Identification And Pathogenicity Of Several Pine Parasitic Nematodes

In view of diversity of pine parasitic nematodes and some problems of pathogenicity, biology and relationship with the host not clear, this paper carried out some research work in following aspects:(1) species identification of pine parasitic nematodes (2) a key for classification of parasitic nematodes in pine in China (3) the real-time polymerase chain reaction (PCR) assay of Several pine parasitic nematodes (4) the pathogenicity of several pine parasitic nematodes (5) embryo development of Aphelenchoides bicaudatusThe results achieved are as follows:(1) Four species were isolated from Pinus armandii of Gansu Province, which were Cylindrotylenchus pini, Aphelenchoides resinosi, A. asteromucronatus, Ektaphelenchus prolobos. A. bicaudatus was isolated from Monochamus alternatus in P. massoniana of Jiansu Province. A. menthae was isolated from P. massoniana of Chongqin county.(2) a key for classification of parasitic nematodes in pine in China was prepared(3) The ITS regions of B. xylophilus, B. mucronatus, B. rainulfi, B. thailandae, S. lii, S. wuae, B. hofmanni, A. macronucleatus, B. hellenicus were compared with BioEid Software. The nine species has many different bases areas in internal transcribed spacer. Premier express 3.0 Software was used to design primers and fluorescent probes of five species. The primers and fluorescent probes were highly specific for B. xylophilus, B. mucronatus, B. thailandae, S. wuae. Detecting results of sensitivity of the 4 species indicated that the corresponding primers and probes (F/R-bx and P-bx, F/R-bm and P-bm, F/R-bt and P-bt, F/R-swt and P-sw) also successfully detected single nematodes from pinewood samples respectively.(4) Twenty-three strains of Bursaphelenchus mucronatus inoculated 2-year-old P. taiwanensis and P. thunbergii, studies indicated that different strains of B. mucronatus have different pathogenicity. According to disease index, morbidity rate and disease rate of B. mucronatus to two-year-old seedling of P. thunbergii, twenty-three isalates of B. mucronatus were divided into three levels:ClassⅠ(the strongest pathogenicity),ClassⅡ(weak pathogenicity) and ClassⅢ(no pathogenicity).(5) Eleven species of other parasitic nematodes inoculated 2-year-old seedling of P. thunbergii. The following ten species are non-pathogenic whcih were Seinura wuae, B. hofmanni, B. rainulfi (GD,ZJ106D,CQ),A. macronucleatus, B. thailandae, B. hellenicus, A. menthae, A. bicaudatus, A. asteromucronatus, Aphelenchoides.Sp. After inoculating B. corneolus and B. rainulfi (GS), one seedling showed external disease symptoms respectively, and a few free-living nematodes were detected from the two seedings. This indicated that the two nematodes maybe weak pathogenicity. (6) A. bicaudatus reproduced parthenogenetically, only one pronucleus was found, and completed its embryogenesis in 2.5d at 25℃. Egg cell divided symmetrically along the axis, in 2-cell stages, two equal-sized cells positioned side-by-side.