Histological Responses of Different Resistant Families of Pinus thunbergii and P. densiflora to an Invasion of Pine Wood Nematode.

Abstract

Responses of different resistant families of Pinus thunbergii and P. densiflora to the pine wood nematode (Bursaphelenchus xylophilus) were investigated from the view points of xylem water conductan-

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).…”

“…Physiological changes in symptom development of pine wilt disease have been dealt with in many papers; decrease in photosynthesis (Fukuda et al, 1992a;Kaneko, 1989;Masuda, 1976;Ohyama and Kaminaka, 1975), denaturation of xylem and cortex parenchyma cells (Fukuda et al, 1992b;Ikeda, 1996a, Ikeda andKiyohara, 1995;Ikeda and Suzaki, 1984;Ikeda et al, 1994;Ishida et at., 1993;Kuroda et al, 1988;Mamiya, 1975Mamiya, , 1980Mamiya, , 1984Mamiya, , 1985Nobuchi et al, 1984;Sugawa, 1978Sugawa, , 1982, traumatic resin canal formation (Sugawa, 1978(Sugawa, , 1982, cambium destruction (Fukuda et al, 1992b;Ikeda, 1996a;lkeda et al, 1994;Myers, 1986;Sasaki et al, 1984), production of phytotoxic substances Kawazu et al, 1996a, b;Oku, 1988;Oku et al, 1980Oku et al, , 1985Shaheen et al, 1984;Ueda et aL, 1984), enhanced respiration (Mori and Inoue, 1983;Ohyama and Kaminaka, 1975) and ethylene production (Fukuda et al, 1994, Mori andInoue, 1986), water potential and transpiration of leaves and heat pulse velocity (Fukuda et al, 1988a(Fukuda et al, , b, c, 1992aIkeda and Kiyohara, 1995;Ikeda and Suzaki, 1984;…”

“…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.…”

Polymorphism of Japanese isolates of the pinewood nematode, Bursaphelenchus xylophilus (Aphelenchida: Aphelenchoididae), at heat-shock protein 70A lucus and the field detection of polymorphic populations

“…The same code number as that in Table 2 is used to denote each of the PWN subpopulations analyzed. low pathogenicity while Ka4, NS (a subculture of an isolate 'Shimabara' in Ikeda et al (1994)), S10, S6-1 and T4 have rather high pathogenicity against host pine species (e.g., Kiyohara and Bolla, 1990;Ikeda et al, 1994;Aikawa et al, 2003a). According to the PCR-RFLP pattern of hsp70A, two isolates, C14-5 and OKD1, were typed into one group, and five isolates, Ka4, NS, S10, S6-1, and T4 into another (Fig.…”

“…These isolates were maintained as laboratory cultures (Table 1). Among the 29 isolates examined, some have been well investigated for their pathogenicity: C14-5 and OKD1 have considerably low pathogenicity while Ka4, NS (a subculture of an isolate 'Shimabara' in Ikeda et al (1994)), S10, S6-1 and T4 have rather high pathogenicity against host pine species (e.g., Kiyohara and Bolla, 1990;Ikeda et al, 1994;Aikawa et al, 2003a). As one isolate from Kasama City was found to have the rarer of the two alleles found in the 29 isolates, field populations were again collected from this locality (Table 2).…”