First Report of Tobacco Fusarium Root Rot Caused by Fusarium verticillioides in China

Rhodiola sachalinensis (family Crassulaceae), a perennial herbaceous plant with adaptogenic properties, cardiopulmonary protective effects, and central nervous system activities, is widely used as a traditional Chinese medicine (3). R. sachalinensis naturally exists only above 1,500 m elevation in the mountain area of Changbai Mountain (average July temperature ≤10°C), China. Introduction and cultivation of R. sachalinensis has been carried out in several low-altitude districts of northeast China. From 2007 to 2010, severe root rot disease was observed on R. sachalinensis in Siping districts, Jilin, China. Approximately 75 to 95% of the fields were affected with root rot disease incidence ranging from 85 to 100% under conditions of high temperatures (24 to 30°C) and high humidity. As the disease progressed, brown lesions expanded on lateral and main roots, and aboveground tissues shriveled and died. Over the 4- to 5-year period from culture to harvest, root rot became more serious. Symptomatic plants were collected from Siping districts. Samples were rinsed in tap water, necrotic areas were excised and cut into 2-mm pieces, surface sterilized with 5% NaOCl for 30 s, and rinsed in four successive changes of sterile distilled water. A single fungus was isolated on potato dextrose agar (PDA). The fungus was white, then pink and cottony, with nearly round margins after 8 days (27°C). Hyphae were separate and hyaline but macroconidia were sparse and occurred in a false head. Conidiogenous cells were monophialides. Microconidia in chains were abundant and mostly nonseptate, oval to clavate, and measured 8.1 to 14.5 × 2.0 to 3.4 μm. Morphological characteristics suggested the isolate was Fusarium verticillioides (Gibberella fujikuroi), which differed from the reported root rot pathogen of R. sachalinensis, F. oxysporum by forming microconidia in chains (1). The sexual stage of F. verticillioides was not observed. The internal transcribed spacer (ITS) fragments were amplified using ITS1 and ITS4 as primers and the 351-bp sequence was deposited in GenBank (Accession No. HQ025928). The ITS sequence showed 100% nucleotide sequence identity with F. verticillioides (GenBank Accession No. AY188916.1.). For pathogenicity tests, the isolate was cultured on PDA for 8 days. Inoculations were performed on 15 healthy R. sachalinensis plants by spraying a conidial suspension (2.0 × 105 microconidia ml–1) on roots wounded with a metal needle (6 wounds cm–2) (2). Ten plants were mock inoculated with water. Plants were incubated in a growth chamber (25°C, 70 to 80% relative humidity, 300 μmol·m–2·s–1 light intensity, and a 12-h photoperiod). After 15 days, defoliation and root rot symptoms were similar to the original symptoms observed under field conditions. F. verticillioides was reisolated from the roots of infected plants. Control plants remained asymptomatic. To our knowledge, this is the first report of F. verticillioides on R. sachalinensis in China. References: (1) X. Y. Li et al. J. Northeast For. Univ. 34:12, 2003. (2) M. Ma. Syahit et al. Am. J. Appl. Sci. 6:902, 2009. (3) T. F. Yan et al. Conserv. Genet. 4:213, 2003.

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First Report of Fusarium Root Rot on Chinese hickory (Carya cathayensis) Caused by Fusarium oxysporum in China

Plant Disease ◽

10.1094/pdis-01-15-0073-pdn ◽

2015 ◽

Vol 99 (9) ◽

pp. 1284-1284 ◽

Cited By ~ 2

Author(s):

C. Q. Zhang ◽

Y. H. Liu ◽

B. C. Xu

Keyword(s):

Fusarium Oxysporum ◽

Root Rot ◽

Fusarium Root Rot ◽

First Report ◽

Carya Cathayensis

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First Report of Fusarium verticillioides Causing Stalk and Root Rot of Sorghum in Spain

Plant Disease ◽

10.1094/pdis-11-11-0958-pdn ◽

2012 ◽

Vol 96 (4) ◽

pp. 584-584 ◽

Cited By ~ 2

Author(s):

D. Palmero ◽

J. Gil-Serna ◽

L. Gálvez ◽

M. D. Curt ◽

M. De Cara ◽

...

Keyword(s):

New York ◽

Root Rot ◽

Sweet Sorghum ◽

Fusarium Verticillioides ◽

Pcr Amplification ◽

Dry Weight ◽

The United States ◽

Potato Dextrose Agar Medium ◽

Laboratory Manual ◽

First Report

Sweet sorghum (Sorghum bicolor L.) is considered one of the most promising crops for bioethanol production in many countries and is a focus of bioenergy research worldwide. In July 2011, plants of the sweet sorghum cv. Suchro 506 in Oropesa (Toledo, Spain, 40.048577°N, 5.360298°W) (European Datum 1950 UTM zone 30 N) were observed with severe wilting. Upon examination, the lower internodes were found to be straw colored. When the plant was split, the internal pith was reddish, soft, and disintegrating. Small pieces of symptomatic stems and roots were surface disinfected in sodium hypochlorite (0.5% wt/vol) for 2 min and air dried. The sections were then placed on either PDA (potato dextrose agar) medium or Komada agar and incubated for 5 days at 25°C. Isolations from diseased stem and root tissue consistently yielded Fusarium verticillioides (Sacc.) Nirenberg (3). The small, hyaline, mostly single-celled, oval to club-shaped microconidia of F. verticillioides were produced in long catenate chains arising from monophialides. PCR amplification of the ITS1-5.8S-ITS2 was performed using the primers and protocols described elsewhere (4) and the fragments obtained were subsequently sequenced in both directions. Sequences were deposited in the EMBL Sequence Database (Accession Nos. HE652878, HE652879, HE652880, and HE652881). Four of the recovered F. verticilliodes isolates were tested in pathogenicity assays. One-week-old cultures of each isolate were homogenized in 400 ml of sterile water and 200 ml were used to inoculate water-growth-chamber-grown plants in 500-ml pots. Two pots each with three plants of cv. Suchro 506 were inoculated for each isolate. Water with sterile PDA was used as a control. All plants were kept at 20 to 25°C under a photoperiod of 14 h at 12,000 lux. After 21 days, above- and belowground parts were dried for 24 h at 60°C. Total length and dry weight of both sections were obtained. Inoculated plants produced root rot symptoms characteristic of F. verticillioides with dark red discolorations of the cortex of seedling roots (1), whereas the plants watered with water containing only PDA did not produce symptoms. Inoculated plants also had a decrease in dry weight for above- and belowground sections (P = 0.05) compared with the control with 43 and 47% reductions, respectively. The length of aerial parts was approximately 5% less in inoculated plants compared with control plants. F. verticillioides was reisolated from all inoculated plants. Sorghum stalk and root rot caused by F. verticillioides has been reported in different countries including India (2) and the United States (3). To our knowledge, this is the first report of F. verticillioides causing stalk and root rot of sorghum in Spain. An increase of production of this crop is expected to meet targets of the renewable energy share in Spain and any disease compromising yield may be a threat to this endeavour. References: (1) R. A. Frederiksen and G. N. Odvody. Compendium of Sorghum Diseases. The American Phytopathological Society. St. Paul, MN, 2000. (2) N. N. Khune et al. Indian Phytopathol. 37:316, 1984. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

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