Physiological Process of the Symptom Development and Resistance Mechanism in Pine Wilt Disease :

• Fukuda,Kenji

  Laboratory of Forest Botany, Graduate School of Agricultural and Life Sciences, the University of Tokyo

抄録

Pathophysiological changes during the symptom development of pine wilt disease are reconsidered from recent investigations. The symptom development is divided into two stages: the early and the advanced stages. In the early stage, small number of nematodes migrate in cortex, then in xylem of the stem, and induce denaturation and necrosis of parenchyma cells. These changes in parenchyma are regarded as defense reactions of pines which result in terpene synthesis in xylem cells and embolism in tracheids. Such changes in the early stage can be induced in both susceptible and resistant pine species by either virulent or avirulent isolates of pinewood nematode (Bursaphelenchus xylophilus), or by B. mucronatus. No change occur in physiological status of leaves, and nematode reproduction is suppressed during this stage. Pine trees can survive if symptom does not progress from this stage. The symptoms of the advanced stage usually occur only in susceptible pines infected by virulent nematode isolates. At the beginning of the advanced stage, enhanced ethylene production by stem which coincides with cambial destruction occurs, and results in embolism of the outermost xylem in the portion. The embolism causes decrease in leaf water potentlal and cessation of photosynthesis. After cessation of photosynthesis, symptoms develop drastically with a burst of nematode population. There seems to be some unknown mechanism which suppress nematode reproduction and invasion to the cambial zone. This mechanism is thought to be photosynthesis-dependent, so that in photosynthesis-decreased conditions, even avirulent nematodes can multiply and invade cambium to induce tree death. Water stress in hot and dry summer should accelerates symptom development from the early to the advanced stage through such decrease of photosynthesis-dependent "cambial resistance."

収録刊行物

• Journal of forest research

  Journal of forest research 2 (3), 171-181, 1997-08-16

  Japanese Forestry Society

キーワード

• Bursaphelenchus mucronatus
• Bursaphelencllus xy!ophilus
• cambial resistance
• Pinus densiflora
• Pinus thunbergii

詳細情報

• CRID: 1540009770407915392
• NII論文ID: 110002663821
• NII書誌ID: AA11074682
• Web Site: http://dl.ndl.go.jp/info:ndljp/pid/10774981
• 本文言語コード: en
• データソース種別:
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