scholarly journals First Report of Ziziphus jujuba Wilt Caused by Fusarium oxysporum in China

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 586-586 ◽  
Author(s):  
F. Gao ◽  
Z. Xiang ◽  
Y. L. Zhang
Keyword(s):  
Fusarium Oxysporum ◽  
Vascular Tissue ◽  
Herbal Remedy ◽  
Wilt Disease ◽  
Healthy Plant ◽  
Natural Occurrence ◽  
Chinese Jujube ◽  
First Report ◽  
Stunted Growth ◽  
Ziziphus Jujuba

Chinese jujube (Ziziphus jujuba Mill.) is widely planted in Xinjiang Province of China for fruit and as an effective herbal remedy. Wilt symptoms were observed on field-grown Z. jujuba during the spring and fall of 2010 and 2011. Diseased plants exhibited symptoms including wilted leaves, stunted growth, extensive brown discoloration on stems, and eventually death. In severe cases, approximately 60% of the plants in the field died. Repeated isolations from discolored stem vascular tissues were made on potato dextrose agar (PDA) after disinfestation in 1% HgCl2 for 1 min and dipping in 70% ethanol for 10 s. Petri dishes were then incubated in complete darkness at 26°C for 7 days. All colonies on PDA had pale pink-salmon-colored mycelia. Macroconidia were mostly three to five septate, slightly curved, and ranged from 2.9 to 11.9 × 29.5 to 45 μm. Microconidia were abundant, generally single celled, oval to kidney shaped, and ranged from 2.5 to 5 × 7.5 to 11.5 μm in false heads on short monophialides. Chlamydospores were single or in pairs and profusely distributed. These characteristics were similar to those of Fusarium oxysporum (2). The internal transcribed spacer (ITS) rDNA region was amplified with primers ITS1/ITS4 and sequenced (1). BLASTn analysis of the sequence (GenBank Accession No. JQ039331) showed a 99% homology with several isolates of F. oxysporum in the GenBank database. Pathogenicity tests were conducted on healthy, 2-month-old seedlings and 1-month-old rooted cuttings of Z. jujuba under greenhouse conditions. Plants were inoculated with sterilized mixtures of wheat and barley seeds (1:1) that were incubated in a F. oxysporum isolate spore suspension (1 × 107 conidia/ml) at 25°C for 7 to 10 days. The seeds (3 g per plant) were placed around the collar of each healthy plant under the soil surface and incubated at 25 to 28°C in a greenhouse. Control plants were sown in sterile soil without inoculated seeds. In 3 weeks, inoculated plants developed leaf wilt and chlorosis, stunted growth, brown discolored vascular tissue on stems, and finally died, which is similar to that observed in the field. F. oxysporum was reisolated from the stems of diseased plants, confirming Koch's postulates. Control seedlings were symptom free. F. oxysporum has been known to cause wilt disease on cotton and tomato in Xinjiang Province (3). However, to our knowledge, this is the first report of a natural occurrence of Chinese jujube wilt disease on commercial fields caused by F. oxysporum in China. References: (1) G. M. Arruda et al. Plant Pathol. 54:53, 2005. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) F. X. Tian et al. Acta Phytopathol. Sin. 11:27, 1981.

scholarly journals First Report of Fusarium Wilt of Cilantro Caused by Fusarium oxysporum in California

Plant Disease ◽  
2005 ◽  
Vol 89 (10) ◽  
pp. 1130-1130 ◽  
Author(s):  
S. T. Koike ◽  
T. R. Gordon
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Vascular Tissue ◽  
Fusarium Species ◽  
Wilt Disease ◽  
Apium Graveolens ◽  
Peat Moss ◽  
State University ◽  
First Report ◽  
Vascular Discoloration

Cilantro, or coriander (Coriandrum sativum), is a leafy vegetable in the Apiaceae and is grown commercially in California primarily for use as a fresh herb. During 2002 and 2003 in coastal California (Santa Barbara County), commercial cilantro fields showed symptoms of a wilt disease. Affected plants grew poorly and were stunted. Lower foliage turned yellow with reddish tinges, and plants wilted during warmer times of the day. The main stem, crown, and taproot exhibited vascular discoloration that was reddish to light brown. As disease progressed, plants eventually died. For both years, the disease distribution was limited to isolated small patches (each patch measuring less than 1 m2 in area). A fungus was consistently isolated from symptomatic vascular tissue in crowns and taproots. On the basis of colony and conidial morphology, the isolates were identified as Fusarium oxysporum (2). No other fungi or bacteria were recovered from these plants. To test pathogenicity, suspensions containing 1 × 106 conidia/ml were prepared for five isolates. The roots of 30-day-old cilantro plants of four cultivars (30 plants each of Festival, Leisure, Santo, and LSO 14) were clipped and then soaked in the suspensions for 20 min. The roots of 30 plants of each cultivar were soaked in water as a control. Plants were repotted into new redwood bark + peat moss rooting medium and maintained in a greenhouse setting at 24 to 26°C. After 1 month, 95% or more of the inoculated plants showed yellowing and vascular discoloration symptoms similar to those seen in the field. F. oxysporum was reisolated from all inoculated plants. The four cilantro cultivars did not show differences in disease severity. Control plants showed no symptoms, and the fungus was not recovered from these plants. The experiment was repeated and the results were the same. Experiments also were conducted to determine if cilantro isolates could cause disease in celery (Apium graveolens var. dulce). Celery transplants and cilantro seedlings were prepared and inoculated as described above. However, after 2 months, celery plants did not show any disease symptoms, while the cilantro developed wilt symptoms and eventually died. A Fusarium wilt disease has been reported on coriander in Argentina and India where the pathogen was named F. oxysporum f. sp. coriandrii (1,3). To our knowledge, this is the first report of Fusarium wilt of cilantro in California. References: (1) M. Madia et al. Fitopatologia 34:155, 1999. (2) P. E. Nelson et al. Fusarium species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, 1983. (3) U. S. Srivastava. Indian Phytopathol. 22:406, 1969.

scholarly journals First Report of Race 2 of Fusarium oxysporum f. sp. lycopersici, the Causal Agent of Fusarium Wilt on Tomato in Taiwan

Plant Disease ◽  
2006 ◽  
Vol 90 (1) ◽  
pp. 111-111 ◽  
Author(s):  
Z. M. Sheu ◽  
T. C. Wang
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Banding Pattern ◽  
Vascular Tissue ◽  
First Report ◽  
Intergenic Spacer Region ◽  
Stunted Growth ◽  
Vascular Discoloration ◽  
Race 1 ◽  
Race 2

Fusarium wilt caused by Fusarium oxysporum Schlechtend.:Fr. f. sp. lycopersici (Sacc.) W.C. Snyder & N.H. Hans. is a destructive disease of tomato crops worldwide. The use of resistant varieties is the best strategy for disease control. There are three reported races of the pathogen. Recent surveys indicated that many of the commercial cultivars with resistance to F. oxysporum f. sp. lycopersici race 1 planted in Taiwan displayed Fusarium wilt symptoms. Yellowing on the older leaves was observed on one side of the stems close to fruit maturity. The yellowing gradually affected most of the foliage and was accompanied by wilting of the plants. The vascular tissue was usually dark brown and discoloration extended to the apex. The wilting became more extensive until plants collapsed and died. A total of 87 isolates obtained from typical diseased plants throughout Taiwan from 2002 to 2005 were analyzed to determine the race and distribution of this pathogen in Taiwan. Isolates were confirmed at the species level using F. oxysporum-specific primers FOF1 and FOR1 (4). Subsequently, isolates were characterized for pathogenicity, race and restriction fragment length polymorphisms of the intergenic spacer region of rDNA (IGS-RFLP) with two reference isolates, Fol 11A (race 1) and Fol 34-1 (race 2). Pathogenicity tests and race determination were conducted using root-dip inoculation (3) on 2-week-old seedlings of host differentials Bonny Best (no resistance), UC82-L (resistant to race 1), and Florida MH-1 (resistant to races 1 and 2). Thirty-six seedlings of each cultivar were arranged into three replications and inoculated with each isolate. Disease reaction was evaluated 3 weeks after inoculation. The disease severity rating (DSR) was determined on individual plants according to the following scale: 0 = plant healthy without external symptoms; 1 = slight vascular discoloration with or without stunted growth; 2 = severe vascular discoloration usually with stunted growth; and 3 = plant wilted beyond recovery or dead. The presence of severe vascular discoloration indicated a susceptible reaction. All isolates were race 2, and over 70% of the isolates showed strong virulence with a DSR >2 on cvs. Bonny Best and UC-82L. This result was different from a previous report of race 1 from Taiwan (2). Two IGS-RFLP haplotypes generated by EcoRI, RsaI, and HaeIII digestions (1) were identified. Eighty-six isolates displayed one banding pattern, and one unique isolate displayed a second banding pattern. The results demonstrated the predominance of race 2 and low diversity within the Taiwan population. To our knowledge, this is the first report regarding the predominant race and IGS-RFLP haplotype identification of F. oxysporum f. sp. lycopersici in Taiwan. Our study indicates that tomato varieties in Taiwan should possess resistance to race 2. References: (1) G. Cai et al. Phytopathology 93:1014, 2003. (2) K. S. Elias and R. W. Schneider. Phytopathology 82:1421, 1992. (3) J. W. Gerdemann and A. M. Finley. Phytopathology 41:238, 1951. (4) P. K. Mishra et al. FEMS Microbiol. Lett. 218:329, 2003.

scholarly journals First Report of Fusarium Wilt of Lavandula pubescens Caused by Fusarium oxysporum in Saudi Arabia

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1163-1163 ◽  
Author(s):  
K. Perveen ◽  
N. Bokhari
Keyword(s):  
Saudi Arabia ◽  
Fusarium Oxysporum ◽  
Vascular Tissue ◽  
Agricultural Research ◽  
Indian Agricultural Research Institute ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Potential Threat ◽  
King Saud University ◽  
First Report

In November 2008, a wilt of lavender (Lavandula pubescens) seedlings was observed in the greenhouse at King Saud University, Riyadh, Saudi Arabia. Affected seedlings were wilted and the root system was poorly developed. Diseased stems developed a dark coloration that extended down to the roots. Vascular tissue of the affected seedlings appeared red or brown. Isolations consistently yielded a fungus growing from the discolored stem tissue when placed on potato dextrose agar. The macroscopic characteristics of the colony, as well as microscopic structures, were used to identify the fungus as Fusarium oxysporum (2). Oval to elliptical microconidia without septa and originating from short phialides were used to distinguish the species from F. solani (1). The fungus was authenticated by the ITCC (Indian Type Collection Centre), Indian Agricultural Research Institute, New Delhi, India, and given I.D. No. 7532.09. For conducting further experiments, healthy seedlings of L. pubescens were obtained from the botanical garden of the King Saud University and grown in steam-sterilized soil. Healthy seedlings of lavender were inoculated using a root-dip method with a conidial suspension (1 × 107 CFU/ml) of one strain of F. oxysporum obtained from infected plants. Inoculated seedlings were then transplanted into steam-sterilized soil. Plants inoculated with sterilized water (1 ml per plant) served as control treatments. Wilt symptoms and vascular discoloration in the roots and crown developed within 20 days on all plants inoculated with the pathogen, while control plants remained asymptomatic. F. oxysporum was consistently reisolated from symptomatic plants. The pathogenicity test was conducted twice. To our knowledge, this is the first report of F. oxysporum on L. pubescens in Saudi Arabia or elsewhere in the world, and this newly identified disease may be a potential threat to commercial production of lavender. References: (1) J. F. Leslie and B. A. Summerell. Page 212 in: The Fusarium Laboratory Manual. Blackwell Publishing Professional, Hoboken, NJ, 2006. (2) P. C. Nelson et al. Clin. Microbiol. Rev. 7:479, 1994.

scholarly journals Fusarium Wilt of African Daisy (Osteospermum sp.) Caused by Fusarium oxysporum in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 309-309 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Fusarium Oxysporum ◽  
Vascular Tissue ◽  
Vascular System ◽  
Selective Medium ◽  
Northern Italy ◽  
Wilt Disease ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Average Temperature ◽  
Brown Discoloration

During the fall of 2002, African daisy (Osteospermum sp.) plants showing symptoms of a wilt disease were observed in a commercial, nonheated glasshouse in Albenga in northern Italy. Wilted plants were first observed when outside temperatures were between 15 and 28°C. Symptoms were first observed on seedlings 40 days after they had been transplanted into pots. The vascular tissues of affected plants appeared brown. These plants were stunted and developed yellowed leaves with brown or black streaks in the vascular system. The vascular streaks in the yellow leaves extended from the crown and were continuous with a brown discoloration in the vascular system of the crown and upper taproot. Fusarium oxysporum was consistently and readily isolated from symptomatic vascular tissue onto a Fusarium-selective medium (1). Healthy, rooted, 40-day-old plants were inoculated by root-dip with a conidial suspension (1 × 107 CFU/ml) of three isolates of F. oxysporum obtained from infected plants and transplanted into pots filled with steam-sterilized soil. Noninoculated plants served as control treatments. Plants (10 per treatment) were grown in a glasshouse at an average temperature of 25°C (minimum of 12°C and maximum of 39°C). Wilt symptoms and vascular discoloration in the roots, crown, and veins developed within 20 days on each inoculated plant, while noninoculated plants remained healthy. F. oxysporum was consistently reisolated from infected plants. The pathogenicity test was conducted twice. To our knowledge, this is the first report of F. oxysporum on Osteospermum sp. in Italy or elsewhere in the world. Reference: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975.

scholarly journals First Report of a Wilt Disease of Blackberry Caused by Fusarium oxysporum in California

Plant Disease ◽  
2016 ◽  
Vol 100 (5) ◽  
pp. 1018-1018 ◽  
Author(s):  
T. R. Gordon ◽  
S. C. Kirkpatrick ◽  
P. M. Henry ◽  
M. Kong ◽  
J. C. Broome
Keyword(s):  
Fusarium Oxysporum ◽  
Wilt Disease ◽  
First Report

scholarly journals First Report of Fusarium wilt disease on Watermelon Caused by Fusarium oxysporum f. sp. niveum (FON) in Malaysia

Plant Disease ◽  
2021 ◽  
Author(s):  
Muhammad Ziaur Rahman ◽  
Khairulmazmi Ahmad ◽  
Yasmeen Siddiqui ◽  
Norsazilawati Saad ◽  
Tan Geok Hun ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Cover Crops ◽  
Fungal Pathogen ◽  
Disease Incidence ◽  
Wilt Disease ◽  
Likelihood Method ◽  
Distilled Water ◽  
First Report ◽  
Fusarium Wilt Disease

Fusarium wilt disease incited by Fusarium oxysporum f. sp. niveum (FON) is the utmost devastating soil-inhabiting fungal pathogen limiting watermelon (Citrullus lanatus) production in Malaysia and globally. The field disease survey of fusarium wilt was carried out during December 2019 and November 2020, in three major production areas (3 farmer fields per location) in Peninsular Malaysia namely, Mersing, Serdang and Kuantan and disease incidence of 30 and 45%, was recorded for each year, respectively. Infected watermelon plants showed symptoms such as vascular discoloration, brown necrotic lesions to the soil line or the crown, one-sided wilt of a plant, or a runner or the whole plant. Infected root and stem tissues, 1-2 cm pieces were surface sterilized with 0.6% NaOCl for 1 minute followed by double washing with sterile water. The disinfected tissues were air-dried and transferred onto semi-selective Komada’s medium (Komada 1975) and incubated for 5 days. The fungal colonies produced were placed on potato dextrose agar (PDA) to attain a pure culture and incubated at 25±2℃ for 15 days. The pure fungal colony was flat, round and light purple in color. Macroconidia were straight to slightly curved, 18.56-42.22 µm in length, 2.69-4.08 µm width, predominantly 3 septate and formed in sporodochia. Microconidia measured 6.16-10.86 µm in length and 2.49-3.83 µm in width, kidney-shaped, aseptate and were formed on short monophialides in false-heads. Chlamydospores were single or in pairs with smooth or rough walls, found both terminally or intercalary. To confirm their pathogenicity, two-week-old watermelon seedlings (cv. NEW BEAUTY) were dipped into spore suspension (1 ˟ 106 spores/ml) of representative isolates of JO20 (Mersing), UPM4 (Serdang) and KU41 (Kuantan) for 30 second and then moved into 10 cm diameter plastic pots containing 300 g sterilized soil mix. Disease symptoms were assessed weekly for one month. Control seedlings were immersed in sterile distilled water before transplanting. The inoculated seedlings showed typical Fusarium wilt symptoms like yellowing, stunted growth, and wilting, which is similar to the farmer field infected plants. However, the seedlings inoculated by sterile distilled water remained asymptomatic. The pathogen was successfully re-isolated from the infected seedlings onto Komada’s medium, fulfilling the Koch’s postulate. For the PCR amplification, primers EF-1 and EF-2 were used to amplify the tef1-α region. A Blastn analysis of the tef1-α sequences of the isolates JO20 (accession nos. MW315902), UPM4 (MW839560) and KU41 (MW839562) showed 100% similarity; with e-value of zero, to the reference sequences of F. oxysporum isolate FJAT-31690 (MN507110) and F. oxysporum f. sp. niveum isolate FON2 790-2 (MN057702). In Fusarium MLST database, isolates JO20, UPM4 and KU41 revealed 100% identity with the reference isolate of NRRL 22518 (accession no. FJ985265). Though isolate FJ985265 belongs to the f. sp. melonis, earlier findings had revealed Fusarium oxysporum f. sp. are naturally polyphyletic and making clusters with diverse groups of the Fusarium oxysporum species complex (O’Donnell et al. 2015). The isolates JO20, UPM4 and KU41 were identified as F. oxysporum f. sp. niveum based on the aligned sequences of tef1-α and molecular phylogenetic exploration by the maximum likelihood method. To the best of our knowledge, this is the first report of F. oxysporum f. sp. niveum as a causative pathogen of Fusarium wilt disease of watermelon in Malaysia. Malaysia enables to export watermelon all-year-round in different countries like Singapore, Hong-Kong, The United Arab Emirates (UAE), and Netherlands. The outburst of this destructive soil-borne fungal pathogen could cause hindrance to watermelon cultivation in Malaysia. Thus, growers need to choice multiple management tactics such as resistant varieties, cultural practices (soil amendments and solarization), grafting, cover crops and fungicide application to control this new pathogen.

scholarly journals First Report of Fusarium Wilt Caused by Fusarium oxysporum on Roselle in the United States

Plant Disease ◽  
2007 ◽  
Vol 91 (5) ◽  
pp. 639-639 ◽  
Author(s):  
R. C. Ploetz ◽  
A. J. Palmateer ◽  
D. M. Geiser ◽  
J. H. Juba
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
Plant Pathogens ◽  
Vascular Tissue ◽  
The United States ◽  
South Florida ◽  
Maximum Parsimony Analysis ◽  
Culture Collections ◽  
Early Date ◽  
First Report

Roselle, Hibiscus sabdariffa var. sabdariffa, is an annual that is grown primarily for its inflated calyx, which is used for drinks and jellies. It is native from India to Malaysia, but was taken at an early date to Africa and is now widely grown in the tropics and subtropics (2). In late 2005, dying plants were noted by a producer in South Florida. Plants wilted, became chlorotic, and developed generally unthrifty, sparse canopies. Internally, conspicuous vascular discoloration was evident in these plants from the roots into the canopy. After 5 days on one-half-strength potato dextrose agar (PDA), salmon-colored fungal colonies grew almost exclusively from surface-disinfested 5 mm2 pieces of vascular tissue. On banana leaf agar, single-spored strains produced the following microscopic characters of Fusarium oxysporum: copious microconidia on monophialides, infrequent falcate macroconidia, and terminal and intercalary chlamydospores. Partial, elongation factor 1-α (EF1-α) sequences were generated for two of the strains, O-2424 and O-2425, and compared with previously reported sequences for the gene (3). Maximum parsimony analysis of sequences showed that both strains fell in a large, previously described clade of the F. oxysporum complex (FOC) that contained strains from agricultural hosts, as well as human clinical specimens (2; clade 3 in Fig. 4); many of the strains in this clade have identical EF1-α sequences. Strains of F. oxysporum recovered from wilted roselle in Egypt, O-647 and O-648 in the Fusarium Research Center collection, were distantly related to the Florida strains. We are not aware of other strains of F. oxysporum from roselle in other international culture collections. Roselle seedlings were inoculated with O-2424 and O-2425 by placing a mycelial plug (5 mm2, PDA) over a small incision 5 cm above the soil line and then covering the site with Parafilm. Parafilm was removed after 1 week, and plants were incubated under ambient temperatures (20 to 32°C) in full sun for an additional 5 weeks (experiment 1) or 7 weeks (experiment 2). Compared with mock-inoculated (wound + Parafilm) control plants, both O-2424 and O-2425 caused significant (P < 0.05) vascular disease (linear extension of discolored xylem above and below wound site) and wilting (subjective 1 to 5 scale); both isolates were recovered from affected plants. F. oxysporum-induced wilt of roselle has been reported in Nigeria (1) and Malaysia (4) where the subspecific epithet f. sp. rosellae was used for the pathogen. We are not aware of reports of this disease elsewhere. To our knowledge, this is the first report of F. oxysporum-induced wilt of roselle in the United States. Research to determine whether the closely related strains in clade 3 of the FOC are generalist plant pathogens (i.e., not formae speciales) is warranted. References: (1) N. A. Amusa et al. Plant Pathol. J. 4:122, 2005. (2) J. Morton. Pages 81–286 in: Fruits of Warm Climates. Creative Resource Systems, Inc., Winterville, NC, 1987. (3) K. O'Donnell et al. J. Clin. Microbiol. 42:5109, 2004. (4) K. H. Ooi and B. Salleh. Biotropia 12:31, 1999.

scholarly journals First Report of Mimosa Wilt Disease of Silk Tree (Albizia julibrissin) in California Caused by Fusarium oxysporum f. sp. Perniciosum

Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 487-487 ◽  
Author(s):  
R. B. Nesbitt ◽  
T. E. Tidwell ◽  
R. J. Stipes ◽  
G. J. Griffin
Keyword(s):  
Fusarium Oxysporum ◽  
Lateral Roots ◽  
Residential Area ◽  
Wilt Disease ◽  
Potato Dextrose Agar ◽  
Water Suspension ◽  
Albizia Julibrissin ◽  
First Report ◽  
Agar Media ◽  
Fusarium Sp

A Fusarium sp. was isolated from a 12-year-old Silk Tree (Albizia julibrissin) in a residential area of Redlands, CA. The scaffold branches and trunk exhibited gummosis, the sap oozing from fissures or intact bark. Internally the wood exhibited brown to black broad streaks of discoloration from the scaffold branches down into lateral roots below the root crown, similar to symptoms observed in Virginia (2). Wilted and dried foliage remained on the scaffold branches. Two-week-old cultures of the isolate grown on Komada (1) and acidified potato dextrose agar media developed short conidiophores, macroconidia, and colony morphology typical of Fusarium oxysporum. To complete Koch's postulates, 1-month-old seedlings were root-dip inoculated with a water suspension of macro- and microconidia (106 per ml). Two weeks after inoculation, typical Fusarium wilt symptoms developed in all inoculated seedlings. The fungus was reisolated from symptomatic seedlings. This is the first report of mimosa wilt disease in California. The disease has the potential to adversely impact California's nursery and landscape industry. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) R. J. Stipes and P. M. Phipps. Phytopathology 65:188, 1975.

scholarly journals First Report of Fusarium oxysporum Causing Coriander Wilt Disease in North China

Plant Disease ◽  
2021 ◽  
Author(s):  
Lijuan Yang ◽  
Wei Gao ◽  
Chunxiang Zhang ◽  
Lei Xu ◽  
Yong Wang
Keyword(s):  
North China ◽  
Vascular Tissue ◽  
Sequence Data ◽  
Management Strategies ◽  
Morphological Characteristics ◽  
Wilt Disease ◽  
Soil Samples ◽  
Mlst Database ◽  
Running Water ◽  
First Report

Coriander or cilantro (Coriandrum sativum L.) is extensively used as a fresh herb in China. During the summer of 2019 in Tianjin, China, coriander plants showed a previously unknown wilt in commercial fields. In severely infected fields, approximately 85% of the plants at vegetative stages were stunted, chlorotic, wilted or dead. Vascular tissues of the main stem and root were discolored. Soil samples were collected from five fields with a history of severe wilt disease in Tianjin since the fall of 2019. Seeds of coriander cultivar “ansemi” were sown in soil from the five fields, and cultured in a greenhouse at 22°C/20°C (12 h /12 h, light/dark) and 75%  relative humidity. After 50 days’ cultivation, infected seedlings exibited similar symptoms to those of plants in the field. Twenty symptomic seedlings from each of the collected field soil samples were harvested and washed for 3 min under running water. Then the vascular tissue fragments (3 mm2) of stem and root at the boundary of the symptomatic area were excised, and placed on improved Komada’s medium, which is selective for Fusarium sp. (Komada 1975). After incubation at 25°C for 5 days in the dark, 70% of the isolates generated white to pale pink aerial hyphae on PDA (Fig. S1). Microconidia were single-celled, hyaline, non-septate and ovoid, and measured 5.6 to 14.1 μm long and 2.1 to 3.8 μm wide (n = 40). Macroconidia were three to five-septate, slightly curved at apex, and ranged from 11.2 to 38.6 μm long × 3.2 to 4.5 μm wide (n = 40). Based on morphological characteristics, these fungi were preliminarily identified as F. oxysporum (Leslie and Summerell 2006). For molecular identification, the ITS gene, TEF1-α gene and mtSSU gene of cultures from two representative single spored isolates XC02 and XC03 were amplified and sequenced (White et al. 1990; Carbone and Kohn 1999; Li et al. 1994). The sequences were submitted to GenBank (MT579855 and OK326765 for ITS; MT597425 and OK256882 for TEF1-α; MT587799 and OK330480 for mtSSU). BLASTn analysises indicated that the nucleotide sequences of the three loci of the two isolates were 99.8% to 100% homologous to sequences of F. oxysporum in the NCBI database and Fusarium MLST database. A multilocus phylogenetic tree was drawn via UPGMA analysis of the combined ITS, TEF1-α and mtSSU partial sequence data from Fusarium MLST database (Fig. S2). Pathogenicity of each isolate was tested on ten 15-day-old healthy coriander seedlings in each treatment according to the method of Yang et al. (2020). The first wilt symptoms developed 3 days after inoculation, and 7 to 10 days after inoculation 90% to 100% of the plants were dead. Control plants remained healthy. To fulfill the Koch's postulates, F. oxysporum were reisolated from the diseased tissues and verified based on morphology and sequencing as described above. The experiments were repeated twice with similar results. F. oxysporum has been reported to cause coriander wilt disease in India, Argentina, California (Koike and Gordon 2005), and Italy (Gilardi et al. 2019). To our knowledge, this is the first report of F. oxysporum causing coriander wilt disease in north China. Compared with F. equiseti in the previous report (Yang et al. 2020), F. oxysporum isolates possessed higher separation frequence and stronger pathogenicity to coriander seedlings. Thus attentions should be taken on F. oxysporum causing coriander wilt diseases when developing effective management strategies in north China.

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