N. Malajczuk

The ability of 16 ectomycorrhizal fungi to increase growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell.

The effectiveness of 16 fungal isolates in forming ectomycorrhizas and increasing the growth and phosphorus uptake of Eucalyptus globulus Labill. and E. diversicolor F. Muell. seedlings was examined in the glasshouse. Seedlings were grown in yellow sand at 2 phosphorus levels (4 and 12 mg P kg-1 sand). At the time of harvest (100 days), the non-inoculated seedlings and seedlings inoculated with Paxillus muelleri (Berk.) Sacc. and Cortinarius globuliformis Bougher had a low level of contamination from an unknown mycorrhizal fungi. Seedlings inoculated with Thaxterogaster sp. nov. and Hysterangium inflatum Rodway had developed mycorrhizas of the superficial type whereas Hydnangium carneum Wallr. in Dietr., Hymenogaster viscidus Massee & Rodway, Hymenogaster zeylanicus Petch, Setchelliogaster sp. nov., Laccaria laccata (Scop. ex. Fr.) Berk., Scleroderma verrucosum (Vaillant) Pers., Amanita xanthocephala (Berk.) Reid & Hilton, Descolea maculata Bougher and Malajczuk and Pisolithus tinctorius (Pers.) Coker & Couch formed typical pyramidal ectomycorrhizas. The dry weight of non-inoculated and inoculated E. globulus seedlings at 12 mg P kg-1 sand did not differ, whereas several isolates caused growth depression of E. diversicolor. By contrast, at 4 mg P kg-1 sand growth increases ranged from 0–13 times above that of non-inoculated seedlings. P. tinctorius produced the largest growth increase on both eucalypt species. In general, isolates which developed more extensive mycorrhizas on roots produced the largest growth responses to inoculation. Isolates which increased plant growth also increased phosphorus uptake by the plant. Seedlings inoculated with L. laccata and S. verrucosum retained more phosphorus in their roots than plants inoculated with the other fungal isolates.

Recolonisation of rehabilitated bauxite mine sites in western Australia by mycorrhizal fungi

Abstract Recolonisation of rehabilitated mine sites by (i) vesicular arbuscular ( va ) mycorrhizal and (ii) ectomycorrhizal fungi was examined and compared with populations of these fungi in surrounding native (jarrah) forest. While Eucalyptus marginata was the dominant tree species in the latter, four species of Eucalyptus , in even-aged stands ranging from 1 to 7 years old, had been planted on the former mine sites. Diversity and abundance of both types of fungi increased with stand age on the rehabilitated sites. In a 7-year-old stand, the number of va species, the abundance of their spores, and the percentage of roots colonized by them were comparable to their levels of activity in native forest. Numbers of species of ectomycorrhizal fungi associated with 7-year-old stands were less than half of those associated with native forest, with only a few species being common to both habitats. This difference is probably indicative of the early phase of development of the rehabilitated sites. A clearly defined succession of ectomycorrhizal fungi was observed as the stands of trees increased in age, the changes being correlated with the development of a layer of leaf litter. There was a close relationship between the identities of fungi producing fruitbodies and being responsible for the formation of ectomycorrhizae.

The diversity of ectomycorrhizal fungi associated with introduced Pinus spp. in the Southern Hemisphere, with particular reference to Western Australia

A device and method for collecting a liquid, such as urine, with little or no contamination thereof. The device when delivered for use includes a container member, an intermediate member secured to the container and a cap member encased in a closed bag and in turn secured to the intermediate member through the bag. During use the cap member is removed from the intermediate member and placed on a convenient surface, still in the closed bag. The intermediate member has a handle which then permits the user easily to hold the container in position for voiding urine into the container. The intermediate member is then removed from the container and discarded. The uncontaminated cap member is then removed from the closed bag and is threadably secured to the container so that the urine contained therein can be delivered for analysis in a substantially uncontaminated state.

Variation in Pisolithus based on basidiome and basidiospore morphology, culture characteristics and analysis of polypeptides using 1D SDS-PAGE

One hundred Pisolithus isolates, 85 Australian and 15 non-Australian collections, were compared and classified according to basidiospore and basidiome morphology, cultural characteristics and separation of polypeptides using 1D SDS-PAGE. Basidiocarps were extremely varied and 13 types were recognized ranging in size from 2 to 20 cm with various stipe types, peridium features and different coloured spore masses. Four basidiospore types were recognized within Australia. These corresponded to a large group found Australia-wide, a smaller group found throughout south-western Australia and two small groups confined to single locations. Seven culture types were described, ranging from submerged, slow growing colonies to aerial, fast growing colonies. 1D SDS-PAGE of all Pisolithus isolates identified 30 soluble polypeptides between 24 and 43 kDa that were used to group the isolates using a numerical taxonomic analysis. Basidiospore groups were readily discernible within the polypeptide groups. In addition, analysis of the polypeptide patterns alone or in combination with basidiospore and culture characteristics, resulted in groups that corresponded to host species and geographic location. These observations were further demonstrated by an ordination using the multi-dimensional scaling procedure. One cluster was composed of all the non-Australian isolates collected beneath Pinus, whilst within Australia, isolates from the eastern, southern and western seaboards fell into distinct clusters. These studies indicate that phenotypic analysis of polypeptide patterns can provide a meaningful classification system to assist in isolate selection for future experiments.

Effects of bacteria on mycorrhizal development and growth of container grown Eucalyptus diversicolor F. Muell. seedlings

The development of ectomycorrhizas on inoculated eucalypt seedlings in commercial nurseries is often slow so that only a small percentage of roots are mycorrhizal at the time of outplanting. If mycorrhizal formation could be enhanced by co-inoculation with bacteria which promote rapid root colonisation by specific ectomycorrhizal fungi, as demonstrated by certain bacteria in the Douglas fir-Laccaria bicolor association, this would be of advantage to the eucalypt forest industry. Two bacterial isolates with a demonstrated Mycorrhization Helper Bacteria (MHB) effect on ectomycorrhiza formation between Pseudotsuga menziesii and Laccaria bicolor (S238), and seven Western Australian bacterial isolates from Laccaria fraterna sporocarps or ectomycorrhizas were tested in isolation for their effect on ectomycorrhizal development by three Laccaria spp. with Eucalyptus diversicolor seedlings. Mycorrhizal formation by L. fraterna (E710) as measured by percentage infected root tips, increased significantly (p < 0.05) by up to 296% in treatments coinoculated with MHB isolates from France (Pseudomonas fluorescens Bbc6 or Bacillus subtilis MB3), or indigenous isolates (Bacillus sp. Elf28 or a pseudomonad Elf29). In treatments coinoculated with L. laccata (E766) and the MHB isolate P. fluorescens (Bbc6) mycorrhizal development was significantly inhibited (p < 0.05). A significant Plant Growth Promoting Rhizobacteria (PGPR) effect was observed where the mean shoot d.w. of seedlings inoculated only with an unidentified bacterium (Elf21), was 49% greater than the mean of uninoculated controls (-fungus, -bacterium). Mean shoot d.w. of seedlings coinoculated with L. bicolor (S-238), which did not form ectomycorrhizas with E. diversicolor, and an unidentified bacterium (Slf14) or Bacillus sp. (Elf28) were significantly higher than uninoculated seedlings or seedlings inoculated with L. bicolor (S-238) alone. This is the first time that an MHB effect has been demonstrated in a eucalypt-ectomycorrhizal fungus association. These organisms have the potential to improve ectomycorrhizal development on eucalypts under nursery conditions and this is particularly important for fast growing eucalypt species where the retention time of seedlings in the nursery is of short duration (2–3 months).

Effect of fungal-isolate aggressivity on the biosynthesis of symbiosis-related polypeptides in differentiating eucalypt ectomycorrhizas

Changes in protein biosynthesis were examined during the early stages of differentiation of Eucalyptus grandis-Pisolithus tinctorius ectomycorrhizas by two-dimensional polyacrylamide gel electrophoresis of 35S-labelled proteins. Three distinct isolates of P. tinctorius Coker & Couch were chosen based on the rate of ectomycorrhizal formation (i.e. infectivity) with E. grandis W. Hill ex Maiden. The isolate H506 was not able to induce mycorrhiza, isolate 441 showed moderate infectivity and isolate H2144 exhibited a very high infectivity. Mycorrhiza were produced in vitro in a system where seeds were germinated in the presence of fungal mycelium and exudates. The non-mycorrhizal isolate caused no changes in root protein biosynthesis as analyzed by two-dimensional polyacrylamide gel electrophoresis, whereas drastic alterations in protein biosynthesis were observed from initial contact with the aggressive mycobionts. During mycorrhizal development, there was a marked inhibition of plant polypeptides synthesis, enhanced accumulation of some fungal polypeptides and the emergence of symbiosis-specific polypeptides, the so-called ectomycorrhizins. The major changes were observed in a group of fungal acidic polypeptides (apparent molecular weight 28–32 kDa) including the ectomycorrhizin E32. These polypeptides first appeared at contact and their synthesis increased during mycorrhizal formation, suggesting a role in mycorrhizal development, most likely as structural proteins. Up-regulation of the synthesis of fungal symbiosis-related polypeptides was tightly correlated to the infectivity of the strain.

Fruiting of putative ectomycorrhizal fungi under blue gum (Eucalyptus globulus) plantations of different ages in Western Australia

Abstract The species richness of putative ectomycorrhizal (EM) fungi fruiting in blue gum (Eucalyptus globulus Labill.) plantations in Western Australia was investigated in relation to plantation age. Eleven plantations, 1–8 years old, were selected for study and two native Eucalyptus forest sites in the same region were chosen for comparison. Sporocarps of 44 species of putative EM fungi were collected from the 13 sites. Of these, 30 species were found in blue gum plantations. The number of fungal species was highly positively correlated with plantation age and inversely correlated with soil pH. Young plantations (1–5 years) had 2–9 fungal species and were overwhelmingly dominated by species of Laccaria and Scleroderma. In older plantations (6–8 years), the relative abundance of sporocarps of each species within the fungal community decreased, accompanied by an increase in the number of fungal species (12–17 per site). A brief survey of the two native eucalypt forests in this region revealed a much higher number of fungal species than that observed in plantations. In plantations, species of Descolea, Laccaria, Pisolithus and Scleroderma typically fruited in young plantations. Species of epigeous fungi of the genera Boletus, Cortinarius, Hydnum, Inocybe, Lactarius, Paxillus, Russula and hypogeous fungi, including species of Descomyces, Hysterangium and Mesophellia, were found only in older plantations, or in native forests. Some of the fungi that fruit in young plantations are now being evaluated for use in commercial spore inoculation programs to increase the species diversity of EM fungi in exotic eucalypt plantations.

Mycorrhiza formation and growth of Eucalyptus globulus seedlings inoculated with spores of various ectomycorrhizal fungi

Abstract As many eucalypts in commercial plantations are poorly ectomycorrhizal there is a need to develop inoculation programs for forest nurseries. The use of fungal spores as inoculum is a viable proposition for low technology nurseries currently producing eucalypts for outplanting in developing countries. Forty-three collections of ectomycorrhizal fungi from southwestern Australia and two from China, representing 18 genera, were tested for their effectiveness as spore inoculum on Eucalyptus globulus Labill. seedlings. Seven-day-old seedlings were inoculated with 25 mg air-dry spores in a water suspension. Ectomycorrhizal development was assessed in soil cores 65 and 110 days after inoculation. By day 65, about 50% of the treatments had formed ectomycorrhizas. By day 110, inoculated seedlings were generally ectomycorrhizal, but in many cases the percentage of roots colonized was low (<10%). Species of Laccaria, Hydnangium, Descolea, Descomyces, Scleroderma and Pisolithus formed more ectomycorrhizas than the other fungi. Species of Russula, Boletus, Lactarius and Hysterangium did not form ectomycorrhizas. The dry weights of inoculated seedlings ranged from 90% to 225% of the uninoculated seedlings by day 110. Although plants with extensively colonized roots generally had increased seedling growth, the overall mycorrhizal colonization levels were poorly correlated to seedling growth. Species of Laccaria, Descolea, Scleroderma and Pisolithus are proposed as potential candidate fungi for nursery inoculation programs for eucalypts.

Effect of organic matter on the survival of Phytophthora cinnamomi rands in soil

Soil organic matter collected from beneath an unburnt stand of Eucalyptus marginata was added in increasing amounts to lateritic soil. Phytophthora cinnamomi incubated in soils containing 50% or more organic matter was extensively lysed, and many of the sporangia produced were abortive. With increasing organic matter there is an increase in nutrient concentrations and in the microbial population and it is suggested that these factors are the basis of the antagonism.

Effects of P fertilisation on productivity and nutrient accumulation in a Eucalyptus grandis × E. urophylla plantation in southern China

Phosphorus deficiency is the main constraint to productivity of eucalypt plantations in southern China, but knowledge of P application on nutrient utilisation by eucalypt plantations in China is limited. This study, therefore, investigates the impacts of P fertiliser rate on biomass production, nutrient uptake, partition and use, efficiency of a 75-month-old clonal plantation of Eucalyptus grandis x E. urophylla on a high P sorption oxisol near Kaiping, southern China. Results show that P application significantly increased tree growth, biomass production, N, P and K uptake, and decreased understorey biomass and litter dry weight. Application of 208 kg P ha-1 was adequate for tree growth. The proportion of stem-wood was increased and the proportion of root biomass was decreased as the quantity of phosphorus applied increased. The application of P also increased the proportion of tree biomass:total biomass of tree, understorey and litter. The N and K use efficiencies for tree biomass and stem-wood production increased with P supply. The P use efficiency was highest in the 13 kg P ha-1 treatment, and decreased at higher rates of P. The P recovery by tree uptake was between 7.6 and 25.3% and decreased as the quantity of P applied increased. It is suggested that harvest residue, as well as understorey and litter should be retained on the site after harvest so that the accumulated P in these components following P fertilisation can benefit tree growth in the next rotation. The study also indicated that N is likely to limit productivity after P due to the high uptake of N by the understorey.