Identification of tobacco-parasitizing cyst nematode and intrapopulation rDNA-ITS-RFLP analysis in Shandong Province rDNA-ITS restriction fragment length polymorphism of cereal cyst nematodes in some regions of Qinghai, Shaanxi and Henan Province,China Study on Molecular Identif ica tion and Genetic Rela tionships ofEctomycorrhiza l Stra ins of Su illus Gene