Molecular identification and pathogenicity of Fusarium and Alternaria species associated with root rot disease of wolfberry in Gansu and Ningxia provinces,China

Wolfberry (Lycium barbarum) ranks in the top 10 best-selling medicinal plants in China and it has been used for centuries as a medicine and a food supplement. It is suggested to have benefits on human health due to the rich content of polysaccharides, carotenoids, flavonoids, and alkaloids contained in its fruits, leaves, and root bark. Recently, severe root rot diseases have been causing plant losses in major growing areas. Here, we report fungi causing root rot disease in Chinese wolfberry plants. The analysis of nucleotide sequences of the internal transcribed spacer (ITS) region revealed a total of 92 isolates isolated from both soil and plant material samples. Fusarium spp. were the most abundant (58%), followed by Penicillium spp. (9%), and Alternaria spp. (5%). Fusarium spp. included F. oxysporum (36%), F. solani (30%), F. chlamydosporum (9%), F. nematophilum (9%), and F. tricinctum (8%). Sequences from the translation elongation factor 1-α gene (TEF-1α) were used to confirm the identity of Fusarium spp. and showed the predominance of F. oxysporum and F. solani. To confirm the pathogenicity of isolates, four isolates belonging to Fusarium spp. and one isolate belonging to Alternaria spp., isolated from wolfberry root tissues with root rot symptoms, were tested in outdoor and laboratory conditions. Results revealed that the five tested isolates were pathogenic with varying degrees of aggressiveness and ability to induce symptoms of root rot in wolfberry seedlings. The five isolates were recovered from inoculated seedlings, completing Koch's postulates. This is the first report on causative agents of root rot in Chinese wolfberry.     

Fusarium Redolens f.sp asparagi, Causal Agent of Asparagus Root Rot, Crown Rot and Spear Rot

Two Fusarium species, F. oxysporum f.sp. asparagi and F. proliferatum, are known to be involved in the root and crown rot complex of asparagus. We have investigated reports on the involvement of F. redolens, a third species, which until recently was considered conspecific with F. oxysporum because of morphological similarities. RFLP analysis of the rDNA internal transcribed spacer region and AFLP fingerprinting identified eight strains from asparagus unambiguously as F. redolens. Four of these were tested and found to be pathogenic to asparagus either in this study (two strains) or in a previous one in which they were classified as F. oxysporum (three strains). Disease symptoms and disease development were the same as with F. oxysporum f.sp. asparagi and F. proliferatum. Present data and literature reports identify F. redolens as a host-specific pathogen involved in root, crown and spear rot of asparagus. The pathogen is formally classified as F. redolens Wollenw. f.sp. asparagi Baayen.     

Identification of fungal pathogens and analysis of genetic diversity of Fusarium tricinctum causing root rots of alfalfa in north-east China

Alfalfa root rot is a devastating disease complex found worldwide. Population structure and genetic diversity of fungal pathogens causing alfalfa root rot in north-east China are not well understood. In this study, 480 fungal isolates were collected from six major alfalfa-growing regions in Heilongjiang province, China. They were identified as Fusarium tricinctum, F. oxysporum, F. acuminatum, F. solani, F. equiseti, Phoma medicaginis, Plectosphaerella cucumerina, Alternaria alternata, and Chaetomium globosum and caused root rot on alfalfa in greenhouse studies. F. tricinctum was the predominant species among the isolates, and P. medicaginis and C. globosum had not previously been reported causing alfalfa root rot in north-east China. Of the 73 F. tricinctum isolates identified, the majority were moderately or highly aggressive on alfalfa. No isolate of F. tricinctum was sensitive to carbendazim (1 and 10 μg/ml), indicating that, although commonly used, it is not suitable for management of the disease in this area. F. tricinctum isolates were analysed using AFLP markers and divided into eight genetic groups with 28 pairs of primers. Analysis of molecular variance indicated significant correlation between genetic groups of F. tricinctum isolates and their geographical locations or aggressiveness. Pairwise comparison and STRUCTURE analysis also indicated that geographical locations and aggressiveness of isolates had a significant effect on population differentiation. This study provides insight into the genetic diversity and reproductive biology of F. tricinctum, enhances understanding of the population diversity of alfalfa root rot pathogens in north-east China, and facilitates development of effective strategies for managing this destructive disease complex.     

甘草根腐病病原菌鉴定

 甘草(Glycyrrhiza uralensis Fish.)别名甜草、蜜草、甜根子, 为豆科多年生草本植物, 以根与根茎入药, 具有补脾益气、清热解毒、祛痰止咳、缓急止痛、调和诸药之功效, 是我国临床常用的中药材, 也可用作食品添加剂。甘草主要分布在我国的内蒙古、甘肃和宁夏, 在青海、陕西、新疆、黑龙江、辽宁、吉林、河北、山西等地局部地区也有分布。宁夏盐池县是我国乌拉尔甘草的重要产区, 面积大、贮量多、品质好, 1995年被誉为“中国甘草之乡” ^[1]。近年来, 野生甘草遭到了大规模采挖, 甘草蕴藏量急剧减少, 目前主要通过人工种植来满足市场需求。随着甘草种植面积的不断扩大, 甘草病虫害日趋严重, 根腐病危害尤为突出, 直接影响甘草的产量和品质, 造成巨大经济损失。     

Genetic diversity of Fusarium oxysporum and related species pathogenic on tomato in Algeria and other Mediterranean countries

In order to characterize the pathogen(s) responsible for the outbreak of fusarium diseases in Algeria, 48 Fusarium spp. isolates were collected from diseased tomato in Algeria and compared with 58 isolates of Fusarium oxysporum originating from seven other Mediterranean countries and 24 reference strains. Partial sequences of the translation elongation factor EF‐1α gene enabled identification of 27 isolates as F. oxysporum, 18 as F. commune and three as F. redolens among the Algerian isolates. Pathogenicity tests confirmed that all isolates were pathogenic on tomato, with disease incidence greater at 28°C than at 24°C. All isolates were characterized using intergenic spacer (IGS) DNA typing, vegetative compatibility group (VCG) and PCR detection of the SIX1 (secreted in xylem 1) gene specific to F. oxysporum f. sp. lycopersici (FOL). No DNA polymorphisms were detected in the isolates of F. redolens or F. commune. In contrast, the 27 Algerian isolates of F. oxysporum were shown to comprise nine IGS types and 13 VCGs, including several potentially new VCGs. As none of the isolates was scored as SIX1+, the 27 isolates could be assigned to F. oxysporum f. sp. radicis‐lycopersici (FORL). Isolates from Tunisia were also highly diverse but genetically distinct from the Algerian isolates. Several Tunisian isolates were identified as FOL by a PCR that detected the presence of SIX1. The results show that isolates from European countries were less diverse than those from Tunisia. Given the difference between Algerian populations and populations in other Mediterranean countries, newly emergent pathogenic forms could have evolved from local non‐pathogenic populations in Algeria.     

Characterization of Fusarium population associated with wilt of jojoba in Israel

Fusarium wilt, caused by Fusarium oxysporum, is a major disease of jojoba, causing serious economic losses. This study was aimed at characterizing the Fusarium populations associated with jojoba in Israel. Fifty Fusarium isolates used in this study included 23 isolates from the 1990s (“past”) and 27 recently isolated (“recent”). All the isolates were characterized by arbitrarily primed (ap)-PCR and 16 representatives were additionally delineated using multilocus (tef1, rpb1, rpb2) phylogeny and evaluated for their pathogenic potential. Consequently, 88% of the isolates were identified and characterized to the F. oxysporum species complex. The remaining 12% grouped within the F. fujikuroi, F. solani, and F. redolens species complexes. Variations in the infection rate (16.7%–100%), disease symptoms (0.08–1.25, on a scale of 0–3), and fungal colonization index (0.67–2.17, on a scale of 0–4) were observed within the tested isolates, with no significant differences between the past and recent isolates. The representative isolates were assigned to 11 groups based on ap-PCR. Pathogenicity tests showed that isolates from Groups II, IV, and V were the most aggressive, whereas isolates from Groups III, VIII, and IX were the least aggressive. Among the tested isolates, F. oxysporum sensu lato was the most aggressive, followed by F. proliferatum, while F. nygamai was the least aggressive. This study demonstrates the complexity and genetic diversity of Fusarium wilt on jojoba in Israel, indicating possible multiple introductions of infected germplasm into the country.     

The elegans fusaria causing wilt disease of carnation. II. Distinction of vegetative compatibility groups

The vegetative compatibility patterns among isolates ofElegans fusaria causing wilt disease of carnation were investigated. Nitrate non-utilizing mutants were generated from 16 isolates labelledF. redolens, nine of which came from carnation, and from 33 isolates labelledF. oxysporum, 19 of which came from carnation. Pairings of the mutants revealed five vegetative compatibility groups among the isolates from carnation, corresponding withF. oxysporum f.sp.dianthi race 1 (VCG1), race 2 (VCG2) and race 4 (VCG3),F. redolens f.sp.dianthi (VCG4) andF. redolens isolates from foot rot-diseased carnations (VCG5). Besides three isolates typical ofF. redolens, VCG4 comprised a now slightly deviating subculture of the type isolate ofF. redolens f.sp.dianthi of which the cultural characteristics correspond toF. oxysporum instead ofF. redolens. This observation may be taken to support previous conclusions that the distinction between both taxa is not justified. Otherwise, the compatibility patterns did not provide decisive evidence to accept or reject conspecificity of both taxa. Isolates from carnation did not form heterokaryons with other formae speciales ofF. oxysporum.Samenvatting De vegetatieve compatibiliteitspatronen bij isolaten vanElegans-fusaria die verwelkingsziekte bij anjer veroorzaken werden onderzocht. Van 16 isolaten vanF. redolens, waarvan negen afkomstig van anjers, en van 33 isolaten vanF. oxysporum, waarvan 19 afkomstig van anjers, werden mutanten gegenereerd die zonder een organische stikstofbron geen luchtmycelium meer konden vormen. Paringen tussen mutanten van isolaten afkomstig van anjers brachten een vijftal vegetatieve compatibiliteitsgroepen aan het licht, die overeenkwamen metF. oxysporum f.sp.dianthi fysio 1 (VCG 1), fysio 2 (VCG 2) en fysio 4 (VCG3),F. redolens f.sp.dianthi (VCG4) enF. redolens isolaten afkomstig van aan voetrot lijdende anjers (VCG5). Naast drie voorF. redolens karakteristieke isolaten omvatte VCG4 ook een afwijkende subculture van het type-isolaat vanF. redolens f.sp.dianthi, die in cultuureigenschappen overeen kwam metF. oxysporum in plaats vanF. redolens. Deze waarneming geeft enige steun aan eerdere conclusies dat het onderscheid tussen beide taxa niet gerechtvaardigd is. Daarbuiten gaven de compatibiliteitspatronen geen uitsluitsel over de mogelijke conspecificiteit van beide taxa. Isolaten afkomstig van anjers vormden geen heterokaryons met andere formae speciales vanF. oxysporum.     

The Elegans fusaria causing wilt disease of carnation. I. Taxonomy

The distinction of the wilt disease pathogen of carnationFusarium (oxysporum var.)redolens fromF. oxysporum (var.oxysporum) is considered. Previous reports that isolates of both taxa cause indistinguishable diseases in carnation are confirmed.F. (oxysporum var.)redolens andF. oxysporum were found to form one variable complex on morphological criteria. Apparently, host specialization rather than morphological variation reflects the evolutionary relationships in theFusarium sectionElegans. The distinction ofF. redolens fromF. oxysporum does therefore not seem justified, neither at specific nor at varietal level.Samenvatting Het onderscheid tussenFusarium (oxysporum var.)redolens enF. (oxysporum var.)oxysporum als verwekkers van verwelkingsziekte bij anjer wordt ter discussie gesteld. Fytopathologisch onderzoek bevestigde vermeldingen in de literatuur dat voor anjer pathogene isolaten van beide soorten ziekten veroorzaken die niet te onderscheiden zijn; dit is ook bekend voor andere gewassen. Op morfologische gronden blekenF. (oxysporum var.)redolens enF. oxysporum één variabel complex te vormen. Kennelijk geeft de pathogene specialisatie inFusarium sectieElegans de evolutionaire verwantschappen beter weer dan de morfologische variatie. Het onderscheiden vanF. redolens naastF. oxysporum is daarom noch als soort, noch als variëteit gerechtvaardigd.     

Root rot pathogens in field soil,roots and seeds in relation to common bean (Phaseolus vulgaris), disease and seed production

The interrelationships among bean productivity, prevalence of pathogens in roots, seeds and soil, and root rot disease were described at the pod maturity stage in 13 commercial fields. The soil population and frequency of pathogens isolated from seeds varied by pathogen species and field location. Fusarium solani was the most prevalent fungus isolated from bean seeds and field soil compared to Rhizoctonia solani, Macrophomina phaseolina and F. oxysporum. Principal component analysis revealed that the first component explaining 32% of the total variance was correlated with the root rot index. PC1 was more strongly linked to root and seed infections in comparison with soil populations of pathogens. Based on a correlation between PC2 (accounting for 23% of the total variance) and the number of seeds per bean plant, charcoal, Fusarium and Rhizoctonia root rots were recognized as more important determinants of seed losses to root rot disease. There were correlations among the major pathogens infecting either roots or seeds of beans. These findings provide useful information for future experimental plans to optimize management strategies for bean root rots.     

Identification of pathovars and races of <Emphasis Type="Italic">Pseudomonas syringae,</Emphasis> the main causal agent of bacterial disease in pea in North-Central Spain,and the search for disease resistance

A total of 298 bacterial isolates were collected from pea cultivars, landraces and breeding lines in North-Central Spain over several years. On the basis of biochemical-physiological characteristics and molecular markers, 225 of the isolates were identified as Pseudomonas syringae, either pv. pisi (110 isolates) or pv. syringae (112), indicating that pv. syringae is as frequent as pv. pisi as causal agent of bacterial diseases in pea. Most strains (222) were pathogenic on pea. Further race analyses of P. syringae pv. pisi strains identified race 4 (59.1% of the isolates of this pathovar), race 2 (20.0%), race 6 (11.8%), race 5 (3.6%) and race 3 (0.9%). Five isolates (4.6%) showed a not-previously described response pattern on tester pea genotypes, which suggests that an additional race 8 could be present in P. syringae pv. pisi. All the isolates of P. syringae pv. syringae were highly pathogenic when inoculated in the tester pea genotypes, and no significant pathogenic differences were observed. Simultaneous infections with P. syringae pv. pisi and pv. syringae in the same fields were observed, suggesting the importance of resistance to both pathovars in future commercial cultivars. The search for resistance among pea genotypes suitable for production in this part of Spain or as breeding material identified the presence of resistance genes for all P. syringae pv. pisi races except for race 6. The pea cultivars Kelvendon Wonder, Cherokee, Isard, Iceberg, Messire and Attika were found suitable sources of resistance to P. syringae pv. syringae.     

Identification and characterization of pathogens associated with root rot of winter peas grown under organic management in Germany

Root rots are limiting factor for pea production worldwide. This disease is caused by a pathogen complex and the role of single pathogens is unclear. This study aimed at identifying pathogens involved in a root rot of organically grown field pea in Germany, and establishing their importance in the disease complex. The potential of yard waste compost to suppress the diseased was also studied. Average disease severity index was similar in 2010 and 2011 (DI of 4.56 to 4.59, respectively) but it increased in 2012 to DI 5.8. Peyronellaea pinodella was most frequently isolated pathogen, with isolation frequency from 86%, 73% and 86% in 2010, 2011 and 2012, respectively. In addition, Didymella pinodes, Fusarium solani f. sp. pisi, F. oxysporum f. sp. pisi and F. avenaceum were the main fungi recovered from pea roots. In pathogenicity test all of the tested pathogens caused weak symptoms on the pigmented winter variety EFB33 and moderate to severe symptoms on the white flowering summer variety Santana. F. avenaceum was the most aggressive pathogen on Santana with DI of 7.4 followed by P. pinodella with DI of 5.7. The high aggressiveness combined with the wide host range highlights the possibility of F. avenaceum emerging as potential risk for organic crop rotation. High levels of resistance of EFB33 against all pathogens shows the potential of this variety to serve as a resource in further research for identification and development of new sources of resistance against root rot diseases of pea.     

Defense strategies of pea embryo axes with different levels of sucrose to Fusarium oxysporum and Ascochyta pisi

The aim of this study was to compare the defense responses of embryo axes of Pisum sativum L. cv. Kwestor with different sucrose levels to pathogenic fungi, i.e. systemic acting Fusarium oxysporum f. sp. pisi and locally acting Ascochyta pisi. Embryo axes were cultured on Heller medium for 96 h. Four variants were compared: these included inoculated embryo axes cultured with or without 60 mM sucrose (+Si and −Si) and non-inoculated embryo axes cultured with or without 60 mM sucrose (+Sn and −Sn). After inoculation of the pea embryo axes with pathogenic fungi a generally higher concentration of free radicals was detected by electron paramagnetic resonance (EPR), in comparison to non-inoculated embryo axes. The inoculation with F. oxysporum caused stronger generation of free radicals in −Si than in +Si embryo axes. A different response was observed after inoculation with A. pisi; starting from 48 h, the concentration of free radicals in +Si axes was found to be 1.5 times higher than in −Si embryo axes. The values of spectroscopic splitting coefficients for these radicals suggest that they are semiquinone radicals. The EPR method also revealed Mn²⁺ ion accumulation after 24 h of culture. Over time, high levels of these ions were recorded in +Si embryo axes inoculated with F. oxysporum, while in +Si embryo axes inoculated with A. pisi they decreased. Up to 48 h after inoculation with the pathogenic fungi, Mn²⁺ ion levels were higher in +Si embryo axes than in +Sn axes. The activity of superoxide dismutase (SOD, EC 1.15.1.1) increased in +Si embryo axes up to 72 h after inoculation with pathogenic fungi; however, it was generally lower than in +Sn axes. Catalase activity (CAT, EC 1.11.1.6) increased up to 72 h after inoculation with F. oxysporum and the values were higher than in the non-inoculated tissue. Especially high activity of this enzyme was noted in −Si embryo axes after inoculation with either F. oxysporum or A. pisi. Peroxidase activity (POX, EC 1.11.1.7) towards pyrogallol in embryo axes increased during culture; however, it was lower or similar to that in non-inoculated embryo axes. SOD, CAT and POX zymograms showed that the synthesis of new isoforms was induced after inoculation with pathogenic fungi. Peroxidase isozymes detected by the reaction with diaminobenzidine in native PAGE were intensely stained in +Si embryo axes after inoculation with pathogenic fungi. Respiratory activity of the inoculated tissues was considerably higher than in non-inoculated tissues. The respiration rate was generally much higher in +Si than in −Si embryo axes. Growth of −Si embryo axes was more significantly retarded as a consequence of inoculation than that of +Si embryo axes.These results indicate that, depending on the manner of influence of a pathogenic fungus, both similar and differing defensive strategies may be initiated and a raised sugar levels in pea tissues limit the development of F. oxysporum and A. pisi.     

枸杞根腐病病原菌鉴定及其拮抗菌的筛选

为了针对根腐病实施有效的生物防治，分离鉴定枸杞根腐病病原菌及其拮抗菌，采用组织分离法获得腐根上的病原菌，结合形态学与分子生物学特征鉴定病原菌；利用稀释涂布、滤纸片法和共培养法从健康根际土壤筛选拮抗细菌，通过形态学观察、生理生化鉴定和16S rDNA序列分析对拮抗效果较好的菌株进行鉴定。结果表明：从枸杞根腐病分离得到腐皮镰刀菌（Fusarium solani）和尖孢镰刀菌（Fusarium oxysporum）两种主要致病菌，从健康枸杞根际土壤中分离获得12株对两种镰刀菌具有拮抗作用的细菌，其中J7-3、J7-8、J7-9和J10-8对腐皮镰刀菌的抑菌率均在80%以上，J7-3和J10-8对尖孢镰刀菌的抑菌率均在70%以上。菌株J7-3和J10-8对根腐病病原菌的抑菌作用较好，分别鉴定为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）和枯草芽孢杆菌（Bacillus subtilis），其中J10-8的拮抗作用和溶菌效果最好，可作为研发微生物菌剂的菌种资源。     

Fusarium oxysporum,F. proliferatum and F. redolens associated with basal rot of onion in Finland

In recent years in Finland, Fusarium infections in onions have increased, both in the field and in storage, and Fusarium species have taken the place of Botrytis as the worst pathogens causing post‐harvest rot of onion. To study Fusarium occurrence, samples were taken from onion sets, harvested onions and also from other plants grown in the onion fields. Isolates of five Fusarium species found in the survey were tested for pathogenicity on onion. Fusarium oxysporum was frequently found in onions and other plants, and, of the isolates tested, 31% caused disease symptoms and 15% caused growth stunting in onion seedlings. Fusarium proliferatum, a species previously not reported in Finland, was also identified. Over 50% of the diseased onion crop samples were infected with F. proliferatum, and all the F. proliferatum isolates tested were pathogenic to onion. Thus, compared to F. oxysporum, F. proliferatum seems to be more aggressive on onion. Also some of the F. redolens isolates were highly virulent, killing onion seedlings. Comparison of the translation elongation factor 1α gene sequences revealed that the majority of the aggressive isolates of F. oxysporum f. sp. cepae group together and are distinct from the other isolates. Incidence and relative proportions of the different Fusarium species differed between the sets and the mature bulbs. More research is required to determine to what extent Fusarium infections spoiling onions originate from infected onion sets rather than the field soil.     

Aetiology of garlic rot,an emerging disease in France

The incidence of garlic rot has constantly increased in France since the early 2000s. To set up an efficient method of garlic protection against this disease, we have clarified its aetiology. This was achieved by surveying garlic from the two main French basins of garlic production over 3 years. Fungi were isolated from 5,493 garlic cloves belonging to pink, purple, and white garlic types. Sequencing of the translation elongation factor 1α gene of 1,171 strains revealed that 94% of the strains belonged to the species Fusarium proliferatum and 6% belonged to F. oxysporum. The pathogenicity of both species on garlic was confirmed by artificial inoculations and reisolations. There was significantly more F. oxysporum in garlic cloves with symptoms coming from the southeast basin (9.44%) than from the southwest basin (2.76%). This study confirms that garlic rot is present in pink, purple, and white types. However, pink type garlic harbours F. oxysporum significantly less frequently (1.59%) than white (9.39%) and purple (7.34%) types. Sequencing of rpb1, rpb2, ITS, and IGS regions of a subsample of strains revealed that there is little genetic diversity in the French population of F. proliferatum.     

新疆南疆枣树根腐病病原的分离与鉴定

<正>枣为鼠李科(Rhamnaceae)枣属(Ziziphus M ill.)植物,在我国拥有悠久的栽培历史。枣树的喜光、喜温、耐寒、耐旱等栽培特点,非常适合在新疆这种气候条件特殊的地区生长。近年来,随着新疆红枣产业的迅速发展,枣树病害问题也逐渐突显。2010和2011年,新疆南疆多地枣园出现枣树根腐病,该病害主要造成枣树实生苗和多年生枣树根部腐烂,叶片黄化,植株树势衰弱,最终导致植株     

Soil receptivity toFusarium solani f. sp.pisi and biological control of root rot of pea

Potential antagonists ofFusarium solani f. sp.pisi (Fsp) were selected from soil samples with varying degrees of receptivity to this pathogen. They were tested against Fsp isolate 48 (Fs48), in increasingly complex systems. Most species testedin vitro were able to antagonize Fs48. No relation could be establishedin vitro between the receptivity of the soil from which an isolate originated and its antagonism to Fs48. In soils naturally infested with pea root rot pathogens, which were stored humid at 4°C for a period longer than a year, various isolates ofFusarium, Gliocladium andPenicillium spp. were able to reduce root rot. After sterilization of these soils, onlyGliocladium roseum isolates, added at 10⁵ conidia g^–1 dry soil, significantly reduced disease severity and prevented root weight losses caused by Fs48 at 10⁴ conidia g^–1 dry soil. In soils in which the biota were activated by growing peas before the assays, doses of 10⁶ and 10⁷ ofG. roseum were required to reduce root rot. In these soils, the antagonistic effects of fluorescent pseudomonad strains from soil of low receptivity to Fsp were variable. Some strains of fluorescent pseudomonads, from soil moderately receptive to Fsp and from highly infested soils, were also able to reduce root rot. Disease suppression by pseudomonad strains was more evident in the absence than in the presence ofAphanomyces euteiches in the root rot pathogen complex. The role of receptiveness of the soil with regard to potential antagonists is discussed.     

Pathogenic fungi involved in root rot of peas in the Netherlands and their physiological specialization

Research on root rot pathogens of peas in the Netherlands has confirmed the prevalence ofFusarium solani, F. oxysporum, Pythium spp.,Mycosphaerella pinodes andPhoma medicaginis var.pinodella. Aphanomyces euteiches andThielaviopsis basicola were identified for the first time as pea pathogens in the Netherlands. Other pathogens such asRhizoctonia solani andCylindrocarpon destructans were also found on diseased parts of roots. F. solani existed in different degrees of pathogenicity, and was sometimes highly specific to pea, dwarf bean of field bean, depending on the cropping history of the field.A. euteiches was specific to peas, whereasT. basicola showed some degree of physiological specialization.     

A novel lineage in the Fusarium incarnatum-equiseti species complex is one of the causal agents of fusarium rot on melon fruits in Northeast Brazil

Fusarium rot on melon fruits is a postharvest disease and its importance in Brazil is increasing since its first report in 1999. Initially this disease was attributed to the fungus Fusarium semitectum based on pathogen morphology. However, there is controversy regarding the aetiology of this disease because, in the current species concept based on phylogenetic analysis, F. semitectum is regarded as a synonym to different Fusarium species. With the objective of elucidating the disease aetiology in Northeast Brazil, Fusarium isolates were obtained from melon fruits showing rot symptoms in the main producing areas of the country. From the phylogenetic analyses of TEF1 and RPB2 gene sequences, the isolates were identified as belonging to two phylogenetic species of the Fusarium incarnatum-equiseti species complex (FIESC), one in the Incarnatum clade (Fusarium sulawense) and the other in the Equiseti clade, which corresponds to a new lineage. The newly identified lineage is close to Fusarium lacertarum. Isolates from the two species showed morphological characteristics typical of the Incarnatum and Equiseti clades, agreeing with the molecular identification, and were pathogenic when inoculated on melon fruits. This is the first report of F. sulawense on melon fruits. The data generated in this study are potentially useful for a better management of the fusarium rot on melon.     

Fusarium commune associated with wilt and root rot disease in rice

Wilt and root rot disease in plants has been caused mainly by Fusarium species. Previous studies reported that members of the Fusarium oxysporum species complex (FOSC) were usually associated with this disease, but there has been no report of it being caused in rice by specific Fusarium species. However, in this study, Fusarium commune was identified and characterized as a causal agent of wilt and root rot disease of rice. Four Fusarium isolates (BD005R, BD014R, BD019R, and BD020R) were obtained from different parts (root, stem, and seeds) of diseased rice plants. In morphological studies, these isolates produced key characteristics of F. commune, such as long and slender monophialides, polyphialides, and abundant chlamydospores. In molecular studies, the isolates were identified as F. commune based on sequences of the translation elongation factor 1-α (TEF1) gene that had 99.7%–100% sequence identity with the reference strain F. commune NRRL 28058. The phylogenetic tree showed that all four isolates belonged to the F. commune clade. A mating type test determined that three isolates carried MAT1-2. Their teleomorph stage was still unknown. Pathogenicity assays showed that all the isolates produced wilt and root rot symptoms and the isolate BD019R was observed as the most virulent among the isolates. To our knowledge, this is the first report of F. commune causing wilt and root rot disease on rice.