| RAPD (randomly amplified polymorphic DNA), which based on PCR technique, is by far one of the most commonly used molecular approach to reveal DNA polymorphism. The basic priciple of this approach is that a primer (usually 10bp oligonudetide) is employed to amply random segments of DNA, and a small number of fragments will be amplified when the primer anneals on each strand over a length range. If sequence varition is present at the priming site, then a fragment may not be amplified, so the DNA polymorphic can be detected. RAPD analysis has the peculiarity such as simplicity, sensitivity, cheapness and lower requirement of materials, and more important, it can be used without prior knowledge of DNA sequence, so this approach has the potential use in a large variety of organisms.Katydid is a sort of insects which are famous for their songs, in taxonomy respect, they belong to Tettigonioidea, Qrthopera. Many works has been done in its systematics, but the research of molecular systematics in Tettigonioidea is just at the stage of beginning. In this paper, the approach of RAPD was used in 64 species of katydids, which belonging to 28 genera, 6 families, in order to discuss their taxonomy status and genetic relationship in molecular level, and enrich the the research of molecular systematics in Tettigonioidea.The genome DNA of the 64 species were isolated by the method of CTAB isolation of total DNA. The reaction condition was used as following: 25-50ng template, 0.15mM dNTP, 1×buffer, 1.875mM MgCl2, 2.5u TaqDNA polymerase in a 20 ul reaction volume. The initial denaturation step was used at 94℃for 1 mm 30 seconds, then denature at 94℃ for 30 seconds, anneal at 37℃ for 1min 30 seconds, extend at 72℃ for 2min and repeat the cycle 45 times, at last, extend at 72 ℃ for 10min.42 primers were used in RAPD experiment, among them, only 5 primers can amplified clear and reproducible fragments in 17 species belonging to 10 genera of the family Phaneropteridae; and 11 primers in 6 species belonging to 2 genera of the Pseudophyllidae; 11 primers in 10 species belonging to 2 genera in Meconemetidae; 4 primers in 7 populations of the specis Mecopoda.nzpoensis belonging to Mecopodidae; 10 primers in 14 species belonging to 6 genera of the Tettigoniidae; 9 primers in 1 6species belonging to 7 genera of the Conocephalidae. Thermocycled PCR samples were resolved electrophoretically on 1.5% agarose gels and photography using a Polaroid camera. The ststistical results was analyzed by the SPSS software, and the clustering figures were obtained.Conclusions can be drawn from the study as following:1. By the approach of RAPD, the molecular systemstics of 64 species of katydids, which belonging to 28 genera 6 family in Tettigonioidea, has been studied2.It is the first time that the method of CTAB isolation of total DNA has been used in katydid, and the isolated samples can be apllied successfully in RAPD amplication.3.RAPD is one of the good genetic marker in the systematics research of Tittigonoiidea, it can be used widely to discuss intra- and inter-specific genetic relationship. It also could be used to study the phylogenetic relationships of closely related genera, but for those genera which are less-closly related, the usefulness of RAPD has large limitations.4.42 primers was used to investigate the genetic relationships among some species and genera in Pseudophyllidae, Meconemetidae, Tettigoniidae and Conocephalidae. The results ,which concluded from clustering analysis, were mostly the same as that concluded from the phylogenetic analysis by using morphological characters and one of the conclusions support the idea that Gampsocleis. inflata Uvarov should be moved to the genera Uuarouina Ramme, wheares, the conclusions of Phaneropteridae is in disorder, so species in this family shoud have more investagation.5.Samples of Mecopoda. nipoensis (belonging to Mecopodidae) from 7 location site were also analyzed for genetic polymorphisms using RAPDCR, the clustering result showed that this 7 populations s...
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