scholarly journals First Report of Fusarium Wilt of Endive (Cichorium endivia) Caused by Fusarium oxysporum in Italy

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 1078-1078 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. Troisi ◽  
M. L. Gullino

In the summer of 2007, a wilt of endive (Cichorium endivia) cv. Myrna plants was observed on several commercial farms near Alessandria in northern Italy. Approximately 40% of the plants on each farm were symptomatic. Affected plants were stunted and yellow and their root systems were poorly developed. Basal leaves eventually wilted. Black streaks were observed in the proximal part of the leaf vascular system. Fusarium oxysporum was consistently isolated from symptomatic vascular tissue on a Fusarium-selective medium (1). To confirm identification of the pathogen, the translation elongation factor 1α and the ribosomal DNA intergenic spacer (IGS) region were partially sequenced (2). Genomic DNA was extracted from mycelia growing on potato dextrose agar. Amplification of the EF-1α region generated a sequence of 648 bp; the IGS amplicon was 2,500 bp. The EF-1α sequence (GenBank Accession No GQ398152) was 99% similar to the sequence of a F. oxysporum strain isolated from soil and a strain pathogenic on cotton plants (GenBank Accession No. EU246574). The IGS sequence (GenBank Accession No GQ398153) was 97% similar to the sequence of a F. oxysporum strain (GenBank Accession No. EF661647). Pathogenicity tests were conducted on 15-day-old endive plants (cv. Myrna). Ten plants were inoculated by dipping their roots in a 1 × 106 CFU/ml suspension of one of the isolates recovered from a wilted endive plant. Inoculated and noninoculated plants were transplanted into pots filled with steamed soil and maintained in a glasshouse at 23 to 28°C. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 60 days after inoculation. F. oxysporum was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was conducted twice. To our knowledge, this is the first report of wilt caused by F. oxysporum on endive in Italy. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) G. Mbofung et al. Phytopathology 97:87, 2007.

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 496-496 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
A. Poli ◽  
M. L. Gullino

In the summer of 2009, a wilt of chicory was observed on 25 to 30% of 30-day-old Cichorium intybus L. cv. Clio plants grown outdoors on a commercial farm in Piedmont (northern Italy). Affected plants were chlorotic and stunted with poorly developed root systems compared with healthy plants. Black streaks were observed in the stem and proximal part of the leaf vascular system in wilted plants. Fusarium oxysporum Schltdl. was isolated from symptomatic vascular tissue on a Fusarium-selective medium (1) from 80% of samples. Grown on potato dextrose agar (PDA) for 4 days at 23°C, the colonies, initially white and later pale pink, produced hyaline microconidia that were oval-elliptical and cylindrical in shape measuring 5.6 to 14.9 (average 10.2) × 2.1 to 4.5 (3.0) μm, borne on short monophialides measuring 8.2 to 16.1 (average 13.2) × 2.1 to 4.2 (3.3) μm. Macroconidia were slightly curved, three-septate, with a slightly hooked apical cell and a foot-shaped basal cell measuring 24.9 to 41.6 (average 32.2) × 3.2 to 5.2 (4.3) μm. Chlamydospores were both terminally and intercalary, solitary but also in short chains (2 to 4 elements) measuring 21.1 to 41.0 (average 27.2) μm (2). The internal transcribed spacer (ITS) rDNA region was amplified using the primers ITS1/ITS4 and sequenced. BLASTn analysis of the 527-bp amplicon (GenBank Accession No. HQ644423) obtained had 98% sequence identity with F. oxysporum (GenBank Accession No. FJ605247). The translation elongation factor-1α (EF-1α) gene was amplified using primers EF-1/EF-2 and sequenced (GenBank Accession No. GU564259). The 663-bp fragment had 99% sequence identity with F. oxysporum (GenBank Accession Nos. EU313540, EU313539, and DQ837696). Pathogenicity tests were conducted on 15-day-old chicory plants from two cultivars (Clio and Katia). Thirty-five plants per cultivar were inoculated by dipping their roots in a 1 × 106 CFU/ml suspension of isolate FusCic45B recovered from wilted chicory. Inoculated and noninoculated plants were transplanted into five pots filled with 10 liters of steamed mix (peat/perlite/sand, 60:20:20 vol/vol) and were maintained in a glasshouse at 25 to 27°C. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 15 days after inoculation on all inoculated plants. Plants of cv. Clio were more susceptible. F. oxysporum was always reisolated from infected plants using the Fusarium-selective medium. All noninoculated plants remained healthy. The pathogenicity test was conducted twice. To our knowledge, this is the first report of wilt caused by F. oxysporum on chicory, C. intybus, in Italy as well as worldwide. References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983.


Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 309-309 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino

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.


Plant Disease ◽  
2002 ◽  
Vol 86 (9) ◽  
pp. 1052-1052 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. L. Gullino

In spring 2001, plants of the lettuce cv. Salad Bowl showing symptoms of a wilt disease were observed in several commercial plastic greenhouses near Bergamo, in northern Italy. Wilted plants were first observed during the spring and summer of 2001 when temperatures were between 26 and 35°C. Symptoms were observed in the same area and the same farms in March 2002, in concomitance with a period of high temperatures. Although the distribution of the disease was generally uniform, symptoms were more severe in the central part of the greenhouses where temperatures were warmest. Symptoms were first observed at thinning, when seedlings (30 days old) appeared wilted. Vascular tissues of affected seedlings appeared red or brown. Affected plants were stunted and developed yellow leaves and brown or black streaks in the vascular system. The vascular streaks in the yellow leaves extended from the crown and were continuous with a red-brown discoloration in the vascular system of the crown and upper taproot. Symptoms were typically not visible on the outside of the crowns or roots. Fusarium oxysporum was consistently and readily isolated from symptomatic vascular tissues on a Fusarium-selective medium (2). Seeds of cv. Salad Bowl were planted in steam-sterilized soil artificially infested with 1 × 104 CFU/g soil of each of two isolates of F. oxysporum obtained from infected plants. Plants grown in noninfested soil served as noninoculated control treatments. Plants (25 per treatment) were grown at 25 to 28°C in growth chambers. Wilt symptoms and vascular discoloration of the roots, crown, and veins developed 20 days after seeding for all plants grown in the infested soil, and 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 lettuce in Europe. A wilt of lettuce attributed to F. oxysporum f. sp. lactucae was reported in Japan in 1967 (3) and in the United States in 1993 (1), in the latter case the incitant organism was described as F. oxysporum f. sp. lactucum. References: (1) J. C. Hubbard and J. S. Gerik. Plant Dis. 77:750, 1993. (2) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (3) T. Matuo and S. Motohashi. Trans. Mycol. Soc. Jpn. 8:13, 1967.


Plant Disease ◽  
2004 ◽  
Vol 88 (1) ◽  
pp. 83-83 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. L. Gullino

Lamb's lettuce (Valerianella olitoria), also known as corn salad, is increasingly grown in Italy and used primarily in the preparation of mixed processed salad. In the summer of 2003, plants of lamb's lettuce cvs. Trophy and Palmares exhibiting wilt symptoms were observed in several commercial greenhouses near Bergamo in northern Italy. Wilted 30-day-old plants were observed first during the month of June, at the time of thinning when temperatures ranged between 28 and 35°C. Disease was generally uniform in the greenhouses and 30 to 50% of the plants were affected. Vascular tissue of affected seedlings appeared red or brown but later turned brown or black. Affected plants were stunted and developed yellowed leaves. Vascular discoloration was continuous from the upper taproot through the crown to the leaf. Fusarium oxysporum was consistently isolated from symptomatic vascular tissue onto a Fusarium-selective medium (1). Seeds of the same cultivars (Trophy and Palmares) affected by the wilt in the field were artificially inoculated by dipping them for 15 min into spore suspensions (1 × 106 conidia per ml) of three isolates of F. oxysporum obtained from infected plants. Noninoculated seeds served as control treatments. Forty seeds per treatment were sown in pots (1-liter volume) containing steam-sterilized soil and maintained at 25°C in a growth chamber programmed for 12 hours of light per day. Wilt symptoms developed on both cultivars 20 days after seeding, and F. oxysporum was consistently reisolated from infected plants. The plants obtained from noninoculated seeds remained healthy. The pathogenicity test was carried out twice with similar results. To our knowledge, this is the first report of F. oxysporum causing vascular wilt of lamb's lettuce and may warrant a new forma specialis designation. Reference: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975.


Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 201-201 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. L. Gullino

Two types of rocket are available on the market in Italy: (i) Eruca vesicaria (synonym E. sativa) known as ruchetta or cultivated garden rocket; and (ii) several species of Diplotaxis (Diplotaxis erucoides, D. muralis, and D. tenuifolia), which are wild plants now widely cultivated. Rocket is increasingly used in the mediterranean cuisine as salad and or to decorate dishes. In spring 2002, plants of the cultivated (E. vesicaria) and wild (Diplotaxis spp.) rocket showing symptoms of a wilt disease were observed in several commercial plastic greenhouses near Bergamo, in northern Italy. Wilted plants were first observed during the spring and summer of 2001 when temperatures were between 26 and 35°C. In May 2002, symptoms were again observed in the same area, on the same farm as well as other farms. Although the distribution of the disease was generally uniform, symptoms were more severe in the central part of the greenhouses where temperatures were warmest (30 to 60% of plants were affected). Diseased plants were stunted and chlorotic with brown or black streaks in the vascular system. Vascular tissues of affected plants appeared red or brown. Vascular streaks in the chlorotic leaves extended from the crown and were continuous with a red-brown discoloration in the vascular system of the crown and upper taproot. Fusarium oxysporum was consistently and readily isolated from symptomatic vascular tissues when plated on a Fusarium-selective medium (2). Microconidia measured 8.8 × 3.0 µm. E. vesicaria and Diplotaxis spp. were grown in steam-sterilized soil, and 10 days after emergence they were artificially inoculated by root dipping in a spore suspension (1 × 105 CFU/ml) of three F. oxysporum strains collected from infected plants. Uninoculated plants served as control. Plants (60 per treatment) were grown at 25 to 28°C in growth chambers. Wilt symptoms developed on all plants 20 days after inoculation, and 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 cultivated rocket in Europe and the first on wild rocket (Diplotaxis spp.) in the world. A wilt of E. sativa attributed to F. oxysporum f. sp. erucae was previously reported in India in 1973 (1). Studies are being carried out to determine if the Italian isolates of F. oxysporum belong to the same formae speciales. References: (1) C. Chatterjee and J. N. Rai. Indian Phytopathol 28:309, 1973. (2) H. Komada. Rev. Plant Prot. Res. 8:114, 1975.


Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 684-684 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
M. L. Gullino

During the spring of 2004, bitterroot (Lewisia cotyledon (S. Wats.) B.L. Robins), a flowering perennial of interest for rock gardens, showed symptoms of a wilt disease in several commercial nurseries located in Piedmont (northern Italy). Ten to thirty percent of plants from several different nurseries were affected. Wilted plants were first observed approximately 20 days after being transplanted into containers when outside temperatures ranged from 15 to 22°C. Symptomatic plants were stunted with yellowed leaves and brown-to-black veins. The vascular browning extended into the crown and was continuous with a brown discoloration in the vascular system of the crown and upper taproot. Fusarium oxysporum, identified on the basis of colony and conidia morphology (1), was consistently and readily isolated from symptomatic vascular tissue onto a Fusarium-selective medium (2). Three isolates were transferred to casein hydrolysate and grown for 10 days to produce conidial inoculum. Healthy 30-day-old plants were inoculated by dipping roots into a (1 × 106 CFU/ml) conidial suspension. Plants were then transplanted into pots filled with steam-sterilized soil. Noninoculated plants served as a control. Plants (12 per treatment) were placed in a climatic chamber at 25°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 symptomatic plants. The pathogenicity test was conducted twice with the same result. One isolate of the pathogen has been deposited in the ATCC culture collection. To our knowledge, this is the first report of F. oxysporum on L. cotyledon in Italy and elsewhere in the world. Currently, this disease is present in several nurseries in the Piedmont Region of Italy. References: (1) C. Booth. Fusarium. CMI, Kew, UK, 1977. (2) H. Komada. Rev. Plant Prot. Res. 8:114, 1975.


Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1191-1191 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Pensa ◽  
A. Poli ◽  
M. L. Gullino

During summer 2010, symptoms of a wilt disease were observed in a commercial farm in northern Italy on Crassula ovata (jade plant). First symptoms consisted of chlorosis and premature drop of still turgid leaves. As the disease progressed, leaves turned yellow and wilted before dropping off and the stem wilted, bent, and eventually rotted starting from the base. In some cases, the stem broke or the basal portion of the leaf rotted. Brown discolorations were observed in the vascular system. Of 10,000 plants, 65% (cv. Mini) and 5% of 600 plants (cv. Magical Tree) were affected. Premature dropping of leaves was more frequent on cv. Magical Tree. Using the Komada's Fusarium-selective medium, a fungus was consistently and readily isolated from symptomatic vascular tissues of plants belonging to both cultivars. Isolates obtained from both cultivars were purified, subcultured on potato dextrose agar (PDA), and single-spore cultures were obtained. On PDA, both isolates produced pale violet, abundant, aerial mycelium, felted in old cultures, with purple pigments in the agar. The isolates were grown on Spezieller Nährstoffarmer agar for characterization of macroconidia and microconidia (1). Both isolates produced sparse, 3 to 5 septate, nearly straight macroconidia measuring 30 to 56 × 3 to 5 (average 40 × 4) μm with a short apical cell and a foot-shaped basal cell. Sporodochia were not observed. Unicellular, oval-elliptical microconidia measuring 5 to 13 × 3 to 4 (average 8 × 3) μm were produced on short monophialides. Chlamydospores were abundant, single and sometime in pairs, terminal and intercalary, rough walled, and measured 6 to 9 μm. Such characteristics are typical of Fusarium oxysporum (3). The ITS region (internal transcribed spacer) of rDNA was amplified with primers ITS1/ITS4 (4) and sequenced. BLASTn analysis of an isolate from C. ovata cv. Mini (515 bp, Accession No. HQ682196) and C. ovata cv. Magical Tree (509 bp, Accession No. HQ682197) showed an E-value of 0.0 with F. oxysporum. For these sequences, pairwise alignment of EMBOSS (E.B.I. - The European Bioinformatics Institute) revealed identity and similarity of 99.0%. To confirm pathogenicity, tests were conducted on 5-month-old plants of cvs. Mini and Magical Tree. Plants (three per treatment) were inoculated by dipping roots in a 1 × 106 CFU/ml conidial suspension of the two isolates of F. oxysporum prepared from 10-day-old cultures grown on casein liquid medium (2), shaken (90 rpm) for 10 days at 24°C ± 1 (12-h fluorescent light, 12-h dark). Inoculated plants were transplanted into pots filled with steamed mix (sphagnum peat/perlite/pine bark/clay; 50:20:20:10) and maintained in a plant growth chamber at 25 ± 1°C under a regimen of 12 h per day of fluorescent light. Inoculated plants belonging to both cultivars showed typical first symptoms of Fusarium wilt after 13 days. In the following days, leaves dropped, stems wilted, and plants died. Noninoculated plants remained healthy. F. oxysporum was reisolated from inoculated plants. The pathogenicity test was conducted twice. This is, to our knowledge, the first report of F. oxysporum on C. ovata in Italy or worldwide. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Professional, Ames, IA, 2006. (2) A. Minuto et al. Phytoparasitica 36:294, 2008. (3) B. A. Summerell et al. Plant Dis. 87:117, 2003. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.


Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1163-1163 ◽  
Author(s):  
K. Perveen ◽  
N. Bokhari

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.


Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 282-282 ◽  
Author(s):  
Y. Li ◽  
L. D. Chi ◽  
L. G. Mao ◽  
D. D. Yan ◽  
Z. F. Wu ◽  
...  

Ginger (Zingiber officinale Roscoe) is an important commercial crop that is planted in 60,000 to 70,000 ha every year in Shandong Province, China. In 2010, rotted rhizomes of cultivar Laiwu Big Ginger were reported on 20 ha in Anqiu, Shandong Province, and yield losses of up to 70% were reported. The aboveground symptoms were the water-conducting portion of symptomatic rhizomes was discolored brown and had a black dry rot of the cortex tissues (3). Thirty symptomatic rhizomes were sampled from six fields in six farms. Komada's method (1) was used to isolate the pathogen. Ten pieces from each rhizome were washed with sterile distilled water and plated on Komada selective medium at 25°C. White fungal colonies turned orchid after 7 days of incubation. Two types of asexual spores were associated with the colonies: microconidia and macroconidia. The microconidia were the most abundantly produced spores and were oval, elliptical or kidney shaped, and produced on aerial mycelia. Macroconidia had three to five cells and gradually pointed or curved edges, varied in size from 3 to 5 × 19 to 36 μm. The rDNA of the internal transcribed spacer regions 1 and 2 and the 5.8S gene in five isolates were amplified using primers ITS1 and ITS4, and the nucleotide sequence was the same as isolate no. 3, which was deposited in GenBank (Accession No. KC594035). A BLAST search showed 99% identity with the strain Z9 of Fusarium oxysporum (EF611088). Pathogenicity tests of five isolates were carried out in a greenhouse and the pathogenicity test of isolate no. 3 was selected for the method description. Ten 1-month-old ginger plants (cv. Laiwu Big Ginger) were grown in plastic pots (diameter 20 cm) with sandy soil and inoculated. Ten plants were used as untreated controls. Isolate no. 3 was grown on casein hydrolysate medium (4) for 72 h and the spores were harvested in sterile distilled water. Aqueous spore suspensions of isolate no. 3 were adjusted with deionized water to 1 × 108 CFU/ml as the inoculum. The prepared inoculum was injected with a syringe into the soil around the rhizome of ginger plants. Inoculated plants were placed in the greenhouse at 24 to 26°C and assessed for rhizome rot on the 14th day after inoculation. Disease severity was recorded based on a scale in which – = no symptoms; 1 = small lesions on seedlings, no rot; 2 = seedling rot; and 3 = plant dead. Similar rhizome rot symptoms were observed after inoculation. The inoculated isolate was re-isolated from diseased rhizomes, confirming its pathogenicity. To our knowledge, this is the first report of rhizome rot of ginger caused by F. oxysporum in China. Rhizome rot of ginger caused by Fusarium spp. is well known in Asian countries such as India (2). References: (1) H. Komada. Rev. Plant Prot. Res. 8:114, 1975. (2) V. Shanmugam et al. Biol Control. 66:1, 2013. (3) E. E. Trujillo. Diseases of Ginger (Zingiber officinale) in Hawaii, Circular 62, Hawaii Agricultural Experiment Station, University of Hawaii, December, 1964. (4) G. E. Wessman. Appl. Microbiol. 13:426, 1965.


Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1132-1132 ◽  
Author(s):  
L. Riccioni ◽  
A. Haegi ◽  
M. Valvassori

Lentil (Lens culinaris Medik.) is a traditional crop in Sicily, Italy. Near Villalba (Caltanissetta), a local lentil landrace, “Lenticchia di Villalba”, is commonly grown. From 2002 to 2004, wilt was observed in five lentil fields (≈1 ha each) at rates from 5 to 20%. Affected plants were yellow and stunted with discoloration in the vascular tissue of stems and crowns. Pieces of brown vascular tissue from stems were disinfested in 2% sodium hypochlorite for 2 min, rinsed with sterile distilled water, placed on potato dextrose agar, and incubated at 23°C. Isolates with morphological characteristics of Fusarium oxysporum Schlecht.:Fr. (2) were consistently recovered from affected plants. For molecular identification of five isolates, the rDNA internal transcribed spacer (ITS) region and a portion of the elongation factor EF-1α were sequenced using ITS5/4 and EF1/2 primers, respectively (1). Two sequences of the ITS region were obtained: a 468-bp sequence from isolates ER1259, ER1260, and ER1275 (submitted as GenBank Accession No. EU159118) and a 483-bp sequence from isolates ER1274 and ER1276 (submitted as GenBank Accession No. EU281661). The two sequences shared 93% similarity. A sequence homology search using the NCBI BLAST program revealed that the first sequence had 100% homology with the ITS sequences of more than 50 F. oxysporum isolates of various formae speciales in GenBank and the second shared 100% homology with the ITS sequences of five isolates of F. redolens Wollenw. (e.g., GenBank Accession No. X94169 of the strain CBS 360.87). Amplification of the EF-1α produced a sequence from isolates ER1274 and ER1276 (submitted as GenBank Accession No. EU281660) with 99 to 100% homology to sequences of F. redolens and a sequence from strains ER1259, ER1275, and ER1260 (submitted as GenBank Accession No. EU281659) with 100% homology to that of more than 50 F. oxysporum strains in GenBank. Although F. redolens and F. oxysporum are morphologically similar, recent molecular studies have shown that they are distinct and phylogenetically distant species (3). On the basis of genetic sequences, isolates ER1274 and ER1276 were identified as F. redolens. These isolates were evaluated for pathogenicity on lentil. For each isolate, 10 2-week-old seedlings of “Lenticchia di Villalba” were inoculated by submerging roots in a suspension of 2.5 × 106 conidia/ml for 10 min. Plants were put into separate tubes containing 70 ml of a nutritional liquid medium (7 ml of HydroPlus Olikani per liter; Yara, Nanterre, France) and incubated in a growth chamber at 20°C with 12 h of light per day. Seedlings dipped in sterile water served as the control treatment. The pathogenicity test was repeated twice. Inoculated seedlings started to wilt 1 week after inoculation and developed root rot and vascular discoloration. After 2 weeks, 70% of the inoculated plants were affected by both isolates and 40 and 10% died when inoculated with ER1274 and ER1276 isolates, respectively. F. redolens was consistently reisolated from the stems of wilted plants. Noninoculated plants remained healthy. Currently, only F. oxysporum f. sp. lentis Vasud. and Sriniv. has been reported as the cause of Fusarium wilt of lentil. To our knowledge, this is the first report of F. redolens as a pathogen on lentil. References: (1) R. P. Baayen et al. Phytopathology 91:1037, 2001. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, 1983. (3) K. O'Donnell et al. Mycologia 90:465, 1998.


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