Abstract:

After the 1.5-year-old Masson Pine (Pinus massoniana) seedlings was inoculated with Pine Wood Nematode(Bursaphelenchus xylophilus,PWN),the changes of phenylpropanes metabolism in the pine seedlings and the internal relations between the changes and disease development were studied. The results showed that PWN infection had obvious influence on the way of phenylpropanes metabolism of the host plants. The activities of phenylalanine ammonia-lyase(PAL) , peroxidase (POD) and polyphenoloxidase(PPO) in the stems of the infected seedlings increased with the elapse of time but decreased after the attack of the disease,the peak of activities of phenylalanine ammonia-lyase(PAL) , peroxidase (POD) in the needles appeared behind that in the stems and were coincident with the development of the disease in the needles. The total phenols content in the stems increased gradually with the extending of the attack time and came up to the top. The increase of the total phenols content was related to the acceleration of phenylpropanes metabolism. The accumulation of phenol substances and the rising of PPO activity might be the main factors to cause the brown stain and necrosis of the cells in the hosts. All these showed that activity changes of the three enzymes were closely related to PWN disease and some changes of the ways of metabolism controlled by them had participated in the occurrence and development of the disease.

Key words: Bursaphelenchus xylophilus, phenylalanine ammonia-lyase(PAL), peroxidase (POD), polyphenoloxidase(PPO), phenols, Pinus massoniana