Chitinase andβ1,3-glucanase isoforms expressed in pea roots inoculated with arbuscular mycorrhizal or pathogenic fungi

Chitinases were studied in an endomycorrhiza-resistant mutant and wild type pea (Pisum sativum L. cv. Frisson) in order to characterize plant hydrolases specific to pathogenic (Aphanomyces euteiches andChalara elegans) or mycorrhizal (Glomus mosseae) root interactions. Stimulation of constitutive and induction of new chitinase activities was detected by native PAGE for acidic proteins in both pea genotypes inoculated with pathogenic fungi. In contrast, a different additional chitinase isoform was induced inG. mosseae-colonized roots. This isoform was also not elicited in chemically-stressed roots, confirming its mycorrhiza-specificity. Investigations of basic chitinase and-1,3-glucanase activities provided further evidence for differential pea responses during pathogenic and symbiotic interactions.     

Glomus intraradices, Pseudomonas alcaligenes, and Bacillus pumilus: effective agents for the control of root-rot disease complex of chickpea (Cicer arietinum L.)

The effects of Glomus intraradices, Pseudomonas alcaligenes and Bacillus pumilus on the root-rot disease complex caused by the root-knot nematode Meloidogyne incognita and the root-rot fungus Macrophomina phaseolina in chickpea was assessed by quantifying differences in the shoot dry mass, pod number, nodulation, and shoot content of chlorophyll, nitrogen, phosphorus and potassium. Inoculation of plants with G. intraradices, P. alcaligenes and B. pumilus alone and in combination significantly increased shoot dry mass, pod number, and content of chlorophyll, nitrogen, phosphorus and potassium in plants inoculated with pathogens over that in the uninoculated control plants. P. alcaligenes caused a greater increase in shoot dry mass, pod number, chlorophyll, nitrogen, phosphorus and potassium in plants with pathogens than did G. intraradices or B. pumilus. Combined application of G. intraradices, P. alcaligenes and B. pumilus to plants inoculated with pathogens caused a greater increase in shoot dry mass, pod number, nitrogen, phosphorus, and potassium than did an application of P. alcaligenes plus B. pumilus or of G. intraradices plus B. pumilus. Root colonization by G. intrardices was high when used alone, while inoculation with the pathogens reduced root colonization by G. intraradices. In the presence of P. alcaligenes and B. pumilus, root colonization by G. intraradices increased. In plants inoculated with just one antagonist, P. alcaligenes reduced galling and nematode multiplication the most, followed by G. intraradices, then B. pumilus. The greatest reduction in galling, nematode multiplication and root-rot was observed when both bacterial species and G. intraradices were applied together.     

AM真菌对加拿大一枝黄花与菌根植物和非菌根植物种间作用的影响

为明确丛枝菌根(arbuscular mycorrhizal,AM)真菌对加拿大一枝黄花Solidago canadensis与本地菌根植物和非菌根植物种间竞争格局的调控作用,采用温室盆栽试验,通过接种摩西球囊霉Glomus mosseae(GM)、根内球囊霉G. intraradices(GI)及其混合菌种(GM+GI)3种处理,分析AM真菌对加拿大一枝黄花与本地菌根植物玉米Zea mays和非菌根植物油菜Brassica campestris种间作用的影响。结果表明:与对照相比,接种AM真菌均显著提高了加拿大一枝黄花和玉米的菌根侵染率,菌根侵染率为13.720%～50.015%,且前者的菌根侵染率明显高于后者。单独种植时,与对照相比,接种AM真菌尤其是接种混合菌种显著提高了加拿大一枝黄花的株高、叶片数和总干重。在加拿大一枝黄花与玉米混合种植时,与单独种植相比,加拿大一枝黄花的株高、叶片数、根长和总干重均较低;同时,与对照相比,接种AM真菌显著提高了玉米的相对竞争强度而对加拿大一枝黄花的相对竞争强度没有显著影响。在加拿大一枝黄花和油菜混合种植时,与对照相比,接种AM真菌则显著提高了加拿大一枝黄花的株高、叶片数、净光合速率和总干重;同时,接种AM真菌促进了入侵种的竞争优势而抑制了非菌根植物油菜的生长。说明加拿大一枝黄花与本地种的竞争格局受到与之混生物种的菌根依赖性强度以及AM真菌的种类差异影响。     

Evaluation of Natural Chemical Compounds Against Root-lesion and Root-knot Nematodes and Side-effects on the Infectivity of Arbuscular Mycorrhizal Fungi

The survival of two species of plant parasitic nematodes: the root-lesion nematode Pratylenchus brachyurus, and the root-knot nematode Meloidogyne javanica, was evaluated in saturated atmospheres of 12 natural chemical compounds. The infectivity of two isolates of arbuscular mycorrhizal fungi: Glomus mosseae and Glomus intraradices, under identical experimental conditions, was also determined. All the compounds tested exerted a highly significant control against M. javanica and among them, benzaldehyde, salicilaldehyde, borneol, p-anisaldehyde and cinnamaldehyde caused a mortality rate above 50% over P. brachyurus. The infectivity of G. intraradices was inhibited by cinnamaldehyde, salicilaldehyde, thymol, carvacrol, p-anisaldehyde, and benzaldehyde, while only cinnamaldehyde and thymol significantly inhibited mycorrhizal colonization by G. mosseae.     

The early nodulin enod40 is induced by,and also promotes arbuscular mycorrhizal root colonization

Expression of Tenod40, a tobacco (Nicotiana tabacum cv. Xanthi nc) homologue of Msenod40, a gene expressed early during alfalfa (Medicago sativa) nodule development, was significantly and consistently increased (about three-fold) in tobacco roots of plants grown in sand and colonized by the arbuscular mycorrhizal (AM) fungus Glomus intraradices, as compared to non-mycorrhizal controls. In alfalfa (Medicago sativa cv. Gilboa), a similar induction of Msenod40 expression was also detected in mycorrhizal vs. non-mycorrhizal roots. In the same experimental system, the application of the cytokinin 6-benzylaminopurine to non-mycorrhizal roots resulted in a similar increase in Msenod40 expression. A significantly higher incidence of AM fungal colonization (vesicles per cm of root) in M. sativa cv. Gilboa roots was observed following application of luteolin-induced Sinorhizobium meliloti exudates as compared to plants amended with non-induced exudates. Moreover, overexpression of the Mtenod40 gene in Medicago truncatula plants under the control of a 35S constitutive promoter resulted in significantly enhanced colonization as compared to non-transgenic plants. The fact that enod40 gene expression was increased both in a legume and in a non-legume during colonization by the AM fungus, and that colonization levels were higher in enod40 -overexpressing transgenic plants strongly suggests that this gene is involved in the establishment of the fungal partner in its host.     

Interactions between Plasmopara helianthi, Glomus mosseae and Two Plant Activators in Sunflower Plants

Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators DL--amino-n-butyric acid (BABA) and CGA 245704 (acibenzolar-S-methyl (BTH)) in sunflower plants susceptible to downy mildew were studied in four experiments using different methods of treatment and pathogen inoculation. Both chemicals were applied as soil drenches and foliar sprays, whereas P. helianthi infection was obtained by root and cotyledon inoculations of the seedlings. Soil drenches at the rates of 50 and 100mgkg^–1 soil of BABA and BTH given 1 and 3 days before P. helianthi inoculation, respectively to mycorrhizal plants, provided moderate protection against the pathogen (about 50–55%). Morphological changes and decrease in mycorrhizal colonization in roots of BTH-treated plants and in BTH-treated mycorrhizal plants were also observed. Delay in the emergence and reduction of the root systems were more evident at the highest concentration but decreased with time. These effects were absent with the BABA treatment.Foliar spray treatment of BABA and BTH, applied at 4000 and 200µgml^–1, respectively (1 day post-inoculation) to mycorrhizal plants provided good protection (about 80%) against P. helianthi foliar infections. No effects on mycorrhizal colonization or on root systems were observed. In vitro tests on the effect of the compounds on the mycorrhizal fungus showed that the germination of G. mosseae sporocarps increased with BABA treatment whereas it was greatly inhibited by BTH treatment.     

Effects of organic wastes,Glomus intraradices andPseudomonas putida on the growth of tomato and on the reproduction of the Root-knot nematodeMeloidogyne incognita

Effects of organic wastes (biosolids, horse manure, sawdust and neem leaf litter [NLL]), an arbuscular mycorrhizal (AM) fungusGlomus intraradices, and a plant growth-promoting rhizobacteriumPseudomonas putida, were studied on the growth of tomato and on the reproduction ofMeloidogvne incognita. Pseudomonas putida andG. intraradices promoted tomato growth in nematode-infected and nematode-free plants but growth promotion was higher in the infected ones. WhenP. putida andG. intraradices were applied together, the increase in tomato growth was greater than when either agent was applied alone. Of the organic wastes, NLL was better in improving tomato growth of nematode-infected plants followed by biosolids, horse manure and sawdust. Combined use of NLL withP. putida plusG. intraradices was best in improving growth of the infected plants. Root colonization byP. putida was increased more when inoculated withG. intraradices than when inoculated singly. Of the organic wastes, use of sawdust withP. putida caused a greater increase in root colonization by fluorescent pseudomonads followed by NLL, horse manure and biosolids. Nematode parasitism had an adverse effect on root colonization byP. putida. Inoculation ofP. putida and organic wastes increased the root colonization caused by the AM fungus.P. putida was better in reducing galling and nematode multiplication thanG. intraradices, whereas use of the two together was better than that of either of them alone. Among organic wastes, NLL was better in reducing galling and nematode multiplication followed by biosolids, horse manure and sawdust. Combined use of NLL withP. putida plusG. intraradices was better in reducing galling and nematode multiplication than any other treatment.     

Effects of arbuscular mycorrhizal fungi on severity of root rot of bananas caused by Cylindrocladium spathiphylli

The interaction between four arbuscular mycorrhizal (AM) fungi, Glomus sp., G. proliferum , G. intraradices and G. versiforme , and the root-rot fungus Cylindrocladium spathiphylli , and subsequent effects on growth and phosphorus nutrition of banana ( Musa acuminata , AAA, cv. Grande Naine) were investigated under glasshouse conditions. Overall, root infection by C. spathiphylli reduced the growth of banana plants, but preinoculation with AM fungi significantly attenuated this detrimental effect. Lower disease severity, stimulation of growth and increase of shoot P content were observed for the plants inoculated with one of the four AM fungi. Glomus sp. and G. proliferum induced the largest increase in growth parameters and shoot P content as compared to G. intraradices and G. versiforme , in the presence as well as in the absence of C. spathiphylli . Root damage caused by C. spathiphylli was decreased in the presence of AM fungi, but the inoculation of mycorrhizal plants with C. spathiphylli also decreased the intensity of AM fungal root colonization, indicating a clear interaction between the two organisms.     

Effect of Glomus mosseae on concentrations of rosmarinic and caffeic acids and essential oil compounds in basil inoculated with Fusarium oxysporum f.sp. basilici

This study investigated the potential of the arbuscular mycorrhizal (AM) fungus Glomus mosseae to protect basil (Ocimum basilicum) against Fusarium oxysporum f.sp. basilici (Fob). It was hypothesised that G. mosseae could confer a bioprotective effect against Fob as a result of increases in leaf rosmarinic (RA) and caffeic acids (CA) or essential oil concentrations. Glomus mosseae conferred a bioprotective effect against Fob by reducing plant mortality to 20% compared to 33% in non‐mycorrhizal (NM) plants. This bioprotective effect was not related to improved phosphorus (P) nutrition, as AM and NM plants treated with Fob had similar shoot P concentrations (6 and 8 mg g^?1 dry weight (DW), respectively). Both AM and NM plants treated with Fob had similar leaf and root RA and CA concentrations. Furthermore, phenolic (40–70 mg CA g^?1 DW) or essential oil concentrations (0·1–0·6 mg g^?1 DW) were not increased in plants treated with the AM fungus and Fob. Therefore, the bioprotective effect conferred by G. mosseae was not a result of increases in the phytochemicals tested in this study. However, under the AM symbiosis, basil plants treated with Fob had lower methyleugenol concentrations in their leaves (0·1 mg g^?1 DW) than NM plants treated with the pathogen (0·6 mg g^?1 DW).     

Biocontrol traits of plant growth suppressive arbuscular mycorrhizal fungi against root rot in tomato caused by <Emphasis Type="Italic">Pythium aphanidermatum</Emphasis>

Arbuscular mycorrhizal (AM) fungi known to cause plant growth depressions in tomato were examined for their biocontrol effects against root rot caused by Pythium aphanidermatum. The main hypothesis was that plant growth suppressive AM fungi would elicit a defence response in the host plant reducing Pythium root rot development. To test this hypothesis a fully factorial experiment was performed with AM fungi (Glomus intraradices, G. mosseae, G. claroideum or nonmycorrhizal), Pythium (± P. aphanidermatum) and harvest (7 and 14 days after pathogen inoculation (dapi)) as the main factors. Two weeks after AM fungi inoculation, roots were challenged with P. aphanidermatum. Variables evaluated at each harvest were root colonization levels of the interacting fungi, plant growth responses, and expression of a plant pathogenesis related protein gene (PR-1). All of the tested AM fungi caused marked growth suppressions, but did not affect PR-1 gene expression or the phosphorous concentration in the host plant. Plants singly inoculated with P. aphanidermatum had an increased PR-1 expression and phosphorous concentration. Among the AM fungi included in the study only G. intraradices reduced the pathogen root infection level, measured both in terms of Pythium ELISA and by recovery on selective media and only at the first harvest. Likewise, P. aphanidermatum root infection reduced colonization levels of G. intraradices, but not that of the two other AM fungi. In conclusion, plant growth suppressive AM fungi may offer plant beneficial traits in terms of biocontrol of root cortical pathogens.     

丛枝菌根真菌和甜菜夜蛾的相互作用

为探索丛枝菌根(arbuscular mycorrhiza,AM)真菌与植食性昆虫的相互作用,将摩西管柄囊霉(Funneliformis mosseae BEG167,Fm)、根内球囊霉(Glomus intraradices BEG141,Gi)和地表球囊霉(Glomus versiforme Berch,Gv)3种AM真菌以及甜菜夜蛾Spodoptera exigua分别接种至花生和番茄上,通过测定AM真菌的侵染定殖和甜菜夜蛾的生长发育指标分析AM真菌与甜菜夜蛾的相互作用。结果显示,甜菜夜蛾取食菌根花生植株后,Fm、Gv和Gi的侵染率和泡囊数均有增加,侵染率分别是未取食的1.15、1.10和1.11倍,而Fm的泡囊数增加最显著,是未取食的1.27倍。在菌根番茄植株上,Fm和Gv的侵染率显著增加,分别是未取食的1.24倍和1.94倍,Fm、Gv和Gi的泡囊数均显著增加,分别是未取食的1.50、1.98和1.42倍。甜菜夜蛾取食菌根花生和菌根番茄植株后,幼虫存活率下降,幼虫历期和蛹期明显延长;Fm对其影响最显著,甜菜夜蛾在花生上的存活率、幼虫历期和蛹期分别为26.67%、26.78 d和10.67 d,在番茄上分别为35.52%、24.33 d和10.39 d,与取食非菌根植株处理差异显著。表明甜菜夜蛾能在一定程度上促进AM真菌的侵染和定殖,而AM真菌能抑制甜菜夜蛾的生长和发育,但其影响因AM真菌种类而不同。     

Are field populations of arbuscular mycorrhizal fungi able to suppress the transmission of seed-borne <Emphasis Type="Italic">Bipolaris sorokiniana</Emphasis> to aerial plant parts?

The development of seed-borne Bipolaris sorokiniana in barley in the presence of arbuscular mycorrhizal fungi was studied. To exploit natural variation in their ability to control disease development, arbuscular mycorrhizal fungi from various Swedish arable soils were multiplied in trap cultures using a mixture of plant species. Six out of eight trap culture soil inocula were able to reduce transmission of B. sorokiniana from seeds to stem bases when grown together with infected barley seed. Based on this result two soil inocula, of different origin, from semi-natural grassland and barley respectively, were chosen for further greenhouse studies. Both soil inocula gave significant reductions in pathogen transmission from seeds to seedlings compared to the untreated control. In addition, treatment with spore inocula, collected from the different trap culture soils, showed disease suppression. Treatment with spores from the pure culture Glomus intraradices gave significant reduction in leaf lesion development. A treatment with the commercial inoculum Vaminoc^® was included and gave some suppression of the pathogen. In conclusion this study has shown that AM soil inocula from trap cultures suppressed the transmission of seed-borne B. sorokiniana in the aerial parts of barley plants.     

Effects of antagonistic fungi,plant growth-promoting rhizobacteria,and arbuscular mycorrhizal fungi alone and in combination on the reproduction of <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> and growth of tomato

Antagonistic fungi (Aspergillus niger CA and Penicillium chrysogenum CA1), plant growth-promoting rhizobacteria (PGPR) (Burkholderia cepacia 4684 and Bacillus subtilis 7612) and AM fungi (Glomus intraradices KA and Gigaspora margarita AA) were assessed alone and in combination for their effects on the growth of tomato and on the reproduction of Meloidogyne incognita in glasshouse experiments. Application of antagonistic fungus, PGPR, or AM fungus alone or in combination significantly increased the length and shoot dry mass of plants both with and without nematodes. The increase in shoot dry mass caused by Gl. intraradices KA in plants without nematodes was greater than that caused by PGPR or antagonistic fungi. Similarly, the increase in shoot dry mass caused by Bu. cepacia 4684 in plants with nematodes was greater than that caused by P. chrysogenum CA1. Application of Bu. cepacia 4684 caused a 36.1% increase in shoot dry mass of nematode-inoculated plants followed by Ba. subtilis 7612 (32.4%), A. niger CA (31.7%), Gl. intraradices KA (30.9%), Gi. margarita AA (29.9%) and P. chrysogenum CA1 (28.8%). Use of Bu. cepacia 4684 with A. niger CA caused a highest (65.7%) increase in shoot dry mass in nematode-inoculated plants followed by Ba. subtilis 7612 plus A. niger CA (60.9%). Burkholderia cepacia 4684 greatly reduced (39%) galling and nematode multiplication, and the reduction was even greater (73%) when applied with A. niger CA. Antagonistic fungi had no significant effect on root colonization caused by AM fungi. Applying Bu. cepacia 4684 with A. niger CA may be useful in the biocontrol of M. incognita on tomato.     

Effects of Ampropylfos (RS)-1-aminopropylphosphonic acid) on zoospore formation,repeated zoospore emergence and oospore formation in Aphanomyces spp.

The effects on growth, asexual and sexual reproduction of different Aphanomyces species by the new fungicide ampropylfos ((RS)-1-aminopropylphosphonic acid) were tested using highly synchronized cultures. Ampropylfos reduced mycelial growth in Aphanomyces astaci, A. euteiches and A. stellatus. The fungicide was found to reduce zoospore numbers in all Aphanomyces species tested except A. euteiches. In one species, A. stellatus, zoospore production was inhibited at much lower fungicide concentrations than in the other species tested. In the pea pathogen A. euteiches, ampropylfos reduced the number of oospores, whereas the fungicide had little effect on asexual reproduction.     

Mycorrhiza induced resistance in potato plantlets challenged by Phytophthora infestans

Biological control of soil-borne pathogens by arbuscular mycorrhizal (AM) fungi has been repeatedly demonstrated. However, their role in the control of above-ground hemibiotrophic pathogens is less conclusive. Here, we investigated in vitro the impact of an AM fungus on Phytophthora infestans in potato plants. The leaf infection index was decreased in mycorrhizal potato plants. Real-Time Quantitative PCR revealed the induction of two pathogenesis related genes (PR1 and PR2) in the leaves of mycorrhizal plants shortly after infection with P. infestans. These results suggested a systemic resistance in mycorrhizal plants, related to the priming of the two PR genes in potato.     

Competence of <Emphasis Type="Italic">Xanthomonas campestris</Emphasis> from Cruciferous Weeds and Wallflower (<Emphasis Type="Italic">Erysimum cheiri</Emphasis>) to Induce Black Rot in Cabbage

Aphanomyces euteiches Drechsler is an oomycete pathogen of leguminous crops that causes root rot, a severe disease of pea (Pisum sativum L.) worldwide. An improved understanding of the genetic structure of A. euteiches populations would increase knowledge of pathogen evolution and assist in the design of strategies to develop pea cultivars and germplasm with stable disease resistance. Twenty six primers pairs were used to amplify Sequence Related Amplified Polymorphisms (SRAP) among 49 A. euteiches isolates sampled from pea. A total of 190 polymorphic SRAP bands were generated, of which 82 were polymorphic between all the A. euteiches isolates. The percentage of polymorphic bands per primer pair ranged from 22 to 75%. According to the PIC value estimated for each marker, 60% of the SRAP markers were highly to reasonably informative (PIC > 0.25). Genetic structure of A. euteiches populations sampled in different American and French locations showed low to high genetic diversity within populations. The largest variation occurred within countries, with a total estimated genetic diversity of 0.477 and 0.172 for American and French populations, respectively. This was particularly evident from a principal component analysis (PCA) and a Minimum Spanning Networks (MSN) based on genetic profiles of isolates, which generated two different clusters, one corresponding to the French isolates and four American isolates (MV1, MV5, MV7, Ath3), and the other to American isolates. A. euteiches populations from cultivated pea in France appeared as a single unstructured population, whereas American isolates of A. euteiches diverged into three different populations.     

Pathogenicity of Aphanomyces spp. from Different Leguminous Crops in Sweden

Host range and pathogenicity of a range of Aphanomyces spp. isolates obtained from pea roots but also from a range of other field-grown leguminous crops in southern Sweden was investigated. The Aphanomyces euteiches isolates originating from pea and the few obtained isolates originating from alfalfa, green bean and yellow sweet-clover were highly pathogenic only to pea. The A. euteiches isolated from common vetch differed from these isolates by being weakly pathogenic to pea and other legumes, but highly pathogenic to common vetch. Vetch isolates also formed a well-defined separate cluster based on principal component analysis of pathogenicity pattern on tested crops. Oospores of A. euteiches were observed in root tissue of pea as well as common vetch, alfalfa, green bean, broad bean, red clover and yellow sweet-clover in the greenhouse pathogenicity tests. An Aphanomyces sp. that morphologically differed from A. euteiches, was frequently isolated from several leguminous plants, but was non-pathogenic to all tested crops in the pathogenicity tests. In isozyme analysis the banding pattern of these isolates resembled the pattern of A. cladogamus. Another, different and so far unidentified Aphanomyces sp. from roots of green bean and broad bean, was also non-pathogenic to the tested legume species. Based on the isolates tested, the results obtained suggest that the population of Aphanomyces spp. infecting legume roots in Sweden consists of a pea-specific and a vetch-specific group of A. euteiches. Two other groups comprised (i) Aphanomyces sp. isolates that resembled A. cladogamus, and (ii) isolates, which resembled neither A. euteiches nor A. cladogamus. In addition, the host range of Swedish A. euteiches isolates was not as broad as reported for A. euteiches isolates from other countries.     

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.     

Sexual mating preferences in vitro and in planta among Japanese isolates of Phytophthora infestans

The sexual preferences of Japanese isolates of Phytophthora infestans were determined by mating on agar, in broth, or in plants. The influence of their sexual preference was confirmed in the host tissues. Three wild-type isolates and a -glucuronidase (GUS) transformant were co-cultured to identify the origin of antheridia and oogonia. Japanese A1 isolate had a unique sexual preference compared with foreign isolates. It produced self-fertile oospores with about 40% of total gametangia but tended to form antheridia on V-8 agar medium. In addition, oospores were formed in plants, but their sexual preference could not be reflected in vitro.     

Genetic diversity of the pea root pathogen Aphanomyces euteiches in Europe

The oomycete pathogen Aphanomyces euteiches causes root rot in various legume species. In this study we focused on A. euteiches causing root rot in pea (Pisum sativum), thereby being responsible for severe yield losses in pea production. We aimed to understand the genetic diversity of A. euteiches in Europe, covering a north-to-south gradient spanning from Sweden, Norway and Finland to the UK, France and Italy. A collection of 85 European A. euteiches strains was obtained, all isolated from infected pea roots from commercial vining pea cultivation fields. The strains were genotyped using 22 simple-sequence repeat markers. Multilocus genotypes were compiled and the genetic diversity between individual strains and population structure between countries was analysed. The population comprising strains from Italy was genetically different and did not share ancestry with any other population. Also, strains originating from Finland and the eastern parts of Sweden were found to be significantly different from the other populations, while strains from the rest of Europe were more closely related. A subset of 10 A. euteiches strains from four countries was further phenotyped on two susceptible pea genotypes, as well as on one genotype with partial resistance towards A. euteiches. All strains were pathogenic on all pea genotypes, but with varying levels of disease severity. No correlation between the genetic relatedness of strains and virulence levels was found. In summary, our study identified three genetically distinct groups of A. euteiches in Europe along a north-to-south gradient, indicating local pathogen differentiation.