Morphological And RDNA Comparison Of The Major Cyst Forming Nematodes, Heterodera, Occurring In China

Morphological and molecular comparisons were made among different soybean cyst nematode populations (Heterodera glycines}, cereal cyst mematode (H. avenae), H. sinensis and a cyst forming nematode population parasitizing tobacco used in this study.Some important morphological characters, such as the shape of lip region and the number of lateral lines of J2 of intra- and inter-species of Heterodera were observed with both Light microscope and Scanning Electron Microscope (SEM). Some morphometrics of Ji, for example, the body length, stylet, tail and clear tail were measured, and it revealed that the cyst forming nematode population parasitized on the root of tobacco (Heterodera sp.) was identical to that of H. glycines, and distinct differences were detected among H. sinensis with the other cyst forming nematode species occurring in China.The ITS regions of rDNA of all the cyst forming nematodes, including H. glycines, H. avenae, H. sinensis and the cyst forming nematode populations parasitizing tobacco, were amplified and digiested with 8 different restriction enzymes, AM, Bsh1236I, BsurI, CfoI, DdeI, HinfI., MspI and RsaI. It indicated that all the inter- or intra-species of cyst forming nematodes yield identifical amplified ITS region products, with the sequencing length about l,030bp. PCR-RFLPs of the ITS region of 11 intra-populations of soybean cyst forming nematodes were made with five restriction enzymes. Four of which, Alu I, Cfo I , Rsa I and Mva I , produced the same digest pattern among all the 11 populations. Two digiest phenotypes were detected in the population from Taigu, Shanxi when digeseted with Ava I, which revealed the heterogeneity of the species in intra-population. Great differences were revealed between inter-species of H.sinensis and H.glycines after the digestion of 7 restriction enzymes, except for Cfol, and the cyst forming nematode population parasitizing on the tobacco produced the identical digest patterns with H. glycines when the 8 restraction enzymes were used.Sequence alignments of the ITS region of inter-population of soybean cystnematodes from different area of China showed little variation, and the cyst forming nematode population parasitizing tobacco, from Xuchang, Henan province also presents mini-difference with that of soybean cyst nematodes, and the sequence similarity reaches 99%. Comparing to both morphological and the rDNA characteristics, the cyst forming nematode population parasitizing tobacco was identified as soybean cyst nematode, H. glycines. It was found that there are clear sequence differences based on ITS region between H. sinensis and H. glycines, and the similarity is only 77%. This was the first report about the molecular data of H. sinensis, which show high similirity to that of H. sacchari. The phylogenetic relationship based on rDNA sequencing was identical to the grouping according to the morphological characters made by Subbotin et al. (2001).The present research indicates that it is stable and accessible for the identification of inter-species of Heterodera by the ITS region of rDNA, but it could not be used for the differentiation of the inter-population of the same species.