Efficacy of a bacterial preparation of <Emphasis Type="Italic">Aneurinibacillus migulanus</Emphasis> against downy mildew of cucumber (<Emphasis Type="Italic">Pseudoperonospora cubensis</Emphasis>)

The reniform nematodes of the genus Rotylenchulus are semi-endoparasites of numerous herbaceous and woody plant roots and distributed in regions with Mediterranean, subtropical and tropical climates. In this study, we provide morphological and molecular characterisation of three out of 11 valid species of the genus Rotylenchulus: R. macrodoratus, R. macrosoma, and R. reniformis from Greece (Crete), Italy and Spain. The overall prevalence of reniform nematodes in wild and cultivated olives in Greece, Italy, and Spain was 11.5%, 19.0% and 0.6%, respectively. In Greece, R. macrodoratus and R. macrosoma were detected in cultivated olive with a prevalence of 8.2% and 6.2%, respectively, but none of them were found in wild olive. This is the first report of R. macrosoma in Greece. Only one reniform nematode species was detected in olive from Italy and Spain, viz. R. macrodoratus and R. macrosoma, respectively. The parasitism of R. macrosoma on hazelnut in northern Spain was also confirmed for the first time. This study demonstrates that R. macrodoratus and R. macrosoma have two distinct rRNA gene types in their genomes, specifically the two types of D2-D3 for R. macrosoma and R. macrodoratus, the two types of ITS for R. macrodoratus and the testing of the ITS variability in other R. macrosoma populations in different countries. Rotylenchulus macrosoma from Greece and Spain showed differences in nucleotide sequences in the ITS region and D2-D3 of 28S rRNA gene.     

First report of leaf spot caused by <Emphasis Type="Italic">Alternaria alternata</Emphasis> on <Emphasis Type="Italic">Drimia maritima</Emphasis>

Drimia maritima (squill) is a historically important medicinal plant. During the spring of 2016, small, yellow leaf spots, which became brown and finally necrotic, were observed on squill plants in Kohgiluyeh and Boyer-Ahmad Provinces in Iran. A fungus was consistently isolated from infected leaves and identified as Alternaria alternata based on morphological and phylogenetic analyses. Pathogenicity tests confirmed A. alternata to be the causal agent of the newly observed leaf spot disease. This is the first report of leaf spot on D. maritima caused by A. alternata in the world.     

Morphological and molecular analysis of <Emphasis Type="Italic">Paratrichodorus teres</Emphasis> (Hooper 1962) (Nematoda: Trichodoridae): a groundwork for discussion on the phylogeny and pathogenicity of <Emphasis Type="Italic">Paratrichodorus</Emphasis> species

Due to its ability to transmit plant viruses, Paratrichodorus teres (Hooper in Nematologica, 7, 273–280, 1962) is recognized as an economically important trichodorid species. Morphological and molecular analyses (18S and 28S rDNA) were performed, and 10 new plant hosts are reported for Polish P. teres populations. Major morphological features and the measurements obtained for the investigated specimens were within the wide ranges indicated for this species. However, a more detailed comparative analysis of Polish and Iranian P. teres showed significant morphological differences, particularly, in the shape and the structure of the walls of pars proximalis vaginae and the shape of the rectum.Phylogenetic study based on the 18S rDNA data suggests positioning of the Polish P. teres sequences within a cluster of sequences originating from the Netherlands. A comparison of the 28S rDNA fragment from Polish populations with the only P. teres 28S rDNA sequence available (from Iran) in GenBank revealed a sequence variability of 9.3%. The variation across these two representatives was higher than in the case of many other pairs of Trichodoridae species. The results obtained on the Polish P. teres specimens are discussed in the framework of the species taxonomy and phylogenetic relationships.     

Effect of simultaneous and sequential inoculations of <Emphasis Type="Italic">Meloidogyne incognita</Emphasis>, <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> and <Emphasis Type="Italic">Phomopsis vexans</Emphasis> on eggplant in sand mix and fly ash mix soil

Effects simultaneous and sequential inoculations of Meloidogyne incognita, Ralstonia solanacearum and Phomopsis vexans were studied on the growth, chlorophyll and carotenoid contents of eggplants grown in 25% fly ash and 25% sand mix soil. Plants grown in 25% fly ash mix soil had lesser plant growth than grown in 25% sand ash mix soil. Inoculation of M. incognita / R. solanacearum or P. vexans caused reduction in plant growth, chlorophyll and carotenoid contents in both types of soils but these pathogens in combination caused a greater reduction in than individual inoculation. Inoculation of M. incognita 20 days prior to R. solanacearum caused a greater reduction in plant growth than inoculation of M. incognita prior to P. vexans. Inoculation of P. vexans prior to R. solanacearum caused a lesser reduction in plant growth, chlorophyll and carotenoid contents than inoculation of P. vexans prior to M. incognita. Inoculation of R. solanacearum 20 days prior to M. incognita caused a greater reduction in plant growth, chlorophyll and carotenoid contents than inoculation of R. solanacearum prior to P. vexans. Galling and multiplication of M. incognita was higher in plants grown in 25% sand amended soil than with 25% fly ash soil. R. solanacearum and P. vexans had adverse effects on galling and nematode multiplication. Wilt and blight indices caused by R. solanacearum and P. vexans were 3 respectively. Wilt and blight indices were 4 when two pathogens were inoculated together.     

Races of <Emphasis Type="Italic">Phytophthora infestans</Emphasis> isolated from potato in Hokkaido,Japan

The virulence of 29 isolates of Phytophthora infestans collected in potato fields in Hokkaido, Japan, in 2013 and 2014, was tested for race identification. Thirteen different races were identified, each of which had five to eight virulence factors. All of the isolates caused a virulent reaction against plants with R1 and R7, and most of the isolates caused a virulent reaction against plants with R3, R4, R10, and R11. On the other hand, no isolate was virulent against plants with R9. These results demonstrate that the current Japanese P. infestans population is more complex than the population in the 1990s from the viewpoint of race.     

<Emphasis Type="Italic">Dittrichia viscosa</Emphasis> and<Emphasis Type="Italic">Rubus ulmifolius</Emphasis> as reservoirs of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) and the role of certain Coccinellid species

The role of the self-sown shrubsDittrichia viscosa (L.) W. Greuter andRubus ulmifolius Schott as reservoirs of aphid parasitoids was investigated. In the field studies conducted,D. viscosa grew adjacent to crops of durum wheat and barley andR. ulmifolius grew adjacent to cotton. The relative abundance of the parasitoids of(a) Capitophorus inulae (Passerini) onD. viscosa, (b) Rhopalosiphum padi (Linnaeus) on durum wheat and barley,(c) Aphis ruborum (Börner) onR. ulmifolius, and(d) Aphis gossypii Glover on cotton in various parts of Greece, was assessed during the years 1996–2000. In 2000, the fluctuation of parasitization of the above four aphid species was recorded and the action of the aphidophagous predators of the family Coccinellidae was studied. It was observed thatAphidius matricariae Haliday predominated onC. inulae andR. padi in all sampling cases. In contrast,Lysiphlebus fabarum (Marshall) was the dominant species parasitizingA. ruborum onR. ulmifolius andA. gossypii on cotton in Thessaly (central Greece) and Macedonia (northern Greece), whereasLysiphlebus confusus Tremblay et Eady andBinodoxys acalephae (Marshall) were the dominant parasitoid species in Thrace (northern Greece).Coccinella septempunctata Linnaeus was the most abundant coccinellid species on durum wheat, whereasAdonia variegata (Goeze) predominated on cotton. However, coccinellid individuals were scarce on bothD. viscosa andR. ulmifolius. The present study indicated that these two shrubs can be regarded as useful reservoirs of aphid parasitoids.     

Morphological and molecular characterisation of <Emphasis Type="Italic">Ditylenchus stenurus</Emphasis> n. sp. (Nematoda: Anguinidae) from western Iran

A new species in the genus Ditylenchus, D. stenurus n. sp. collected from western Iran, is described and illustrated herein based on morphological and molecular studies. The new species is characterised by a body length of 772 (663–863) μm, delicate stylet 6 (5–7) μm long, six lines in the lateral field. Median bulb of pharynx well-developed, muscular with crescentic valve. Post-vulval uterine sac well-developed, 35 (30–45) μm long, female tail elongate-conoid, becoming narrow suddenly with finely rounded terminus. The new species comes close in morphology and morphometrics to five known species of the genus, namely D. arachis, D. caudatus, D. clarus, D. myceliophagus, and D. nanus. DNA sequencing data was obtained on the partial 18S, D2/D3 expansion segments of the 28S rRNA gene and internal transcribed spacer (ITS). The phylogenetic relationships of this species with other Ditylenchus spp. using partial 18S–rDNA and D2/D3 indicated that D. stenurus n. sp. clustered together with several species belongs to the D. triformis-group i. e. D. africanus, D. destructor and D. halictus: all sharing a rounded tail terminus and six lines in lateral fields.     

Application of the consolidated species concept to identify the causal agent of strawberry anthracnose in Iran and initial molecular dating of the <Emphasis Type="Italic">Colletotrichum acutatum</Emphasis> species complex

Anthracnose caused by Colletotrichum spp. is one of main strawberry diseases worldwide. The disease recently arrived in Iran and become epidemic in the Kurdistan province. A combination of morphological, molecular and pathogen-host interaction approaches (referred to the consolidated species concept) were applied to isolates from symptomatic strawberry tissues collected in Iran. Multi-gene phylogenetic analysis based on ITS-rDNA, beta-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) identified the species as the S5 clade of Colletotrichum nymphaeae. No significant intraspecies variation was observed in terms of morphology and pathogenicity. No significant genetic variation was observed among the isolates using inter simple sequence repeat analysis (ISSR) and primer pair combination of ERIC1/BOX and ERIC2/BOX fingerprinting markers. Based on the results of this study, it can be postulated that the C. nymphaeae population in Iran established itself from a single origin due to a founder effect. More generally, molecular dating based on relaxed clocks indicates co-radiation of C. nymphaeae S5 and strawberry plants and suggests high reciprocal specificity between the host and pathogen.     

Association of <Emphasis Type="Italic">Pantoea ananatis and Pantoea agglomerans</Emphasis> with leaf spot disease on ornamental plants of Araceae Family

During a survey in 2011–2012, three ornamental plants of Araceae namely Aglaonema nitidum, Syngonium podophyllum and Dieffenbachia amoena showing foliar disease symptoms were collected from central region of Iran. Infected plants exhibited spots on their leaves which appeared as yellow and water-soaked with chlorotic haloes and necrotic center. To investigate the etiology of this disorder, symptomatic leaves were collected from affected plants and six bacterial strains (B2Y, J3Y, SY, E60Y, E68Y and E5MM) were isolated and identified as Pantoea ananatis or P. agglomerans based on morphological, physiological, biochemical and molecular characters. The pathogenicity tests of the isolates demonstrated that they were not host specific. Furthermore, 16S rRNA gene sequencing revealed that the strains were phylogenetically closely related to genus Pantoea. Multilocus sequence analysis (MLSA) of concatenated partial atpD, gyrB and rpoB gene sequences of the six isolates showed a high similarity of B2Y, J3Y, and SY strains to P. ananatis and also of E60Y, E5MM and E68Y strains to P. agglomerans. These results were confirmed by phylogenetic analysis. To the best of our knowledge, this is the first report of leaf spot and necrosis of A. nitidum, S. podophyllum and D. amoena caused by the genus Pantoea.     

Identification,virulence factors characterization,pathogenicity and aggressiveness analysis of <Emphasis Type="Italic">Fusarium</Emphasis> spp., causing wheat head blight in Iran

Fusarium head blight (FHB), mainly caused by Fusarium graminearum species complex (FGSC) and also by other species of this genus, is one of the most destructive cereal diseases with high yield losses and mycotoxin contamination worldwide. The aim of this study was to identify Fusarium species, characterize their virulence factors such as trichothecene genotypes and cell wall degrading enzymes (CWDEs), and also investigate virulence of the isolates obtained from wheat plants with FHB symptoms in Golestan province of Iran. Among 41 isolates tested, 24 were F. graminearum sensu stricto (s.s.), six were F. proliferatum, four were F. culmorum, three isolates belonged to each of F. subglutinans and F. meridionale species and one isolate of F. asiaticum was identified. Among Fusarium isolates, the nivalenol (NIV) genotype could be found more frequently, followed by 3-acetyl deoxynivalenol (3-ADON) and 15-acetyl deoxynivalenol (15-ADON) genotypes. Production of trichothecenes in autoclaved rice cultures was analyzed by gas chromatography (GC) and confirmed by GC–MS. The mean levels of NIV, 3-ADON and 15-ADON produced by Fusarium spp. were 824, 665 and 622 μg kg^?1, respectively. All Fusarium isolates were capable of producing CWDEs, mainly cellulase and xylanase. Lipase and pectinase activities appeared later and at less quantities. In overall, the isolates FH1 of F. graminearum and FH8 of F. proliferatum showed the maximum activity of CWDEs, which was correlated with high level of their virulence and aggressiveness on wheat. On the other hand, correlation was observed between the level and type of trichothecene produced by each isolate and its virulence on wheat. Virulence of trichothecene producing isolates was higher than that of non-trichothecene producing isolates. Our results suggested that CWDEs and trichothecenes, as virulence factors, have considerable roles on virulence and aggressiveness of the pathogen. This is the first report on the effect of trichothecenes and CWDEs on virulence and aggressiveness of Fusarium spp. associated with FHB disease in wheat growing regions of Iran.     

Survival and development of spotted bollworm, <Emphasis Type="Italic">Earias vittella</Emphasis> (Fabricius) (Lepidoptera: Nolidae) on different transgenic <Emphasis Type="Italic">Bt</Emphasis> and isogenic non-<Emphasis Type="Italic">Bt</Emphasis> cotton genotypes

Four Bt cotton hybrids, each with one of four different events, viz., MRC 6301 Bt (cry1Ac gene), JKCH 1947 Bt (modified cry1Ac gene), NCEH 6R Bt (fusion cry1Ac/cry1Ab gene) and MRC 7017 Bollgard II (cry1Ac and cry2Ab genes) were compared for survival and development of Earias vittella (Fabricius) along with their isogenic non-Bt genotypes. None of the neonates were able to complete the larval period and reach pupal stage on squares of 90, 120 and 150 days old crop of all Bt hybrids. Likewise, on bolls also, zero per cent larval survival was observed in all Bt hybrids except JKCH 1947 Bt where 0.67 per cent larvae could manage to reach pre-pupal stage at 120 and 150 days old crop but failed to form cocoon and enter pupal stage. The surviving larva took more development time (3.7 to 5.4 days) as compared to larvae fed on bolls of JKCH 1947 non-Bt. The average survival period (ASP) of larvae was in order of 150 > 120 > 90 days old crop among the crop ages; JKCH 1947 Bt > MRC 6301 Bt > NCEH 6 R Bt > MRC 7017 Bollgard II among Bt hybrids; and bolls > squares between fruiting bodies. However, reverse was true for speed index of toxic effect. The concentration of Cry toxin varied significantly in squares and bolls and also among the crop ages. The amount of Cry toxin in squares and bolls had significant negative correlation with ASP of the E. vittella larvae.     

Diversity and potential impact of Botryosphaeriaceae species associated with <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> plantations in Portugal

Eucalyptus globulus, a non-native species, is currently the most abundant forest species in Portugal. This economically important forest tree is exploited mainly for the production of pulp for the paper industry. The community of Botryosphaeriaceae species occurring on diseased and healthy E. globulus trees was studied on plantations throughout the country. Nine species from three different genera were identified, namely Botryosphaeria (B. dothidea), Diplodia (D. corticola and D. seriata) and Neofusicoccum (N. australe, N. algeriense, N. eucalyptorum, N. kwambonambiense, N. parvum and Neofusicoccum sp.). Of these, N. algeriense, D. corticola and D. seriata are reported for the first time on E. globulus, while N. algeriense, N. eucalyptorum and N. kwambonambiense correspond to first reports in Portugal. The genus Neofusicoccum was clearly dominant with N. australe and N. eucalyptorum being the most abundant species on both diseased and healthy trees. In artificial inoculation trials representative isolates from all nine species were shown to be pathogenic to E. globulus but there were marked differences in aggressiveness between them. Thus, D. corticola and N. kwambonambiense were the most aggressive while B. dothidea and D. seriata were the least aggressive of the species studied.     

Phylogenetic relationships of fluorescent <Emphasis Type="Italic">Pseudomonad</Emphasis> isolates associated with bacterial canker of stone fruit trees in Kurdistan province,Iran

Bacterial canker is one of the most important diseases of stone fruit trees in various locations of Kurdistan province, Iran. Genetic diversity and evolutionary relationships among 20 fluorescent pseudomonads isolated from stone fruit trees with symptoms similar to bacterial canker were investigated using a polyphasic approach by means of phenotypic characterizations, repetitive PCR using the REP and ERIC primers and multilocus sequence typing (MLST) of four housekeeping genes (gapA, rpoD, gyrB and gltA). The pathogenicity of strains was carried out under greenhouse conditions. Twelve strains produced an expected amplified DNA fragment of about 752-bp which indicated the presence of the syrB gene. Based on MLST, these strains belonged to P. syringae species complex and included in the genomospecies 1, phylogroup 2b and 2d. Phylogenetic analysis of the other eight fluorescent pseudomonad strains by using gyrB and rpoD sequences allowed the identification of strains into P. fluorescens, P. putida and P. lutea groups. Unweighted pair group method analysis (UPGMA) of genomic fingerprints obtained by rep-PCR revealed 17 different patterns which grouped P. syringae strains into three clusters clearly separated from other fluorescent pseudomonads. MLST confirmed the genetic variability among strains obtained by rep-PCR. Grouping identified of P. syringae strains by both rep-PCR and MLST was related to geographic locations of strains.     

Resistance evaluation of differentials and commercial wheat cultivars to stripe rust (<Emphasis Type="Italic">Puccinia striiformis</Emphasis>) infection in hot spot regions of Canada

Stripe rust of wheat, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat in Canada. This study presents the results from resistance evaluation of Yr genes and western Canadian wheat cultivars from different milling classes, to natural infection in southern Alberta and British Columbia which are considered hot spots of stripe rust occurrence in Canada, due to proximity to Pacific Northwest of the United States where stripe rust epidemics are frequent. Genes Yr1, Yr5, Yr15, and YrSP were effective in all environments; Yr17 and Yr28, which were earlier reported ineffective to existing stripe rust races at the seedling stage in Canada, were effective at adult plant stages in most of the environments because of warmer climates in southerly locations, a favourable condition for expression of the genes. Yr17 is common in winter wheat cultivars and only reported spring wheat cultivar carrying it is CDC Stanley, which can serve as donor parent in breeding programs. Gene Yr24/26 was not very effective in western prairies although reported as effective in eastern prairies. Residual resistance from combination of defeated genes (Yr3, Yr7, Yr9, Yr27) in some supplementary differentials was observed. Most cultivars carry slow-rusting, pleiotropic adult-plant resistance gene Yr18 and some Yr29, which were effective in some locations. These genes failed to provide complete protection under high disease pressure. Seedling and adult plant resistance genes Yr5, Yr15, Yr17 and Yr18, Yr36, respectively could be good targets for resistance breeding. Stacking adult plant resistance genes with seedling resistance genes can provide durable resistance to stripe rust.     

Conidial sporulation of <Emphasis Type="Italic">Stemphylium solani</Emphasis> under laboratory conditions and infectivity of the inoculum produced <Emphasis Type="Italic">in vitro</Emphasis>

Potato virus Y (PVY) is the type-species of the genus Potyvirus, family Potyviridae, being reported as a major tomato (Solanum lycopersicum L.) pathogen in several regions of the world. Pepper yellow mosaic virus (PepYMV) was originally described as a resistance-breaking Potato virus Y (PVY) isolate on Capsicum annuum L. cultivars, and afterwards it was also reported infecting tomatoes in Brazil. In the present work, a search for sources of resistance to both PepYMV and PVY was conducted in a collection of 119 accessions belonging to seven Solanum (section Lycopersicon) species. This germplasm was initially evaluated to PepYMV reaction by mechanical inoculation followed by symptom observations and ELISA. Potential PepYMV resistance sources were identified for the first time in S. habrochaites, S. peruvianum, S. corneliomuelleri, S. chilense, S. pimpinellifolium, and one accession derived from an interspecific cross (S. lycopersicum x S. peruvianum). A sub-group of 24 accessions with negative serology for PepYMV was also challenged with a PVY isolate, followed by serological and molecular detection with universal primers. Solanum habrochaites ‘L.03683’ and ‘L.03684’ were the only accessions found with stable resistance to both viruses. These results confirm S. habrochaites as the most important source of multiple resistance factor(s) to distinct Potyvirus species.     

Morphological and molecular characterization of <Emphasis Type="Italic">Diaporthe (</Emphasis>anamorph <Emphasis Type="Italic">Phomopsis)</Emphasis> complex and pathogenicity of <Emphasis Type="Italic">Diaporthe aspalathi</Emphasis> isolates causing stem canker in soybean

The complex of Diaporthe (asexual morph) species occurring on soybean constitutes an important pathogenic group associated with diseases such as pod and stem blight, seed decay and stem canker. Stem canker, caused by Diaporthe aspalathi, has been reported as the most aggressive form of canker and its occurrence has limited soybean crop productivity in the southern United States. The main form of pathogen control is the use of stem canker resistant soybean varieties. In this study, strains of Diaporthe and Phomopsis were isolated from stem and seeds of soybean in different locations in South America during the years 1989–2014. Genomic DNA from 26 isolates were analyzed by PCR-restriction fragment length polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) techniques, and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Phomopsis longicolla, D. phaseolorum var. sojae, D. caulivora and D. aspalathi. An analysis of the pathogenicity of 13 isolates of D. aspalathi inoculated in soybean genotypes carrying different resistance genes to stem canker (Rdm1, Rdm2, Rdm3, Rdm4, Rdm5 and Rdm?) enabled us to identify the occurrence of at least three races of D. aspalathi occurring in Brazil. Among the isolates identified as D. aspalathi, both molecular and phenotypic analyses showed clustering depending on the date of collection and pathogenicity, which revealed the existence of variability of the pathogen.     

Presence of less-preferred hosts of the aphid parasitoids <Emphasis Type="Italic">Aphidius ervi</Emphasis> and <Emphasis Type="Italic">Praon volucre</Emphasis> reduces parasitism efficiency

Parasitoids are characterized by a defined range of hosts, either more specialist or generalist. Under natural conditions, females may encounter different host species on the same plant or in the same location. In this case, their preference for one host could influence their choice. However, the presence of less suitable hosts may also affect their choice and, in some cases, may reduce their interest in a patch where both preferred and less preferred hosts are available. The aim of the present study was to test the consequences of the simultaneous presence of three cereal aphids (Sitobion avenae Fabricius, Metopolophium dirhodum Walker, and Rhopalosiphum padi Linnaeus) on the parasitism by two of their parasitoids, Aphidius ervi Haliday and Praon volucre Haliday. Firstly, in the no-choice experiment, A. ervi parasitized on S. avenae at a significantly higher rate as compared to M. dirhodum, whereas no parasitism on R. padi was observed. P. volucre parasitized the three species of cereal aphids with a significant preference for S. avenae. Interestingly, when two or three host species were offered simultaneously in the same quantity to pairs of parasitoids, the level of parasitism was less than that observed for one host species alone. This observation exhibits a distractive effect on non-host species, from the defense mechanism of a non-suitable host or from the perception of bad quality patches. These results raise the question of the practical application of inundative release of parasitoids for biocontrol when several hosts are available simultaneously.     

Confirmation of <Emphasis Type="Italic">Peronospora agrimoniae</Emphasis> as a distinct species

Leaves with typical symptoms of downy mildew were found on common agrimony in the Czech Republic in 2014 and 2015 and at several locations in Germany from 2010 to 2014. The causal agent of downy mildew of agrimony was often reported as Peronospora agrimoniae, but sometimes also as P. sparsa. Morphological characteristics of the pathogens found in both countries are in the range of previous works for P. agrimoniae, but also other downy mildews parasitic on Rosaceae, rendering their discrimination based on published observations difficult. For molecular identification sequencing of several loci (nrITS rDNA, cox1 and cox2) was performed. Phylogenetic analyses based on nrITS rDNA clearly separated P. agrimoniae from other Peronospora species infecting Rosaceae. Thus, considering P. agrimoniae as separate species seems justified. Two German specimens were identical to two Czech samples in both nrITS rDNA and cox1 mtDNA sequences, but differed in a single nucleotide substitution in cox2 region. To our knowledge, this is the first verified record of P. agrimoniae on common agrimony in the Czech Republic.     

Relative potency of culture supernatants of <Emphasis Type="Italic">Xenorhabdus</Emphasis> and <Emphasis Type="Italic">Photorhabdus</Emphasis> spp. on growth of some fungal phytopathogens

In previous research, concentrated metabolites produced by bacteria of the genera Xenorhabdus and Photorhabdus (which are symbionts of entomopathogenic nematodes) were reported to be highly suppressive to fungal and oomycete plant pathogens. Conceivably, application of non-concentrated bacterial filtrates would be more economically feasible compared to using concentrated metabolites. We evaluated the potency of 10 % v/v cell-free supernatants of the bacteria X. bovienii, X. nematophila, X. cabanillasii, X. szentirmaii, P. temperata, P. luminescens (VS) and P. luminescens (K22) against Fusicladium carpophilum (peach scab), F. effusum (pecan scab), Monilinia fructicola (brown rot), Glomerella cingulata (anthracnose) and Armillaria tabescens (root rot). A bioactive compound derived from Photorhabdus bacteria, trans-cinnamic acid (TCA), was also compared with the bacterial filtrates. Fungal colony size based on manual measurements was compared for accuracy to measurements taken by image analysis. Supernatants of Xenorhabdus spp. exhibited stronger suppressive effects on spore germination and vegetative growth when compared with Photorhabdus spp. Overall, TCA was the most effective treatment; vegetative growth was completely inhibited by TCA (1.27 mg/ml). TCA treatments also suppressed spore germination of F. carpophylium and F. effussum by approximately 90 %. The efficacy of supernatants varied among Xenorhabdus species depending on the species tested, but X. szentirmaii filtrates tended to cause greater inhibition relative to the other bacteria supernatants. Manual measurement of colony diameter required at least two replicate estimates of the colony to avoid a type II error. Area measurements were slightly overestimated based on ruler measurements, but did not affect the outcome of the analysis. Supernatants of Xenorhabdus spp., Photorhabdus spp., or TCA, did not cause any phytotoxic effects when applied to various plant species in the greenhouse. Our results indicate the potential of using TCA or Xenorhabdus cell free supernatants as bio-fungicides. Such a product, based on bacterial culture supernatants, would be economically viable, marketable and easily applicable by the end-users in many situations.     

Suppression subtractive hybridization and microarray analysis reveal differentially expressed genes in the <Emphasis Type="Italic">Lr39/41</Emphasis>-mediated wheat resistance to <Emphasis Type="Italic">Puccinia triticina</Emphasis>

Wheat leaf rust caused by Puccinia triticina (Pt) is one of the most severe fungal diseases threatening the global wheat production. The use of leaf rust resistance (Lr) genes in wheat breeding programs is the major solution to solve this issue. Wheat isogenic line carrying the Lr39/41 gene has shown a moderate to high resistance to most of the Pt pathotypes detected in China. In the present study, a typical hypersensitive response (HR) was observed using microscopy in leaves of the Lr39/41 isogenic line inoculated with the avirulent Pt pathotype THTT from 48 h-post inoculation. Two Lr39/41 resistance-associated suppression subtractive hybridization (SSH) libraries with a total of 6000 clones were established. Microarray hybridizations were performed on all obtained SSH clones using RNAs extracted from leaves of the Pt-inoculated and non-inoculated Lr39/41 isogenic lines, and leaves of the Pt-inoculated and non-inoculated Thatcher susceptible lines. Differentially expressed clones were analyzed by significance analysis of microarrays (SAM), followed by further sequencing. A total of 36 Lr39/41-resistance-related differentially expressed genes (DEGs) were identified, many of which had been previously reported to be involved in the plant defense response. The expression levels of eight selected DEGs during different stages of the Lr39/41-mediated resistance were further quantified by a qRT-PCR assay. Several pathogenesis-related (PR) and HR-related genes seem to be crucial for the Lr39/41-mediated resistance. In general, a brief profile of DEGs associated with the Lr39/41-mediated wheat resistance to Pt was drafted.