Morphological And Molecular Identification Of Inter-and Intro-populations Of Three Hirschmanniella Species Occuring In China

Rice root nematode(Hirschmanniella spp.)is an important group of migratory endoparasitic plant parasitic nemades,which is widespread almost all over the world. In this study,morphological and molecular comparisons and analysis were made among seven different geographic populations of Hirschmanniella.According to the morphological classification and identification,three species were identified.They were H.oryzae,H.mucronata and H.gracilis.Some morphometrics of H.oryzae and H.mucronata varied slightly from the original descriptions of type specimen.However,most of other morphometrics were within the specific range.Compared with the origional descriptions of type specimen, morphometrics of H.gracilis were smaller.Totally,the rDNA ITS regions of 22 rice root nematodes in seven different geographic regions were amplified and phylogenetic analysis were made together with the associated sequcences in Genbank.At the same time,all the cloned PCR products were digested with 7 different restriction enzymes,Aluâ… ,Ddeâ… ,EcoRâ… , Haeâ…¢,Hin6â… ,Hinfâ… and Pstâ… .It was found that the fragments length of ITS region of all the 22 nematode specimen were about 750bp.Three'species were confirmed according to the phylogenetic tree.ITS-RFLPs showed that different Species yield different digestion patterns.Some ITS-RFLPs phenotypes variation were detected among the intro-species populations.Two restriction enzymes,EcoRâ… and Pstâ… ,were selected,which could be effectively used to distinguish the three species in this study.This is the first attempt to classify and identify rice root nematodes with the method of PCR-RFLPS in China and even all over the world.