were sprayed with sterile water as noninoculated controls. Cotton seedlings were then incubated in a moist chamber at 21.1°C for 48 h. Within 1 week, all inoculated plants showed symptoms similar to those of diseased field plants. Symptoms were not observed on noninoculated control plants. The fungus was reisolated five times from symptomatic leaves and grown in pure culture. Conidia and conidiophores were identical to the morphology of the original isolates, and were similar to descriptions of C. cassiicola (2). To confirm the identity of the pathogen, DNA was extracted from a week-old culture and amplified with specific primers for loci “ga4” and “rDNA ITS” (1). DNA sequences obtained with the Applied Biosystems 3730xl 96-capillary DNA Analyzer showed 99% identity to C. cassiicola from BLAST analysis in GenBank. The resulting sequence was deposited into GenBank (Accession No. JQ717069). To our knowledge, this is the first report of this pathogen in Georgia. Given the increasing prevalence of this disease in southwestern Georgia, its confirmation is a significant step toward management recommendations for growers. Because foliar diseases caused by C. cassiicola are commonly referred to as “target spot” in other crops (e.g., soybeans), it is proposed that Corynespora leaf spot of cotton be known as “target spot of cotton.” References: (1) L. J. Dixon et al. Phytopathology 99:1015, 2009. (2) M. B. Ellis and P. Holliday. CMI Description of Pathogenic Fungi and Bacteria, 303, 1971. (3) J. P. Jones. Phytopathology 51:305, 1961.

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First Report of Clover Yellow Edge Phytoplasma in Corylus (Hazelnut)

Plant Disease ◽

10.1094/pdis.2000.84.1.102b ◽

2000 ◽

Vol 84 (1) ◽

pp. 102-102 ◽

Cited By ~ 5

Author(s):

R. Jomantiene ◽

J. D. Postman ◽

H. G. Montano ◽

J. L. Maas ◽

R. E. Davis ◽

...

Keyword(s):

Dna Sequences ◽

Sequence Similarity ◽

Rrna Gene ◽

Apple Proliferation ◽

Universal Primer ◽

First Report ◽

Chain Reactions ◽

Root Grafts ◽

Corylus Avellana L ◽

Tree Leaf

During investigations into the cause of a stunt syndrome affecting cultivated European hazelnut trees (Corylus avellana L.) in Oregon, the clover yellow edge (CYE) phytoplasma was detected for the first time in this crop. The cause of hazelnut stunt syndrome (HSS) is unknown, but the disease has been transmitted by grafting and apparently has moved within orchards through root grafts (1). Severely affected trees persist for many years, but their nut production is greatly reduced. Previous attempts to detect viruses, bacteria, and other pathogens have been unsuccessful. HSS has been observed only in Oregon and already had been present for more than 10 years when it was first reported in 1970 (1). In June, 1999, leaf samples were collected from two affected and two apparently healthy (symptomless) hazelnut trees in a field plot at Oregon State University, Corvallis, and from a healthy greenhouse-grown tree. Leaf samples were sent to the USDA Beltsville, MD, laboratory, where they were assessed for phytoplasma infection, using nested polymerase chain reactions (PCRs). PCRs were primed by phytoplasma universal primer pairs P1/P7 and F2n/R2 (3) for amplification of phytoplasma 16S ribosomal (r) DNA (16S rRNA gene) sequences according to the procedures of Gunderson and Lee (2). Phytoplasma-characteristic 1.2-kbp DNA sequences were amplified from all field-tree samples. No DNA sequences were amplified from samples of the greenhouse-grown tree. Restriction fragment length polymorphism patterns of rDNA digested with AluI, KpnI, HhaI, HaeIII, HpaII, MseI, RsaI, and Sau3A1 endonucleases indicated that all diseased hazelnut trees as well as symptomless field trees were infected by a phytoplasma classified in group 16SrIII (peach X-disease group), subgroup B (III-B, type strain CYE phytoplasma). No phytoplasmas were detected in samples from the greenhouse-grown tree. Nucleotide sequences were determined for 16Sr DNA fragments amplified from the hazelnut CYE phytoplasma in nested PCRs primed with F2n/R2. The sequences were deposited in GenBank under Accession no. AF189288. Sequence similarity between 16Sr DNAs of the hazelnut CYE strain (CYE-Or) and the Canadian clover yellow edge strain (CYE-C, GenBank Accession no. AF175304) phytoplasma was 99.9%. Decline and yellows disorders of hazelnut in Germany and Italy have been associated with infections by apple proliferation, pear decline, and European stone fruit yellows phytoplasmas (4). These phytoplasmas are classified in 16Sr group X, the apple proliferation group of phytoplasmas. This is the first report of the CYE phytoplasma infecting Corylus. References: (1) H. R. Cameron. Plant Dis. Rep. 54:69, 1970. (2) D. E. Gunderson and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) R. Jomantiene et al. HortScience 33:1069, 1998. (4) C. Marcone et al. Plant Pathol. 45:857,1996.

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