松材線蟲新內部寄生菌ESTEYA VERMICOLA 之病原學,生理學及微細構造之探討(3/3)
Date Issued
2002
Date
2002
Author(s)
曾顯雄
DOI
902313B002335
Abstract
More recently, a new endoparasitic fungus, Esteya vermicola, has been
isolated from naturally infected pinewood nematode, Bursaphelenchus xylophilus,
retrieved from a wilted pine tree in Yangmingshan, Taipei City. E. vermicola
possesses a potential for biocontrol of the pinewood nematode to alleviate the
devastating pine wilt disease. However, fully understanding of E. vermicola ,
particularly in the aspects of pathogenesis, physiological characters, and
ecological adaptations, appears to be compulsory, and merit for study.
Ultrastructural studies show that the lunate conidium harbors an ovoid
endospore, and the slightly indented side is coated with an adhesive mucilage.
After adhesion to the nematode cuticle for 18 hours or more, the conidium
germinates, an infection peg derived from the endospore penetrates the nematode,
and forms submuscular vesicles, which later separate from the peg and flow in the
body cavity of the prey. The vesicles grow, ramify, become cylindrical, septate,
branched assimilative hyphae, consume and destroy the host organ and tissue, and
lead to the death of the host in 48 hours. After nematode died, the trophic
mycelium protrudes the cuticle, and forms a new crop of flask-shaped
conidiophore and adhesive lunate conidia driectly, or generates mycelium, which
grows and sporulates to form adhesive conidia. The topographic position and
angle of the lunate conidium seems to be crucial for attachment to nematode. The
drop-off conidia seem incapable to adhere to nematode.
E. vermicola produced tremendous number of blastospores, but a trace
amount of adhesive conidia in submerged culture conditions. However, a large
number of adhesive conidium produced when subculture the balstospores to
nutrient poor water agar. The blastospores also showed substantial growth and
sporulation when inoculated onto autoclaved pinewood blocks, implicating the
potential for biocontrol of pinewood nematode. This viewpoint was further
strengthened by its specific infectivity to leaf and stem nematodes, i.e.,
Aphelenchoides besseyi, an Aphelenchoides sp., and B. xylophilus. Some
protective fungicides and a nematicide, Century, are inhibitory to the growth of E.
vermicola. Therefore, the coapplication of these pesticides, particularly, Century,
should be avoided.
Subjects
pinewood nematode
fungal natural enemy
pinewood wilting
biocontrol
Publisher
臺北市：國立臺灣大學植物病理與微生物學系暨研究所
Type
other
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