A Study On Induced Resistance Of Pine Trees To Pine Wilt Disease

Pine wilt disease(PWD) is a devastating epidemic to pine trees, this disease concerned with many factors is very complex,the pathogenic mechanism of PWD does not still settle so far ,so there are not effective means to control up to the present .Inoculated black pine seedling and masson pine seedling with Bursaphelenchus xylophilus,this experiment studied the induced resistance of pine seedlings to PWN with biotic factor of SA and abiotic factor of avirulent isolates of Bursaphelenchus mucronatus,and studied the changes of the activity of phenylalanine ammonia-lyase(PAL) and peroxidase(POD) in the induced process .the main research results are shown below:Inoculated 1-year-old black pine seedlings with the nematode by manual hyodermic method, this experiment indentified the pathogenicity of 6 B.xylophilus isolates and 2 B. mucronatus isolates .Results indicated that the isolates of 12# B. mucronatus can not kill the pine seedlings and is avriulent isolates,others isolates all can kill the pine seedlings,though they are the variation of the pathogenicity. The 11# B.xylophilus is virulent isolates and can kill the pine seedlings quickly in the short time.Biotic factor of SA can induce the resistance in different degree on pine seedlings to PWD by sprying leaves and sooking roots .The induced resistance is strongest when the concentration of SA is 0.01mM by spaying leaves with SA at various concentration.The induced resistance is the strongest when the time of soaking is 3hs by soaking roots with SA. Induced resistance of soaking roots is better than the induced resistance of spaying leaves as a whole .It is very important of the accumulation of SA in the plant and the concentration of SA to the induced resistance.The induced resistance of defiant inoculation at NO .5d is better than at NO.10d with SA by spaying leaves and soaking roots.Abiotic factor of 12# B. mucronatus.avirulent isolates can induce the resistance in different degree on pine seedlings of different ages to PWD. By inoculated 12# B. mucronatus. avirulent isolates,the 4-month-old black pine seedlings the induced resistance in 1d and reach best in 3d; the 1-year -old black pine seedlings come into being the induced resistance in 3d and reach best at 7d and 12d.and the induced resistance was not obvious distinction of 3-year-old seedlings to defiant inoculation at NO. 5d and at NO.10d.It shown a trend when the inoculative volume of 12# B. mucronatus. avirulent isolates was more biger ,the induced resistance on black pine seedlings to PWD was better, moreover, there were interaction on 12# B. mucronatus avirulent isolates with 11# B.xylophilus virulent isolates to induced resistance.the trituration of 2# B.xylophilus and 5# B.xylophilus and 12# B. mucronatus isolates all can induced the resistance on 6-monte-old massion pine seedlings to PWD.The trituration of 11B.xylophilus virulent isolates and 13# B. mucronaius low virulent isolates can not induce and resistance on 6-month-old massion pine seedlings to PWD.And soaking roots with the trituration of 11# B.xylophilus virulent isolates can accelerate the development of PWD .It maybe relate sonte pathogenic substance of the suspension of 11# B.xylophilus virulent isolates .The changes of PAL and POD during induced interaction phase between inducer and host and B.xylophilus and B. mucronatus isolates were studied by inoculateing 6-month -old massion pine and black pine seedlings .Results shown that the matter including SA and 12" B. mucronaius avirulent isolates and the trituration of T B.xylophilus and 5 B.xylophilus and 12# B. mucronatus isolates all can excited increasment of PAL and POD .And these matter all can induced the resistance on pine trees to PWD . 13#B. mucronatus low virulent isolates can not induced the resistance on pine trees and not excited increasement of PAL and POD too.11# B.xylophilus virulent isolates accelerate the development of PWD ,and it can excited inreasment of PAL and POD . These shown the enzyme activity changes of PAL and POD and the host were comblined with...