Polish Glomales

The morphological features of spores of Glomus pustulatum found in Poland are described and illustrated, and the worldwide occurrence of this species is characterized. Spores of G. pustulatum from Poland do not differ from those originally found in Canada and the United States of America. They were found in only one of more than 300 soil samples taken from over 100 localities in Poland. G. pustulatum was associated with roots of Ammophila arenaria colonizing maritime sand dunes of the Sowinski National Park, with a mean spore density of 12 in 100 g dry soil. Associated species of G. pustulatum were Acaulospora dilatata and Scutellospora dipurpurascens. G. pustulatum was found in Poland for the first time and is probably a species new to Europe.     

In situ collection of endangered arbuscular mychorrhizal fungi in a Mediterranean UNESCO Biosphere Reserve

We report the establishment of the first in situ collection of beneficial symbiotic microorganisms (arbuscular mycorrhizal fungi) in the world, located in an integrally protected area of coastal sand dunes, within the UNESCO Biosphere Reserve “Selva Pisana”, in Tuscany, Italy. In this collection the genus Scutellospora, which has been reported to be threatened by anthropogenic disturbance, was a regular component of Ammophila arenaria and Helichrysum stoechas rhizospheres, and was represented by two species: Scutellospora fulgida and Scutellospora persica. Such species were morphologically identified and molecularly characterised by SSU and ITS sequence analyses. The establishment of an in situ collection of Scutellospora species in a protected area, where anthropogenic impact is under control of national and international authorities, is important for the conservation of rare and endangered microorganisms, representing a precious resource for future generations.     

Arbuscular fungi and mycorrhizae (Glomales) of the Hel Peninsula,Poland

In the years 1985–1989, the occurrence of arbuscular fungi and mycorrhizae on the Hel Peninsula (Poland) was investigated with the help of 45 soil and root samples collected under 20 plant species of eight families. Except for Zea mays, the other plant species were from uncultivated sites. All soil samples contained spores of arbuscular fungi, of which about 45% were of the genus Glomus. Acaulospora spp. preferred members of the Cupressaceae. Spores of Gigaspora occurred rarely and only in two plant families. Glomus spp. were most frequently associated with plants of the Rosaceae, and species of Scutellospora were found at markedly higher frequencies among roots of plants of the Gramineae and Cupressaceae. A total of 29 spore-forming species and Glomus tenue (a fungus recognizable by its distinctive infections) were found. The most frequently recovered fungus, Glomus tenue, was present in roots of 56.8% of examined plants. Of the spore-forming fungi, the most frequently isolated spores were those of Scutellospora dipurpurascens, then Glomus constrictum, Acaulospora 61, and Glomus microcarpum. The overall spore density in examined samples averaged 99.8 in 100 g dry soil in the range 1 to 547, and was highest in a sample taken from around roots of Festuca arundinacea. The dominant fungi forming spores in sampled soils were Glomus constrictum, Glomus microcarpum, and Scutellospora dipurpurascens. The average species density was 3.9 in 100 g dry soil in the range 1 to 10, and was highest in Corynephorus canescens, Rosa canina, and Thuja occidentalis. Levels of colonization by arbuscular fungi ranged from 0.0 to94.0% (mean 23.3%) of the root length and were highest in Festuca arundinaceae and Zea mays.     

Invasive plants and their escape from root herbivory: a worldwide comparison of the root-feeding nematode communities of the dune grass <Emphasis Type="Italic">Ammophila arenaria</Emphasis> in natural and introduced ranges

Invasive plants generally have fewer aboveground pathogens and viruses in their introduced range than in their natural range, and they also have fewer pathogens than do similar plant species native to the introduced range. However, although plant abundance is strongly controlled by root herbivores and soil pathogens, there is very little knowledge on how invasive plants escape from belowground enemies. We therefore investigated if the general pattern for aboveground pathogens also applies to root-feeding nematodes and used the natural foredune grass Ammophila arenariaas a model. In the late 1800s, the European A. arenariawas introduced into southeast Australia (Tasmania), New Zealand, South Africa, and the west coast of the USA to be used for sand stabilization. In most of these regions, it has become a threat to native vegetation, because its excessive capacity to stabilize wind-blown sand has changed the geomorphology of coastal dunes. In stable dunes of most introduced regions, A. arenaria is more abundant and persists longer than in stabilized dunes of the natural range. We collected soil and root samples and used additional literature data to quantify the taxon richness of root-feeding nematodes on A.␣arenaria in its natural range and collected samples from the four major regions where it has been introduced. In most introduced regions A. arenaria did not have fewer root-feeding nematode taxa than the average number in its natural range, and native plant species did not have more nematode taxa than the introduced species. However, in the introduced range native plants had more feeding-specialist nematode taxa than A. arenaria and major feeding specialists (the sedentary endoparasitic cyst and root knot nematodes) were not found on A. arenaria in the southern hemisphere. We conclude that invasiveness of A. arenaria correlates with escape from feeding specialist nematodes, so that the pattern of escape from root-feeding nematodes is more alike escape from aboveground insect herbivores than escape from aboveground pathogens and viruses. In the natural range of A. arenaria, the number of specialist-feeding nematode taxa declines towards the margins. Growth experiments are needed to determine the relationship between nematode taxon diversity, abundance, and invasiveness of A. arenaria.     

Adaptation in perennial coastal plants-with particular reference to heritable variation in Puccinellia maritima and Ammophila arenaria

Perennial species invading the early stages of primary successions face constant, and often rapid, change in their biotic and abiotic environment. The relative abilities of different species to adapt to this change is reflected in the zonation patterns which characterize coastal vegetation. Variation in those species with wide ecological amplitudes, particularly in populations near the boundary of the realized niche, is likely to be particularly revealing.The pattern of heritable variation in Puccinellia maritima on salt marshes indicates directional selection for traits increasing plant vigour and competitive ability; presumably the effect of increasing plant density. Adaptation is by both genetic differentiation and phenotypic flexibility, the former being evident in adjacent grazed and ungrazed marshes and the latter in a mosaic of tall and short vegetation types. By contrast variation in Ammophila arenaria on dunes exhibits high levels of phenotypic flexibility, growth in a range of environments indicating that plants from fore-dune populations are higher responders than those from mature dunes.Among the implications of these results, and by comparison with other species, is the fact that, ironically, niche expansion for some salt marsh perennials may require the evolution of an annual strategy, and that a Darwinian selection model may help to explain variation in Ammophila's apparent vigour in dunes of different age.Nomenclature follows Tutin et al.: Flora Europaea (1964–1980).I am grateful to several colleagues and students, past and present, who have helped with the studies of Puccinellia and Ammophila and I am particularly indebted in this respect to Richard Scott.     

Oxidation of elemental-S in coastal-dune sands and soils

Summary S-oxidation was studied in samples of (a) coastal sands lacking vegetation; (b) sands from beneath isolated stands ofAmmophila arenaria andHippophaë rhamnoides; and (c) dune soils obtained from beneath vegetation growing on mature dunes. S-oxidation in samples taken from dune environments was compared with the process in a fertile garden soil.Elemental-S was oxidized to SO ₄ ^2– in all samples, with S₂O ₃ ^2– being formed as intermediates. S-oxidation was most pronounced in the dune soil, followed by the garden soil,Ammophila arenaria andH. rhamnoides rhizospheres and finally the non-vegetated sand. The rate of S-oxidation thus generally increased with increasing C and N content, increasing vegetation cover and decreasing soil-sand pH.Maximum S-oxidation occurred at 30–37°C, but some of the intermediates appeared even at 45°C, presumably indicating abiotic S-oxidation at high temperatures. S-oxidation decreased the pH of the two soils studied, but did not markedly acidify the unvegetated or rhizosphere sands.     

Diversity of AMF associated with Ammophila arenaria ssp. arundinacea in Portuguese sand dunes

Dune vegetation is essential for the formation and preservation of sand dunes and the protection of the coast line. Coastal sand dunes are harsh environments where arbuscular mycorrhizal fungi (AMF) play an important role in promoting plant establishment and growth. We present a study of the diversity of AMF associated with A. arenaria ssp. arundinacea in two locations of the Portuguese coast under a Mediterranean climate. These two locations were selected to compare a well-preserved dune system from a protected area with a degraded dune system from a public beach. AMF diversity was assessed mainly by cloning and sequencing of a fragment of the ribosomal SSU using the primer NS31 and AM1. Most of the 89 AMF clones obtained from the rhizosphere and roots of A. arenaria belonged to the genus Glomus, the largest clade within the Glomeromycota. Higher AMF diversity was found in the least disturbed site, in which spores of Scutellospora persica, Glomus constrictum and Glomus globiferum were found in the rhizosphere of A. arenaria.     

Vesicular-arbuscular mycorrhizal fungi in coastal dune plant communities I. Spore formation ofGlomus spp. predominates under a patch ofElymus mollis

Vesicular-arbuscular (VA) mycorrhizal fungi in pure patches of coastal dune plantsElymus mollis, Wedelia prostrata andZoysia macrostachya were examined for frequency of occurrence and number of spores of VA mycorrhizal fungi over one year. Six species in three genera of VA mycorrhizal fungi were recovered. Under a patch ofE. mollis, spores ofAcaulospora sp. 1,Glomus tortuosum, Glomus sp. 1,Glomus sp. 2 andScutellospora gregaria were recovered. Spores ofGlomus spp. were most common. In patches ofW. prostrata andZ. macrostachya spores ofAcaulospora sp. 1,G. tortuosum, Glomus sp. 1,Glomus sp. 2,S. gregaria andScutellospora sp. 1 were found.Contribution No. 112, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

The growth of external AM fungal mycelium in sand dunes and in experimental systems

We estimated the biomass and growth of arbuscular mycorrhizal (AM) mycelium in sand dunes using signature fatty acids. Mesh bags and tubes, containing initially mycelium-free sand, were buried in the field near the roots of the dune grass Ammophila arenaria L. AM fungal mycelia were detected at a distance of about 8.5 cm from the roots after 68 days of growth by use of neutral lipid fatty acid (NLFA) 16:1ω5. The average rate of mycelium extension during September and October was estimated as 1.2 mm day⁻¹. The lipid and fatty acid compositions of AM fungal mycelia of isolates and from sand dunes were analysed and showed all to be of a similar composition. Phospholipid fatty acids (PLFAs) can be used as indicators of microbial biomass. The mycelium of G. intraradices growing in glass beads contained 8.3 nmol PLFAs per mg dry biomass, and about 15% of the PLFAs in G. intraradices, G. claroideum and AM fungal mycelium extracted from sand dunes, consisted of the signature PLFA 16:1ω5. We thus suggest a conversion factor of 1.2 nmol PLFA 16:1ω5 per mg dry biomass. Calculations using this conversion factor indicated up to 34 μg dry AM fungal biomass per g sand in the sand dunes, which was less than one tenth of that found in an experimental system with Glomus spp. growing with cucumber as plant associate in agricultural soil. The PLFA results from different systems indicated that the biomass of the AM fungi constitutes a considerable part of the total soil microbial biomass. Calculations based on ATP of AM fungi in an experimental growth system indicated that the biomass of the AM fungi constituted approximately 30% of the total microbial biomass. This revised version was published online in June 2006 with corrections to the Cover Date.     

Colonization of the root zone ofAmmophila arenaria by harmful soil organisms

The role of harmful soil organisms in the degeneration ofAmmophila arenaria at coastal foredunes was examined by the growing of seedlings ofA. arenaria in soil samples collected from its root zone. Three sites, each representing a successive stage in foredune succession were examined: (1) a highly mobile dune (sand accretion of 80 cm year⁻¹) with vigorousA. arenaria, colonizing only the upper 30-cm of the annually deposited layer of sand, (2) a mobile dune with vigorousA. arenaria (sand accretion of 22 cm year⁻¹) and a 1-metre soil profile completely colonized by roots and (3) a stable dune (no sand accretion) with degeneratedA. arenaria and young roots mainly present in the upper 0–10 cm. In the upper part of the highly mobile site, the presence of harmful soil organisms was confined to the root layers and at the mobile site for all depth layers a significant growth reduction ofA. arenaria was observed due to the activity of harmful soil organisms. At the stable site, however, growth had only been reduced in some of the depth layers. At all sites newly formed roots ofA. arenaria had been colonized by harmful soil organisms within one year. If present in sand prior to root growth harmful soil organisms reduced root length and root hair formation severely and they enhanced branching of the roots. It is concluded that harmful soil organisms initiate degeneration ofA. arenaria in stable dunes by attack of the root system, which makes the plants suffer from abiotic stress.     

Sporicidal activity of tertiary butyl hydroperoxide

Tertiary butyl hydroperoxide (t-BOOH) was found to be sporicidal for Bacillus megaterium ATCC19213. Sporicidal action was very temperature dependent, and the potency of t-BOOH increased about tenfold for each increase in temperature of 15 °C over the range from 30° to 70 °C. At still higher temperatures, heat and molar levels of t-BOOH were mutually potentiating for killing. Vegetative cells and germinated spores were some thousand times less resistant to t-BOOH than dormant spores. The order of resistance for spores was: Bacillus stearothermophilus ATCC7953 > Bacillus subtilis var. niger = Bacillus megaterium ATCC33729 > Bacillus megaterium ATCC19213. Killing was not enhanced by decoating and occurred without germination or loss of refractility of the spores. Spore resistance to t-BOOH was lower at more acid pH values and was decreased also by demineralization. Spores could be protected by the chelator o-phenanthroline, especially in association with Fe²⁺. Overall, it seemed that killing was associated with nonmetabolic formation of alkyl peroxyl radicals, which are thought to be responsible for killing of vegetative cells by organic hydroperoxides.Abbreviation A-BOOH tertiary butyl hydroperoxide     

Unexpected progeny obtained from glasshouse study of soil pH influence onAcaulospora laevis inoculum

Summary Potential growth stimulation of two hosts by acid-tolerantAcaulospora laevis was tested in a soil adjusted to 5 pH levels from 5.0 to 7.7. By wet-sieving methods, the field-source inoculum was essentially a pure culture ofA. laevis spores. Upon harvest of sweetgum a completely different spore-type was found in large quantities;A. laevis spores were relatively few to non-existent. The results dramatically underscore the need for caution against relying solely on pre-trial identifications of inoculum spores or presuming that apparently single-species cultures/inoculum will remain pure throughout an experiment.Contribution of the Oregon State University Agricultural Experiment Station in cooperation with the US Department of Agriculture, Agricultural Research Service, technical paper #7366 of the former.     

Characterization of a heavy metal-tolerant endomycorrhizal fungus from the surroundings of a zinc refinery

An arbuscular mycorrhizal fungus was isolated from the rhizosphere of Agrostis capillaris growing in the contaminated surroundings of a zinc refinery in The Netherlands. After examination of the infection pattern and the spores, it was characterized as Scutellospora dipurpurescens, which was first isolated from a reclaimed coal mine area in West Virginia.     

Arbuscular mycorrhiza of Arnica montana under field conditions—conventional and molecular studies

Two distinct populations of Arnica montana, an endangered medicinal plant, were studied under field conditions. The material was investigated using microscopic and molecular methods. The analyzed plants were always found to be mycorrhizal. Nineteen arbuscular mycorrhizal fungal DNA sequences were obtained from the roots. They were related to Glomus Group A, but most did not match any known species. Some showed a degree of similarity to fungi colonizing liverworts. Conventional analysis of spores isolated from soil samples allowed to identify different fungal taxa: Glomus macrocarpum, Glomus mosseae, Acaulospora lacunosa, and Scutellospora dipurpurescens. Their spores were also isolated from trap cultures.     

Subtle differences in two non‐native congeneric beach grasses significantly affect their colonization,spread, and impact

Comparisons of congeneric species have provided unique insights into invasion ecology. Most often, non‐native species are compared to native ones to look for traits predicting invasion success. In this study, we examine a different facet of congeneric comparisons in which both species are non‐native. Ecological variability among non‐native congeners might 1) lead to the inhibition or facilitation of either species’ ability to colonize and spread, 2) result in larger cumulative impacts due to synergies between species, and 3) depend on the physical context of the invaded habitat. To explore these possibilities, we studied the distribution and abundance of two non‐native beach grasses: European beach grass Ammophila arenaria and American beach grass Ammophila breviligulata, their interaction with one another, and their biotic and physical impacts on dune ecosystems of the Pacific coast of North America. We found that over a two‐decade period, A. breviligulata has increased its dominance over A. arenaria on dunes where it was originally planted in 1935 and has actively spread to new sites formerly dominated by A. arenaria. Our results also show that dune plant species richness was lower at A. breviligulata sites, although there was an increase in the native beach grass Elymus mollis. More significantly, we found that the two grass species are associated with significantly different foredune shapes that are likely controlled by a combination of variability in sand supply along the coast and subtle differences in the congeners’ morphology and growth form. These differences have significant implications for the coastal protection services of dunes to humans and the conservation of native species. They provide a cautionary tale on the impacts of introducing novel species based purely on analogy with closely related species.     

Does salt stress constrain spatial distribution of dune building grasses Ammophila arenaria and Elytrichia juncea on the beach?

Rising sea levels threaten coastal safety by increasing the risk of flooding. Coastal dunes provide a natural form of coastal protection. Understanding drivers that constrain early development of dunes is necessary to assess whether dune development may keep pace with sea‐level rise. In this study, we explored to what extent salt stress experienced by dune building plant species constrains their spatial distribution at the Dutch sandy coast. We conducted a field transplantation experiment and a glasshouse experiment with two dune building grasses Ammophila arenaria and Elytrigia juncea. In the field, we measured salinity and monitored growth of transplanted grasses in four vegetation zones: (I) nonvegetated beach, (II) E. juncea occurring, (III) both species co‐occurring, and (IV) A. arenaria dominant. In the glasshouse, we subjected the two species to six soil salinity treatments, with and without salt spray. We monitored biomass, photosynthesis, leaf sodium, and nutrient concentrations over a growing season. The vegetation zones were weakly associated with summer soil salinity; zone I and II were significantly more saline than zones III and IV. Ammophila arenaria performed equally (zone II) or better (zones III, IV) than E. juncea, suggesting soil salinity did not limit species performance. Both species showed severe winter mortality. In the glasshouse, A. arenaria biomass decreased linearly with soil salinity, presumably as a result of osmotic stress. Elytrigia juncea showed a nonlinear response to soil salinity with an optimum at 0.75% soil salinity. Our findings suggest that soil salinity stress either takes place in winter, or that development of vegetated dunes is less sensitive to soil salinity than hitherto expected.     

Spore germination in Dictyostelium discoideum

Mutant spores of Dictyostelium discoideum, strain SG-10, differ from wild type spores in their ability to spontaneously germinate, to be activated with 5% dimethyl Sulfoxide (DMSO), and to be deactivated with 0.2 M sucrose. Both heat-activated wild type and mutant spores began to swell after a lag of 60–75 min at ambient temperature. Suspension of heat activated spores in 5% DMSO resulted in blockage of spore swelling and a concomitant severe inhibition of respiration; removal of 5% DMSO allowed resumption of respiration and the spores began to swell after a lag of only 15 min. It was concluded that 5% DMSO allowed the early reactions (M) to proceed but blocked the later reactions (R) of post-activation lag.Treatment of one day old spores with 20% DMSO solution for 30–120 min quantitatively activated the population. The post-activation lag time was directly dependent on the time of 20% DMSO treatment. Spores activated with 20% DMSO treatment could be deactivated by incubation at 0°C; the spores most quickly deactivated at 0°C were those within 10 min of swelling. Mitochondrial transport inhibitors such as azide and cyanide caused deactivation in an analogous manner. It is hypothesized that spores proceed to the second portion of the lag phase called (R) before the environment determines if dormancy is reimposed or if germination will proceed. The sensitive strain (SG-10) showed a greater degree of damage than the wild type after supraoptimal treatment with 40% DMSO. The spores became more resistant with age to the damaging action of 40% DMSO. All the observed effects of DMSO treatment were compatible with our multistate model of activation which suggests that the early portion of the lag phase (M) may involve a relative uncoupling of oxidative phosphorylation while the later portion (R) may require tight coupling.     

Vertical transmission and overwintering of microsporidia in the gypsy moth, Lymantria dispar

Vertical transmission and the overwintering success of three different microsporidia infecting Lymantria dispar (Lepidoptera: Lymantriidae) larvae were investigated. Endoreticulatus schubergi, a midgut pathogen, was transmitted to offspring via female and male via the egg chorion (transovum transmission). Between 8% and 29% of the emerging larvae became infected. No spores of E. schubergi were found in surface-washed eggs. Nosema lymantriae, a microsporidium that causes systemic infections, was transovarially transmitted. Between 35% and 72% of the progeny were infected. Vairimorpha disparis, a fat body pathogen, was not vertically transmitted. The infectivity of spores that overwintered in cadavers of infected L. dispar varied by species, placement in the environment, and weather conditions. Spores of E. schubergi were still infective after an eight month exposure period of cadavers on the ground. Spores of N. lymantriae and V. disparis remained highly infective only when cadavers overwintered under a more or less continuous snow cover for four months.     

Cooccurring plants forming distinct arbuscular mycorrhizal morphologies harbor similar AM fungal species

Arbuscular mycorrhizal (AM) fungal spores were isolated from field transplants and rhizosphere soil of Hedera rhombea (Miq) Bean and Rubus parvifolius L., which form Paris-type and Arum-type AM, respectively. DNA from the spore isolates was used to generate molecular markers based on partial large subunit (LSU) ribosomal RNA (rDNA) sequences to determine AM fungi colonizing field-collected roots of the two plant species. Species that were isolated as spores and identified morphologically and molecularly were Gigaspora rosea and Scutellospora erythropa from H. rhombea, Acaulospora longula and Glomus etunicatum from R. parvifolius, and Glomus claroideum from both plants. The composition of the AM fungal communities with respect to plant trap cultures was highly divergent between plant species. Analysis of partial LSU rDNA sequences amplified from field-collected roots of the two plant species with PCR primers designed for the AM fungi indicated that both plants were colonized by G. claroideum, G. etunicatum, A. longula, and S. erythropa. G. rosea was not detected in the field-collected roots of either plant species. Four other AM fungal genotypes, which were not isolated as spores in trap cultures from the two plant species, were also found in the roots of both plant species; two were closely related to Glomus intraradices and Glomus clarum. One genotype, which was most closely related to Glomus microaggregatum, was confined to R. parvifolius, whereas an uncultured Glomeromycotan fungus occurred only in roots of H. rhombea. S. erythropa was the most dominant fungus found in the roots of H. rhombea. The detection of the same AM fungal species in field-collected roots of H. rhombea and R. parvifolius, which form Paris- and Arum-type AM, respectively, shows that AM morphology in these plants is strongly influenced by the host plant genotypes as appears to be the case in many plant species in natural ecosystems, although there are preferential associations between the hosts and colonizing AM fungi in this study.