First report of Fuasium wilt caused by Fusarium kyushuense in China

Gerbera daisy, Gerbera jamesonii H. Bolus ex. Hooker, is an important flower grown globally. In September 2020, gerbera seedlings in a greenhouse farm in the region of Fujian, China, developed symptoms of severe wilting and stunting. The main stem exhibited reddish to light brown vascular discoloration. Approximately 30% of the 60,000 plants showed symptoms. To isolate the causal agent, necrotic tissue pieces (3×3 mm) from the symptomatic stem were surface-disinfected with 1% NaClO for 1 min and washed three times with sterile water. The disinfected pieces were dried and placed on potato dextrose agar (PDA) at 25°C in the darkness for 4 days inside a dark chamber. Reddish-white and floccose mycelia developed on PDA after 3 days incubation. Ten single-spored isolates were identified as Fusarium kyushuense based on morphological features (Aoki & O'Donnell, 1998). Hyaline and straight or slightly curved macroconodia were observed with 3 to 5 septate, 24.5 - 46.6 × 3.6 - 5.7 μm (n = 100). Microconidia were ellipsoidal to clavate, 0 to 1 septate, and 6.3 to 19.5 × 3.2 to 5.3 μm (n = 100). No chlamydospores were observed. In order to validate this result, partial RNA polymerase second largest subunit (RPB2) combined with translation elongation factor (EF-1α) gene regions were amplified and sequenced from three isolates with primers 5f2/11ar (Liu et al., 1999) and primers EF1/EF2 (Geiser et al. 2004), respectively. Fusarium MLST analysis showed that the RPB2 (Genbank accession No. MZ130468, No. MZ130469, No. MZ130470) matched 99.72% (MH582170) to F. kyushuense, and the EF-1α (MZ130471, MZ130472, MZ130473) matched 99.84% (MH582297) to F. kyushuense in the Fusarium MLST. Besides, a phylogenetic analysis was conducted using the neighbor-joining algorithm based on the RPB2 and EF-1α gene sequences. The isolates clustered with F. kyushuense. To assess pathogenicity, the three molecularly identified isolates were used. The isolates were grown on carboxylmethyl cellulose (CMC) medium (carboxymethyl-cellulose (Sigma C-4888) 15.0 gram, NH4NO3 1.0 gram, KH2PO4 monobasic 1.0 gram, MgSO4·7H2O 0.5 gram, yeast extract 1.0 gram, distilled water filled to 1.0 liter) for sporulation. The roots of 12 healthy 30-day-old gerbera plants were inoculated by treating them with 10 mL of conidia suspension (1×106 conidial/mL). A group of 12 seedlings of the same age was treated with sterile water to serve as the control. Plants were grown in a glasshouse at 23 °C, relative humidity >70%, and 16 h light per day. Typical symptoms of wilt and discoloration of the vascular system in roots and stems developed within 10 days. Uninoculated plants remained healthy. Isolates were consistently re-isolated from the symptomatic stem and the recovered isolates were identified as F. kyushuense by amplifing the EF-1α gene. The assays were conducted twice. F. kyushuense has been reported to cause wilt and rot of tobacco (Wang et al., 2013), maize ears (Wang et al., 2014) and rice (Zhao et al., 2007) in China. To the best of our knowledge, this is the first report of F. kyushuense causing stem and root wilt on G. jamesonii. The disease must be considered in existing management practices.

Download Full-text

First Report of Fusarium stem and root rot of Gerbera jamesonii caused by Fusarium incarnatum in China

Plant Disease ◽

10.1094/pdis-02-21-0440-pdn ◽

2021 ◽

Author(s):

Shuning Chen ◽

Wei Sun ◽

Huizhu Yuan ◽

Xiaojing Yan

Keyword(s):

Root Rot ◽

Vascular System ◽

Elongation Factor ◽

Morphological Observation ◽

Conidial Suspension ◽

Gerbera Jamesonii ◽

Gene Sequences ◽

Plastic Container ◽

First Report ◽

Brown Discoloration

Gerbera (Gerbera jamesonii Bolus) is an important cut flower grown globally. In 2020, gerbera plants (Redaicaoyuan, Baimawangzi, and Hongditan cultivars) with roots, crowns, and stems rot were found in a greenhouse in Nanping, Fujian, China. Approximately 30% of the 60,000 plants showed symptoms. Diseased plants were stunted with chlorotic leaves. The leaves and flower heads were wilted and withered. Brown discoloration with red to black streaks occurred in the vascular system of the crown and stem. The stem pieces (3×3 mm) showing the symptom were surface-disinfected with 1% NaClO for 1 min and washed three times with sterilized water. The stem pieces were then dried and placed on potato dextrose agar (PDA) at 25℃ inside a dark chamber. Ten single-spored isolates were identified as Fusarium incarnatum based on morphological features. White to light brown mycelia were observed among the isolates on PDA medium. Falculate, multicelluar, straight to slightly curved macroconidia produced in monophialide sporodochia without distinctive foot shaped basal cell; and chlamydospores produced in some isolates (Leslie and Summerell). The size of macroconidia was 36.4 ± 5.20 × 4.6 ± 1.3 μm (n = 100) with 3 to 5 septates. Microconidia were mostly 0 to 1 septate measured 14.6 ± 1.9 × 2.6 ± 0.5 μm (n=100). Based on the morphological observation, isolates were further identified by molecular method. The ITS1/4 region combined with partial gene fragments of translation elongation factor (EF-1α, primer EF1/EF2, Geiser et al.) and calmodulin (CAM, primer CL1/CL2A, O’Donnell.) from the isolates were amplified and sequenced. All of the three tested isolates showed identical gene sequences. Sequences amplified from one represented isolate FIN-1 were submitted to Genbank. BLAST searches revealed that ITS1/4 (MW527088), EF-1α (MW556488), and CAM (MW556487) had 99.22%, 99.53%, 99.42% identity compared to F. incarnatum (MN480497, MN233577, and LN901596, respectively) in GenBank. FUSARIUM-ID (Geiser et al. 2004) analysis also showed 99 to 100% similarity with sequences of the F. incarnatum-equiseti species complex (FIESC) (FD_01636 for CAM, FD_01643 for EF-1α). The phylogenetic analysis was conducted using neighbor-joining algorithm based on the ITS, EF-1α, and CAM gene sequences. The isolate was clustered with F. incarnatum clade. Then, the pathogenicity of the fungus was confirmed by performing Koch’s postulates. Pure single-spored cultures were grown on carboxymethyl-cellulose (CMC) medium for sporulation. G. jamesonii plants used for pathogenicity tests were grown on sterilized potting soil in a plastic container to the ten-leaf stage prior to inoculation. Spores harvested from the CMC medium were adjusted to a concentration of 1×105 conidial/ml. Twelve healthy rooted gerbera seedlings were inoculated by drenching 10 ml of the conidial suspension onto roots. Twelve gerbera seedlings treated with 10 ml sterile water served as control treatments. Plants were grown in the glasshouse at temperatures of 23°C, relative humidity >70%, and 16 h light per day. After 10 days, blackening stems and withered leaf edges began to appear on inoculated seedlings, whereas control seedlings remained healthy. F. incarnatum was consistently re-isolated from the symptomatic stems, whereas no isolates were obtained from the control seedlings. The assay was conducted twice. To the best of our knowledge, this is the first report of F. incarnatum causing stem and root rot on G. jamesonii.

Download Full-text

First report of Fusarium solani causing stem rot of Dracaena in Iran

Journal of Plant Protection Research ◽

10.1515/jppr-2016-0013 ◽

2016 ◽

Vol 56 (1) ◽

pp. 100-103 ◽

Cited By ~ 1

Author(s):

Mostafa Abedi-Tizaki ◽

Doustmorad Zafari ◽

Jamal Sadeghi

Keyword(s):

Fusarium Solani ◽

Elongation Factor ◽

Stem Rot ◽

Pathogenicity Test ◽

Translation Elongation Factor ◽

Translation Elongation ◽

First Report ◽

Brown Discoloration ◽

Elongation Factor 1 Alpha ◽

Elongation Factor 1

Abstract In July 2013, symptoms of stem rot were observed in the Dracaena sanderiana cuttings in greenhouses of Mahallat County, Markazi Province, Iran. The symptoms first appeared as severe wilting. Later, leaves became brown and necrotic. Symptoms on the cuttings were observed as rotted areas on the middle of the stems. The cortical tissues of the plants showed a distinct brown discoloration. Eventually, the infected plants died. The pathogen was isolated from Dracaena stems and identified as F. solani by a fragment of the translation elongation factor 1-alpha (EF-1α) gene. Fusarium solani was confirmed by a pathogenicity test, and the causal agent was re-isolated from infected D. sanderiana plants. To the best of our knowledge, this is the first report of stem rot caused by F. solani on the cuttings of D. sanderiana.

Download Full-text

First Report of Fusarium Maize Ear Rot Caused by Fusarium meridionale in China

Plant Disease ◽

10.1094/pdis-01-14-0108-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1156-1156 ◽

Cited By ~ 4

Author(s):

H. Zhang ◽

W. Luo ◽

Y. Pan ◽

J. Xu ◽

J. S. Xu ◽

...

Keyword(s):

Fusarium Species ◽

Elongation Factor ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Fusarium Ear Rot ◽

Ear Rot ◽

Translation Elongation Factor ◽

Translation Elongation ◽

First Report

Fusarium is an important genus of fungal pathogens that are responsible for devastating diseases, such as Fusarium ear rot on maize, which may result in yield losses and/or mycotoxin contamination. In September 2013, a survey to determine population composition of Fusarium species on maize was conducted at 22 fields in 18 counties in Gansu Province. Maize ears with clear symptoms (with a white to pink- or salmon-colored mold at the ear tip) were collected. Symptomatic seeds were surface-sterilized with 70% ethanol and 10% sodium hypochlorite and rinsed three times with sterile water to eliminate hypochlorite residues. After drying on sterile filter paper, the seeds were placed on potato dextrose agar (PDA) and incubated at 25°C in the dark for 3 days. Mycelium that was characteristic of Fusarium spp. (2) was purified by transferring single spores to fresh PDA. Fusarium species were identified by morphological characteristics (2), multilocus genotyping assay (MLGT) (3), and sequence analysis of the translation elongation factor-1α (TEF) gene. Several Fusarium species were identified and Fusarium verticillioides and F. proliferatum were the predominant species. Based on MLGT, two strains from Chenghong County were identified as F. meridionale with NIV chemotype, a species in F. graminearum species complex (FGSC). Morphological characteristics were also identical to FGSC. Colonies grew rapidly on PDA and produce relatively large amounts of dense mycelia and red pigments. Slender, thick-walled, and moderately curved or straight macroconidia were observed with 5- to 6-septate. Furthermore, conidia on SNA also showed typical characteristics of F. meridionale, as the dorsal and ventral lines were often parallel and gradually curved. Sequences comparison of the partial translation elongation factor (TEF-1α, 644 bp) gene (1) was used to validate these observations. BLASTn analysis with the FUSARIUM-ID database revealed 100% sequence identity to F. meridionale (GenBank Accession No. KJ137017). Thus, both morphological and molecular criteria supported identification of the strains as F. meridionale. A pathogenicity test was performed on Zhengdan958, the maize variety with the largest planted acreage in China. Four days after silk emergence, 2 ml conidial suspension (105 macroconidia/ml) of each isolate were injected into each of 10 maize ears through silk channel. Control plants were inoculated with sterile distilled water. Typical FER symptoms (reddish-white mold) was observed on inoculated ears and no symptoms were observed on water controls. Koch's postulates were fulfilled by re-isolating the same fungus from the infected seeds. F. meridionale was one of the pathogens causing Fusarium head blight on wheat and barley in China and produced nivalenol (4,5) and it also has been isolated from maize in Korea and Nepal. To our knowledge, this is the first report of F. meridionale causing Fusarium ear rot on maize in China. Further studies on biological characteristics such as temperature sensibility and fungicide resistance are needed to gain a better understanding of this new pathogen. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) T. J. Ward et al. Fungal Genet. Biol. 45:473, 2008. (4) L. Yang et al. Phytopathology 98:719, 2008. (5) H. Zhang et al. Plos one 7:e31722, 2012.

Download Full-text

First Report of Botryosphaeria dothidea Causing Gray Mold on Tartary Buckwheat in Southwest China

Plant Disease ◽

10.1094/pdis-07-21-1403-pdn ◽

2021 ◽

Author(s):

Yong Tang ◽

Jun Yan ◽

Yan Peng ◽

Wenfeng Weng ◽

Xin Yao ◽

...

Keyword(s):

Southwest China ◽

Elongation Factor ◽

Morphological Characteristics ◽

Gray Mold ◽

Tartary Buckwheat ◽

Diseased Plant ◽

Sterile Water ◽

Translation Elongation Factor ◽

Translation Elongation ◽

Elongation Factor 1

Tartary buckwheat (Fagopyrum tataricum, Polygonaceae) is an annual plant originating in Southwest China. It has a short growth cycle, barren soil tolerance, and strong stress resistance (Zhang et al. 2021). Because of its high content of proteins, starch, trace elements, phenols, and dietary fiber, Tartary buckwheat is beneficial to the human body and hence has received widespread attention (Joshi et al. 2019; Dc ja, B, et al. 2020). In the period from September to November 2020, a diseased plant infected with gray mold was found among M2 generation plants treated using ethyl methanesulfonate (EMS) in a location with potted Tartary buckwheat plants in Huaxi District, Guiyang City, Guizhou Province, China. The diseased plant started to show symptoms during the initial flowering stage; water-soaked spots appeared at first, that the spots increased in size and turned into light brown patches, with the leaf edges scorched brown. In severe cases, the leaves turned yellow, the diseased spots became dry, and finally the leaves necrotic (Figure 1A). Among the leaves that showed disease symptoms, severely susceptible leaves were selected; a piece of tissue (2×2 mm) was removed at the junction of the diseased and healthy tissues. The tissue was then soaked in 75% ethanol for 2 to 3 s, transferred to 1% sodium hypochlorite solution and soaked for 3 min, rinsed three times with sterile water, and placed on sterilized filter paper to dry. Sterile tweezers were used to transfer the tissue blocks to Potato Dextrose Agar medium (Bio-Rad Ltd. Com, USA) containing a Streptomyces–Penicillium mixture (100 μg/mL), and they were incubated on this medium for 7 to 10 days at 25°C and 70% humidity under 16 h light and 8 h dark conditions. The colonies were white at the early stages, with developed aerial hyphae; subsequently, they gradually turned gray-green (Figure 1B). In the later stages, the back of the colony was black and piles of conidia could be seen (Figure 1C). The conidia are scattered, which were colorless and transparent, fusiform or fusiform, with a size of 8.02–11.13 μm×2.06–3.22 μm (average=9.51 μm×2.69 μm, n=50) (Figure 1D). Based on their morphological characteristics, These cultural and morphological characteristics were consistent with the descriptions of as B. dothidea (Fan et al. 2021). The ITS1/ITS4 (Mills et al. 1992), Bt-2a/Bt-2b primers (Glass and Donaldson 1995), and EF1-728F/EF1-986R (Slippers et al. 2004) were amplified and sequenced to analyze the ITS region, β-tubulin genes translation elongation factor 1-α (TEF1-α), and translation elongation factor 1-α (TEF1-α), respectively. According to BLAST search in GenBank, the sequences of ITS (MZ326853), TUB2 (MZ399162) and TEF1-α (MZ399163) had 99.40%, 100% and 100% similarity to sequences NR111146.1, AY236927.1, and AY236898.1 of B. dothidea ex-type strain CMW8000, respectively. The three nucleotide sequences were concatenated together, and MEGA-X (with the neighbor-joining method) with 1,000 bootstraps was used to construct a phylogenetic tree. The results showed that our isolate was closely related to B. dothidea (Figure 2). Healthy Tartary buckwheat from the M2 generation was used for the pathogenicity test. Disinfect with 75% alcohol and 1×105 mL-1 of spore suspension was sprayed on the leaves. Each treatment included three plants, and it was repeated three times with sterile water as control. The treatments were kept in a houseat25°C for 24 h, then transferred it to the natural environment of 22℃ to 28℃,and sterile water was sprayed every morning and evening to keep the leaves moist. After 10 days, the symptoms seen in the field appeared on the treated plants (Figure 1E), but the control plants did not show any symptoms (Figure 1F). The diseased parts of the leaves were isolated and cultured again, and the isolates were consistent with the original inoculum. Thus, the study conformed to Koch’s postulates. B. dothidea is a fungus with no host preference in the genus Botryosphaeria (Botryosphaeriaceae, Botryosphaeriales). It can cause canker, leaf spots, trunk diseases, fruit rot and die-back of many important wood plants all over the world (Marsberg et al.2017). Recently, it was reported that B. dothidea caused soybean canker in China (Chen et al.2021), but there have been no reports of B. dothidea causing Tartary buckwheat gray mold. To the best of our knowledge, this is the first report of B. dothidea causing gray mold on Tartary buckwheat. This finding will provide a basis for the prevention and treatment of Tartary buckwheat gray mold.

Download Full-text