Characteristice of the Resistance of Pinus armandii var. amamiana, an Endangered Pine Species in Japan, to Pine Wilt Disease after a Pin Sawfly Outbreak

Kyushu Research Center, Foresty and Forest Products Research InstituteForestry and Forest Products Research InstituteProceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:14－19 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

Ectomycorrhizal (ECM) fungal species detected from soil spore banks in <i>Pinus amamiana</i> forests by bioassay experiments using four host species.

<p>The number of seedlings colonized by each ECM fungus is shown, along with sequence accession numbers and BLAST results.</p

Ectomycorrhizal fungal communities in endangered <i>Pinus amamiana</i> forests

<div><p>Interactions between trees and ectomycorrhizal (ECM) fungi are critical for the growth and survival of both partners. However, ECM symbiosis in endangered trees has hardly been explored, complicating conservation efforts. Here, we evaluated resident ECM roots and soil spore banks of ECM fungi from endangered <i>Pinus amamiana</i> forests on Yakushima and Tanegashima Islands, Kagoshima Prefecture, Japan. Soil samples were collected from remaining four forests in the two islands. The resident ECM roots in soil samples were subjected to molecular identification. Soil spore banks of ECM fungi were analyzed via bioassays using a range of host seedlings (<i>P</i>. <i>amamiana</i>, <i>P</i>. <i>parviflora</i>, <i>P</i>. <i>densiflora</i> and <i>Castanopsis sieboldii</i>) for 6–8 months. In all remaining <i>P</i>. <i>amamiana</i> forests, we discovered a new <i>Rhizopogon</i> species (<i>Rhizopogon</i> sp.1), the sequence of which has no match amoung numerous <i>Rhizopogon</i> sequences deposited in the international sequence database. Host identification of the resident ECM roots confirmed that <i>Rhizopogon</i> sp.1 was associated only with <i>P</i>. <i>amamiana</i>. <i>Rhizopogon</i> sp.1 was far more dominant in soil spore banks than in resident ECM roots, and its presence was confirmed in nearly all soil samples examined across the major remaining populations. While <i>Rhizopogon</i> sp.1 did not completely lose compatibility to other pine species, its infection rate in the bioassays was highest in the original host, <i>P</i>. <i>amamiana</i>, the performance of which was improved by the infection. These results indicate that <i>Rhizopogon</i> sp.1 is very likely to have a close ecological relationship with endangered <i>P</i>. <i>amamiana</i>, probably due to a long co-evolutionary period on isolated islands, and to play the key role in seedling establishment after disturbance. We may need to identify and utilize such key ECM fungi to conserve endangered trees practically.</p></div

Ectomycorrhizal (ECM) fungal species detected on resident tree roots from <i>Pinus amamiana</i> forests.

<p>The number of soil samples containing each ECM fungus is shown, along with sequence accession numbers and BLAST results.</p

Study site characteristics.

<p>Study site characteristics.</p

Non-metric multidimensional scaling (NMDS) depicting soil propagule bank communities of ECM fungi in three endangered <i>Pinus amamiana</i> forests.

<p>Stress = 0.066. Black, light gray, dark gray and white symbols indicate the communities assayed with <i>P</i>. <i>amamiana</i>, <i>P</i>. <i>parviflora</i>, <i>P</i>. <i>densiflora</i> and <i>Castanopsis sieboldii</i>, respectively. Circles, diamonds, and squares represent communities assayed with soils from sites 1, 2, and 3, respectively.</p

Non-metric multidimensional scaling (NMDS) depicting ECM fungal communities of resident trees in four endangered <i>Pinus amamiana</i> forests.

<p>Stress = 0.089. White, gray and black symbols indicate the communities on <i>P</i>. <i>amamiana</i>, <i>Tsuga sieboldii</i> and Fagaceae, respectively. Circles, diamonds, squares and triangles represent communities at sites 1, 2, 3 and 4, respectively.</p