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Fusarium is one of the most important phytopathogenic fungi of agricultural and human concern. More than 300 species have been described, many of which are pathogenic to important crops, flowers, forest trees, animals, and humans. Species belonging to this genus have been detected in all environments: grassland, desert, littoral, agricultural, alpine zones, aquatic, man-made, and hospitals. Despite the importance of molecular techniques for the identification of a fungal species, morphological criteria still have an important role, including for Fusarium species, for which morphological identification of species requires adequate training and experience. In this paper, we present FusaHelp, a computer-based, user-friendly tool for the morphological identification of common Fusarium species, based on the wide experience of the authors who have devoted most of their scientific careers to the identification and characterization of these species. The web-location of FusaHelp (https://www.fusahelp.com) will greatly facilitate morphological identification and is intended to provide support for all those people who work with this important genus and need a quick clue on the identification, even incomplete, of the Fusarium species that they are working with. more...

Several Fusarium species cause disease on human hosts, including commonly fatal infections in immunocompromised individuals. Recently, cases of hospitalized patients affected by fusaria were reported in the Tyrrhenian Island of Sardinia, Italy. To precisely characterize the Fusarium species and haplotypes present in hospitals of the region, a multilocus DNA sequence typing (MLST) approach was applied. Water distribution systems in four departments belonging to four Sardinian hospitals were sampled. Fusarium species and sequence types (STs) were identified using MLST based on sequences of the elongation factor 1-alpha (EF-1α) gene, the nuclear ribosomal DNA intergenic spacer region (IGS rDNA), and/or a portion of the second-largest subunit of RNA polymerase (RPB2) gene. The majority of isolates obtained from Sardinian hospitals (90.7%) were identified as representatives of the Fusarium oxysporum species complex (FOSC), followed by those of the F. solani species complex (FSSC) (8.2%), and F. dimerum (1.1% of all isolates). Ten STs were found among the FOSC and FSSC, with more than 60% of the isolates identified as either FOSC ST 33 or FSSC 1 (F. petroliphilum). More than half of the FOSC isolates obtained from the water systems in all four hospitals belonged to the worldwide distributed clonal lineage ST 33. This haplotype is the most prevalent among the FOSC in different countries, being responsible for the vast majority of cases of human fusariosis. more...

Monosporascus root rot and vine decline of melon (MRRVD) is a destructive disease complex mainly occurring in semiarid cultivation areas. In the last decade, in the melon producing area of Sardinia (Italy), yield reductions up to 100% were recorded due to the occurrence of MRRVD. The present study aimed to undertake a two-year survey of fungal pathogens associated with MRRVD grown as a monocrop in two locations in Central Sardinia, Sinis, and Sassu, and to investigate the possible role of soil fungal diversity in the disease development. Melon plants were affected by similar symptoms but colonized by a set of soil-borne fungal pathogens different between surveyed sites and cropping seasons, including Plectosphaerella melonis, P. cucumerina, Fusarium solani, Macrophomina phaseolina and Monosporascus cannonballus. Olpidium bornovanus and O. virulentus were isolated using bait plants and detected by NGS analysis. Bait plants had a general decrease in biomass and yellowing of foliage. The presence of most of the isolated pathogens was also confirmed by the NGS analysis of the soil microbiome. Our results confirm that among the fungal complex implicated in the occurrence of RRVD in Sardinia, O. bornovanus along with O. virulentus likely assume a key role in the development of the disease alone and possibly in association with other pathogens. Differences in the pathogenic fungal spectrum here recorded in symptomatic roots may be associated with agricultural practices, soil physicochemical characteristics, and fungal community composition and function profile. more...

International audience; Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. Previously (Geiser et al. 2013; Phytopathology 103:400-408. 2013), the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani Species Complex (FSSC). Subsequently, this concept was challenged by one research group (Lombard et al. 2015 Studies in Mycology 80: 189-245) who proposed dividing Fusarium into seven genera, including the FSSC as the genus Neocosmospora, with subsequent justification based on claims that the Geiser et al. (2013) concept of Fusarium is polyphyletic (Sandoval-Denis et al. 2018; Persoonia 41:109-129). Here we test this claim, and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species recently described as Neocosmospora were recombined in Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural and practical taxonomic option available. more...

This study aimed to explore the incidence of Fusarium fungi and their mycotoxins in marketed feed in Qatar. Samples of mixed-grain-cereal, maize, wheat, millet, barley, oat and soybean were tested for the presence of zearalenone (ZEN), fumonisins, T2/HT2 and deoxynevalenol (DON)mycotoxins. PCR-based identification of the Fusarium isolates was followed by investigation into genes involved in trichothecenes (tri gene cluster), fumonisins (fum gene cluster)and ZEN (pks gene)biosynthesis. In-vitro mycotoxin production potential of the isolates was compared with their molecular profiles. Mixed-grain cereals showed highest contamination with Fusarium, followed by maize and wheat. The incidence of ZEN was highest in mixed grain samples (87.5%)followed by maize (50%), millet (42.85%)and wheat (40%). In case of DON; 62.5%, 30%, 40%, 14.28%, 50% and 66.67% of the tested mixed cereal grain, maize, wheat, millet, barley and soybean samples were positive. Based on PCR results, F. verticillioides showed highest frequency distribution (34%), followed by F. graminearum (16%), F. oxysporum (15%), F. proliferatum (13%), F. culmorum (8%), F. solani (7%), F. subglutinans (4%)and F. avenaceum (3%)in the feed cereals. All the isolates of F. verticillioides presented both fum1 and fum13 genes, and produced fumonisin mycotoxins in-vitro. All the isolates of F. graminearum and F. culmorum had the tri5 and tri6 genes and resulted in DON accumulation in rice media. In addition to DON, all the F. culmorum isolates produced ZEN in artificially contaminated media, in line with their molecular profile of having tri5, tri6 and pks13 genes. The findings of present study confirmed the occurrence of toxigenic Fusarium and their mycotoxins in animal feed, all below the maximum limit set by EU. Further, the in-vitro mycotoxin production potential of the isolates was in agreement with their tri, fum and pks genetic profiles. - 2019 Elsevier Ltd This publication was made possible by the NPRP Grant '8-392-4-003 ' from the Qatar National Research Fund (a member of the Qatar Foundation ). The statements made herein are solely the responsibility of the authors. Appendix A Scopus more...

Several

Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1–3, ten prenylated derivatives (coded 4–13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD50) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3′-dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4–13, evidencing ester 13 as the most active. This compound presented MIC and LD50 values (62–250 µM and 7.8–125 µM, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy. more...

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the

Here, we report on the morphological, molecular, and chemical characterization of a novel

Fusarium culmorum is a soil-borne fungal pathogen which causes foot and root rot and Fusarium head blight on small-grain cereals, in particular wheat and barley. It causes significant yield and quality losses and results in the contamination of kernels with type B trichothecene mycotoxins. Our knowledge of the pathogenicity factors of this fungus is still limited. A transposon tagging approach based on the mimp1/impala double-component system has allowed us to select a mutant altered in multiple metabolic and morphological processes, trichothecene production and virulence. The flanking regions of mimp1 were used to seek homologies in the F. culmorum genome, and revealed that mimp1 had reinserted within the last exon of a gene encoding a hypothetical protein of 318 amino acids which contains a ROGDI-like leucine zipper domain, supposedly playing a protein-protein interaction or regulatory role. By functional complementation and bioinformatic analysis, we characterized the gene as the yeast Rav2 homologue, confirming the high level of divergence in multicellular fungi. Deletion of FcRav2 or its orthologous gene in F. graminearum highlighted its ability to influence a number of functions, including virulence, trichothecene type B biosynthesis, resistance to azoles and resistance to osmotic and oxidative stress. Our results indicate that the FcRav2 protein (and possibly the RAVE complex as a whole) may become a suitable target for new antifungal drug development or the plant-mediated resistance response in filamentous fungi of agricultural interest. more...

Fusarium Head Blight (FHB) is one of the most important diseases affecting wheat production. The disease causes yield and quality losses and hinders commercialization because of frequent grain contamination with trichothecenes, sesquiterpene mycotoxins that are harmful to human and animals and act as pathogenicity factors for FHB. Although not always effective, application of fungicides is the most common method for FHB management; thus, there is an urgent need to develop new efficient and sustainable tools. We analyzed the inhibitory activity of a group of commercially available naturally occurring compounds on the production of trichothecenes and on the severity of FHB on field-grown wheat spikes inoculated with Fusarium graminearum. The gene TRI5 codifies trichodiene synthase, the enzyme that catalyzes the synthesis of trichodiene, a volatile intermediate to trichothecenes. Our first aim was to obtain a trichothecene non-producing mutant of the pathogen by gene disruption of this gene. Seventeen putative ΔTRI5 mutants produced in the laboratory were characterized for pathogenicity and trichothecene production. The target gene was correctly and efficiently replaced in more than 75% of the transformants obtained, indicating a high efficacy of the approach used for gene disruption. Selected commercially available natural inhibitors -eugenol, apocynin, caffeic acid and propyl gallate-, were used to test their effect on trichodiene production in vitro and in field-grown wheat spikes inoculated with F. graminearum, using a ΔTRI5 mutant as non-trichodiene production control. Fungal volatile organic compounds production was measured by gas chromatography coupled to mass spectrometry. Caffeic acid, apocynin and eugenol produced a significant reduction of trichodiene production in vitro. In field assays, sesquiterpene inhibition was also significant at 2 days post inoculation (dpi), showing that effective inhibition of the trichothecene precursor can be achieved through the action of commercially available naturally occurring compounds. However, at later stages (>7 dpi) the production of trichodiene was similar to that of the F. graminearum-inoculated control. At 21 dpi, FHB severity did not differ between the treatments with inhibitors and the inoculated control. Hence, further experiments are required to identify the most appropriate inhibitors concentrations and formulations to improve their bioavailability and to achieve long lasting protection against F. graminearum infections. more...

Coniella hibisci is reported for the first time in Lao P.D.R. The pathogen was isolated from roselle (Hibiscus sabdariffa var. sabdariffa) stem and leaf samples from a farm in Thateng district, Sekong province, and deposited with the International Collection of Microorganisms from Plants (ICMP). The identification of the pathogen was based on morphological features and the results of sequencing the ITS, LSU, and tef1 genetic loci. Pathogenicity tests on four-week-old roselle plants reproduced field symptoms, satisfying Koch’s postulates. more...

The use of yeast-derived volatile organic compounds (VOCs) represents a promising strategy for the biological control of various plant pathogens, including mycotoxin-producing fungi. Previous studies demonstrated the efficacy of the low-fermenting yeast Candida intermedia isolate 253 in reducing growth, sporulation, and ochratoxin A biosynthesis by Aspergillus carbonarius MPVA566. This study aimed to investigate whether the inhibitory effect of the yeast volatilome is solely attributable to 2-phenylethanol, its major component, or if a synergistic effect of all volatilome components is required to achieve an effective control of the fungal growth and metabolism. Microbiological methods, HPLC measurements and a UPLC-MS/MS approach were used to investigate the metabolic profile of A. carbonarius MPVA566 at different growing conditions: standard incubation (control), exposed to C. intermedia 253 volatilome, and incubation in the presence of 2-phenylethanol. Both yeast volatilome and 2-phenylethanol succeeded in the macroscopic inhibition of the radial mycelial growth, along with a significant reduction of ochratoxin A production. Functional classification of the fungal proteome identified in the diverse growing conditions revealed a different impact of both yeast VOCs and 2-phenylethanol exposure on the fungal proteome. Yeast VOCs target an array of metabolic routes of fungal system biology, including a marked reduction in protein biosynthesis, proliferative activity, mitochondrial metabolism, and particularly in detoxification of toxic substances. Exposure to 2-phenylethanol only partially mimicked the metabolic effects observed by the whole yeast volatilome, with protein biosynthesis and proliferative activity being reduced when compared with the control samples, but still far from the VOCs-exposed condition. This study represents the first investigation on the effects of yeast-derived volatilome and 2-phenylethanol on the metabolism of a mycotoxigenic fungus by means of proteomics analysis. Chemical compounds studied or used in this article: 2-Phenylethanol (PubChem CID: 6054); ochratoxin-A (PubChem CID: 442530); sodium dodecyl sulfate (PubChem CID: 3423265); dithiothreitol (PubChem CID: 446094); phenylmethylsulfonyl fluoride (PubChem CID: 4784); iodoacetamide (PubChem CID: 3727); ammonium bicarbonate (PubChem CID: 14013); acetic acid (PubChem CID: 176); and acetonitrile (PubChem CID: 6342). - 2019 The Authors This publication was made possible by NPRP grant # 8-392-4-003 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. Scopus more...

Fusarium nygamai Burgess & Trimboli was first described in 1986 in Australia (1) and subsequently reported in Africa, China, Malaysia, Thailand, Puerto Rico, and the United States. F. nygamai has been reported on sorghum, millet, bean, cotton, and in soil where it exists as a colonizer of living plants or plant debris. F. nygamai was also reported as a pathogen of the witch-weed Striga hermonthica (Del.) Benth. To our knowledge, no reports are available on its pathogenicity on crops of economic importance. In a survey of species of Fusarium causing seedling blight and foot rot of rice (Oryza sativa L.) carried out in Sardinia (Oristano, S. Lucia), F. nygamai was isolated in association with other Fusarium species—F. moniliforme, F. proliferatum, F. oxysporum, F. solani, F. compactum, and F. equiseti. Infected seedlings exhibited a reddish brown cortical discoloration, which was more intense in older plants. The identification of F. nygamai was based on monoconidial cultures grown on carnation leaf-piece agar (CLA) (2). The shape of macroconidia, the formation of microconidia in short chains and false heads, and the presence of chlamydospores were used as the criteria for identification. Two pathogenicity tests comparing one isolate of F. nygamai with one isolate of F. moniliforme were conducted on rice cv. Arborio sown in artificially infested soil in a greenhouse at 22 to 25°C. The inoculum was prepared by growing both Fusarium species in cornmeal sand (1:30 wt/wt) at 25°C for 3 weeks. This inoculum was added to soil at 20 g per 500 ml of soil. Pre- and post-emergence damping-off was assessed. Both F. nygamai and F. moniliforme reduced the emergence of seedlings (33 to 59% and 25 to 50%, respectively, compared to uninoculated control). After 25 days, the seedlings in infested soil exhibited a browning of the basal leaf sheaths, which progressed to a leaf and stem necrosis. Foot rot symptoms caused by F. nygamai and F. moniliforme were similar, but seedlings infected by F. nygamai exhibited a more intense browning on the stem base and a significant reduction of plant height at the end of the experiment. Either F. nygamai or F. moniliforme were consistently isolated from symptomatic tissue from the respective treatments. References: (1) L. W. Burgess and D. Trimboli. Mycologia 78:223,1986. (2) N. L. Fisher et al. Phytopathology 72:151,1982. more...

During the summer of 2004, severe symptoms of wilt were observed on 25-year-old plants of Canary Island Date Palm (Phoenix canariensis Hort. ex Chabaud) located at the seafront of Poetto Beach in the metropolitan area of Cagliari, southern Sardinia, Italy. Symptoms consisted of one-sided leaflet dieback of fronds, necrotic and brown streaking on the lower rachis base of older leaves, and necrosis of vascular bundles. Of 300 palms, there were 90 plants that were symptomatic and at least 4 were dead. Fusarium oxysporum Schlecht. emend. Snyder & Hansen has been consistently isolated from surface-sterilized petioles of symptomatic leaves sampled from affected palms. The opportunistic pathogen Gliocladium vermoesenii (Biourge) Thom was frequently associated with F. oxysporum in diseased samples, confirming previous reports of a disease complex between these two fungi (1). Five F. oxysporum isolates collected from different symptomatic plants were analyzed with a polymerase chain reaction (PCR)-based assay with the F. oxysporum f. sp. canariensis-specific primers HK66 + HK67 (2). The thermocycling schedule was as follows: initial denaturation at 94°C for 5 min, 35 cycles each of 1 min at 94°C, 1 min at 62°C, 1 min and 30 s at 72°C, followed by a final extension at 72°C for 5 min. A 567-bp PCR product of the expected size was obtained from all tested F. oxysporum isolates, allowing their identification as F. oxysporum f. sp. canariensis. This disease was previously reported from other Italian regions (Sicily, Marche, and Liguria), but its presence in Sardinia should be considered carefully since it represents a serious threat to ornamental palms, which are abundant all over the island. The source of this outbreak may be related to the importation of seedlings from areas where F. oxysporum f. sp. canariensis is widely established. References: (1) H. D. Ohr. Pink rot (Gliocladium Blight). Pages 24–25 in: Diseases and Disorders of Ornamental Palms. A. R. Chase and T. K. Broschat, eds. The American Phytopathological Society, St. Paul, MN, 1991. (2) T. R. Plyler et al. Phytopathology 89:407, 1999. more...

Fusarium spp. are common human pathogenic fungi implicated in invasive mycoses and infections. In humans, Fusarium spp., particularly F. verticillioides, F. solani and F. oxysporum, are frequently reported as the cause of several dermatological affections such as onychomycoses and paronychia, but they may also induce keratitis episodes, mainly as a consequence of contaminated lens solutions. In our previous studies, devoted to the search of effective sustainable fungicides in agriculture, we have observed antifungal activity of magnolol 1 and honokiol 2 against F. graminearum and F. culmorum in vitro [1] and in silico [2]. Magnolol 1 and honokiol 2 are two hydroxylated biphenyls representing the main components of the bark of Magnolia officinalis. These compounds have long been important substances in traditional chinese and Ayurvedic medicine due to their wide biological activities. Magnolol 1 manifested the highest anti-fungal activity among a wide range of natural occurring phenols and it is generally recognized as harmless for humans and animal as well as its isomer honokiol 2. Unfortunately, the poor aqueous solubility of these two hydroxylated biphenyls has hampered their broad clinical application. This study shows a synthetic strategy to improve the bioactivity of magnolol 1 and honokiol 2 by transformation of their hydroxyl groups in an ester group or in an acetal group with a glucosyl unit. The synthetic methodology presented followed diverse sustainable and pratical approaches, including the use of green reaction media and alternative technologies such as microwave. Magnolol 1, honokiol 2 and their derivatives 3-8 were tested for their anti-fungal activity and specificity towards human and nosocomial isolates and their activity was compared with that of terbinafine and fluconazole, two conventional fungicides [3]. more...

Rapporto di ricerca del secondo anno di attività della dottoranda di ricerca, Safa Oufensou, presentata alla SIPCAM ITALIA S.p.A, finanziatrice della borsa di dottorato. Tutor: Quirico Migheli, co-Tutors: Giovanna Delogu e Virgilio Balmas L'attività di ricerca ha riguardato l' individuazione di molecole naturali o natural-simili con attività fungicida da applicare nella concia della semente di frumento allo scopo di impedire l'attacco da 'mal del piede' nelle prime fasi fenologiche. Inoltre sono state utilizzati composti naturali e naturali-simile ad attività inibitoria nei confronti dei tricoteceni di tipo B nella fase di antesi per il controllo della fusariosi della spiga e la riduzione delle tossine prodotte dagli agenti causali. In questo secondo anno di dottorato sono state eseguite le seguenti prove con i composti naturali selezionati dal CNR-ICB: - prove in serra nei confronti del 'mal del piede' (FCR) usando cariossidi di grano conciate - prove in serra nei confronti del 'mal del piede' (FCR) usando un trattamento con un elicitore del sistema di difesa delle piante - prove in serra nei confronti della fusariosi della spiga (FHB) - prove in vitro nei confronti di F. culmorum su substrato di crescita PDA - prove in campo nei confronti della fusariosi della spiga (FHB) - prove in piastra micro_array nei confronti della produzione di micotossine usando dei ceppi trasformati Fusarium graminearum e Aspergillus nidulans che esprimono una proteina fluorescente sotto il controllo delle vie biosintetiche della micotossina. Questa attività è stata svolta presso BOKU University-Depatment of Genetic and Cellular Biology DAGZ, Tulln, Università di Vienna more...

This study was designed to explore the incidence of aflatoxin M1 (AFM1) in milk and dairy products marketed in Qatar. Milk (n = 72), yogurt (n = 21), cheese (n = 46), butter (n = 18) and laban (n = 25) samples were initially screened by competitive enzyme linked immunosorbent assay (ELISA) for the presence of AFM1, followed by confirmation with ultra-high-performance liquid chromatography (UHPLC). AFM1 was detected in 85%, 76%, 85%, 67% and 76% of the milk, yogurt, cheese, butter and laban samples, respectively. The levels of AFM1 in pasteurized vs ultra-high temperature (UHT) milk and full-vs low-fat yogurts showed a non-significant difference. Halloumi and Kashkaval cheese varieties showed a significantly higher AFM1 contents as compared to Mozzarella, Edam, Cheddar, cream and Moshalal cheese. Likewise, unsalted butter demonstrated significantly (p < 0.05) higher AFM1 values than salted butter samples. None of the tested samples presented AFM1 levels above the EU maximum limits of 50 ng/L or kg for milk, yogurt and butter, and 250 ng/kg for cheese. From the finding of present study, it can be concluded that, although high percentage of dairy products marketed in Qatar demonstrated AFM1 contents, but do not represent a public health concern considering the EU maximum limits. This publication was made possible by NPRP grant # NPRP8-392-4-003 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. Scopus more...

Many foods and beverages in temperate and tropical regions are prone to contamination by ochratoxin A (OTA), one of the most harmful mycotoxins for human and animal health. Aspergillus ochraceus and Aspergillus carbonarius are considered among the main responsible for OTA contamination. We have previously demonstrated that four low or non- fermenting yeasts are able to control the growth and sporulation of OTA-producing Aspergilli both in vitro and on detached grape berries: the biocontrol effect was partly due to the release of volatile organic compounds (VOCs). Aiming to further characterise the effect of VOCs produced by biocontrol yeast strains, we observed that, beside vegetative growth and sporulation, the volatile compounds significantly reduced the production of OTA by two A. carbonarius and A. ochraceus isolates. Exposure to yeast VOCs also affected gene expression in both species, as confirmed by downregulation of polyketide synthase, non-ribosomal peptide synthase, monooxygenase, and the regulatory genes laeA and veA. The main compound of yeast VOCs was 2-phenylethanol, as detected by Headspace-Solid Phase Microextraction-Gas Chromatography-Tandem Mass Spectrometry (HS-SPME-GC?MS) analysis. Yeast VOCs represent a promising tool for the containment of growth and development of mycotoxigenic fungi, and a valuable aid to guarantee food safety and quality. This publication was made possible by NPRP grant # 8-392-4-003 from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the authors. We acknowledge constructive comments provided by anonymous reviewers. Scopus more...

Bakanae disease, caused by the fungal phytopathogen Fusarium fujikuroi, can be detected in most rice (Oryza sativa L.) growing areas worldwide. In this study, we investigated the population structure of this fungus in southern Lao PDR, a country located near the geographic origin of rice domestication. Microsatellites (SSRs) and mating type (MAT) analyses, pathogenicity and fungicide sensitivity tests were integrated in the study. The first key finding is that the population genetic structure of F. fujikuroi in Lao PDR is consistent with high clonal reproduction. Indeed, (i) "true" clones were identified; (ii) within populations, MAT types were frequently skewed from 1:1 ratio, (iii) linkage disequilibrium (among SSRs as also among SSRs and MAT) was present, and (iv) gene-flow between opposite MAT types within the same population is restricted. The presence of genetic divergence among areas and populations and the occurrence of positive spatial autocorrelation of genetic variation, indicate that migration is restricted, and that genetic drift plays an important role in the evolution of this fungus. Two main well-defined groups of isolates were detected (FST = 0.213) that display a non-random spatial distribution. They differ in the ability to induce seedlings death but not seedlings elongation (the typical Bakanae symptom) suggesting that the pathogen's ability to induce the two symptoms is under different genetic control. Finally, we compared two agroecosystems with contrasting characteristics: low-input and traditional (Lao PDR) vs high-input and modern (Italy). We found differences in the level of population structuring and of spatial autocorrelation. This suggests that the evolutionary potential of the fungus not only depends on its intrinsic characteristics, but is strongly influenced by other external factors, most likely by the dynamics of infested seed exchange. Thus, quarantine and chemical treatments are a way to reduce population connectivity and hence the evolutionary potential of this pathogen. more...

The isolation of Fusarium fujikuroi from rice plants with elongated stems typical of bakanae disease in the Lao PDR is reported for the first time. The identification was based on both molecular and morphological markers. Koch’s postulates were fulfilled. Bakanae disease has long been recognized in the Lao PDR based on symptomatology, but the etiology of the disease has not been clearly defined. This study was part of a continuing program to assist with the development of checklists of pathogens and plant diseases for Lao PDR for biosecurity purposes and integrated disease management. more...

Fusarium oxysporum f.sp. niveum is reported for the first time in the Lao PDR. It was isolated from watermelons (Citrullus lanatus) in Songkhon district, Savannahkhet province following a limited ad hoc survey during January and February of 2015. Infected plants showed symptoms of wilt, vascular discolouration, necrosis in the collar region, lower stem base and upper taproot regions, and whole plant death. Identification of the pathogen was confirmed through phylogenetic analysis of the EF1-α locus and a pathogenicity test satisfying Koch’s postulates. more...

We examined the local adaptation patterns in a system comprising several interconnected heterogeneous plant populations from which populations of two phylogenetically closely related pathogens were also sampled. The host is Hordeum vulgare (cultivated barley); the pathogens are Pyrenophora teres f. teres (net form) and Pyrenophora teres f. maculata (spot form), the causal agents of barley net blotch. We integrated two approaches, the comparison between the population structures of the host and the pathogens and a cross-inoculation test. We demonstrated that two closely related pathogens with very similar niche specialisation and life-styles can give rise to different co-evolutionary outcomes on the same host. Indeed, we detected local adaptation for the net form of the pathogen but not for the spot form. We also provided evidence that an a-priori well-known resistance quantitative-trait-locus on barley chromosome 6H is involved in the co-evolutionary ‘arms race’ between the plant and the net-form pathogen. Moreover, data suggested latitudinal clines of host resistance and that different ecological conditions can result in differential selective pressures at different sites. Our data are of interest for on-farm conservation of plant genetic resources, as also in establishing efficient breeding programs and strategies for deployment of resistance genes of P. teres. more...