FUSARIUM-ID v.3.0: An Updated, Downloadable Resource for Fusarium Species Identification

Genetic Diversity and Pathogenicity of the Fusarium Species Complex on Soybean in Serbia

Using morphological and cultural characteristics for identification, 36 Fusarium isolates were recovered from diseased roots, stems, and seeds of soybean from several localities throughout Vojvodina Province, Serbia. Based on molecular characterization, 12 Fusarium species were identified: F. acuminatum, F. avenaceum, F. commune, F. equiseti, F. graminearum, F. incarnatum, F. oxysporum, F. proliferatum, F. solani, F. sporotrichioides, F. subglutinans, and F. tricinctum. The elongation factor 1-α-based phylogeny grouped the isolates into 12 well-supported clades, but polymorphisms among sequences in some clades suggested the use of the species complex concept: (i) F. incarnatum-equiseti species complex (FIESC)-F. incarnatum and F. equiseti; (ii) F. oxysporum species complex (FOSC)-F. oxysporum; (iii) F. solani species complex (FSSC)-F. solani; and (iv) F. acuminatum/F. avenaceum/F. tricinctum species complex (FAATSC)-F. acuminatum, F. avenaceum, and F. tricinctum. Pathogenicity tests showed that the most aggressive species causing soybean seed rot were F. sporotrichioides, F. graminearum, FIESC, and F. avenaceum. Furthermore, F. subglutinans, FSSC, and F. proliferatum showed a high percentage of pathogenicity on soybean seeds (80 to 100%), whereas variability in pathogenicity occurred within isolates of F. tricinctum. FOSC, F. commune, and F. acuminatum had the lowest pathogenicity. To our knowledge, this is the first study of the characterization of Fusarium species on soybean in Serbia. This study provides valuable information about the composition of Fusarium species and pathogenicity that will be used in further research on soybean resistance to Fusarium-based diseases.

Pathogenicity, Host Resistance, and Genetic Diversity of Fusarium Species under Controlled Conditions from Soybean in Canada

Fusarium spp. are commonly associated with the root rot complex of soybean (Glycine max). Previous surveys identified six common Fusarium species from Manitoba, including F. oxysporum, F. redolens, F. graminearum, F. solani, F. avenaceum, and F. acuminatum. This study aimed to determine their pathogenicity, assess host resistance, and evaluate the genetic diversity of Fusarium spp. isolated from Canada. The pathogenicity of these species was tested on two soybean cultivars, 'Akras' (moderately resistant) and 'B150Y1' (susceptible), under greenhouse conditions. The aggressiveness of the fungal isolates varied, with root rot severities ranging from 1.5 to 3.3 on a 0-4 scale. Subsequently, the six species were used to screen a panel of 20 Canadian soybean cultivars for resistance in a greenhouse. Cluster and principal component analyses were conducted based on the same traits used in the pathogenicity study. Two cultivars, 'P15T46R2' and 'B150Y1', were consistently found to be tolerant to F. oxysporum, F. redolens, F. graminearum, and F. solani. To investigate the incidence and prevalence of Fusarium spp. in Canada, fungi were isolated from 106 soybean fields surveyed across Manitoba, Saskatchewan, Ontario, and Quebec. Eighty-three Fusarium isolates were evaluated based on morphology and with multiple PCR primers, and phylogenetic analyses indicated their diversity across the major soybean production regions of Canada. Overall, this study contributes valuable insights into host resistance and the pathogenicity and genetic diversity of Fusarium spp. in Canadian soybean fields.

Fungicide Sensitivity of Fusarium oxysporum f. sp. lentis and Fusarium acuminatum Affecting Lentil in the Northern Great Plains

Fusarium oxysporum f. sp. lentis and F. acuminatum cause wilting and root rot in pulse crops including lentil. Fungicide seed treatments are widely used, but information about Fusarium spp. sensitivity in lentils is limited. Here, 30 F. oxysporum f. sp. lentis and 30 F. acuminatum isolates from Montana, southern Canada, North Dakota, and Washington were identified, tested for pathogenicity, and assayed for in vitro sensitivity to pyraclostrobin, prothioconazole, ipconazole, and thiophanate-methyl. F. oxysporum f. sp. lentis and F. acuminatum differed in their sensitivity to all fungicides. No resistant isolates were identified, but F. oxysporum f. sp. lentis had lower EC50 values in pyraclostrobin (averaging 0.47 μg a.i./ml) than F. acuminatum (averaging 0.89 μg a.i./ml) for mycelia assays. Both species had lower EC50 values in prothioconazole, averaging EC50 0.23 in F. oxysporum f. sp. lentis and 0.53 μg a.i./ml in F. acuminatum. F. oxysporum f. sp. lentis isolates had the lowest EC50 values on ipconazole compared to F. acuminatum (0.78 and 1.49 μg a.i./ml). The pathogens were least sensitive to thiophanate-methyl (1.74 μg a.i./ml for F. oxysporum f. sp. lentis and 1.91 μg a.i./ml for F. acuminatum). Overall sensitivity to the fungicides was higher in F. oxysporum f. sp. lentis than F. acuminatum. This study provides reference EC50 values while pointing to the possibility of differential fungicide efficacies on Fusarium spp. This will be helpful to monitor shifts in sensitivity of Fusarium spp. and devise robust root rot/wilt management approaches.

Morphological and phylogenetic analyses reveal three new species of Fusarium (Hypocreales, Nectriaceae) associated with leaf blight on Cunninghamialanceolata in China

Chinese fir (Cunninghamialanceolata) is a special fast-growing commercial tree species in China with high economic value. In recent years, leaf blight disease on C.lanceolata has been observed frequently. The diversity of Fusarium species associated with leaf blight on C.lanceolata in China (Fujian, Guangxi, Guizhou, and Hunan provinces) was evaluated using morphological study and molecular multi-locus analyses based on RNA polymerase second largest subunit (RPB2), translation elongation factor 1-alpha (TEF-1α), and RNA polymerase largest subunit (RPB1) genes/region as well as the pairwise homoplasy index tests. A total of five Fusarium species belonging to four Fusarium species complexes were recognized in this study. Two known species including Fusariumconcentricum and F.fujikuroi belonged to the F.fujikuroi species complex, and three new Fusarium species were described, i.e., F.fujianense belonged to the F.lateritium species complex, F.guizhouense belonged to the F.sambucinum species complex, and F.hunanense belonged to the F.solani species complex. To prove Koch's postulates, pathogenicity tests on C.lanceolata revealed a wide variation in pathogenicity and aggressiveness among the species, of which F.hunanense HN33-8-2 caused the most severe symptoms and F.fujianense LC14 led to the least severe symptoms. To our knowledge, this study also represented the first report of F.concentricum, F.fujianense, F.fujikuroi, F.guizhouense, and F.hunanense causing leaf blight on C.lanceolata in China.

Didymella pinodella: An Important Pea Root Rot Pathogen in France to Watch Out For?

Root rot pathogens restrict pea and wheat production globally. In the EU, pea and pea-based cereal mixtures are being promoted; however, root rot pathogen dynamics in such mixtures are poorly understood. Winter pea and wheat were grown either in pure stands or in mixtures in the field in western France, and the severity of root rot in pea, wheat, and their mixtures, as well as the key pathogens associated with these crops, were assessed. Disease severity was moderate in pea and low in wheat, with no effect of sowing pattern. Didymella pinodella, a previously unreported pathogen in the pea-root rot complex in France, emerged as the most dominant pathogen in pea. It also occurred in low frequencies in wheat. Subsequent greenhouse aggressiveness tests showed that ten of the commonly grown pea cultivars in France lack resistance to D. pinodella. Among the Fusarium spp. isolated, F. avenaceum was the most frequent, occurring at similar frequencies in pea and wheat. In conclusion, D. pinodella may be an important pea root rot pathogen in France and there is a lack of resistance in the tested pea cultivars. In addition, F. avenaceum is a shared pathogen of wheat and pea.

Isolation and characterization of Fusarium spp. From unhatched eggs of Caretta caretta in Tuscany (Italy)

Sea Turtle Egg Fusariosis (STEF) is a worldwide emergent fungal disease affecting eggs and causing embryos mortality in turtle's nests such as those of Caretta caretta. It is caused by a complex of species belonging to Fusarium genus, particularly those included in the Fusarium Solani Species Complex (FSSC). During the samplings carried out in summer 2020 along the Tuscany coastlines (Italy), C. caretta eggs showed clinical signs resembling those caused by STEF. A total of 32 fungal isolates were obtained from lesioned eggs whose molecular characterization allowing identifying as belonging to FSSC / Neocosmospora spp., Fusarium oxysporum Species Complex (FOSC) / F. oxysporum and Fusarium nodosum, i.e., fungal genera and speciesincluding also well-known plant pathogens. Isolates inoculated on several plant hosts did not result in any pathogenic activity but F. nodosum causing, on wheat spikes, disease symptoms.This is the first time F. nodosum has been isolated from portions of eggs showing evident signs of fungal infection. This work represents the first report of Fusarium spp. isolated from C. caretta eggs showing lesions resembling those caused by STEF on Tuscan coast thus posing a significant concern to loggerhead sea turtle conservation also in this region.

Identification and Pathogenicity of Cladosporium, Fusarium, and Diaporthe spp. Associated with Late-Season Bunch Rots of Grape

Fungal pathogens continue to pose a significant threat to grape production. Previous studies of pathogens associated with late-season bunch rots in Mid-Atlantic vineyards had elucidated the primary causal agents of these diseases, but the significance and identity of the less commonly isolated genera was unclear. Therefore, to more fully understand the identity and pathogenicity of Cladosporium, Fusarium, and Diaporthe spp. associated with late-season bunch rots of wine grapes in the Mid-Atlantic, phylogenic analyses and pathogenicity assays were conducted. Isolates were characterized to the species level by sequencing the TEF1 and Actin, TEF1 and TUB2, and TEF1 genes for 10, 7, and 9 isolates of Cladosporium, Diaporthe, and Fusarium, respectively. Four Cladosporium, three Fusarium, and three Diaporthe species were identified, and C. allicinum, C. perangustum, C. pseudocladosporioides, F. graminearum, and D. guangxiensis had not yet been isolated from grape in North America. The pathogenicity of each species was evaluated on detached table and wine grapes, and D. eres, D. ampelina, D. guangxiensis, and F. fujikuroi were found to be the most aggressive on both table and wine grapes. Further investigations through more extensive isolate collection and of myotoxicity testing may be warranted due to the prevalence and pathogenicity of D. eres and F. fujikuroi.

Identification and Pathogenicity of Fusarium Isolated from Soybean in Poland

Fungi belonging to the Fusarium genus are commonly isolated from soybean plants and seeds but not all of them are pathogenic. The aim of this study was to compare the pathogenicity among different Fusarium isolates obtained from soybean plants with disease symptoms originating from an experimental field located in the southeast of Poland. Nineteen fungal isolates were selected for the pathogenicity assay, including eight isolates of F. oxysporum, six isolates of F. graminearum, four isolates of F. culmorum and one isolate of F. redolens. Species identification of these isolates was carried out using microscopic methods and sequencing of two genes: translation elongation factor 1-alpha (TEF1) and RNA polymerase second largest subunit (RPB2). To our knowledge, this is the first report of F. redolens being isolated from soybean in Europe. The pathogenicity test was set up by fungal inoculation of healthy soybean seeds of three cultivars: Abelina, Atlanta and Mavka. Symptoms were assessed seven days after inoculation. Disease area percentage of Fusarium inoculated seeds was significantly higher compared to uninoculated control. Nineteen isolates differed in their aggressiveness as the median disease area percentage ranged between 5.0 and 88.0% depending on isolate. The obtained isolates of four Fusarium species may be used in the future screening of soybean cultivars for resistance to these pathogens.

Identification of Fusarium Basal Rot Pathogens of Onion and Evaluation of Fungicides against the Pathogens

Onion (Allium cepa L.) is an economically important vegetable crop worldwide. However, various fungal diseases, including Fusarium basal rot (FBR), neck rot, and white rot, reduce onion production or bulb storage life. FBR caused by Fusarium species is among the most destructive onion diseases. In this study, we identified Fusarium species associated with FBR in Jeolla and Gyeongsang Provinces in South Korea and evaluated fungicides against the pathogens. Our morphological and molecular analyses showed that FBR in onions is associated with Fusarium commune, Fusarium oxysporum, and Fusarium proliferatum. We selected seven fungicides (fludioxonil, hexaconazole, mandestrobin, penthiopyrad, prochloraz-manganese, pydiflumetofen, and tebuconazole) and evaluated their inhibitory effects on mycelial growth of the pathogens at three different concentrations (0.01, 0.1, and 1 mg/mL). We found that prochloraz-manganese was highly effective, inhibiting 100% of the mycelial growth of the pathogens at all concentrations, followed by tebuconazole. Fludioxonil showed < 50% inhibition at 1 mg/mL for the tested isolates.

Fusarium diversity associated with diseased cereals in China, with an updated phylogenomic assessment of the genus

Fusarium species are important cereal pathogens that cause severe production losses to major cereal crops such as maize, rice, and wheat. However, the causal agents of Fusarium diseases on cereals have not been well documented because of the difficulty in species identification and the debates surrounding generic and species concepts. In this study, we used a citizen science initiative to investigate diseased cereal crops (maize, rice, wheat) from 250 locations, covering the major cereal-growing regions in China. A total of 2 020 Fusarium strains were isolated from 315 diseased samples. Employing multi-locus phylogeny and morphological features, the above strains were identified to 43 species, including eight novel species that are described in this paper. A world checklist of cereal-associated Fusarium species is provided, with 39 and 52 new records updated for the world and China, respectively. Notably, 56 % of samples collected in this study were observed to have co-infections of more than one Fusarium species, and the detailed associations are discussed. Following Koch's postulates, 18 species were first confirmed as pathogens of maize stalk rot in this study. Furthermore, a high-confidence species tree was constructed in this study based on 1 001 homologous loci of 228 assembled genomes (40 genomes were sequenced and provided in this study), which supported the "narrow" generic concept of Fusarium (= Gibberella). This study represents one of the most comprehensive surveys of cereal Fusarium diseases to date. It significantly improves our understanding of the global diversity and distribution of cereal-associated Fusarium species, as well as largely clarifies the phylogenetic relationships within the genus. Taxonomic novelties: New species: Fusarium erosum S.L. Han, M.M. Wang & L. Cai, Fusarium fecundum S.L. Han, M.M. Wang & L. Cai, Fusarium jinanense S.L. Han, M.M. Wang & L. Cai, Fusarium mianyangense S.L. Han, M.M. Wang & L. Cai, Fusarium nothincarnatum S.L. Han, M.M. Wang & L. Cai, Fusarium planum S.L. Han, M.M. Wang & L. Cai, Fusarium sanyaense S.L. Han, M.M. Wang & L. Cai, Fusarium weifangense S.L. Han, M.M. Wang & L. Cai. Citation: Han SL, Wang MM, Ma ZY, Raza M, Zhao P, Liang JM, Gao M, Li YJ, Wang JW, Hu DM, Cai L (2023). Fusarium diversity associated with diseased cereals in China, with an updated phylogenomic assessment of the genus. Studies in Mycology 104: 87-148. doi: 10.3114/sim.2022.104.02.

Characterization of root-associated fungi and reduced plant growth in soils from a New Mexico uranium mine

Characterizing the diverse, root-associated fungi in mine wastes can accelerate the development of bioremediation strategies to stabilize heavy metals. Ascomycota fungi are well known for their mutualistic associations with plant roots and, separately, for roles in the accumulation of toxic compounds from the environment, such as heavy metals. We sampled soils and cultured root-associated fungi from blue grama grass (Bouteloua gracilis) collected from lands with a history of uranium (U) mining and contrasted against communities in nearby, off-mine sites. Plant root-associated fungal communities from mine sites were lower in taxonomic richness and diversity than root fungi from paired, off-mine sites. We assessed potential functional consequences of unique mine-associated soil microbial communities using plant bioassays, which revealed that plants grown in mine soils in the greenhouse had significantly lower germination, survival, and less total biomass than plants grown in off-mine soils but did not alter allocation patterns to roots versus shoots. We identified candidate culturable root-associated Ascomycota taxa for bioremediation and increased understanding of the biological impacts of heavy metals on microbial communities and plant growth.

Diversity, Ecological Characteristics and Identification of Some Problematic Phytopathogenic Fusarium in Soil: A Review

The genus Fusarium includes many pathogenic species causing a wide range of plant diseases that lead to high economic losses. In this review, we describe how the Fusarium taxonomy has changed with the development of microbiological methods. We specify the ecological traits of this genus and the methods of its identification in soils, particularly the detection of phytopathogenic representatives of Fusarium and the mycotoxins produced by them. The negative effects of soil-borne phytopathogenic Fusarium on agricultural plants and current methods for its control are discussed. Due to the high complexity and polymorphism of Fusarium species, integrated approaches for the risk assessment of Fusarium diseases are necessary.

Specific Detection and Quantification of Major Fusarium spp. Associated with Cereal and Pulse Crops

Plant pathogenic Fusarium spp. are widespread and cause important diseases on a wide host range, including economically important cereal and pulse crops. A number of molecular methods have been used to detect, identify, and quantify a long list of plant pathogenic Fusarium spp. In general, these methods are much faster, highly specific, more sensitive, and more accurate than culture-based methods and can be performed and interpreted by personnel with no specialized taxonomical expertise. The accurate isolation and identification of these pathogens is required to effectively manage diseases caused by pathogenic Fusarium spp. In this chapter, we present detailed molecular methods for detection, quantification, and differentiation between many of the Fusarium spp. associated with cereal and pulse crops.

Evaluation of Pathogenic Fusarium spp. Associated with Soybean Seed (Glycine max) in Hubei Province, China

Soybean (Glycine max L.) seeds showing serious symptoms from rotted pods were collected from fields during the harvesting period (July to August 2020) in Taihu Farm, Jingzhou City, Hubei Province, China. Fusarium strains were frequently encountered during fungal isolation. According to the morphology and prepathogenicity tests, six strains showing variable effects on the seeds were selected for identification based on morphology and multilocus phylogenetic analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA, translation elongation factor (EF-1α), calmodulin (CAM), β-tubulin (TUB), and partial RNA polymerase second largest subunit (RPB2), and to evaluate the pathogenic abilities on seed, root, and pod. The results indicated that the strains contained two species (Fusarium fujikuroi and F. proliferatum) in the Fusarium fujikuroi species complex (FFSC) and two species (F. luffae and F. sulawense) from the Fusarium incarnatum-equiseti species complex (FIESC). The two species of FFSC were more aggressive than those of FIESC on soybean seed, root, and pod. Among the strains, F. proliferatum YZU 201408 exhibited the most pathogenicity on all tests, with 72.2 to 90% disease severity.

First report of Fusarium fujikuroi causes leaf spot in Polygonatum odoratum (Mill.) Druce in China

Polygonatum odoratum (Mill.) Druce, a member of Liliaceae, is one of the traditional Chinese herbal plants mainly used in Jilin, Hubei, Guangxi, Zhejiang, Liaoning, Hunan and Guangdong provinces. Leaf spot disease of P. odoratum was continuously observed in the Planting Demonstration Garden in Changsha (28 °48 N; 113° 34E), Hunan Province of China, in May 2021 and May 2022. The symptoms initially appeared as tiny reddish-brown spots and continued to expand, resulting in round, oval, or irregular tan lesions with necrotic, film-shaped, or perforated central tissues. Leaf spot disease affects approximately 60-70% of plants. For pathogen isolation, symptomatic leaf samples were collected and disinfected with 70% ethanol for 30 s and 3% sodium hypochlorite for 2 min, followed by rinsing with sterile distilled water. Subsequently, small pieces (3 × 3 mm) of diseased tissues were placed on potato dextrose agar (PDA) and incubated in the dark at 25 °C for 24 h to 36 h. The emerging fungal hyphal tips were transferred to PDA and purified by the single-spore method (Yu, et al., 202). In total, 50 disease spots were isolated, and 10 cultures with the same appearance were obtained. Two strains coded as hnxryzy and hnxryzy01 were randomly selected for identification. After 6 days of culture in PDA, dense pink colonies were observed with a mean radial growth rate of 7.5 mm/day. Strains cultured 6 days on synthetic low nutrient medium, microconidia were oval or ovate (7.5-9.67 µm × 2.49-3.57 µm(n = 50)), and macroconidia were sickle-shaped and slightly curved, gradually tapering at both ends, with 2-5 pseudoseptate (10.01-22.14 µm × 2.07-4.22 µm (n = 50)). These morphological characteristics were consistent with the description of Fusarium fujikuroi (Fang, et al., 2021). Furthermore, primers ITS1/ITS4, EF728F/EF986R, Bt2a/Bt2b, RPB1-F5/RPB1-R8 and fRPB2-5F2/fRPB2-7cR (Li, et al., 2013, Xie, et al., 2022) were used to amplify the partial region of the internal transcribed spacer (ITS) , the translation elongation factor EF-1α,β-tubulin,polymerase II largest subunit (RPB1) and RNA polymerase II second largest subunit (RPB2) genes from strains hnxryzy and hnxryzy01, respectively. Amplicons were sequenced by Tsingke Biotechnology Co., Ltd. The expected sequences of ITS, EF-1α, β-tubulin, RPB1 and RPB2 of hnxryzy and hnxryzy01 were obtained. The sequence alignment of hnxryzj and hnxryzj01 with the Fusarium ID databased and NCBI shows the following results: The sequences of ITS region, EF-1α, β-tubulin , RPB1 and RPB2 of strain hnxryzy (GenBank accession nos. ON797440, ON820553, ON820554, OP413443, and OP413445, respectively) and strain hnxryzy01 (GenBank accession nos. ON965284, ON968721, ON968722, OP413444, and OP413446, respectively) were 99% to 100% identical to those of F. fujikuroi (GenBank accession numbers CP023090, KC874784, MN490089, MN193916, and MN193888, respectively). Then a phylogenetic tree based on EF-1α, RPB1, and RPB2 sequences was constructed (Torres-Cruz, et al., 2022). The strains hnxryzy and hnxryzy01 were more closely related to F. fujikuroi ( NRRL13566 GenBank accession nos. AF160279, JX171456, and JX171570, respectively), with bootstrap values of 99%. Two sets (5 plants in each set) of potted plants were used in pathogenicity assays. Wounded leaves were sprayed with conidial suspensions (100 µL, 1 × 107 spores/mL) and sterile water as control. Inoculated plants were covered with plastic bags for 24 h, and maintained at 25 ° C in 12/12 h light/dark conditions in the greenhouse (Yu, et al., 2022). Pathogenicity assays were repeated thrice. Dark brown spots identical to those seen in the field were observed 14 days after inoculation, while the control leaves did not exhibit any symptoms. In this study, the pathogen F. fujikuroi was successfully reisolated from the leaves of inoculated samples showing symptoms, thereby verifying Koch's postulate. To our knowledge, this is the first report of F. fujikuroi inducing leaf spot on P. odoratum in China. Since F. fujikuroi is a common pathogenic fungus that infects different plant species(Qiu, et al., 2020), more attention should be paid to its prevalence in P. odoratum and the potential risk of outbreak in other provinces of China.

First report of Fusarium oxysporum causing stem spots on Polygonatum odoratum in China

Polygonatum odoratum (Mill.) Druce is a perennial herb in the Liliaceae family and it is one of the traditional Chinese medicinal plants. Modern pharmaceutical studies demonstrate that P. odoratum contains polysaccharides, saponins, alkaloids, flavonoids, volatile oil, and other active components (Jiang-Nan, et al., 2018). From May to June 2022, the stem spot disease was discovered on P. odoratum in the planting demonstration garden in Changsha (28°20N; 113°07E), Hunan province of China. The disease seriously retarded plant growth and was estimated to have affected approximately 40-50% of the plants, significant economic losses to growers. Plants had oval tan spots on the stems, which were light in the center and dark at the margin. The spots in the back expanded and joined together, where the disease was severe, and chlorosis was near the stem spot, while many leaves turned completely yellow and withered before falling to the ground. Finally, the whole plant faded to light green and dried up. In order to isolate pathogens, symptomatic stem samples (5×5 mm) were collected from the edges of the lesions and excised symptomatic tissues consisting of diseased and healthy parts were surface-sterilized with 2% solution of sodium hypochlorite (0.1% active ingredient of chlorine) for 1 min and 75% ethanol for 30 s. The samples were then washed thrice with sterile distilled water, air-dried on the sterile filter papers under aseptic conditions, and finally plated onto Potato Dextrose Agar (PDA) plates, which were incubated at 25 °C for 24 h to 36 h in the dark. Additionally, the emerging fungal hyphal tips were transferred to PDA and purified by the single-spore method. Next, forty plants with stem spots were isolated, and 8 cultures with the same appearance were obtained. Two strains coded hnxryzj and hnxryzj1 were randomly selected, for identification. With a mean radial growth rate of 7.5 mm/day, white and dense colonies were observed after 6 days of culture on PDA. After hnxryzj was cultured on SNA, microconidia were oval or ovate (9.25-14.8µm × 2.18-3.76µm), macroconidia were sickle-shaped and slightly curved, with 2-5 septa (21.52-23.49µm × 2.64-4.51µm (n = 50)). These morphological characteristics were consistent with the description of Fusarium oxysporum (Mirghasempour, et al., 2022) Furthermore, we amplified the partial region of the internal transcribed spacer (ITS) region, the translation elongation factors EF-1α, β-tubulin, polymerase II largest subunit (RPB1) and RNA polymerase II second largest subunit (RPB2) genes from strain hnxryzj and hnxryzj1, based on the primer pairs ITS1/ITS4, EF728F/EF986R, Bt2a/Bt2b, RPB1-F5/RPB1-R8 and fRPB2-5F2/fRPB2-7cR (Li, et al., 2013, Xie, et al., 2022), and amplicons were sequenced by Tsingke Biotechnology Co. Ltd. By sequence alignment, the ITS, EF-1α, β-tubulin , RPB1 and RPB2 of hnxryzj and hnxryzj1 were identical, respectively. The sequence alignment of hnxryzj and hnxryzj1 with the Fusarium ID database and NCBI shows the following results: the ITS region, EF-1α, RPB1 and RPB2 sequences of the strain hnxryzj (GenBank accession nos. ON872218, ON897740, OP467556 and OP467557) and hnxryzj1 (GenBank accession nos. OP071248, OP087208, OP467558 and OP467559) were 100% identical to those of F. oxysporum (GenBank accession nos. MZ890536, LC469784 , MT179509 and MW368380, respectively); whereas the β-tubulin sequences of the strain hnxryzj (GenBank accession nos. ON897741) and hnxryzj1 (GenBank accession nos. OP087207) were 96.9% identical to those of F.oxysporum (CBS144135 GenBank accession nos. MH485136). Subsequently, a phylogenetic tree was established combining EF-1α, RPB1, and RPB2. Strains hnxryzj and hnxryzj1 were F.oxysporum (JW257006 GenBank accession nos. MZ921883, MZ921657 and MZ921752)(Torres-Cruz, et al., 2022), with bootstrap values 100%. The pathogenicity test was carried out by placing mycelial discs obtained from colonies that had been actively growing on PDA for 6 days. In the pathogenicity test, two sets (5 plants in each set) of potted plants, whose stems were wounded, were taken. In one set (5 plants), the PDA cakes with F. oxysporum (d=5mm, the same below) were inoculated on the stems scratched by an inoculation needle (sterilized) (the front of the colony was close to the wound of the stem). In the other set (5 plants), potted plants inoculated with the sterile PDA cakes were served as controls. In a 25 °C greenhouse, each treatment was given a 12h/12h light/dark cycl(Nabi, et al., 2019). The symptoms were observed, and the fungus cake was removed 5 days after inoculation. Then, after 18 days, typical symptoms of oval tan spots similar to original diseased plants in the field were found on the inoculated stems, and 32 days later, the inoculated plant died, while the control stems remained asymptomatic. In addition, F. oxysporum was isolated and identified from the inoculated, symptomatic stems, verifying Koch's postulates. Based on our knowledge, this is the first report of F. oxysporum causing stem spots on P. odoratum in China. Only one other study from China that root rot of Phyllostachys officinalis also resulted from F. oxysporum (Pang, et al., 2022). Furthermore, P. odoratum is an medicinal material in Hunan province. Therefore, comprehensive prevention and control methods are required.

Global regulatory factor VeA upregulates the production of antitumor substances in endophytic Fusarium solani

A number of studies have demonstrated that endophytic fungi have the potential to produce antitumor active substances with novel structures and significant activities. In our previous studies, we isolated a Fusarium strain from the stem of the medicinal plant Nothapodytes pittosporoides (Oliv.). In this study, we identified this strain as Fusarium solani and found that its crude extract has significant antitumor activity against human alveolar adenocarcinoma cells (A549). We overexpressed the global regulatory factor VeA in F. solani (VeA^OE), resulting in a significant increase in antitumor activity. The MTT assay results showed that the inhibition rate of the VeA^OE mutant extract on A549 cancer cells was significantly higher than that of the WT extract, as the IC₅₀ decreased from 369.22 to 285.89 μg/mL, and the apoptosis ratio was significantly increased by approximately 4.86-fold. In VeA^OE, accumulation of alkaloids, terpenoids, carboxylic acid derivatives, phenols and flavonoid metabolites with potential antitumor activity was significantly increased compared with WT based on metabolomic analysis. Additionally, transcriptome analysis found that the expression patterns of 48 genes related to antitumor activity were significantly changed in VeA^OE, mainly involving glycosyl hydrolases, the Zn(2)-Cys(6) class, cytochrome P450 monooxygenase, 3-isopropylmalate dehydratase, and polyketide synthases. These results suggested that VeA mediated the antitumor activity of the metabolites in F. solani HB1-J1 by regulating multiple metabolic pathways.

DNA Sequence-Based Identification of Fusarium: A Work in Progress

Accurate species-level identification of an etiological agent is crucial for disease diagnosis and management because knowing the agent's identity connects it with what is known about its host range, geographic distribution, and toxin production potential. This is particularly true in publishing peer-reviewed disease reports, where imprecise and/or incorrect identifications weaken the public knowledge base. This can be a daunting task for phytopathologists and other applied biologists that need to identify Fusarium in particular, because published and ongoing multilocus molecular systematic studies have highlighted several confounding issues. Paramount among these are: (i) this agriculturally and clinically important genus is currently estimated to comprise more than 400 phylogenetically distinct species (i.e., phylospecies), with more than 80% of these discovered within the past 25 years; (ii) approximately one-third of the phylospecies have not been formally described; (iii) morphology alone is inadequate to distinguish most of these species from one another; and (iv) the current rapid discovery of novel fusaria from pathogen surveys and accompanying impact on the taxonomic landscape is expected to continue well into the foreseeable future. To address the critical need for accurate pathogen identification, our research groups are focused on populating two web-accessible databases (FUSARIUM-ID v.3.0 and the nonredundant National Center for Biotechnology Information nucleotide collection that includes GenBank) with portions of three phylogenetically informative genes (i.e., TEF1, RPB1, and RPB2) that resolve at or near the species level in every Fusarium species. The objectives of this Special Report, and its companion in this issue (Torres-Cruz et al. 2022), are to provide a progress report on our efforts to populate these databases and to outline a set of best practices for DNA sequence-based identification of fusaria.