Bursaphelenchus xylophilus induced pine wilt: Factors associated with resistance

Abstract

We investigated factors affeeting resistance oi Pinus .spp. to Bursaphelenehus xylophilus. Nematode migration and multiplication was inhibited in resistant P. taeda. As a consequence acceleration of monoterpene synthesis terminated, tracheid-cavitation did not beeome extensive, and xylem sap ascent was not significantly blocked. In P. strobus, inhibition of nematode activity was not as complete as in P. taeda, and temporal needle-wilting was seen on some branches. Although this suggest some blockage of xylem water conduction, we were unable to confirm development of cavitation induced by nematode activity. /3-myrcene concentration in these species was not related to resistance.

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

“…5c). Similar results have been obtained by many researchers (Ikeda, 1996a;Ikeda and Kiyohara, 1995;Ikeda et al, 1994;Kuroda et al, 1991b;Odani et al, 1985b;Sasaki et al, 1984;Tamura et al, 1988). The cambium seemed to be degraded by cellulase activity of the virulent nematodes (Kusunoki, 1987).…”

“…However, symptom development of pine wilt disease is so rapid that many physiological changes appear at the same time. To avoid this problem, some researchers used resistant pine species and families to compare symptom development with susceptible ones (Ikeda et al, 1994;Kuroda et al, 1991b;Tamura et al, 1988;Yamada and Ito, 1993ab). Kiyohara (1989) and Kiyohara and Bolla (1990) reported a wide range of variation in the pathogenicity among pinewood nematode isolates, some of which never kilt pine trees.…”

Inhibiting factors of symptom development in several Japanese red pine (Pinus densiflora) families selected as resistant to pine wilt

“…et Zucc. ), one of the main constituents of forests in Japan (Kuroda et al 1988(Kuroda et al , 1991a. Highly resistant species, such as P. taeda, do not adapt well to the climate of Japan and unfortunately cannot be used for forestation.…”

Fumiquinones A and B, Nematicidal Quinones Produced byAspergillus fumigatus

“…), the dominant species in Japan, have the highest susceptibility to pine wilt disease caused by the pine wood nematode, Bursaphelenchus xylophilus. 7,8) Plant-parasitic nematodes cause crop losses that have been estimated to be 9% of the world's crop yield each year. Conventional control methods are currently based on the use of low-specific biocidal compounds acting as nerve poisons, like carbamates, halogenated organic compounds.…”