54 Arboricultural Abstracts ARBORICULTURAL ABSTRACTS THE MYCOBIOTA IN NONMYCORRHIZAL ROOTS OF HEALTHY AND DECLINING OAKS Erhard Halmschlager and Tadeusz Kowalski A detailed survey of the mycobiota in roots of declining and healthy-looking oak trees was conducted at two sites in eastern Austria that clearly differed in humus and soil type and pH. Overall colonization of living and dead oak roots was 97.7% and 98.5%, respectively. Colonization frequency of the cortex was nearly twice that of the central cylinder in living roots. The species assemblage comprised 126 fungal taxa. Species composition varied greatly between sites and less between living and dead roots from the same site. Fungal association on living roots at Niederweiden was dominated by Cadophora fastigiata Lagerb. & Melin, which occurred in 50% of roots, and Cylindrocarpon destructans (Zinssm.) Scholten. Together with Cryptosporiopsis melanogena Kowalski & Halmschlager and Basidio mycete R157, these two species were also the major components in dead roots. At Patzmannsdorf, the fungal community in living roots was dominated by Cystodendron sp. 1, Cadophora-like R018, and Cryptosporiopsis radicicola Kowalski & Bartnik, whereas in dead roots Xylaria hypoxylon (L. ex Hooker) Grev. was the dominant species. No substantial differences were found between the root mycobiota in healthy and declining trees. Apart from Armillaria ostoyae (Romagnesi Herink and Cylindrocarpon destructans, the majority of isolated species were considered endophytes or saprophytes that are most likely not involved in the dieback of oak roots. (Can. J. Bot. 2004. 82(10):1446– 1458) THE RE-EMERGENCE OF INDIGENOUS FOREST IN AN URBAN ENVIRONMENT, CHRISTCHURCH, NEW ZEALAND Glenn H. Stewart, Maria E. Ignatieva, Colin D. Meurk, and Richard D. Earl Christchurch, the second largest city in New Zealand, is a planned city on a coastal plain on the east coast of the South Island. The birth of the city and the subsequent century of development was characterized by colonial values and tree and garden planting with familiar European species along with those from Australia, North America, and eventually all other continents. The image of an “English garden city” with classical parks of oaks and willow-lined rivers became the accepted norm and the way in which the city has been promoted to potential tourists. Gardening is one of the top two recreational activities and exotic species greatly outnumber native species in the flora and in gardens. This ©2005 International Society of Arboriculture has had serious consequences for the highly fragmented and degraded indigenous vegetation and its co-adapted wildlife. A few hardy indigenous species continued to regenerate through this period, but since the 1970s, there has been a progressive change of attitude and interest in reclaiming the natural heritage of the city, manifest in widespread private and public planting of indigenous species and active habitat restoration. In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on shrub and tree regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban environments, combined with the greater density of indig- enous seed sources, has allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats—from neglected gardens to pavement cracks to exotic plantations. This is despite the competition from the prodigious seed banks and density of exotic trees, shrubs, and ground covers and albeit minimal impacts of introduced browsing and seed eating mammals. If the present trends continue through appropriate management and facilitation, these tentative signs of native forest regeneration should eventually proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region. (Urban For. Urban Green. 2004. 2:149–158) APPLICATIONS OF TAGGING AND MAPPING INSECT RESISTANCE LOCI IN PLANTS G.C. Yencho, M.B. Cohen, and P.F. Byrne This review examines how molecular markers can be used to increase our understanding of the mechanisms of plant resistance to insects and develop insect resistant crops. We provide a brief description of the types of molecular markers currently being employed, and describe how they can be applied to identify and track genes of interest in a marker-assisted breeding program. A summary of the work reported in this field of study, with examples in which molecular markers have been applied to increase under- standing of the mechanistic and biochemical bases of resistance in potato and maize plant/pest systems, is provided. We also describe how molecular markers can be applied to develop more durable insect-resistant crops. Finally, we identify key areas in molecular genetics that we believe will provide exciting and productive research opportunities for those working to develop insect resistant crops. (Annu. Rev. Entomol. 2000. 45:393–422)
January 2005
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
