Morphological and Molecular Characterization of Fusarium solani Isolates

Fusarium solani is a species complex (FSSC) containing isolates that cause diseases in important crops such as root and fruit rot of Cucurbita spp., root and stem rot of pea, sudden death syndrome of soybean, foot rot of bean and dry rot of potato tubers during storage. Based on host range tests, F. solani were subdivided into different formae specialis (f. sp.) and varieties, while DNA sequences of 28S rDNA, internally transcribed spacers (ITS) rDNA and elongation factor (EF-1α) distinguished the ' F. solani complex' in 50 subspecific lineages. In this study we characterized, by cultural, morphological and molecular criteria, 34 isolates of F. solani obtained from potato, other crops and soil. The 34 isolates in the FSSC showed wide variability for their cultural, morphological and molecular traits. The wide variability observed with amplified fragment-length polymorphism (AFLP) and mini-microsatellite analyses is in agreement with the polymorphism observed, in a previous study, within FSSC. Nine of 34 isolates in the FSSC, classified as F. solani var. coeruleum , were morphologically distinguishable from the other F. solani isolates but they were distributed in different clusters; moreover, the nine isolates showed instability of the coeruleum pigmentation of the colonies, supporting the ambiguity of the taxa of this variety of F. solani. Using sequence data from ITS plus 5.8S rDNA region, the isolates were classified into different clades. In particular eight isolates were classified into a well-supported clade including F. solani f. sp . pisi , nine into a clade including only isolates of F. solani f. sp . radicicola and four into a clade including F. solani f. sp . cucurbitae , but this classification could not be used if is not in agreement with host specificity. Two of the nine F. solani var. coeruleum isolates were phylogenetically distinct from all the other FSSC strains.     

Regional Enteritis: Disease Patterns and Medical Management

The clinical picture of regional enteritis was reviewed in 98 cases collected from five hospitals in the City of Edmonton. There was no apparent racial prevalence, although only one case was reported among Indians and Eskimos. More than one-half had their onset between the ages of 11 and 30 years. Men were more commonly affected than women. The onset in 44 patients was acute and closely mimicked acute appendicitis. Twenty-eight patients had had abdominal surgery prior to the onset of symptoms. Major symptoms were abdominal pain, diarrhea and weight loss. Abdominal tenderness, fever and abdominal mass were the most consistent physical signs. The most valuable diagnostic procedure was radiological examination of the bowel. Complications were largely confined to the gastrointestinal tract. In the majority of cases, surgery was the ultimate form of therapy.     

牛蒡根际土壤致害菌Fusarium solani分离鉴定

目的：探索牛蒡根际镰刀菌与牛蒡之间的相互关系。方法：从全国30个地区采集牛蒡根际土壤样品,进行了根际土壤真菌数量和群落的生态学研究,测定镰刀菌发酵液对牛蒡幼苗和牛蒡子萌发的影响,并对其中毒性最强的两株镰刀菌F130和F131进行了形态学和分子生物学的鉴定。结果：镰刀菌为牛蒡根际的最优势类群,贡献率为34.297%,其次为木霉,贡献率为22.519%;绝大多数镰刀菌对牛蒡有明显的毒性作用,其中F130和F131被鉴定为Fusarium solani。结论：Fusarium solani是牛蒡根际土壤中的致害菌。     

Hydrolytic Activities of Fusarium solani and Fusarium solani f. sp. eumartii Associated with the Infection Process of Potato Tubers

The development of dry rot caused by Fusarium solani f. sp. eumartii was evaluated in susceptible (Huinkul) and resistant (Spunta) potato cultivars. Fungal proteolytic and polygalacturanase activities were measured at different days postinoculation either with the pathogenic F. solani f. sp. eumartii, isolate 3122 or with the non‐pathogenic F. solani, isolate 1042. After inoculation with the pathogenic fungus, proteolytic and polygalaturonase activities were higher in the susceptible than in the resistant cultivar. In addition, we found a correlation between the levels of proteolytic activity detected in the intercellular washing fluids with the size of the lesion area caused by F. solani f. sp. eumartii in Huinkul tubers. The action of the proteolytic activity over cell wall proteins of both potato cultivars was assayed. An extracellular potato protein with homology to proteinase inhibitors of the Kunitz family was identified as a substrate of the proteolytic activity in the susceptible cultivar. A microscopic study revealed differences between the potato genotypes in the rate of response to infection by F. solani f. sp. eumartii. In addition, the cell wall alteration caused by F. solani f. sp. eumartii in cortical cells of susceptible tubers was evaluated. The data with respect to the correlation between the course of cyto‐ and biochemical events of the two host–pathogen interactions were discussed.     

Guava Decline: A Complex Disease Involving Meloidogyne mayaguensis and Fusarium solani

In Brazil, Meloidogyne mayaguensis has become a threat to guava production. Approximately a third of the cultivated area is infested, leading almost inevitably to the decimation of the orchards. Because parasitized trees develop rotten roots as the disease progresses, the possibility that a soil‐borne pathogen could be involved was investigated. From several nematode‐free or nematode‐infested orchards, nearly 2000 root fragments were tested for bacteria and fungi. Positive isolations were obtained from nematode‐infested areas only and were predominantly identified as Fusarium sp. In a 5‐month microplot experiment, guava seedlings were uninoculated (control) or were inoculated with M. mayaguensis only or with this nematode and 21 days later with one of 11 Fusarium sp. isolates. A Scott–Knot analysis of several vegetative variables and of the extent of root rot allowed the generation of a dissimilarity dendrogram that indicated that four Fusarium sp. isolates were particularly associated with damage to the seedlings. Upon identification of these isolates as Fusarium solani, a 6‐month microplot experiment was set up, in which guava seedlings were uninoculated or were inoculated with one of the following: (i) M. mayaguensis only, (ii) four F. solani isolates, separately, (iii) four F. solani isolates separately, combined with physical injury of the roots with a knife, (iv) M. mayaguensis, and 21 days later with four F. solani isolates, separately. No root rot and virtually no effect on all variables were observed in the seedlings inoculated with the fungus isolates, with or without physical injury. Major root rot and a negative effect on all variables were observed in the seedlings inoculated with M. mayaguensis and all four F. solani isolates. This characterizes guava decline as a complex disease caused by the synergistic effect of these organisms, in which parasitism by the nematode predisposes the plants to root decay caused by the fungus.     

Computer Identification of Bacteria on the Basis of Their Antibiotic Susceptibility Patterns

A computer program utilizing a Baysean mathematical model was developed to identify bacteria solely on the basis of their antibiotic sensitivities. The model contains probability data on the antibiotic sensitivity patterns for 31 species of bacteria, which account for over 99% of all isolates submitted to our laboratory for testing. During a 4-month test period, antibiotic sensitivity data on 1,000 clinical isolates were processed by the program. The identification achieved by using the model was the same as that of the laboratory for over 86% of the isolates.     

Purification and characterization of nitrilase from Fusarium solani IMI196840

Nitrilase activity in Fusarium solani IMI196840 (approx. 1500 U l⁻¹ of culture broth) was induced by 2-cyanopyridine. The enzyme was purified by a factor of 20.3 at a yield of 26.9%. According to gel filtration, the holoenzyme was an approx. 550-kDa homooligomer consisting of subunits with a molecular weight of approximately 40 kDa, as determined by SDS-PAGE. Mass spectrometry analysis of the tryptic fragments suggested a high similarity of this enzyme to the hypothetical CN hydrolases from Aspergillus oryzae, Gibberella zeae, Gibberella moniliformis and Nectria haematococca. Circular dichroism and fluorescence spectra indicated that secondary structure content and overall tertiary structure, respectively, were almost identical in nitrilases from F. solani IMI196840 and F. solani O1. The melting temperatures of the enzymes were 49.3 °C and 47.8 °C, respectively. The best substrates for the purified nitrilase from F. solani IMI196840 were benzonitrile and 4-cyanopyridine, which were hydrolyzed at the rates of 144 and 312 U mg⁻¹ protein, respectively, under the optimum conditions of pH 8 and 45 °C. The enzyme was highly chemoselective, producing ≤2% amides as by-products.     

Formation of trichothecenes by Fusarium solani var. coeruleum and Fusarium sambucinum in potatoes.

Fusarium solani var. coeruleum can form deoxynivalenol in potato tubers and in liquid medium, although concentrations observed in the rot were highly variable; acetyldeoxynivalenol and HT-2 toxin were detected in 1 to 3 tubers only (of 57). Trichothecenes were also detected in a very few (3 of 20) cultures of Fusarium sambucinum in potato tubers.     

Herbicide Transformation: I. Studies with Whole Cells of Fusarium solani

A strain of Fusarium solani isolated from soil by enrichment techniques used propanil (3′, 4′-dichloropropionanilide) as a sole source of organic carbon and energy for growth in pure culture. The primary product of the transformation of propanil by F. solani was isolated and identified as 3,4-dichloroaniline (DCA). This compound accumulated in the medium to a level (80 μg/ml) which stopped further herbicide utilization. Herbicide utilization by F. solani was influenced by various environmental and nutritional factors. It was more sensitive to acid than alkaline pH. Added glucose and yeast extract increased the rate of propanil decomposition, and the reduced aeration retarded growth of the fungus and herbicide utilization. The growth of F. solani on propionate was inhibited by added DCA.     

Herbicide Transformation: II. Studies with an Acylamidase of Fusarium solani

A strain of Fusarium solani isolated from soil by enrichment techniques used propanil (3′, 4′-dichloropropionanilide) as a sole source of organic carbon and energy for growth in pure culture. The primary product of the transformation of propanil by F. solani was isolated and identified as 3,4-dichloroaniline (DCA). This compound accumulated in the medium to a level (80 μg/ml) which stopped further herbicide utilization. Herbicide utilization by F. solani was influenced by various environmental and nutritional factors. It was more sensitive to acid than alkaline pH. Added glucose and yeast extract increased the rate of propanil decomposition, and the reduced aeration retarded growth of the fungus and herbicide utilization. The growth of F. solani on propionate was inhibited by added DCA.     

Differentiation of Fusarium oxysporum from Fusarium solani by growth and pigmentation on media containing sugar alcohols

The growth and pigmentation of 99 strains of Fusarium , mainly of Fusarium oxysporum and F. solani , on ammonium salts agar containing either mannitol, sorbitol or xylitol as sole source of carbon is described. After 7–14 d incubation strains of F. oxysporum could be distinguished from F. solani by both their pigmentation and the size and shape of conidiogenous cells. The application of these media to routine screening of isolates is discussed.     

小麦赤霉病新抗源的发掘与抗性位点的检测分析

小麦赤霉病是由禾谷镰刀菌引起的世界性重要病害,发掘优异的抗性种质资源、培育抗病品种是持续防治赤霉病最经济且环境友好的措施。为发掘新的赤霉病抗源,本研究于2017—2021年在弥雾保湿大棚中,采用单花滴注法对642份小麦种质资源的赤霉病抗扩展性进行鉴定,同时利用已知抗赤霉病基因/位点Fhb1~Fhb7的分子标记对筛选出的抗性种质基因型进行分析。结果表明,不同年份间赤霉病病小穗率的相关性均达到极显著水平。筛选到3年及以上赤霉病抗性优于扬麦158的种质81份,主要来自长江中下游麦区,其中33份种质连续4年抗性优于扬麦158;筛选到3年及以上抗性与苏麦3号相当的种质9份,分别为望水白、Grandin、浩麦1号、剑子麦、魁小麦、农林26、软秆洋麦、苏麦2号和武农6号,其中剑子麦、软秆洋麦、苏麦2号和Grandin连续4年抗性与苏麦3号相当。对抗性种质携带的抗赤霉病基因/位点进行分析发现,浩麦1号、冀师7225-28、南农13Y110、石优17和武农6号不携带任何已知抗赤霉病基因/QTL,为小麦抗赤霉病研究和品种培育提供了新的种质资源和理论依据。     

Chemical modification results in hyperactivation and thermostabilization of Fusarium solani glucoamylase

Chemical modification of carboxyl groups of glucoamylase from a mesophilic fungus, Fusarium solani, was carried out using ethylenediamine as nucleophile in the presence of water-soluble 1-ethyl-3(3-dimethylaminopropyl)carbodiimide. Modification brought about a dramatic enhancement of catalytic activity and thermal stability of glucoamylase. Temperature and pH optima of ethylenediamine-coupled glucoamylase (ECG) increased as compared with those of native enzyme. The specificity constant (k(cat)/K(m)) of native, ECG-2, ECG-11, and ECG-17 was 136, 173, 225, and 170, respectively, at 55 degrees C. The enthalpy of activation (Delta H*) and free energy of activation (Delta G*) for soluble starch hydrolysis were lower for the chemically modified forms. All of the modified forms were stable at higher temperatures and possessed high Delta G* against thermal unfolding. The effects of alpha-chymotrypsin and subtilisin on the modified forms were activating as compared with native. Moreover, denaturation of ECG-2, ECG-11, and ECG-17 in urea at 4 mol x L(-1) also showed an activation trend. A possible explanation for the thermal denaturation of native and increased thermal stability of ECG-2, ECG-11, and ECG-17 at higher temperatures is also discussed.     

Mycotic Keratitis Caused by <Emphasis Type="Italic">Fusarium solani sensu stricto</Emphasis> (FSSC5): A Case Series

Owing to a lack of appropriate diagnostic and therapeutic approaches for mycotic keratitis, approximately one million cases of preventable corneal blindness are reported each year. The number of keratitis cases due to infection with Fusarium is increasing significantly worldwide, many of which are not treated adequately and in a timely manner due to frequent misdiagnosis. In the current report, we describe three cases of keratitis caused by Fusarium solani sensu stricto (FSSC5) from Turkey and The Netherlands, following ocular trauma. The etiological agent of keratitis, FSSC5, identified by sequencing of the partial tef1-α gene, exhibited low minimum inhibitory concentrations (MICs) of 1 µg/mL for amphotericin B and high MICs above the published epidemiological cutoff values for voriconazole (8 µg/mL). Patients were successfully treated with topical amphotericin B and voriconazole with complete recovery.