Diversity Of Endo-bacteria From Pine Wood Nematode Buraphelenchus Xylophilus And Antioxidant Effect To Their Host

Pine wilt disease is a destructive disease caused by Bursaphelenchus xylophilus but its pathogenesis is still unknown.This disease is a complex forest disease which involved host pine,nematodes,sawyer,bacteria,geographical environment and many other factors.Recently,more attention has been paid to the role of exophytic bacteria of B.xylophilus playing in pathogenesis of the disease.However,as the surface environments were complex,it's hard to explain many phenomenon.We have obtain several endo-bacteria which isolated from B.xylophilus,This study mainly aimed at the diversity of the bacteria in the same host pine from different areas and in the body which can be cultivated.And investigate the influence of antioxidant effect and the causative force of Bursaphelenchus xylophilus in the dominant bacteria.The main results are as follows:1.In this research,endo-bacteria were isolated from PWNs from three provinces of China,Jiangsu,Guangdong and Sichuang.The quantity of Endo-bacteria isolated from Jiangsu were significantly higher than Guangdong and Sichuan Province and the endo-bacteria were Pseudomonas fluoresens and Stenotrophomonas maltophilia.The endo-bacterium in Guangdong was Microbacterium testaceum.The endo-bacteria in Sichuang was Rhizobium radiobacter.Then,endo-bacteria were identified by 16 S rDNA sequence and Biolog plates(GEN?).The results indicated that endo-bacteria species might be related with the PWNs difference geographic location.The dominant endophytic bacteria in Jiangsu Province were Sphingomonas and Herbaspirillum.The dominant endo-bacteria in Guangdong Province were Pseudomonas and Stenotrophomonas.The dominant endo-bacteria in Sichuang Province were Chryseobacterium.2.Inoculations of bacteria-free nematode with P.fluoresens and S.maltophilia.Discusseing the influence of the dominant endo-bacteria to antioxidant effect of nematodes.Results showed that P.fluoresens has a significant role in promoting spawning of nematodes.S.maltophilia has certain inhibitory effect to spawning of nematodes.The dominant endo-bacteria improve the ability of nematode movement behavior under H2O2 and reduce the excess ROS in nematode and improve the activity of three kinds antioxidant enzymes SOD,CAT and GSH-Px.To sum up,the dominant endo-bacteria enhance the antioxidant capacity of nematodes.3.Analysising the influence of the dominant endophytic bacteria P.fluoresens and S.maltophilia in P.massoniana to the gen expression of SOD and 2-Cys Prx in nematodes.Results showed that the gen expression of SOD of Pinus massoniana potted seedlings inoculations with P.fuoresens and S.maltophilia continue to increase after 1d?5d?10?15?20 days compared with the control and rise in decline after 10 days and rise between 0.84 to 1.92 times.The expression of 2-Cys Prx rise and rise in decline after 15 days and rise between 0.94 to 4.67 times.Inoculations of Pinus massoniana potted seedlings with wild type,and bacteria treatment for nematode.Results showed that,the nematodes with bacteria treatment have higher pathogenicity than bacteria-free nematode;the reproduction of nematodes with the endo-bacteria was significantly higher than that of aseptic nematodes after 40 d.This indicated that the endo-bacteria had the promotion effect on virulence of Bursaphelenchus xylophilus,the endo-bacteria play a certain promoting role in the course of the disease,and accelerated the course of the disease.