Establishment of mycorrhizal symbiosis in<Emphasis Type="Italic">Gentiana verna</Emphasis>

The last lowland locality ofGentiana verna in the Czech Republic is a calcareous grassland near Rovná at Strakonice in South Bohemia. This locality was the subject of a recovery programme that included support of the remaining population by micropropagation. The plants were inoculated with arbuscular mycorrhizal fungi (AMF) after their transfer toex vitro and the effect of AMF on their establishment and survival was studied. Although the conventional method of inoculation ofG. verna using spores or colonized root segments as an inoculum source resulted in no or negligible root colonization, the transplantation of gentians to the locality Rovná was successful and the plants became colonized with AMF very rapidly in the field. Successful mycorrhization of gentians under experimental conditions occurred only via the extraradical mycelial network established by neighbouring mycorrhizal plant species (nurse plant effect). Different nurse plant species formed different morphological types of mycorrhiza when inoculated with the same fungal isolate. Gentians always had theParis type of root colonization with intracellular hyphal loops and swellings. Intercellular hyphae, arbuscules and vesicles were not observed. No evidence for a positive growth response was found inG. verna.     

Inoculation of<Emphasis Type="Italic">Rhododendron</Emphasis> cv. Belle-Heller with two strains of<Emphasis Type="Italic">Phialocephala fortinii</Emphasis> in two different substrates

The growth response of an ornamentalRhododendron hybrid to the inoculation withPhialocephala fortinii was studied in two pot experiments in order to decide about the effectiveness of the inoculation of young rhododendron microplants. Two different substrates were used in both experiments, either sterilized or non-sterilized: a horticultural substrate and a soil collected from a field site with dominant ericoid vegetation. Two fungal isolates were used for an inoculation:P. fortinii strain P (UAMH 8433) andP. fortinii strain F, a dark septate endophyte (DSE) previously isolated from naturally-infected roots ofVaccinium myrtillus. BothPhialocephala strains successfully colonized the roots of the host plants forming typical DSE (=pseudomycorrhizal) colonization pattern including the formation of intracellular microsclerotia. However, pseudomycorrhizal colonization did not affect the growth parameters of the host rhododendrons. The results from both experiments indicate a neutral effect of the inoculation with DSE fungi on the growth ofRhododendron cv. Belle-Heller.     

Interactions between<Emphasis Type="Italic"> Trichoderma pseudokoningii</Emphasis> strains and the arbuscular mycorrhizal fungi<Emphasis Type="Italic"> Glomus mosseae</Emphasis> and<Emphasis Type="Italic"> Gigaspora rosea</Emphasis>

The interaction between Trichoderma pseudokoningii (Rifai) 511, 2212, 741A, 741B and 453 and the arbuscular mycorrhizal fungi Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe BEG12 and Gigaspora rosea Nicolson & Schenck BEG9 were studied in vitro and in greenhouse experiments. All T. pseudokoningii strains inhibited the germination of G. mosseae and Gi. rosea except the strain 453, which did not affect the germination of Gi. rosea. Soluble exudates and volatile substances produced by all T. pseudokoningii strains inhibited the spore germination of G. mosseae. The germination of Gi. rosea spores was inhibited by the soluble exudates produced by T. pseudokoningii 2212 and 511, whereas T. pseudokoningii 714A and 714B inhibited the germination of Gi. rosea spores by the production of volatile substances. The strains of T. pseudokoningii did not affect dry matter and percentage of root length colonization of soybean inoculated with G. mosseae, except T. pseudokoningii 2212, which inhibited both parameters. However, all T. pseudokoningii strains decreased the shoot dry matter and the percentage of AM root length colonization of soybean inoculated with Gi. rosea. The saprotrophic fungi tested seem to affect AM colonization of root by effects on the presymbiotic phase of the AM fungi. No influence of AM fungi on the number of CFUs of T. pseudokoningii was found. The effect of saprotrophic fungi on AM fungal development and function varied with the strain of the saprotrophic species tested.     

Chemical defense,mycorrhizal colonization and growth responses in <Emphasis Type="Italic">Plantago lanceolata</Emphasis> L.

Allelochemicals defend plants against herbivore and pathogen attack aboveground and belowground. Whether such plant defenses incur ecological costs by reducing benefits from plant mutualistic symbionts is largely unknown. We explored a potential trade-off between inherent plant chemical defense and belowground mutualism with arbuscular mycorrhizal fungi (AMF) in Plantago lanceolata L., using plant genotypes from lines selected for low and high constitutive levels of the iridoid glycosides (IG) aucubin and catalpol. As selection was based on IG concentrations in leaves, we first examined whether IG concentrations covaried in roots. Root and leaf IG concentrations were strongly positively correlated among genotypes, indicating genetic interdependence of leaf and root defense. We then found that root AMF arbuscule colonization was negatively correlated with root aucubin concentration. This negative correlation was observed both in plants grown with monocultures of Glomus intraradices and in plants colonized from whole-field soil inoculum. Overall, AMF did not affect total biomass of plants; an enhancement of initial shoot biomass was offset by a lower root biomass and reduced regrowth after defoliation. Although the precise effects of AMF on plant biomass varied among genotypes, plants with high IG levels and low AMF arbuscule colonization in roots did not produce less biomass than plants with low IG and high AMF arbuscule colonization. Therefore, although an apparent trade-off was observed between high root chemical defense and AMF arbuscule colonization, this did not negatively affect the growth responses of the plants to AMF. Interestingly, AMF induced an increase in root aucubin concentration in the high root IG genotype of P. lanceolata. We conclude that AMF does not necessarily stimulate plant growth, that direct plant defense by secondary metabolites does not necessarily reduce potential benefits from AMF, and that AMF can enhance concentrations of root chemical defenses, but that these responses are plant genotype-dependent.     

Harvest mice<Emphasis Type="Italic">Micromys minutus</Emphasis> and common dormice<Emphasis Type="Italic">Muscardinus avellanarius</Emphasis> live sympatric in woodland habitat

In an overgrown clearing, which occupied an area of 5 ha within mixed spruce-deciduous forest, 106 and 20 nests of the harvest mouseMicromys minutus (Pallas, 1771) and 81 and 59 nests of the common dormouseMuscardinus avellanarius (Linnaeus, 1758) were recorded in the fourth and fifth years after clear-felling, respectively. The highest densities of nests ofM. minutus andM. avellanarius were 46 nests/ha and 39 nests/ha, respectively, in two different plots. The affinity betweenM. minutus andM. avellanarius was negative in overgrown clearings according to the distribution of their nests. Such a result was expected becauseM. minutus andM. avellanarius used different nest supporting plants:M. minutus used tall grasses, whileM. avellanarius used young trees and shrubs. However, no positive relationship was found between the number of nests ofM. minutus and cover of grass vegetation in plots with the highest density of nests ofM. minutus. Most nests ofM. Minutus were situated in areas covered by young trees among which tall grasses, mainlyCalamagrostis epigeios, grew, often on the borders with the areas covered by grass vegetation. The successionary stage when woody vegetation reached 4–5 years old did not choke grass vegetation yet was favourable for bothM. minutus andM. avellanarius in overgrowing clearings.     

Identification and genomic distribution of<Emphasis Type="Italic"> gypsy</Emphasis> like retrotransposons in<Emphasis Type="Italic"> Citrus</Emphasis> and<Emphasis Type="Italic"> Poncirus</Emphasis>

Transposable elements might be importantly involved in citrus genetic instability and genome evolution. The presence of gypsy like retrotransposons, their heterogeneity and genomic distribution in Citrus and Poncirus, have been investigated. Eight clones containing part of the POL coding region of gypsy like retrotransposons have been isolated from a commercial variety of Citrus clementina, one of the few sexual species in Citrus. Four of the eight clones might correspond to active elements given that they present all the conserved motifs described in the literature as essential for activity, no in-frame stop codon and no frame-shift mutation. High homology has been found between some of these citrus elements and retroelements within a resistance-gene cluster from potato, another from Poncirus trifoliata and two putative resistance polyproteins from rice. Nested copies of gypsy like elements are scattered along the Citrus and Poncirus genomes. The results on genomic distribution show that these elements were introduced before the divergence of both genera and evolved separately thereafter. IRAPs based on gypsy and copia types of retrotransposons seem to distribute differently, therefore gypsy based IRAPs prove a new, complementary set of molecular markers in Citrus to study and map genetic variability, especially for disease resistance. Similarly to copia-derived IRAPs, the number of copies and heterozygosity values found for gypsy derived IRAPs are lower in Poncirus than in Citrus aurantium, which is less apomictic and the most usual rootstock for clementines until 1970.Communicated by C. Möllers     

Distribution of similar self-incompatibility (<Emphasis Type="Italic">S</Emphasis>) haplotypes in different genera,<Emphasis Type="Italic"> Raphanus</Emphasis> and<Emphasis Type="Italic"> Brassica</Emphasis>

The nucleotide sequences of ten SP11 and nine SRK alleles in Raphanus sativus were determined, and deduced amino acid sequences were compared with those of Brassica SP11 and SRK. The amino acid sequence identity of class-I SP11s in R. sativus was about 30% on average, the highest being 52.2%, while that of the S domain of class-I SRK was 77.0% on average and ranged from 70.8% to 83.9%. These values were comparable to those of SP11 and SRK in Brassica oleracea and B. rapa. SP11 of R. sativus S-21 was found to be highly similar to SP11 of B. rapa S-9 (89.5% amino acid identity), and SRK of R. sativus S-21 was similar to SRK of B. rapa S-9 (91.0%). SP11 and SRK of R. sativus S-19 were also similar to SP11 and SRK of B. oleracea S-20, respectively. These similarities of both SP11 and SRK alleles between R. sativus and Brassica suggest that these S haplotype pairs originated from the same ancestral S haplotypes.     

Evaluation of mycelial inocula of edible<Emphasis Type="Italic"> Lactarius</Emphasis> species for the production of<Emphasis Type="Italic"> Pinus pinaster</Emphasis> and<Emphasis Type="Italic"> P. sylvestris</Emphasis> mycorrhizal seedlings under greenhouse conditions

Different methods to inoculate seedlings of Pinus pinaster and P. sylvestris with edible Lactarius species under standard greenhouse conditions were evaluated. Fungal inoculations were performed both under pure culture synthesis in vitro, followed by transplantation of acclimatized seedlings, and directly in the greenhouse using different techniques for inocula production (mycelial slurries, vegetative inoculum grown in peat-vermiculite and alginate-entrapped mycelium). In vitro inoculations with L. deliciosus produced thoroughly colonized seedlings. However, a sharp decrease in mycorrhizal colonization was detected on transplanted seedlings after 4 month's growth in the greenhouse. On the other hand, all the inocula applied directly in the greenhouse, except the alginate-entrapped mycelium, produced a variable number of mycorrhizal seedlings and colonization rates after the first growing season, depending on the plant-fungal combination and the inoculation method. Inoculations with vegetative inocula of the strain 178 of L. deliciosus were the most effective in producing mycorrhizal seedlings. All the seedlings inoculated with this strain were colonized although the colonization rates were relatively low. The commercial feasibility of the different inoculation methods for the production of seedlings colonized with edible Lactarius species is discussed.     

Toxicity of diesel fuel to germination,growth and colonization of <Emphasis Type="Italic">Glomus intraradices</Emphasis> in soil and <Emphasis Type="Italic">in vitro</Emphasis> transformed carrot root cultures

Phytoremediation is the use of selected plants to decontaminate polluted environments. Arbuscular mycorrhizal fungi (AMF) may potentially be useful for phytoremediation, but it is not known how petroleum hydrocarbons influence AMF spore germination and hyphal growth. To address this question, germination of spores and germ tube growth of Glomus intraradices Schenck and Smith and Glomus aggregatum Schenck and Smith were assessed in soil contaminated with up to 3% (w/v) of F2 diesel oil or HAGO reference oil. Hyphal growth, colonization and progeny spore production were assessed in vitro using transformed root cultures of Daucus carota and G. intraradices spores in a F2 diesel contaminated medium. In addition, extraradical hyphal growth of G. intraradices colonizing Daucus carota in the presence of F2 diesel was studied. Neither F2 diesel nor HAGO reference oil affected spore germination or germ tube growth in soil. However, in the presence of plant roots, germ tube growth of G. intraradices was reduced and delayed in the presence of F2 diesel and root colonization was not detected. Hyphal growth of pre-colonized carrot roots by G. intraradices was reduced and delayed in F2 contaminated medium compared to controls. F2 diesel did not inhibit spore germination of these AMF species but did reduce colonization, germ tube and hyphal growth. These results suggest that AMF inoculum can be established in petroleum-contaminated sites. However, it may prove beneficial to plant pre-colonized plants to increase the probability of sufficient AMF colonization and growth. The likely mechanism(s) of petroleum toxicity in this plant-microbe system was discussed.     

FISH analysis of<Emphasis Type="Italic"> Drosophila melanogaster</Emphasis> heterochromatin using BACs and<Emphasis Type="Italic"> P</Emphasis> elements

The heterochromatin of chromosomes 2 and 3 of Drosophila melanogaster contains about 30 essential genes defined by genetic analysis. In the last decade only a few of these genes have been molecularly characterized and found to correspond to protein-coding genes involved in important cellular functions. Moreover, several predicted genes have been identified by annotation of genomic sequence that are associated with polytene chromosome divisions 40, 41 and 80 but their locations on the cytogenetic map of the heterochromatin are still uncertain. To expand our current knowledge of the genetic functions located in heterochromatin, we have performed fluorescence in situ hybridization (FISH) mapping to mitotic chromosomes of nine bacterial artificial chromosomes (BACs) carrying several predicted genes and of 13 P element insertions assigned to the proximal regions of 2R and 3L. We found that 22 predicted genes map to the h46 region of 2R and eight map to the h47 regions of 3L. This amounts to at least 30 predicted genes located in these heterochromatic regions, whereas previous studies detected only seven vital genes. Finally, another 58 genes localize either in the euchromatin-heterochromatin transition regions or in the proximal euchromatin of 2R and 3L. Edited by: B. McKeeN. Corradini and F. Rossi contributed equally to this work     

Effect of<Emphasis Type="Italic">Glomus intraradices</Emphasis> isolated from Pb-contaminated soil on Pb uptake by<Emphasis Type="Italic">Agrostis capillaris</Emphasis> is changed by its cultivation in a metal-free substrate

Development and heavy metal tolerance of two cultivation lineages of the indigenous isolate of arbuscular mycorrhizal fungus (AMF)Glomus intraradices PH5 were compared in a pot experiment in soil from lead (Pb) smelter waste deposits. One lineage was sub-cultured in original Pb-contaminated soil; the second one was maintained for 13 months in an inert substrate (river sand) without Pb stress. The contribution of these cultivation lineages to the Pb uptake and accumulation by the host plantAgrostis capillaris was investigated. The experiment was conducted in a compartmented system where the lateral compartments withAgrostis seedlings were separated from the central pot containing 4-week olderAgrostis plants by a nylon mesh for allowing out-growing of extraradical mycelium (ERM) from the pot. No differences in mycorrhizal colonization, ERM length and viability were observed between the two lineages ofG. intraradices PH5 in the soil of the isolate origin. However, the ability to support plant growth and Pb uptake differed between the lineages and also between the plants in the central pots and the lateral compartments. The growth of the plants in the central pots was positively affected by AMF inoculation. The plants inoculated with the lineage maintained in original soil showed larger shoot biomass and higher shoot P content as compared to the other inoculation treatments. The shoot Pb concentration of these plants was lower when compared to the plants inoculated with the lineage sub-cultured in the inert substrate. However the concentration did not differ from non-mycorrhizal control or from the reference isolateG. intraradices BEG75 from non-contaminated soil. Also shoot Pb contents were similar for all inoculation treatments. The development ofG. intraradices BEG75 in the contaminated soil was very poor; this isolate was not able to initiate colonization of seedlings in lateral compartments. In lateral compartments, growth of seedlings in contaminated soil was inhibited by theG. intraradices PH5 lineage maintained in the inert substrate. Pb translocation from the seedling roots to shoots was increased for plants inoculated with either lineage as compared to the non-mycorrhizal control; however, the increase for the lineage cultivated in the inert substrate was significantly higher in comparison with that maintained in the original soil. After 13 months of cultivation in a metal free substrate, theG. intraradices isolate from Pb contaminated soil did not lose its tolerance to Pb as regards colonization of plant roots and growth of ERM in the soil of its origin. However, its ability to support plant growth and to prevent Pb translocation from the roots to the shoots was decreased.     

Seasonal variation in allelopathic potential of<Emphasis Type="Italic">Artemisia princeps</Emphasis> var.<Emphasis Type="Italic">orientalis</Emphasis> on plants and microbes

We investigated seasonal variations in allelopathic potential ofArtemisia princeps var.orientalis. Aqueous and meth-anol extracts and volatile substances were prepared in the laboratory from samples collected monthly (April through October). Their impacts were then assessed on the germination and seedling growth ofLactuca sativa andAchyranthes japonica. The allelopathic potential varied with the time of sample collection and the concentration tested. For example, germination ofL. sativa was not inhibited by the aqueous extract but seedling growth (shoots and roots) was, with its seasonal effect being significant. ForA. japonica, seed germination was not inhibited at lower concentrations (except for August samples). However, at higher concentrations and in certain months (especially July), germination was more negatively affected. The degree of seedling growth inhibition also differed by month and by extract concentration, with roots being impacted more than shoots. Volatile substances also had a time-dependent influence on the germination and seedling elongation ofA. japonica. In a separate experiment, the ethyl-acetate and water fractions of a crude methanol extract were prepared monthly fromA. princeps var.orientalis. Here, we examined their antimicrobial activities against three gram-positive bacteria (Bacillus cereus, Bacillus subtilis, andStaphylococcus aureus), two gramnegative bacteria (Escherichia coli andPseudomonas fluorescens), and one lactic acid bacterium,Lactobacillus plantar urn. The ethyl-acetate fraction that was sampled in September was remarkably potent againstB. cereus andB. subtilis, whereas the water fraction collected in August and September showed great antimicrobial activity against the grampositive and -negative bacteria. In contrast,L. plantarum was not inhibited by the water fraction, regardless of the sampling month. Likewise, the ethyl-acetate and water fractions collected in April and October had the lowest levels of antimicrobial activity.     

Mutation in <Emphasis Type="Italic">cyaA</Emphasis> in <Emphasis Type="Italic">Enterobacter cloacae</Emphasis> decreases cucumber root colonization

Strains of Enterobacter cloacae show promise as biological control agents for Pythium ultimum-induced damping-off on cucumber and other crops. Enterobacter cloacae M59 is a mini-Tn5 Km transposon mutant of strain 501R3. Populations of M59 were significantly lower on cucumber roots and decreased much more rapidly than those of strain 501R3 with increasing distance from the soil line. Strain M59 was decreased or deficient in growth and chemotaxis on most individual compounds detected in cucumber root exudate and on a synthetic cucumber root exudate medium. Strain M59 was also slightly less acid resistant than strain 501R3. Molecular characterization of strain M59 demonstrated that mini-Tn5 Km was inserted in cyaA, which encodes adenylate cyclase. Adenylate cyclase catalyzes the formation of cAMP and cAMP levels in cell lysates from strain M59 were approximately 2% those of strain 501R3. Addition of exogenous, nonphysiological concentrations of cAMP to strain M59 restored growth (1 mM) and chemotaxis (5 mM) on synthetic cucumber root exudate and increased cucumber seedling colonization (5 mM) by this strain without serving as a source of reduced carbon, nitrogen, or phosphorous. These results demonstrate a role for cyaA in colonization of cucumber roots by Enterobacter cloacae.     

Phylogenetic relationships in the genera<Emphasis Type="Italic"> Zostera</Emphasis> and<Emphasis Type="Italic"> Heterozostera</Emphasis> (Zosteraceae) based on<Emphasis Type="Italic"> matK</Emphasis> sequence data

Phylogenetic analysis of the plastid (chloroplast) DNA matK gene of Zosteraceae species was undertaken. A molecular phylogenetic tree based on matK sequence data showed the monophyly of Heterozostera tasmanica and subgenus Zosterella and did not support the separation of Heterozostera from the genus Zostera. The tree based on matK supported the monophyly of the subgenus Zostera, and showed that Zosteraceae consist of three main groups: Phyllospadix, which is clearly defined by being dioecious; the subgenus Zosterella and Heterozostera; and the subgenus Zostera. Character-state reconstruction of chromosome number and geographic distribution for our molecular phylogenetic tree showed that 2n=12 is a plesiomorphic character for Zostera and Heterozostera, that the chromosome number was doubled or tripled in two lineages, and that the initial speciation of Zostera and Heterozostera occurred in the Northern Hemisphere. The matK tree showed the close affinity of Z. noltii and Z. japonica, which have disjunct distributions. Zostera marina, which is the only widely distributed species in the subgenus Zostera, also occurring in the northern Atlantic, was shown to be embedded within other subgenus Zostera species.     

Lack of arbuscular mycorrhizal colonisation in tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis> L.) plants cultivated in Northern Iran

Soil and roots associated with different tea clones and nearby weeds (Veronica sp., Setaria sp., Salvia sp., Senecio sp. and Tripogon sp.) were sampled for arbuscular mycorrhizal fungi (AMF) in the tea gardens of Northern Iran. Spores were searched for in the soil and AMF colonisation determined microscopically and fatty acid signatures in roots was determined. Root samples from mycorrhizal and non-mycorrhizal clover were used as positive and negative controls. AMF spores were abundant in the tea garden soils; the genera Glomus and Acaulospora dominated. Microscopic observations of stained tea roots showed no sign of AMF. To confirm this, the roots were analysed for fatty acid signature compounds. The average level of PLFA 16:1ω5 as signature molecule for AMF in tea roots was 2 nmol g⁻¹ dry root, while the NLFA 16:1ω5 was not detectable. In mycorrhizal and non-mycorrhizal clover roots, the PLFA 16:1ω5 was 141and 5.74 nmol g⁻¹ dry root, respectively. In roots of weeds in tea plantations, the amount of PLFA 16:1ω5 was in the range 4.9 to 31.1 nmol g⁻¹ dry root. Thus, there was no evidence for AMF association in tea roots and weeds are thought to be the source of the spores in the soils. Finally, no mycorrhizal colonisation was found when tea plant seedlings were inoculated with AMF in pot cultures.     

Expression of<Emphasis Type="Italic"> FoxE</Emphasis> and<Emphasis Type="Italic"> FoxQ</Emphasis> genes in the endostyle of<Emphasis Type="Italic"> Ciona intestinalis</Emphasis>

We have analyzed the expression patterns of two Fox genes, FoxE and FoxQ, in the ascidian Ciona intestinalis. Expression of Ci-FoxE was specific to the endostyle of adults, being prominent in the thyroid-equivalent region of zone 7. Ci-FoxQ was expressed in several endodermal organs of adult ascidians, such as the endostyle, branchial sac and esophagus. In the endostyle, the pattern of Ci-FoxQ expression was similar to that of CiTTF-1, being prominent in the thyroid-equivalent regions of zones 7 and 8. Therefore, these Fox genes may perform thyroid-equivalent functions in the ascidian endostyle.Edited by N. Satoh     

Geographic occurrence of intermediate type between<Emphasis Type="Italic"> Castanopsis sieboldii</Emphasis> and<Emphasis Type="Italic"> C. cuspidata</Emphasis> (Fagaceae) based on the structure of leaf epidermis

The number of layers of epidermis in the leaves is used as a criterion to distinguish between Castanopsis sieboldii (two layers) and C. cuspidata (one layer). An intermediate type, which has one and two layers within a single leaf, is frequently seen in the field. The origin of the intermediate type has been supposed to be a hybrid between C. sieboldii and C. cuspidata. If the intermediate type is produced by hybridization, we expect that the F₁ seedlings of the intermediate type should occur in the co-occurrence area of those two species. To clarify the geographic occurrence of the intermediate type, we collected nuts of 443 mother trees from throughout the distribution area of the genus Castanopsis in Japan. A total of 7,260 seedlings germinated from these nuts were examined as to their leaf structure. The seedlings of the intermediate type occurred not only in the area where C. sieboldii and C. cuspidata coexisted, but also in the area where only C. sieboldii grows. The leaf structure of intermediate seedlings was independent of the traits of mother trees. These findings suggest that the intermediate seedlings that occurred in the area where only C. sieboldii grows are not hybrid between C. sieboldii and C. cuspidata but are a morphological variation of C. sieboldii. The difference in the structure of leaf epidermis is not always appropriate for the identification of the hybrid.     

Responses of mycorrhizal and non-mycorrhizal<Emphasis Type="Italic"> Erica cinerea</Emphasis> and<Emphasis Type="Italic"> Vaccinium macrocarpon</Emphasis> to<Emphasis Type="Italic"> Glomus mosseae</Emphasis>

An investigation was carried out on the mycorrhizal colonisation, growth and nutrition of two members of the Ericaceae in close proximity to an arbuscular mycorrhizal (AM) association. This was undertaken by separating mycorrhizal (EM) and non-mycorrhizal (NEM) Erica cinerea and Vaccinium macrocarpon from AM (inoculated by Glomus mosseae) and non-mycorrhizal (NAM) Plantago lanceolata using a 30 µm nylon mesh in a sand culture/pot system. Ericoid mycorrhizal colonisation by Hymenoscyphus ericae on root systems of E. cinerea and V. macrocarpon was in the range 14–22% and 58–69%, respectively. The presence of AM P. lanceolata had no effect on the ericoid mycorrhizal colonisation of E. cinerea and V. macrocarpon. NEM E. cinerea showed reductions in shoot biomass and shoot nitrogen concentrations after exposure to AM P. lanceolata after incubations of 6 and 9 weeks but there were no differences in dry mass, length, and nitrogen and phosphorus concentrations of the root systems between the treatment combinations. Reductions were also found, after incubations of 6 and 9 weeks, in shoot dry mass, leaf area and shoot nitrogen concentrations of NEM V. macrocarpon in the presence of AM P. lanceolata but no changes occurred in the length and dry mass of the root systems. There were no differences in maximum photosynthesis in V. macrocarpon between treatment combinations but NEM V. macrocarpon in the presence of AM P. lanceolata had the lowest transpiration rates and stomatal conductance and the highest nitrogen- and phosphorus-use efficiencies compared with the other treatment combinations. These results are discussed in relation to the type of interaction found in these compatible and incompatible mycorrhizal associations.     

Detection of<Emphasis Type="Italic">pap</Emphasis>-,<Emphasis Type="Italic">sfa</Emphasis>- and<Emphasis Type="Italic">afa</Emphasis>-specific DNA sequences in<Emphasis Type="Italic">Escherichia coli</Emphasis> strains isolated from extraintestinal material

P-fimbriae, S-fimbriae and AFA-adhesins are virulence factors responsible for adherence ofEscherichia coli strains to extraintestinal host-cell surface. Detection ofpap-,sfa- andafa-specific sequences performed by PCR revealed 74%pap ⁺, 65%sfa ⁺, and 8.3%afa ⁺ strains in a group of 84 extraintestialE. coli isolates. Detection in a group of fecal strains showed 29%pap ⁺, 21%sfa ⁺ and 4%afa ⁺ strains.pap together withsfa were found as the most frequent combination (56%) among extraintestinal isolates probably due to localization ofpap-andsfa-operons on a common pathogenicity island. The occurrence ofafa-specific sequence among 56 urine strains was 11%, although noafa ⁺ strain was detected among 28 gynecological isolates. No strains with detected adhesin operons were found among twenty (24%) extraintestinalE. coli strains.