Application of nrDNA-ITS Sequences in Plant Phylogeny and Evolution

The application of nuclear rDNA ITS sequences in plant phylogeny and evolution analysis was discussed in this paper. Nuclear rDNA is an important nuclear gene fragment, which had been widely used in phylogenetic studies. The internal transcribed spacer of nuclear rDNA was divided into ITS1 and ITS2 by 5.8S rDNA. The length of ITS1 ranges from 165 bp to 298 bp in angiosperms, and the length of ITS2 ranges from 177 bp to 266 bp. ITS sequence is relatively longer in gymnosperms. It much depends on the length of ITS1. As mutate quickly, ITS sequences are capable of providing many variable sites and informative sites, which has become an important molecular marker in plant systematic development and classification researches within low-order angiosperm categories. AT the same time, it can prove important systematic information for exploring polyploidy reticulate evolution and allopolyploid origins.