病原性の異なるマツノザイセンチュウおよびニセマツノザイセンチユウ接種したクロマツ木部の解剖学的変化および通導阻害  [in Japanese] Cavitation and Cytological Changes in Xylem of Pine Seedlings Inoculated with Virulent and Avirulent Isolates of <i>Bursaphelenchus xylophilus</i> and <i>B. mucronatus</i>  [in Japanese]

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Abstract

マツ材線虫病における病原性発現のメカニズムを明らかにするため,病原性の異なる2系統のマツノザイセンチュウ(<i>Bursaphelenchus xylophilus</i>) と,ニセマツノザイセンチュウ (<i>B. mucronatus</i>) をクロマツ苗に接種し,木部柔細胞の細胞学的変化と通導阻害(キャビテーション)とを時間的,空間的に比較した。強病原性のS6-1系統を接種した場合,木部放射組織柔細胞および軸方向柔細胞の脂質の消失,細胞質の変性,およびそれらに続いて木部通導阻害が広範囲に生じ,形成層が壊死して苗は枯死した。弱病原性のC 14-5系統接種および非病原性のニセマツノザイセンチュウ接種では,細胞生理の変化と通導阻害は形成層近傍を除く限られた範囲にのみ生じ,葉の水分生理状態に変化はなかった。一方,キャビテーションを誘導するとされる修酸水溶液で処理した苗は,広範囲に木部柔細胞の変性と通導阻害を生じ,旧葉の変色,当年枝の萎凋という,材線虫病特有の病徴を現した。以上のことから,マツ材線虫病では木部柔細胞の変性,通導阻害の順に病徴が進展し,形成層の壊死と通導阻害が広く生じた場合に枯死にいたることが明らかにされた。

The occurrence of cavitation and cytological changes in xylem parenchymatous cells of Japanese black pine (<i>Pinus thunbergii</i>) seedlings were investigated after inoculation with a virulent isolate (S6-1) and an avirulent isolate (C14-5) of the pine-wood nematode (<i>Bursaphelenchus xylophilus</i>), and the nonpathogenic species, <i>B. mucronatus</i>. Cavitation in tracheids and cytological changes such as the disappearance of lipid droplets and the denaturation of the cytoplasm in xylem parenchymatous cells occurred in wide areas in seedlings inoculated with the virulent isolate, resulting in water deficiency and the death of the seedlings. Meanwhile, in the cases of the avirulent and the nonpathogenic nematodes, cavitation and cytological changes were restricted spatially, with the cambia and newly-formed outer xylem unaffected, so that the seedlings did not show water deficiency. In every case, cytological changes in the xylem parenchymatous cells occurred before the cavitation development and the increase of nematodes. On the other hand, treatment with oxalic acid, which caused denaturation of parenchymatous cells and cavitation over a wide area, induced chlorosis of the older needles and wilting of the whole tree. These symptoms closely resembled the typical symptoms of the pine wilt disease. From the above results, relationships between cell denaturation in xylem parenchyma, cavitation, and nematode distribution during the symptom development are discussed.

Journal

  • JOURNAL OF THE JAPANESE FORESTRY SOCIETY

    JOURNAL OF THE JAPANESE FORESTRY SOCIETY 74(4), 289-299, 1992

    Japanese Forestry Society

Cited by:  14

Codes

  • NII Article ID (NAID)
    110002842126
  • NII NACSIS-CAT ID (NCID)
    AN00198561
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0021485X
  • NDL Article ID
    3787574
  • NDL Source Classification
    RB67(林産--森林保護)
  • NDL Source Classification
    ZR21(科学技術--農林水産--林産)
  • NDL Call No.
    Z18-340
  • Data Source
    CJPref  NDL  NII-ELS  IR  J-STAGE 
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