Submitted to: North Central Regional Symposium on Soybean Cyst Nematodes
Publication Type: Proceedings
Publication Acceptance Date: 1/7/1999
Publication Date: N/A
Technical Abstract: Identification of the parasitic ability (race) of soybean cyst nematode (SCN), Heterodera glycines, populations relies on the use of soybean differentials. The results of race tests often are variable within and among laboratories, and often require more than 3 months to complete. Analysis of nucleotide sequence variation in ribosomal DNA (rDNA) coding and spacer regions has been used to study phylogenetic relationships among many types of organisms, including animals, bacteria, fungi, and plants. We examined the level of polymorphism among the internal transcribed spacer (ITS) regions of H. glycines races 1-6, 9, and 14, H. lespedezae (Lespedeza cyst nematode (LCN )), H. schachtii (Sugarbeet cyst nematode (SBCN)), and H. trifolii (Clover cyst nematode (CCN)) by restriction enzyme digestion of polymerase-chain-reaction-amplified DNA fragments. Second-stage juveniles from all Heterodera populations analyzed produced RDNA fragments of approximately 1.28 kb. The amplified rDNA fragments were digested with 14 restriction endonucleases. We were able to differentiate H. schachtii from the other Heterodera species with three restriction enzymes. All H. glycines races and the H. lespedezae and H. trifolii isolates produced very similar banding patterns with all 14 restriction enzymes. Some variation was observed in the relative intensities of the DNA bands among H. glycines races. We are attempting to determine whether these differences were due to incomplete digestion of the PCR products or the result of race-specific sequence variation in the ITS regions of H. glycines.