A Study On The Classification Of Pine Parasitic Nematodes In Liaoning Province

Parasitic nematode of pine is one of the main pathogenic nematodes of pine,among which Bursaphelenchus xylophilus is the most serious pathogenic nematode that harms pine.Parasitic nematode of pine will cause the loss of water transport function of vascular system of pine after infecting pine,resulting in rapid pine wilt and even death.This study investigated and identified pathogenic nematodes in pine trees in Liaoning province in order to prevent the harm caused by parasitic nematodes in pine trees.The systematic study of parasitic nematodes of pine is helpful to clarify the distribution and evolutionary relationship between pathogenic nematodes and their related populations,and it is of great significance to prevent the occurrence of diseases caused by parasitic nematodes of pine.In this study,several bark and wood samples of dead or dying pine trees collected within Liaoning Province.The nematodes in the pine wood samples were separated by the Baermann funnel method.Morphology and molecular biology were used to identify and phylogenetic analysis of the pine parasitic nematodes.The research has obtained the following main research results:1.Identification and geographic distribution of pine parasitic nematodes: A total of 335 pine wood samples collected from Liaoning Province were isolated and identified for nematodes from 2018 to 2020.Through morphological and molecular identification,a new species of Aphelenchoides genus was identified,named Aphelenchoides dandongensis n.sp.;three new record species of Chinese native pine trees,Ektaphelenchus joyceae,A.paradalianensis and A.heidelbergi;and other three nematodes,B.xylophilus and Laimaphelenchus liaoningensis,A.fujianensis were found in samples.The result enriched the natural resources of pine parasitic nematodes in China.2.Phylogenetic analysis of pine parasitic nematodes: the mitochondrial COI gene and ribosomal ITS,18 S and 28 S r DNA were amplified and sequenced.Phylogenetic relationships among sequences were estimated with Bayesian method(BI),maximum simplicity Method(MP)and Maximum Likelihood(ML).Research results provide a theoretical basis for the identification and integrated control of pine parasitic nematodes.