Arbuscular Mycorrhizae Effects on Growth of Two Hawaiian Species: Indigenous \u3cem\u3eOsteomeles anthyllidifolia\u3c/em\u3e (Rosaceae) and Invasive \u3cem\u3ePsidium cattleianum\u3c/em\u3e (Myrtaceae)

Two important plant species of Hawai\u27i, the indigenous Osteomeles anthyllidifolia (Sm.) Lindl., a component of Hawai\u27i\u27s most endangered habitat, and the highly invasive Psidium cattleianum Sabine were grown with or without arbuscular mycorrhizal fungi in a soilless mix at different soil-solution phosphorus (P) levels. At P levels similar to those in the field (0.007 mg P/liter), shoot biomass of inoculated plants of O. anthyllidifolia was 189% greater than that of controls, and that of P. cattleianum was 93% greater. Root weight of O. anthyllidifolia and leaf-tissue P of both species also were significantly higher in inoculated plants. At a higher concentration of soil-solution P (0.020 mg P/liter), inoculated plants of O. anthyllidifolia had 176% more biomass than controls, and those of P. cattleianum had 49% more. In a growth medium with soil-solution P equivalent to that of good agricultural soil (0.200 mg P/liter), inoculated plants of O. anthyllidifolia were 101% larger than controls. Results suggest that presence of arbuscular mycorrhizal fungi is of vital importance to establishment of O. anthyllidifolia in Hawaiian soils and that their absence may limit P. cattleianum invasion of sites that are highly deficient in available P

Field inoculation of American beachgrass (Ammophila breviligulata) with V-A mycorrhizal fungi

Ammophila breviligulata is the major species planted along the Mid- and North Atlantic Coast of the US to stabilize maritime dunes. Field inoculation with native species of vesicular-arbuscular mycorrhizal fungi (VAMF) in a Massachusetts sand dune resulted in improved establishment, more vigorous early growth, and greater panicle production than that occurring in uninoculated controls. The percentage of root tissue colonized in the inoculated plot was low (2-4%) up to 13 wk after inoculation, but increased to 48.8% at the end of the first growing season (22 wk after planting). -from Author

Arbuscular mycorrhizal fungi in Hawaiian sand dunes: Island of Kaua\u27i

Fourteen species of arbuscular mycorrhizal (AM) fungi were isolated from the roots of plants growing on sand dunes of Kaua\u27i. The dominant AM fungal species included Scutellospora hawaiiensis Koske & Gemma, Glomus 807 (an undescribed species), G. intraradices Schenck & Smith, and G. spurcum Walker ined. Species richness per sample was low and ranged from O to 6 (avg. 2.0). Mean abundance of live spores was 8.9 spores per 100 cm3, and many more dead or parasitized spores were present. The AM fungal community of the dunes of Kaua\u27i was very similar to that of the dunes of the island of Hawai\u27i. The long-distance dispersal mechanisms and similarity of habitats that have resulted in a relatively uniform angiosperm flora on dunes of the tropical Pacific may have produced a corresponding AM fungal community in these sites

A modified procedure for staining roots to detect VA mycorrhizas

A modified technique for staining roots to detect VA mycorrhizas is described. It eliminates as many toxic compounds as possible from root fixation/staining procedures without reducing the resolution of the staining. Success has been achieved with angiosperm, fern, lycopod and psilophyte roots and bryophyte. © 1989, British Mycological Society. All rights reserved

Mycorrhizae and succession in plantings of beachgrass in sand dunes

A survey of arbuscular mycorrhizal fungi (AMF), arbuscular mycorrhizae (AM), and hyphal networks of AMF was carried out in sand dune sites of different successional stages in the Province Lands area of Cape Cod National Seashore, Massachusetts. The study focused on large-scale plantings (each of 12-20 ha) of American beachgrass (Ammophila breviligulata) aged 0-7 yr and five adjacent natural dune areas. Sample sites ranged in vegetative cover from barren to forested. Spores of 17 species of AMF were recovered from the dunes. Over the successional sequence, there were increases in the richness and spore populations of the AMF community, the extent of colonization of A. breviligulata roots, and the mycorrhizal inoculum potential of the soil. Unvegetated sites lacked propagules of AMF, but roots of planted culms of A. breviligulata (which carried propagules of AMF) became mycorrhizal in \u3c1 yr after planting. Spores were recovered from previously AMF-free sites that had been planted with beachgrass for 47 wk, and five species of AMF sporulated in sites \u3c6 yr old. Significant hyphal networks were not present in any of the planted areas (\u3c6 yr old at the time of sampling), but did occur in natural areas. The rate of invasion of areas planted to A. breviligulata by later successional plant species may in part depend upon the establishment of a vigorous network of hyphae of AMF in a site

VA mycorrhizae in strand vegetation of Hawaii: evidence for long- distance codispersal of plants and fungi

Vesicular-arbuscular mycorrhizal fungi (VAMF) were a nearly constant component of the coastal strand of the Hawaiian Islands, occurring in beach sand, driftline debris, in roots of 23 of 31 species of vascular plants examined, and in association with rhizomes of 2 native species, Sporobolus virginicus and Jacquemontia sandwicensis. Mycorrhizae were most frequent and intensity of VAM development was greatest in endemic plants, less in indigenous species, and least in alien species. Spores of VAMF were produced in abundance between the rhizome and the leaf sheaths of Sporobolus. Codispersal of fungus and plant may explain the high frequency of mycotrophy in stand species in the tropical Pacific. -from Author

Arbuscular mycorrhizae in sand dune plants of the north atlantic coast of the U.S.: Field and greenhouse inoculation and presence of mycorrhizae in planting stock

The ability of several sand dune inhabiting plant species to successfully colonize dune sites appears to depend upon the presence in the soil of arbuscular mycorrhizal fungi (AMF) that form mutualistic associations with roots. Dune sites barren of vegetation lack these fungi whose large spores are not readily dispersed to the root zones. Despite the absence of these beneficial fungi from barren sites, however, plantings made in AMF-free dune soils eventually form the mycorrhizal association. Examination of planting stock of several species of plants that are used to vegetate barren sand dunes and dune flats of the eastern seaboard of the U.S.A. revealed that AMF were routinely present in the planting materials prior to outplanting. AMF occurred in planting stock of seven varieties of Ammophila breviligulata, and in Prunus maritima, Rosa rugosa, and Spartina patens, but were absent from Myrica pensylvanica. In a field planting in a previously barren deflation zone in the large parabolic dunes of Cape Cod National Seashore, Massachusetts, culms of A. breviligulata that were inoculated with native species of AMF produced more tillers and inflorescences than did non-inoculated plants, even though 78% of the latter had become mycorrhizal 47 weeks after planting. In greenhouse experiments, P. maritima was found to have an absolute requirement for AMF and Solidago sempervirens was not. The significance of the presence of AMF in planting stock for revegetation and restoration of previously unvegetated sites lacking in AMF is discussed

Mycorrhizae in Hawaiian angiosperms: a survey with implications for the origin of the native flora

Endemic, indigenous, naturalized and cultivated angiosperms growing in a variety of habitats in Hawaii were examined for mycorrhizae. Of 147 species (representing 61 families) examined, 122 were mycorrhizal, and 98% of the latter formed VAM. Ericoid, orchid, and ectomycorrhizae also were found. Mycorrhizae were most frequent in endemic species (90.3%) and least in indigenous species (71.9%). The incidence of mycotrophy in Hawaiian endemic species was significantly greater than in mainland species. VAM often were found in species belonging to families that typically lack mycorrhizae (Aizoaceae, Brassicaceae, Caryophyllaceae, Cyperaceae, Hydrophyllaceae, Juncaceae, Pandanaceae, and Urticaceae). Naturalized weedy species were highly mycorrhizal. The high incidence of mycorrhizae in endemic species suggests that VAM fungi and obligately mycotrophic plant species may have been present in the Hawaiian Islands from the earliest stages of the development of the angiosperm flora. -Author

Observations on ‘sporocarps’ of the VA mycorrhizal fungus Rhizophagus litchii

The structure of ‘sporocarps’ in Rhizophagus litchii is shown to correspond with the stelar anatomy of short lateral roots of Litchi sinensis. Samples of the ‘species’ from Hawaii were also found to contain vesicles, arbuscules, hyphae and coils of VA mycorrhizal fungi. The name R. litchii is considered to be of confused application. © 1989, British Mycological Society. All rights reserved