First Report of Fusarium equiseti Associated on Pecan (Carya illinoinensis) Seeds in Brazil

Pecan [Carya illinoinensis (Wangenh.) K. Koch] is an important producing nut tree that has been intensively cultivated in the state of Rio Grande do Sul (Brazil) in recent decades. This species is commonly grown in association with other crops and more often with cattle or sheep. An elevated incidence of the fungal genus Fusarium was observed during a quality control seed assay of pecan seeds obtained from orchards in the city of Anta Gorda (28°53′54.7″ S, 52°01′59.9″ W). Concomitantly, seedlings of this species, cultivated in a nursery, showed foliar necrosis, wilt, and root rot. The fungus was thereafter isolated from the seeds (from original seeds lots) and subcultured from single spores. Cultures were purified in order to perform pathogenicity tests. The isolated Fusarium sp. was increased on autoclaved wet corn kernels that were incubated for 14 days (1), and then were mixed with commercial substrate (sphagnum turf, expanded vermiculite, dolomitic limestone, gypsum, and NPK fertilizer) in plastic trays (capacity 7 L), with drainage holes. Twenty seeds were sowed and 90 days later, evaluations were undertaken. Forty percent of the seedlings presented symptoms, i.e., foliar necrosis and wilt owing to root rot. Fusarium sp. was re-isolated from the affected roots by transferring hyphal tips to potato dextrose agar (PDA) and carnation leaf agar (CLA) medium in petri dishes in order to identify the species morphologically. On PDA, the colony pigmentation was yellowish brown and the aerial mycelium was whitish to peach; macroconidia were relatively long and narrow (31.75 × 4.02 μm), with 5 septa on average, and whip-like bent apical cells (2). Chlamydospores were not observed on PDA or CLA. Primer pairs ITS1 and ITS4 (3) and EF1-T and EF1-1567R (4) were employed to amplify the internal transcribed spacer (ITS) and elongation factor-1α (TEF 1-α) regions, respectively. The resulting DNA sequences showed 99% for ITS and 98% for TEF 1-α similarity with Fusarium equiseti (Corda) Sacc. and phylogenetic analysis grouped it with sequences of this species. The consensus sequence was submitted to GenBank and received the accession numbers KC810063 (ITS) and KF601580 (TEF 1-α). The pathogen was re-isolated on PDA and CLA substrate in order to complete Koch's postulates. The pathogenicity test was repeated with the same conditions described before and the results were confirmed. No symptoms were observed on the control seedlings. This species is considered a weak parasite (2); however, it has been reported causing wilt in Coffea arabica in Brazil (5). This pathogen could cause serious damage and high losses to seedling in commercial nurseries. Besides that, it could also carry the disease to the field causing further damage on established plants. To our knowledge, this is the first to report of F. equiseti causing foliar necrosis and wilt on C. illinoinensis in Brazil. References: (1) L. H. Klingelfuss et al. Fitopatol. Brasil. 32:1, 2007. (2) W. Gerlach and H. Nirenberg. The Genus Fusarium – a Pictorial Atlas. Biologische Bundesanstalt für Land- und Forstwirtschaft, Braunschweig, Germany, 1982. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications, Academic Press, San Diego, CA, 1990. (4) S. A. Rehner and E. A. Buckley. Mycologia 97:84, 2005. (5) L. H. Pfenning and M. F. Martins. Page 283 in: Simpósio de Pesquisa dos Cafés do Brasil, 2000.

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

Plant Disease ◽

10.1094/pdis-05-21-1123-pdn ◽

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.

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Morpho-molecular identification and first report of Fusarium equiseti in causing chilli wilt from Kashmir (Northern Himalayas)

Scientific Reports ◽

10.1038/s41598-021-82854-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ammarah Hami ◽

Rovidha S. Rasool ◽

Nisar A. Khan ◽

Sheikh Mansoor ◽

Mudasir A. Mir ◽

...

Keyword(s):

Dna Barcoding ◽

Pcr Amplification ◽

Its Region ◽

Fungal Species ◽

Pathogenicity Test ◽

Kashmir Valley ◽

Fusarium Equiseti ◽

Infected Root ◽

Fusarium Sp ◽

High Degree

AbstractChilli (Capsicum annuum L.) is one of the most significant vegetable and spice crop. Wilt caused by Fusarium Sp. has emerged as a serious problem in chilli production. Internal transcribed spacer (ITS) region is widely used as a DNA barcoding marker to characterize the diversity and composition of Fusarium communities. ITS regions are heavily used in both molecular methods and ecological studies of fungi, because of its high degree of interspecific variability, conserved primer sites and multiple copy nature in the genome. In the present study we focused on morphological and molecular characterization of pathogen causing chilli wilt. Chilli plants were collected from four districts of Kashmir valley of Himalayan region. Pathogens were isolated from infected root and stem of the plants. Isolated pathogens were subjected to DNA extraction and PCR amplification. The amplified product was sequenced and three different wilt causing fungal isolates were obtained which are reported in the current investigation. In addition to Fusarium oxysporum and Fusarium solani, a new fungal species was found in association with the chilli wilt in Kashmir valley viz., Fusarium equiseti that has never been reported before from this region. The studies were confirmed by pathogenicity test and re-confirmation by DNA barcoding.

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First Report of Lasiodiplodia theobromae Associated with Decline of Grapevine Rootstock Mother Plants in Spain

Plant Disease ◽

10.1094/pdis-92-5-0832b ◽

2008 ◽

Vol 92 (5) ◽

pp. 832-832 ◽

Cited By ~ 13

Author(s):

A. Aroca ◽

R. Raposo ◽

D. Gramaje ◽

J. Armengol ◽

S. Martos ◽

...

Keyword(s):

Elongation Factor ◽

Aerial Mycelium ◽

Its Region ◽

Pathogenic Fungi ◽

Vascular Lesions ◽

Malt Extract ◽

Pathogenicity Test ◽

Lasiodiplodia Theobromae ◽

First Report ◽

Mother Plants

A field of Richter 110 rootstock mother plants in Valencia Province (eastern Spain) was surveyed during November 2006 to study the mycoflora of declining plants. Two canes with stunted leaves were collected from a plant with a reduced number of shoots. No cankers or vascular lesions were observed in the collected canes. Six wood chips (1 to 2 mm thick) were taken from one basal fragment (3 to 4 cm long) of each cane, surface sterilized in 70% ethanol for 1 min, and plated on malt extract agar supplemented with 0.5 g L–1 of streptomycin sulfate. Petri dishes were incubated for 7 days at 25°C. A fungus was consistently isolated from all samples that showed the following characteristics: colonies grown on potato dextrose agar (PDA) at 25°C developed a white, aerial mycelium that turned gray after 4 to 6 days and produced pycnidia after 1 month on sterile grapevine slivers of twigs placed on the PDA surface; conidia from culture were ellipsoidal, thick walled, initially hyaline, nonseptate, and measuring 20 to 25 (22.5) × 12 to 14 (13) μm; aged conidia were brown, 1-septate with longitudinal striations in the wall; and pseudoparaphyses variable in form and length were interspersed within the fertile tissue. The fungus was identified as Lasiodiplodia theobromae (Pat.) Griffon & Maubl. from the above characteristics (2). Identity was confirmed by analysis of the nucleotide sequences of the internal transcribed spacer (ITS) region from the rRNA repeat and part of the translation elongation factor 1-alpha (EF1-α) and the β-tubulin (B-tub) genes, as done elsewhere (1,3). BLAST searches at GenBank showed a high identity with reference sequences (ITS: 100%, EF1-α: 97%; B-tub: 99%). Representative sequences of the studied DNA regions were deposited at GenBank (Accession Nos.: ITS: EU254718; EF1-α: EU254719; and B-tub: EU254720). A pathogenicity test was conducted on 1-year-old grapevine plants cv. Macabeo grafted onto Richter 110 rootstocks maintained in a greenhouse. A superficial wound was made on the bark of 10 plants with a sterilized scalpel, ≈10 cm above the graft union. A mycelial plug obtained from the margin of an actively growing fungal colony (isolate JL664) was placed in the wound and the wound was wrapped with Parafilm. Ten additional control plants were inoculated with sterile PDA plugs. All control plants grew normally, and the inoculation wound healed 3 months after inoculation. Plants inoculated with L. theobromae showed no foliar symptoms in the same period, but developed cankers variable in size surrounding the inoculation sites. Vascular necroses measuring 8.4 ± 1.5 cm (mean ± standard error) developed in the inoculated plants that were significantly longer than the controls (0.3 ± 0.2 cm). The pathogen was reisolated from all inoculated plants and no fungus was reisolated from the controls. These results confirmed the pathogenicity of L. theobromae to grapevine and points to a possible involvement of L. theobromae in the aetiology of grapevine decline as previously reported (3,4). To our knowledge, this is the first report of L. theobromae isolated from grapevine in Spain. References: (1) J. Luque et al. Mycologia 97:1111, 2005. (2) E. Punithalingam. No. 519 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1976. (3) J. R. Úrbez-Torres et al. Plant Dis. 90:1490, 2006. (4) J. M. van Niekerk et al. Phytopathol. Mediterr. 45(suppl.):S43, 2006.

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First Report of Fusarium sambucinum Associated on Pinus elliottii Seeds in Brazil

Plant Disease ◽

10.1094/pdis-11-12-1045-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 995-995 ◽

Cited By ~ 5

Author(s):

C. G. Maciel ◽

M. F. B. Muniz ◽

P. M. Milanesi ◽

M. Lazarotto ◽

E. Blume ◽

...

Keyword(s):

Apical Cell ◽

Elongation Factor ◽

Pinus Elliottii ◽

Quality Analysis ◽

Fungal Mycelium ◽

Pathogenicity Test ◽

Fusarium Sambucinum ◽

Damping Off ◽

Laboratory Manual ◽

Genus Fusarium

An elevated incidence of the fungal genus Fusarium was ascertained during a health quality analysis of a batch of Pinus elliottii Englm. seeds obtained from the Florestas Institute for Agricultural and Forest Research (Fundação Estadual de Pesquisa Agropecuária [FEPAGRO] Florestas) in Santa Maria (29° 39′ 55″ S and 53° 54′ 45″ W), state of Rio Grande do Sul, Brazil. This genus comprised about 75% of all fungal genera observed in a blotter test. The fungus was then isolated and purified to perform pathogenicity tests. Healthy seeds of P. elliottii were inoculated by contact with fungal mycelium for 48 h (3). Forty-two days after inoculation, a reduction was observed in the germination potential of the seeds; however, those seeds that germinated developed normally until, as seedlings, they suffered damping-off. Fusarium was isolated from the affected vegetal material by transferring mycelium tips to potato dextrose agar (PDA) medium in petri dishes in order to morphologically identify the species. After 72 h, a tan mycelial pad 5.5 cm in diameter had formed. After transfer to carnation leaf agar (CLA), pale orange sporodochia that formed macroconidia could be observed. The macronidia were relatively short and narrow (40.2 × 4.7 μm), each containing a mean of 5 septa; the apical cell was pointed, while the basal one was foot-shaped (2,4). The chlamydospores formed in clusters, while the conidiogenous cells could be seen on top of monophialides. Primer pairs ITS1 and ITS4, EF1-T and EF1-567R, and βtub-F and βtub were employed to amplify the three regions ITS1.8S ITS2, elongation factor – 1α (TEF 1-α), and β-tubulin, respectively. The sequences of these three regions showed 97, 95, and 99% of similarity with Fusarium sambucinum Fückel, respectively. The pathogen was reinoculated on P. elliottii seeds in order to complete Koch's postulates. The pathogenicity test was repeated with the same conditions described before and the results were confirmed. No occurrence of damping-off was observed in the control seedlings. The inoculated seedlings showed, besides damping-off, a visible reduction in root system expansion as well as reductions in fresh and dry tissue weight. F. sambucinum has already been reported on P. radiata D. Don in New Zealand, causing root rot and dieback (1); however, in Brazil, the present study is, to the best of our knowledge, the first to report the association of this pathogen with P. elliottii. References: (1) M. A. Dick and K. Dobbie. N. Z. Plant Prot. 55:58, 2002. (2) W. Gerlach and H. Nirenberg. The Genus Fusarium – A Pictorial Atlas. Biologische Bundesanstalt für Land – und. Forstwirtschaft, Berlin, 1982. (3) M. Lazarotto et al. Summa Phytopathol. 36:134, 2010. (4) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual, 1st ed. Wiley-Blackwell, Hoboken, NJ, 2006.

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Root Rot of Codonopsis tangshen Caused by Ilyonectria robusta In Chongqing, China

Plant Disease ◽

10.1094/pdis-09-21-2080-pdn ◽

2021 ◽

Author(s):

Zhenlei Zheng ◽

Jian Cao ◽

Yanyue Li ◽

Tingting Luo ◽

Tianhui Zhu ◽

...

Keyword(s):

Root Rot ◽

Elongation Factor ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Negative Control ◽

Vascular Bundles ◽

Conidial Suspension ◽

Potted Plants ◽

Light Yellow ◽

Agricultural Applications

Codonopsis tangshen Oliv. belongs to the Campanulaceae, it is one of the most important economically medicinal materials in China.Which is used in medical and agricultural applications (Wu Q N, et al. 2020). In August 2019, root rot of C. tangshen was firstly observed in Fengjie, Chongqing city, southwest China (30°45′ 59″ N; 109°36′36″ E; ), causing approximately 20% yield loss. At the initial stage of the disease, the above-ground stems and leaves turn yellow, and brown to black spots of different sizes appear at the base or root of the stem. With the further development of the disease, the above-ground leaves gradually turn yellow as the diseased spots rot from bottom to top, so that they die, and the diseased spots on the roots expand and begin to rot. Generally, they gradually rot from the bottom up, but the vascular bundles are occasionally normal. If the symptoms of C.tangshen started too late, and the root has not completely rotted by late autumn (late October to early November), the rest part of C.tangshen root will not continue to rot, and it is called half C.tangshen. In the next spring, the halfC. tangshen can continue to sprout, but it will continue to rot, which will seriously affect the yield and quality. In order to identify the pathogen, 25 samples of diseased plants were collected and symptomatic rhizome tissues were surface disinfected with 0.1% HgCl2 solution for 30s, rinsed in sterilized water 3 times, placed on potato dextrose agar (PDA), and incubated at 25℃±1°C in the dark. On the PDA, after seven days of culture, the center appeared light yellow, the edges were white, and the aerial hyphae were felt-like. The surface of the colony was reddish-brown and the margins were white and regular. The conidiophores were simple, usually born on the lateral or apical sides of aerial mycelium, unbranched, or minimally branched. Conidia were abundant, cylindrical, or rod-shaped, straight or slightly curved, usually with 1–3 septa. Macroconidia varied in size depending on the number of cells as follows: one-septate 15.3–26.3×4.2–7.3 μm（n=50）μm, two-septate 20.5-30.5×4.9-7.8μm (n=50), and three-septate 29.3–38.5×5.5–7.4 μm (n=50), round at both ends. For molecular identification, DNA was extracted from a representative isolate using a fungus genomic DNA extraction kit (Solarbio, Beijing, China). The internal transcribed spacer (ITS)(ITS1/ITS4, White, et al. 1990), beta-tubulin (TUB2)(BT2A/BT2B, O’Donnell and Cigelnik 1997), translation elongation factor 1-a (TEF) （ EF446F/EF1035R, Inderbitzin et al. 2005), DNA-dependent RNA polymerase subunit II gene(RPB2, O'Donnell K., et al. 2010 ) and histone H3(HIS3) (CYLH3F/CYLH3R, Crous, et al. 2004b) were amplified. BLAST results indicated that the ITS, TUB2, TEF, HIS3, and RPB2 sequences (GenBank MW392103, MW386994, MW386995 MW392103, and MW915473) showed 96% to 100% identity with Ilyonectria robusta sequences at NCBI (GenBank KU350726, JF335378, MN833103, MN833113, KM232336). The phylogenetic tree was inferred from the combined datasets (ITS, TEF1, TUB, and HIS3) from members of the I. robusta species complex analyzed in this study (Cabral et al. 2012 ). To complete Koch's postulates, a conidial suspension (106 spores/ml) collected from isolate CQ13 was irrigated onto fifteen annual C.tangshen potted plants. Sterile water was used as a negative control, and the pathogenicity assay was repeated three times. Following inoculation, the plants were cultured for 9 days at 75% relative humidity and 25 ℃. The inoculated plants showed symptoms similar to those observed in the field. In contrast, the negative control plants were healthy and unaffected. I. robusta was re-isolated from the infected tissues and identified by morphological characteristics and DNA sequence analysis. To our knowledge, this is the first report of I. robusta causing root rot disease of C.tangshen in China. Our results may help to take appropriate steps to control the disease in the commercial area of C.tangshen. The authors declare no conflict of interest.

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Occurrence of Fusarium commune and F. oxysporum in Horseradish Roots

Plant Disease ◽

10.1094/pdis-06-12-0538-re ◽

2013 ◽

Vol 97 (4) ◽

pp. 453-460 ◽

Cited By ~ 7

Author(s):

J. M. Yu ◽

M. Babadoost

Keyword(s):

Dna Sequences ◽

Root Rot ◽

Sequence Data ◽

Elongation Factor ◽

Small Subunit ◽

Conidial Suspension ◽

Data Set ◽

Dna Sequence Data ◽

Pathogenicity Tests ◽

Almost All

This study was conducted to investigate the etiology of internal discoloration of horseradish roots. Several species of Fusarium and Verticillium were isolated from internally discolored horseradish roots collected from commercial fields in Illinois and research plots in Wisconsin during 2008 and 2009. Eleven isolates of Fusarium, identified as Fusarium oxysporum based on morphological features, were characterized by DNA sequencing of the nuclear translation elongation factor 1α (EF-1α) and mitochondrial small-subunit ribosomal DNA (mtSSU rDNA). Maximum parsimony analyses of DNA sequences from these two regions and the combined data set revealed that six isolates were clearly separated into a common clade that contained F. commune, with the remaining five isolates being grouped into a common clade with F. oxysporum. Based on the DNA sequence data, we considered the six isolates grouped into a common clade with F. commune to be F. commune. Pathogenicity tests of F. commune and F. oxysporum were conducted on two horseradish cultivars, ‘1573’ and ‘Big Top Western’, in a greenhouse. Root segments were inoculated by dipping them in a conidial suspension and then growing them in pots in a greenhouse for 4 months. For plants inoculated with F. commune, internal root discoloration and root rot developed 1 month after inoculation and almost all roots of the plant were completely rotten 4 months after inoculation. Inoculation of the plants with F. oxysporum resulted in only internal root discoloration but not root rot symptoms. This is the first report of F. commune causing internal discoloration and root rot of horseradish.

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First Report of Root Rot of Pedunculate Oak and Other Forest Tree Species Caused by Phytophthora plurivora in the Czech Republic

Plant Disease ◽

10.1094/pdis-94-2-0272b ◽

2010 ◽

Vol 94 (2) ◽

pp. 272-272 ◽

Cited By ~ 2

Author(s):

M. Mrazkova ◽

K. Cerny ◽

M. Tomsovsky ◽

V. Holub ◽

V. Strnadova ◽

...

Keyword(s):

Czech Republic ◽

Dna Sequences ◽

Tree Species ◽

Root Rot ◽

Root Hairs ◽

Aerial Mycelium ◽

Pedunculate Oak ◽

The Czech Republic ◽

First Report ◽

Agar Plug

From 2006 to 2008, several similar Phytophthora isolates were obtained from roots of mature Quercus robur and other tree species (Acer platanoides, Fraxinus excelsior, Q. rubra, and Tilia cordata) in forests and parks in several areas in the Czech Republic. The trees were characterized by chlorotic and reduced foliage, crown dieback, and reduced root hairs. Several isolates of Phytophthora were obtained from necrotic roots of these trees and identified as Phytophthora plurivora Jung & Burgess (1). Isolated colonies grown on V8A medium were radiate to slightly chrysanthemum shaped with limited aerial mycelium in the center. Optimum growth was at 25°C, minimum at 5°C and maximum at 32°C. Radial growth of colonies averaged 6.4 mm/day at 20°C. The isolates were homothallic and produced abundant smooth-walled, spherical oogonia (23.3 to 29.1 μm in diameter), oospores were nearly plerotic or plerotic (21.8 to 26.9 μm in diameter), and the oospore wall was 1.2 to 1.4 μm thick. Antheridia were usually paragynous and measured 8.4 to 12 × 6.5 to 8 μm, but amphigynous antheridia were occasionally observed. Noncaducous, semipapillate sporangia formed on simple or sympodial sporangiophores, were obpyriform, ovoid, ellipsoid or irregular in shape, and occasionally distorted with more than one apex. Sporangia dimensions were 33 to 65 × 24 to 33 μm; L/B ratio 1.2 to 1.6 (–2.1). Comparison of DNA sequences of internal transcribed spacer (ITS) regions of isolates (representative strain GenBank Accession No. FJ952382) confirmed the 100% identity of P. plurivora (1). The soil infestation test was conducted using a P. plurivora isolate acquired from roots of Q. robur and 20 3-year-old plants of Q. robur. Sterilized millet seeds colonized by pathogen with the method as described (2) were used as inoculation medium and added into sterilized peat substrate at the rate of 0.5% (vol/vol). The plants were cultivated in 5.8-liter pots in a greenhouse (20°C, 16-h/8-h photoperiod). After 4 months, the roots of all plants were washed, dried, and weighed. The root biomass of 20 infected plants was significantly reduced by approximately 25% on average compared with the control 20 plants (P < 0.05, t-test, Statistica 7.1). The pathogen was consistently reisolated from the roots of infected plants but not from control plants. Stem inoculation tests were conducted with 20 replicates in each group of 2-year-old plants of oak, maple, ash, and lime and isolates acquired from the hosts. On each seedling, a 5-mm-diameter bark plug was removed 5 cm above the collar. The inoculum (5-mm-diameter V8A agar plug with actively growing mycelium) was applied to the exposed substrate. The wounds were sealed with Parafilm. Stem necrosis developed in all cases after 1 to 2 weeks, whereas control plants remained healthy. The pathogen was successfully reisolated from necrotic stem tissues. To our knowledge, this is the first report of P. plurivora causing root rot on oak, maple, ash, and lime in the Czech Republic. On the basis of the host range and distribution of P. plurivora in the Czech Republic, it can be assumed that, as elsewhere in Europe (1), this pathogen is widespread and is a common cause of decline of many tree species. References: (1) T. Jung and T. I. Burgess. Persoonia 22:95, 2009. (2) C. Robin et al. Plant Pathol. 50:708, 2001.

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Wilt, Crown, and Root Rot of Common Rose Mallow (Hibiscus moscheutos) Caused by a NovelFusariumsp.

Plant Disease ◽

10.1094/pdis-05-16-0717-re ◽

2017 ◽

Vol 101 (2) ◽

pp. 354-358 ◽

Cited By ~ 3

Author(s):

S. L. Lupien ◽

F. M. Dugan ◽

K. M. Ward ◽

K. O’Donnell

Keyword(s):

Rna Polymerase Ii ◽

Root Rot ◽

Molecular Phylogenetics ◽

Phylogenetic Analyses ◽

Elongation Factor ◽

Crown Rot ◽

Root And Crown Rot ◽

Fusarium Sp ◽

Crown And Root Rot ◽

Rot Disease

A new crown and root rot disease of landscape plantings of the malvaceous ornamental common rose mallow (Hibiscus moscheutos) was first detected in Washington State in 2012. The main objectives of this study were to complete Koch’s postulates, document the disease symptoms photographically, and identify the causal agent using multilocus molecular phylogenetics. Results of the pathogenicity experiments demonstrated that the Fusarium sp. could induce vascular wilt and root and crown rot symptoms on H. moscheutos ‘Luna Rose’. Maximum-likelihood and maximum-parsimony phylogenetic analyses of portions of translation elongation factor 1-α and DNA-directed RNA polymerase II largest and second-largest subunit indicated that the Hibiscus pathogen represents a novel, undescribed Fusarium sp. nested within the Fusarium buharicum species complex.

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First Report of Fusarium redolens Causing Root Rot of Soybean in Minnesota

Plant Disease ◽

10.1094/pdis-94-8-1069b ◽

2010 ◽

Vol 94 (8) ◽

pp. 1069-1069 ◽

Cited By ~ 10

Author(s):

J. C. Bienapfl ◽

D. K. Malvick ◽

J. A. Percich

Keyword(s):

Root Rot ◽

Fusarium Species ◽

Apical Cell ◽

Elongation Factor ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Pathogenic Fungi ◽

The United States ◽

First Report ◽

Root Necrosis

Multiple Fusarium species have been found in association with soybean (Glycine max) plants exhibiting root rot in the United States (3). Soybean plants that lacked apparent foliar symptoms, but exhibited 2- to 5-mm brown, necrotic taproot lesions and lateral root necrosis were observed in Minnesota in one field each in Marshall and Otter Tail counties in July of 2007, as well as in one field in Marshall County in July of 2008. Sampling was conducted as part of a study investigating root rot in major soybean-production areas of Minnesota. Plants were arbitrarily dug up at the R3 growth stage. Root systems were washed, surface disinfested in 0.5% NaOCl for 3 min, rinsed in deionized water, and dried. Fusarium isolates were recovered from root sections with necrotic lesions embedded in modified Nash-Snyder medium (1). One resulting Fusarium colony from one plant per county was transferred to half-strength acidified potato dextrose agar (PDA) and carnation leaf agar (CLA) to examine morphological characteristics (4). Culture morphology on PDA consisted of flat mycelium with sparse white aerial mycelium. On CLA, thick-walled macroconidia with a hooked apical cell and a foot-shaped basal cell were produced in cream-colored sporodochia. Macroconidia ranged from 32.5 to 45.0 μm long. Microconidia were oval to cylindrical with 0 to 1 septa, ranged from 7.5 to 11.25 μm long, and were produced on monophialides. Chlamydospores were produced abundantly in chains that were terminal and intercalary in the hyphae of 4-week-old cultures. Morphological characteristics of the three isolates were consistent with descriptions of F. redolens (2,4). The identity of each isolate was confirmed by sequencing the translation elongation factor 1-α (TEF) locus (4). BLAST analysis of the TEF sequences from each isolate against the FUSARIUM-ID database resulted in a 100% match for 17 accessions of F. redolens (e.g., FD 01103, FD 01369). Each F. redolens isolate was tested for pathogenicity on soybean. Sterile sorghum grain was infested with each isolate and incubated for 2 weeks. Sterile sorghum was used for control plants. Soybean seeds of cv. AG2107 were planted in 11.4-cm pots ~1 cm above a 25-cm3 layer of infested sorghum or sterile sorghum. Two replicate pots containing four plants each were used per treatment and the experiment was repeated once. Root rot was assessed 28 days after planting. Each F. redolens isolate consistently caused taproot necrosis on inoculated plants, whereas control plants did not exhibit root necrosis. Isolations were made from roots of inoculated and control plants and the isolates recovered from inoculated plants were identified as F. redolens based on morphological characteristics and TEF sequences. Fusarium species were not isolated from control plants. To our knowledge, this is the first report of F. redolens causing root rot of soybean; however, it is possible F. redolens has been found previously and misidentified as F. oxysporum (2,4). Results from inoculations suggest that F. redolens may be an important root rot pathogen in Minnesota soybean fields. References: (1) J. C. Bienapfl et al. Acta Hortic. 668:123, 2004. (2) C. Booth and J. M. Waterston. No. 27 in: CMI Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, England, 1964. (3) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathological Society, St. Paul, MN, 1999. (4) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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First Report of Lasiodiplodia theobromae Causing Branch Dieback on Castor Bean in Zhanjiang, China

Plant Disease ◽

10.1094/pdis-08-20-1723-pdn ◽

2021 ◽

Author(s):

Jian Rong Tang ◽

Yue Lian Liu ◽

Xue Gui Yin ◽

Jian Nong Lu ◽

Yu Han Zhou

Keyword(s):

Castor Bean ◽

Ricinus Communis ◽

Elongation Factor ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Molecular Data ◽

Pathogenicity Test ◽

First Report ◽

Branch Dieback ◽

Β Tubulin

Castor bean (Ricinus communis L.) is an oil crop of significant economic importance in the industry and medicine. In August 2019, a branch dieback disease was observed on castor bean in a field in Zhanjiang (21.17°N, 110.18°E), China. The incidence rate was 35% (n=600 investigated plants). Symptoms were discoloration of leaves, branch dieback, and discoloration of internal stem tissues. The disease had spread to the whole branches and causing the plant to die. Seven diseased branches were collected from seven plants. Margins between healthy and diseased tissues were cut into 2 mm × 2 mm pieces. The surfaces were disinfested with 75% ethanol for 30 s and 2% sodium hypochlorite for 60 s. Then, the samples were rinsed thrice in sterile water, placed on PDA, and incubated at 28 °C. Pure cultures were obtained by transferring the hyphal tips to new PDA plates. Eighteen isolates were obtained (the isolate rate of 75%), which were the same fungus on the basis of morphological characteristics and molecular analysis of the internal transcribed spacer (ITS). A single representative isolate (RiB-1) was used for further study. The colony of RiB-1 was 5 cm in diameter on the 5th day on the PDA culture. The colony was greenish gray with an irregularly distributed and fluffy aerial mycelium, which turned black after 10 days. The mature conidia were 21.3–26.5 µm × 12.2–15.7 µm in size (n=100) and had two ovoid, dark brown cells with longitudinal striations. The morphological characteristics of the colonies were consistent with the description of Lasiodiplodia sp. (Alves et al. 2008). Three regions of the ITS, translation elongation factor (EF1-α), and β-tubulin genes were amplified and sequenced with the primer pairs ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Alves et al. 2008), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. The resulting sequences were deposited in the GenBank under accession numbers MN759432 (ITS), MN719125 (EF1-α), and MN719128 (β-tubulin). BLASTn analysis demonstrated that these sequences were 100% identical to the corresponding ITS (MK530052), EF1-α (MK423878), and β-tubulin (MN172230) sequences of L. theobromae. Based on the morphological and molecular data, RiB-1 was determined as L. theobromae. A pathogenicity test was performed in a greenhouse with 80% relative humidity at 25 °C to 30 °C. Ten healthy plants of Zi Bi No. 5 castor bean (1-month-old) were grown in pots with one plant in each pot. Five pots were wound-inoculated with 5-mm-diameter mycelial plugs obtained from 7-day cultures. Five additional pots treated with PDA plugs served as the controls. Inoculated stems were moisturized with sterile cotton for five days. The test was conducted three times. Disease symptoms, similar to those in the field, were observed on the inoculated plants two weeks after inoculation, and L. theobromae was 100% reisolated from the inoculated plants. The control plants remained symptomless, and reisolations were unsuccessful. These results consistent with Koch’s postulates. L. theobromae (Lima et al. 1997) and L. hormozganensis (Fábio et al. 2018) had been reported to cause stem rot on castor bean in Brazil, but whether L. theobromae caused the branch dieback on castor bean in China has not been reported yet. Thus, this study is the first report of L. theobromae causing the branch dieback on castor bean in Zhanjiang, China. This study provides an important reference for the control of the disease.

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