scholarly journals First report of Fusarium fujikuroi causing root rot and seedling elongation of soybean in Indiana

Plant Disease ◽  
2021 ◽  
Author(s):  
Christopher Detranaltes ◽  
Christopher Robert Jones ◽  
Guohong Cai
Keyword(s):  
Root Rot ◽  
Lateral Roots ◽  
Small Subunit ◽  
The State ◽  
Gibberella Fujikuroi ◽  
Fusarium Fujikuroi ◽  
Pathogenicity Test ◽  
Single Spore ◽  
New Host ◽  
First Report

In summer 2020, 127 soybean (Glycine max (L.) Merr) seedlings (V1-V3 stage) showing reduced vigor or crown lesions were collected at Purdue’s Agronomy Center for Research and Education in West Lafayette, Indiana. Root tissues from two seedlings with necrotic cotyledons and root rot were surface-sterilized and plated on dichloran-chloramphenicol-peptone agar (Andrews and Pitt 1986). Emerging hyphal tips were transferred to potato dextrose agar (PDA). Single-spore cultures were obtained and grown on PDA. Both isolates developed floccose white aerial mycelia with reddish-pink coloration in the media in 2 weeks on the benchtop. On carnation leaf agar, macroconidia formed on orange sporodochia within 2 weeks in darkness at 25C. Macroconidia were 3-5 septate, measuring 26 – 41 × 2.5 – 3.7 μm (avg. 34.8 × 3.2 μm, n=40). Microconidia were abundant in chains and false heads forming on both mono- and polyphialides, and measured 2.5 – 8.75 x 2.5 μm (avg. 5.9 × 2.5 μm, n=40). These characteristics were consistent with species descriptions of F. fujikuroi [Sawada] Wollenw. (teleomorph Gibberella fujikuroi) (Leslie and Summerell 2006). DNA was extracted from mycelium and the following genes were amplified and sequenced: the internal transcriber spacer (ITS) region using ITS1/ITS4 primers (White et al. 1990) (GenBank accessions MW463362/MW463363), the mitochondrial small subunit (mtSSU) rDNA using MS1/MS2 primers (White et al. 1990) (MW465310/MW465307), and the partial translation elongation factor 1-alpha (TEF1α) gene using 983F/1567R primers (Rehner and Buckley 205) (MW475297/MW475298). In GenBank BLAST searches, these sequences showed 100% identity to both F. proliferatum and F. fujikuroi. Species-specific forward primers Fuji1F and Proli1F were then used in combination with reverse primer TEF1R to amplify another region in the TEF1α gene (Amatulli et al. 2012). Proli1F/TEF1R primers failed under a variety of annealing temperatures while Fuji1F/TEF1R primers succeeded, and the products were sequenced (MW475299/MW475300). GenBank BLAST searches revealed 100% identity of both isolates to F. fujikuroi (MT448248.1). A pathogenicity test was conducted with isolate AC13 in the greenhouse following the protocol of (Ellis et al. 2013). Ten seeds (cv. Williams) each were used for inoculation and control, respectively, with one seed per cup. Root rot symptoms similar to those observed in the field were observed 14 days after planting on all inoculated plants but not on controls (VC stage). Infected plants showed symptoms of pre-emergence damping off, reddish-brown lesions on the tap and lateral roots, and root necrosis. Three plants also exhibited hyper-elongation of the stem (12.5, 11.1, and 18 cm, vs controls: avg. 6.8 cm, max. 8.5 cm, stdev 0.78 cm). F. fujikuroi was successfully reisolated from inoculated plants but not from controls and identified as described above. F. fujikuroi has been reported causing soybean root rot in China (Zhao et al. 2020), Korea (Choi et al. 2019), and the state of Kansas (Pedrozo et al. 2015). To our knowledge this is the first report of F. fujikuroi infecting soybeans in the state of Indiana. F. fujikuroi is known to cause elongated seedlings in rice (Leslie and Summerell 2006). Pedrozo et al. (2015) reported that F. fujikuroi isolated from soybean caused seedling elongation in rice but not in soybean. The increased distribution and new host symptomology observed here warrants heightened attention for the control of this pathogen.

scholarly journals First report of Fusarium falciforme (FSSC 3+4) causing root rot on chickpea in Mexico

Plant Disease ◽  
2021 ◽  
Author(s):  
Sixto Velarde Felix ◽  
Victor Valenzuela ◽  
Pedro Ortega ◽  
Gustavo Fierros ◽  
Pedro Rojas ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Species Complex ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Chickpea (Cicer aretinium L.) is a legume crop of great importance worldwide. In January 2019, wilting symptoms on chickpea (stunted grow, withered leaves, root rot and wilted plants) were observed in three fields of Culiacan Sinaloa Mexico, with an incidence of 3 to 5%. To identify the cause, eighty symptomatic chickpea plants were sampled. Tissue from roots was plated on potato dextrose agar (PDA) medium. Typical Fusarium spp. colonies were obtained from all root samples. Ten pure cultures were obtained by single-spore culturing (Ff01 to Ff10). On PDA the colonies were abundant with white aerial mycelium, hyphae were branched and septae and light purple pigmentation was observed in the center of old cultures (Leslie and Summerell 2006). From 10-day-old cultures grown on carnation leaf agar medium, macroconidias were falciform, hyaline, with slightly curved apexes, three to five septate, with well-developed foot cells and blunt apical cells, and measured 26.6 to 45.8 × 2.2 to 7.0 μm (n = 40). The microconidia (n = 40) were hyaline, one to two celled, produced in false heads that measured 7.4 to 20.1 (average 13.7) μm × 2.4 to 8.9 (average 5.3) μm (n = 40) at the tips of long monophialides, and were oval or reniform, with apexes rounded, 8.3 to 12.1 × 1.6 to 4.7 μm; chlamydospores were not evident. These characteristics fit those of the Fusarium solani (Mart.) Sacc. species complex, FSSC (Summerell et al. 2003). The internal transcribed spacer and the translation elongation factor 1 alpha (EF1-α) genes (O’Donnell et al. 1998) were amplified by polymerase chain reaction and sequenced from the isolate Ff02 and Ff08 (GenBank accession nos. KJ501093 and MN082369). Maximum likelihood analysis was carried out using the EF1-α sequences (KJ501093 and MN082369) from the Ff02 and Ff08 isolates and other species from the Fusarium solani species complex (FSSC). Phylogenetic analysis revealed the isolate most closely related with F. falciforme (100% bootstrap). For pathogenicity testing, a conidial suspension (1x106 conidia/ml) was prepared by harvesting spores from 10-days-old cultures on PDA. Twenty 2-week-old chickpea seedlings from two cultivars (P-2245 and WR-315) were inoculated by dipping roots into the conidial suspension for 20 min. The inoculated plants were transplanted into a 50-hole plastic tray containing sterilized soil and maintained in a growth chamber at 25°C, with a relative humidity of >80% and a 12-h/12-h light/dark cycle. After 8 days, the first root rot symptoms were observed on inoculating seedlings and the infected plants eventually died within 3 to 4 weeks after inoculation. No symptoms were observed plants inoculated with sterilized distilled water. The fungus was reisolated from symptomatic tissues of inoculated plants and was identified by sequencing the partial EF1-α gene again and was identified as F. falciforme (FSSC 3 + 4) (O’Donnell et al. 2008) based on its morphological characteristics, genetic analysis, and pathogenicity test, fulfilling Koch’s postulates. The molecular identification was confirmed via BLAST on the FusariumID and Fusarium MLST databases. Although FSSC has been previously reported causing root rot in chickpea in USA, Chile, Spain, Cuba, Iran, Poland, Israel, Pakistan and Brazil, to our knowledge this is the first report of root rot in chickpea caused by F. falciforme in Mexico. This is important for chickpea producers and chickpea breeding programs.

scholarly journals First Report of Fusarium andiyazi Associated with Rice Bakanae in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1070-1070 ◽  
Author(s):  
M. Dal Prà ◽  
S. Tonti ◽  
D. Pancaldi ◽  
P. Nipoti ◽  
I. Alberti
Keyword(s):  
Oryza Sativa L ◽  
Elongation Factor ◽  
The United States ◽  
Gibberella Fujikuroi ◽  
Fusarium Fujikuroi ◽  
Rice Seed ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Annual Survey

Rice (Oryza sativa L.) is cultivated on approximately 230,000 ha in northern Italy. Since 2001, increasing economical losses presumably caused by Fusarium fujikuroi Nirenberg (Gibberella fujikuroi mating population C), an exotic fungus known as the etiological agent of Bakanae disease, have been reported in Italy. The spread of this disease is primarily seedborne. In 2009, during an annual survey of Italian rice seed, 69 samples were tested for the presence of strains belonging to the G. fujikuroi species complex. Four hundred seeds per sample were surface sterilized and then placed in 90-mm Petri dishes containing potato dextrose agar and incubated for 7 days at 21°C. Thirty two putative G. fujikuroi strains were single-spore purified and identified on the basis of their morphological features on Spezieller Nährstoffarmer agar plates with a piece of sterile filter paper. Strains were characterized at species level by morphological observations (1,2) and translation elongation factor 1-α (TEF) gene sequencing. Unexpectedly, 60% of the strains evaluated belonged to the species F. andiyazi Marasas, Rheeder, Lampr., K.A. Zeller & J.F. Leslie. This fungus, first described on sorghum (Sorghum bicolor L.) in Africa and the United States (1), has been reported to be one of the species associated with Bakanae in Asia and Africa (3). Two F. andiyazi strains, (E432 and E439), isolated in the district of Modena were chosen for pathogenicity testing and their TEF gene sequences were deposited in GenBank (Accession Nos. GU827420 and GU827419). A conidial suspension was produced on Mung-bean liquid media and adjusted to a concentration of 1 × 106 CFU/ml. Italian cv. Galileo was used in the test because of its high susceptibility to Bakanae (Ente Nazionale delle Sementi Elette, Verona, Italy, data unpublished). Rice seeds were heat sterilized for 20 min at 60°C, submerged for 30 min in the conidial suspensions, dried, and subjected to a blotter test. Uninoculated, sterilized seeds served as a control. Seeds were incubated for 15 days in a growth chamber (26°C, 80% relative humidity, and 12-h photoperiod). For each strain, the experiment was repeated three times on samples of 25 seedlings. Results were analyzed by analysis of variance and Tukey test. Symptoms consisted of a generic seedling wilt, a root length reduction ranging from 21 to 48%, and the presence of root discoloration. Seed germination was reduced by 9%. Shoot development was not significantly altered. Proof of pathogenicity was obtained through reisolation of F. andiyazi from symptomatic tissues. To our knowledge, this is the first report of F. andiyazi on rice in Europe. References: (1) W. F. O. Marasas et al. Mycologia 93:1203, 2001. (2) H. I. Niremberg and K. O'Donnell. Mycologia 90:434, 1998. (3) E. G. Wulff et al. Environ. Microbiol. 12:649, 2009.

scholarly journals First report of Mycoleptodiscus terrestris causing root rot of soybean in Indiana

Plant Disease ◽  
2020 ◽  
Author(s):  
Christopher Detranaltes ◽  
Guohong Cai
Keyword(s):  
Root Rot ◽  
Biological Control Agent ◽  
Lateral Roots ◽  
Its Region ◽  
Selective Medium ◽  
Internal Transcribed Spacers ◽  
Root Tissue ◽  
Pathogenicity Test ◽  
First Report ◽  
Soybean Seedlings

During the summers in 2019 and 2020, 137 soybean (Glycine max (L.) Merr) seedlings (V1-V3 stage) showing stunting, delayed emergence, and/or crown lesions were collected at Purdue’s Agronomy Center for Research and Education in West Lafayette, Indiana. Four seedlings were stunted with reddish-brown girdled lesions along the hypocotyl and crown, rotted tap and lateral roots, and brown discoloration of the cortex and vascular tissues. Four fungal isolates (AC4, AC58, AC96, and AC127) were recovered by plating surface-sterilized symptomatic root tissue onto water agar plates and incubating on the benchtop until mycelia emerged. The growing hyphal tips were transferred to the semi-selective medium DCPA (Andrews and Pitt 1986). On potato dextrose agar, the fungal colonies developed olivaceous green mycelia which melanized into a mat of black microsclerotia with time and no conidia were observed. On 1.5% water agar plates amended with twice autoclaved soybean leaf and root tissue collected from flowering soybean plants, conidia were formed in sporodochia in darkness at 28 οC within one week. Conidia were 1-2 septate, cylindrical with two setae on either end, and measured 20.8 to 26.4 x 4 to 5.6 μm (average 23.9 x 4.7 μm, n=20). The morphological characters matched with the description of Mycoleptodiscus terrestris (Gerd.) Ostaz (Gerdemann 1953). Species identification was further confirmed by sequencing the internal transcribed spacers (ITS) region of rDNA amplified by ITS1 and ITS4 primers (White et al. 1990) and the translation elongation factor 1 alpha (TEF1-α) gene using 983F and 1567R primers with annealing temperature at 53 ○C (Rehner and Buckley 2005). The sequences were deposited in GenBank under the following accession numbers: ITS: MW002684, MT998441, MW010258, and MW010260; and TEF1-α: MW015941-MW015944. The GenBank BLAST searches revealed 100% identity in the ITS region (accession NR_145373.1) and 99.75% identity in the TEF1-α region (MK495977.1) to M. terrestris. Pathogenicity test was conducted on soybean seedlings (cv. Williams) at V1 growth stage using a root dip assay. Isolate AC58 was grown in a modified cotton seed meal broth (CSMB) to produce microsclerotia as inoculum (Gray 1978; Shearer and Jackson 2006). Microsclerotia concentration was measured using a hemocytometer and adjusted to 1.5 x 104 per ml. Five soybean seedlings each were dipped into inoculum or sterile CSMB for 30 minutes then planted individually in vermiculite-filled Styrofoam cups placed on flooded trays in 16-hr photoperiod light racks at room temperature. Seven days after inoculation, all inoculated plants were visibly stunted with root and crown symptoms identical to field symptoms while all controls were healthy. M. terrestris was successfully re-isolated from inoculated plants, but not from the controls, and identified by morphology and sequencing as above. M. terrestris has been previously reported causing root rot of soybean in Illinois (Gray 1978) and Wisconsin (Smith et al. 1998). To our knowledge, this is the first report of M. terrestris infecting soybean in Indiana. Increased geographic distribution of this pathogen warrants more attention for its control. M. terrestris has been proposed as a biological control agent against multiple aquatic weeds (Verma and Charudattan 1993; Shearer and Jackson 2006). Introduction of this fungus into soybean production regions should be avoided.

scholarly journals First Report of Fusarium commune Causing Damping-off, Seed Rot, and Seedling Root Rot on Soybean (Glycine max) in the United States

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 284-284 ◽  
Author(s):  
M. L. Ellis ◽  
M. M. Díaz Arias ◽  
D. R. Cruz Jimenez ◽  
G. P. Munkvold ◽  
L. F. Leandro
Keyword(s):  
Root Rot ◽  
Petri Dish ◽  
The United States ◽  
Small Subunit ◽  
Ordinal Scale ◽  
Morphological Identification ◽  
Single Spore ◽  
First Report ◽  
Significant Difference ◽  
Seed Rot

During 2007 to 2009, symptomatic and asymptomatic soybean plants were collected from fields in 18 Iowa counties. Fusarium isolates were recovered from surface-sterilized root tissue on peptone PCNB agar (2). Single-spore isolates were transferred to synthetic low nutrient agar (SNA) overlain with pieces (1 × 2 cm) of sterile filter paper, and to potato dextrose agar (PDA), and placed in the dark for 10 to 14 days for morphological identification (4). Twenty-three isolates were identified as Fusarium commune K. Skovg., O'Donnell & Nirenberg, previously in the F. oxysporum species complex (4). Colonies on PDA had white, fluffy, aerial mycelium with magenta to violet pigmentation in the medium. On SNA, macroconidia, chlamydospores, and microconidia on monophialides and polyphialides were consistent with the species description (4). Identification of all 23 isolates was confirmed by DNA sequencing of the translation elongation factor (EF1-α) gene, using ef1 and ef2 primers, and the mitochondrial small subunit (mtSSU), using primers MS1 and MS2 (4) [GenBank accessions for two representative isolates: EF1-α (JX289892 and JX289893), and mtSSU (JX289894 and, JX289895)]. Pathogenicity of two representative isolates of F. commune was tested on soybean (cv. AG2403) in a greenhouse, in water baths set at 18°C, using autoclaved soil mixed with infested sand-cornmeal inoculum (3). The experiment entailed a completely randomized design (CRD) with five replications (single plant/150 ml cone) per treatment, and was conducted three times. Dry root and shoot weights, and root rot severity (visual estimate of percent root rot on the entire root system) were evaluated after 6 weeks. Mean seedling emergence in soil infested with F. commune was 47 and 40% for the two isolates; in contrast, non-inoculated control plants had 100% emergence. There were significant differences in root (P < 0.0001) and shoot (P < 0.0001) weights, and root rot severity (P < 0.0001), between inoculated and non-inoculated plants. Seedlings that emerged were severely stunted and had dark brown lesions. F. commune was reisolated from infected roots of inoculated plants, but not from non-inoculated plants. Pathogenicity of both isolates to soybean (cv. MN1805) was also tested using a petri dish assay, in which eight seeds were placed on a plate with a 4-day-old culture growing on 2% water agar (1). Plates were rated 7 days later for seed germination, seed rot, and lesion development, using an ordinal scale (1). The experiment entailed a CRD with three replicate plates/treatment, and was conducted three times. Germination of inoculated seeds ranged from 37.5 to 75.0%, and germinated seedlings had dark brown lesions on the taproots. There was a significant difference between isolates in the petri dish assay (P = 0.0030); one isolate was less aggressive, but both isolates resulted in significantly more disease than on the non-inoculated control plants, which had 100% germination and no symptoms (P < 0.0001). F. oxysporum is a known soybean pathogen (1), but isolates of F. commune may have been misidentified as F. oxysporum in previous studies. To our knowledge, this is the first report of F. commune as a pathogen on soybean in the U.S.A. References: (1) K. E. Broders et al. Plant Dis. 91:727, 2007. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (3) G. P. Munkvold and J. K. O'Mara. Plant Dis. 86:143, 2002. (4) K. Skovgaard et al. Mycologia. 94:630, 2003.

scholarly journals First Report of Root Rot of Tobacco Caused by Fusarium brachygibbosum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Rui Qiu ◽  
Juan Li ◽  
Wenming Zheng ◽  
Xinhong Su ◽  
Guozhen Xing ◽  
...  
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Lateral Roots ◽  
Development Project ◽  
Specific Substrate ◽  
Single Spore ◽  
Tissue Samples ◽  
First Report ◽  
Agricultural Sciences ◽  
Tobacco Seedlings

Tobacco (Nicotiana tabacum L.) is an important cash crop in China, with an estimated production of 2.2 million tons every year (Berbeć and Matyka, 2020). In June 2020, a root rot disease was observed on tobacco (cv. Zhongyan 100) in four surveyed counties (Mianchi, Lushi, Duguan and Lingbao) in Sanmenxia. Diseased plants exhibited leaf chlorosis and purplish to brown vascular discoloration of stem, taproot and lateral roots. The disease incidence ranged from 15% to 40% in 11 surveyed fields, 36.7 ha in total. Twenty five diseased tissues were surface sterilized in 75% ethanol and placed on potato dextrose agar (PDA) medium. Fifteen single-spore isolates were obtained from 25 diseased tissue samples. All cultures growing on PDA had white colonies with abundant aerial mycelia initially, turning into yellow to orange in the center and produced red pigmentation after seven days of growth. The 7-day-old cultures grown on carnation leaf agar (CLA) produced macroconidia that were curved with 3-5 septa, had wide central cells, slightly pointy apex, and measured 17.0-45.9 μm long×3.0-4.6 μm wide (n=50). The microconidia formed on CLA were slightly curved, ovoid with zero to two septa, measuring 5.4-15.5 μm long×2.0-3.2 μm wide (n=50). Spherical chlamydospores (7.58-13.52 μm; n=50) were terminal or intercalary, single or in chains. Such characteristics were typical of Fuarium brachygibbosum (Tirado-Ramírez et al. 2018). DNA from one representative single-spore isolate (MC1) was extracted, and the translation elongation factor 1-alpha (EF1-α), RNA polymerase I largest subunit (RPB1) and second largest subunit (RPB2) genes were amplified with primers EF1/EF2, F5/G2R and RPB2F/R respectively (O’Donnell et al. 1998, 2010), and sequenced. Sequences were submitted to GenBank under accession numbers MT947796 (EF1-α), MW679536 (RPB1) and MW430664 (RPB2). The consensus sequences showed 99.70%, 99.94% and 100% identity to the sequences of F. brachygibbosum strain NRRL 34033 (accession no. GQ505418.1, HM347172.1 and GQ505482.1, Wang et al 2021). Morphological and molecular results confirmed this species as F. brachygibbosum (Al-Mahmooli, et al., 2013, Rentería -Martínez, et al., 2018). Pathogenicity tests were performed on tobacco seedlings grown on autoclaved tobacco specific substrate (Tobacco specific matrix, Ainong Biotechnology Co. Ltd, China). Healthy six-leaf stage tobacco seedlings (n=30; Zhongyan 100) were inoculated by placing 7-days old wheat seed (15 seeds per plant) infested with MC1 around the root. Thirty seedlings inoculated with sterile wheat seeds served as controls. All the plants were maintained in a growth chamber at 25±0.5℃ and 70% relative humidity. The assay was conducted three times. Typical symptoms of foliage chlorosis and root browning were observed 7-14 days after inoculation. The pathogen was reisolated from the necrotic tissue from all inoculated seedlings and was identified by sequencing partial EF1-α and RPB2 genes. Control plants remained asymptomatic and no pathogen was recovered from the control plants. Fusarium brachygibbosum is known as a pathogen of grains and cash crops in China (Shan, et al., 2017, Xia, et al., 2018). To our knowledge, this is the first report of F. brachygibbosum causing root rot on tobacco. We believe that our results will help to better understand rhizome fungal diseases affecting tobacco production in China. Acknowledgements: Funding was provided by the Science and Technology Project of Henan Provincial Tobacco Company (2020410000270012), Independent Innovation Project of Hennan Academy of Agricultural Sciences (2020ZC18) and Research and Development project of Henan Academy of Agricultural Sciences (2020CY010). References: Al-Mahmooli, I. H., et al. 2013. Plant Dis. 97:687; https://doi.org/10.1094/PDIS-09-12-0828-PDN Berbeć A. K. and Matyka M. 2020. Agric. 10(11), 551; https://doi.org/10.3390/agriculture10110551 O’Donnell, K., et al. 1998. P. Natl. Acad. Sci. USA. 95(5):2044-2049; https://doi.org/10.1073/pnas.95.5.2044 O’Donnell, K., et al. 2010. J. Clin. Microbiol. 48(10)3708-3718; https://doi.org/10.1128/JCM.00989-10 Rentería -Martínez M.E., et al. 2018. Mex. J. of Phytopathol. 36(2):1-23; https://doi.org/10.18781/R.MEX.FIT.1710-1 Shan, L. Y., et al. 2017. Plant Dis. 101:837; https://doi.org/10.1094/PDIS-10-16-1465-PDN Tirado-Ramírez, M. A., et al. 2018. Plant Dis. 103; https://doi.org/10.1094/PDIS-04-18-0710-PDN Wang, S., et al. 2021. Plant Dis. 2021 Jan 6. doi: 10.1094/PDIS-05-20-0941-PDN. Epub ahead of print. PMID: 33406862. Xia, B., et al. 2018. Plant Dis. 102(11):2372; https://doi.org/10.1094/PDIS-12-17-1939-PDN The author(s) declare no conflict of interest.

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 Colletotrichum boninense Causing Anthracnose on Pepper in China

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 138-138 ◽  
Author(s):  
Y. Z. Diao ◽  
J. R. Fan ◽  
Z. W. Wang ◽  
X. L. Liu
Keyword(s):  
Internal Transcribed Spacer ◽  
Severe Disease ◽  
Causal Agent ◽  
Its Sequences ◽  
Universal Primers ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Species Specific

Anthracnose, caused by Colletotrichum spp., is a severe disease and results in large losses in pepper (Capsicum frutescens) production in China (4). Colletotrichum boninense is one of the Colletotrichum species in pepper in China. In August 2011, anthracnose symptoms (circular, sunken lesions with orange to black spore masses) were observed on pepper fruits in De-Yang, Sichuan Province, China. Three single-spore isolates (SC-6-1, SC-6-2, SC-6-3) were obtained from the infected fruits. A 5-mm diameter plug was transferred to potato dextrose agar (PDA); the isolates formed colonies with white margins and circular, dull orange centers. The conidia were cylindrical, obtuse at both ends, and 10.5 to 12.6 × 4.1 to 5.0 μm. The colonies grew rapidly at 25 to 28°C, and the average colony diameter was 51 to 52 mm after 5 days on PDA at 25°C. Based upon these characters, the causal agent was identified as C. boninense. To confirm the identity of the isolates, the internal transcribed spacer (ITS) regions were amplified with the ITS1/ITS4 universal primers (1). The internal transcribed spacer (ITS) sequences (Accession No. JQ926743) of the causal fungus shared 99 to 100% homology with ITS sequences of C. boninense in GenBank (Accession Nos. FN566865 and EU822801). The identity of the causal agent as C. boninense was also confirmed by species-specific primers (Col1/ITS4) (2). In a pathogenicity test, five detached ripe pepper fruits were inoculated with 1 μl of a conidial suspension (106 conidia/mL) or five fruits with 1 μl of sterile water were kept as control. After 7 days in a moist chamber at 25°C, typical anthracnose symptoms had developed on the five inoculated fruits but not on control fruits. C. boninense was reisolated from the lesions, and which was confirmed by morphology and molecular methods as before. There have reports of C. boninense infecting many species of plants, including pepper (3). To our knowledge, this is the first report of C. boninense causing anthracnose on pepper in China. References: (1) A. K. Lucia et al. Phytopathology 93:581, 2002. (2) S. A. Pileggi et al. Can. J. Microbiol. 55:1081, 2009. (3) H. J. Tozze et al. Plant Dis. 93:106, 2009. (4) M. L. Zhang. J. Anhui Agri. Sci. 2:21, 2000.

scholarly journals First Report of Colletotrichum siamense Causing Anthracnose of Monstera deliciosa in Zhanjiang, China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Yu Han Zhou
Keyword(s):  
Disease Incidence ◽  
Morphological Characteristics ◽  
Pathogenicity Test ◽  
Sterile Water ◽  
Single Spore ◽  
First Report ◽  
Rdna Its ◽  
Colletotrichum Siamense ◽  
Monstera Deliciosa ◽  
Pure Cultures

Monstera deliciosa Liebm is an ornamental foliage plant (Zhen et al. 2020De Lojo and De Benedetto 2014). In July of 2019, anthracnose lesions were observed on leaves of M. deliciosa cv. Duokong with 20% disease incidence of 100 plants at Guangdong Ocean University campus (21.17N,110.18E), Guangdong Province, China. Initially affected leaves showed chlorotic spots, which coalesced into larger irregular or circular lesions. The centers of spots were gray with a brown border surrounded by a yellow halo (Supplementary figure 1). Twenty diseased leaves were collected for pathogen isolation. Margins of diseased tissue was cut into 2 × 2 mm pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite (NaOCl) for 60 s, rinsed three times with sterile water before isolation. Potato dextrose agar (PDA) was used to culture pathogens at 28℃ in dark. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. Fourteen isolates were obtained from 20 leaves. Three single-spore isolates (PSC-1, PSC-2, and PSC-3) were obtained ,obtained, which were identical in morphology and molecular analysis (ITS). Therefore, the representative isolate PSC-1 was used for further study. The culture of isolate PSC-1 on PDA was initially white and later became cottony, light gray in 4 days, at 28 °C. Conidia were single celled, hyaline, cylindrical, clavate, and measured 13.2 to 18.3 µm × 3.3 to 6.5 µm (n = 30). Appressoria were elliptical or subglobose, dark brown, and ranged from 6.3 to 9.5 µm × 5.7 to 6.5 µm (n = 30). Morphological characteristics of isolate PSC-1 were consistent with the description of Colletotrichum siamense (Prihastuti et al. 2009; Sharma et al. 2013). DNA of the isolate PSC-1 was extracted for PCR sequencing using primers for the rDNA ITS (ITS1/ITS4), GAPDH (GDF1/GDR1), ACT (ACT-512F/ACT-783R), CAL (CL1C/CL2C), and TUB2 (βT2a/βT2b) (Weir et al. 2012). Analysis of the ITS (accession no. MN243535), GAPDH (MN243538), ACT (MN512640), CAL (MT163731), and TUB2 (MN512643) sequences revealed a 97-100% identity with the corresponding ITS (JX010161), GAPDH (JX010002), ACT (FJ907423), CAL (JX009714) and TUB2 (KP703502) sequences of C. siamense in GenBank. A phylogenetic tree was generated based on the concatenated sequences of ITS, GAPDH, ACT, CAL, and TUB2 which clustered the isolate PSC-1 with C. siamense the type strain ICMP 18578 (Supplementary figure 2). Based on morphological characteristics and phylogenetic analysis, the isolate PSC-1 associated with anthracnose of M. deliciosa was identified as C. siamense. Pathogenicity test was performed in a greenhouse at 24 to 30oC with 80% relative humidity. Ten healthy plants of cv. Duokong (3-month-old) were grown in pots with one plant in each pot. Five plants were inoculated by spraying a spore suspension (105 spores ml-1) of the isolate PSC-1 onto leaves until runoff, and five plants were sprayed with sterile water as controls. The test was conducted three times. Anthracnose lesions as earlier were observed on the leaves after two weeks, whereas control plants remained symptomless. The pathogen re-isolated from all inoculated leaves was identical to the isolate PSC-1 by morphology and ITS analysis, but not from control plants. C. gloeosporioides has been reported to cause anthracnose of M. deliciosa (Katakam, et al. 2017). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa in ChinaC. siamense causes anthracnose on a variety of plant hosts, but not including M. deliciosa (Yanan, et al. 2019). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa, which provides a basis for focusing on the management of the disease in future.

scholarly journals First Report of Root Rot of Soybeans Caused by Corynespora cassiicola in Wisconsin

Plant Disease ◽  
1999 ◽  
Vol 83 (7) ◽  
pp. 696-696 ◽  
Author(s):  
S. J. Raffel ◽  
E. R. Kazmar ◽  
R. Winberg ◽  
E. S. Oplinger ◽  
J. Handelsman ◽  
...  
Keyword(s):  
Root Rot ◽  
Growth Stage ◽  
Lateral Roots ◽  
Seedling Emergence ◽  
Fluorescent Light ◽  
Corynespora Cassiicola ◽  
First Report ◽  
Seedling Roots ◽  
Symptomatic Tissue ◽  
Soybean Plants

Corynespora cassiicola (Berk. & M. A. Curtis) C. T. Wei was isolated from diseased soybean plants (Glycine max) collected in two fields near Racine and Arlington, WI. Plants sampled at seedling emergence (VC), late vegetative (V5), and mid-reproductive (R5) stages exhibited reddish to dark brown longitudinal lesions on the exterior of the tap root extending vertically on the hypocotyl to the soil line, and extensive necrosis of lateral roots. Sample size at each growth stage was 144 plants per site. Roots were surface sterilized in 0.5% sodium hypochlorite for 2 min and sections of symptomatic tissue placed on water agar (12 g/liter) containing 100 μg of streptomycin per ml. Sporulation occurred on lesions and on mycelium that had grown out from the plant tissue onto the water agar following a 2-week incubation at 24°C under fluorescent light (280 μmol s-1 m-2). Incidence of isolation of C. cassiicola at both sites was 40% of plants sampled at growth stage VC, 67% at V5, and 78% at R5. Conidia characteristic of C. cassiicola were particularly abundant on the surface of necrotic lateral root tissue. Elongated conidia produced on water agar were 151 ± 5 μm × 15 ± 0.5 μm with an average of 13 ± 0.4 cells separated by hyaline pseudosepta (1). To confirm pathogenicity, a 1-cm lateral slice into each of four 5-day-old soybean seedling roots was made and a plug of agar taken from the margin of a colony of C. cassiicola grown on potato dextrose agar was placed in each wound and incubated for 14 days at 24°C in a growth chamber. Symptoms similar to those of diseased field plants were observed and C. cassiicola was reisolated from all plants inoculated with C. cassiicola; all controls treated with agar alone had no symptoms and C. cassiicola was recovered from none of the noninoculated controls. This is the first report of root rot caused by C. cassiicola on soybean in Wisconsin. Reference: (1) W. L. Seaman and R. A. Shoemaker. Can. J. Bot. 43:1461, 1965.

scholarly journals First Report of Pestalotiopsis clavispora Causing Leaf Spot of Carya illinoensis in Brazil

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1826-1826 ◽  
Author(s):  
M. Lazarotto ◽  
M. F. B. Muniz ◽  
T. Poletto ◽  
C. B. Dutra ◽  
E. Blume ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Rio Grande ◽  
Morphological Characterization ◽  
The State ◽  
Morphological Identification ◽  
Pathogenicity Test ◽  
Rio Grande Do Sul ◽  
Carya Illinoensis ◽  
Potato Dextrose Agar Medium ◽  
First Report

Conspicuous leaf spots in combination with fruit spots were observed for the first time in April and May 2010 on a 30-ha pecan [Carya illinoensis (Wangenh.) K. Koch] orchard in the state of Rio Grande do Sul, Brazil. Initially, tiny grey spots were observed on leaves and, over time, the spots expanded to become gray to light brown circles surrounded by a dark brown border, followed by leaves falling. Eventually, fruits were also attacked, with typical symptoms beginning with tiny water soaked spots which then became necrotic. The disease was also observed in pecan nursery and field seedlings. Isolation of the pathogen from symptomatic leaves and morphological identification by conidia characters (number of cells, color, hyaline terminal cells, number of appendages) revealed Pestalotiopsis sp. (2) as the causal agent of the disease. Conidia constituted of transverse septa with four dark intermediate sections and two hyaline terminal sections. One of the terminal sections presented two or three apical appendages. Conidia averaged 6.88 μm wide × 31.00 μm long, not considering the apical appendages. Primers ITS 1 and ITS 4 were used to amplify the internal transcribes spacer ITS 1-5.8S-ITS 2 region. Nucleotide sequences were 99% similar to Pestalotiopsis clavispora (G.F. Atk.) Steyaert. Conidia produced on potato dextrose agar medium were used to inoculate 8 plants with a spore suspension of 2.0 × 106 conidia/ml. Eight additional plants were used as control (non-inoculated). The inoculation was performed by spraying the suspension onto the leaves of Pecan seedlings and the plants were incubated for 72 h in a humid chamber (1). All inoculated plants showed symptoms 25 days after inoculation and the fungus was reisolated. The pathogenicity test was repeated once. Ten more isolates collected from four different cities in the same state were identified as Pestalotiopsis spp. by morphological characterization and pathogenicity was confirmed. Because this disease causes losses on production of nuts indirectly by reducing photosynthetically active area when the pathogen attacks leaves and directly when attacking fruits, it may restrict the production where the pathogen occurs. On some orchards in the state of Rio Grande do Sul, the attack rate reached 80% of the plants. P. clavispora has been reported causing stem end-rot of avocado in Chile (3), but this note constitutes the first report, to our knowledge, of P. clavispora causing leaf spot on C. illinoensis in Brazil. References: (1) A. C. Alfenas and F. A. Ferreira. Page 117 in: Métodos em Fitopatologia. A. C Alfenas and R. G. Mafia (eds.). Editora: UFV, Viçosa, 2007. (2) S. S. N. Maharachchikumbura et al. Fungal Diversity 50:167, 2011. (3) A. L. Valencia et al. Plant Dis. 95:492, 2011.

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