Chinese Bulletin of Botany ›› 2002, Vol. 19 ›› Issue (06): 698-704.

• 研究论文 • Previous Articles     Next Articles

Direct Sequencing of PCR Products or Sequencing by Cloning PCR Products—Method of Determining Internal Transcribed Spacer Sequences of Nuclear Ribosomal DNA inAthrotaxis

LI Chun-Xiang YANG Qun   

  1. (Nanjing Institute of Geology & Palaeontology, The Chinese Academy of Sciences, Nanjing 210008)
  • Received:2001-12-24 Revised:2002-03-12 Online:2002-11-20 Published:2002-11-20
  • Contact: LI Chun-Xiang

Abstract: The results of direct sequencing of PCR products or sequencing by cloning PCR products of the internal transcribed spacers and the 5.8S coding region of nuclear ribosomal DNA in Athrotaxis were compared and analyzed. The rDNA repeat units of A. selaginoides have been homogenized, so its ITS region sequences were determined by direct sequencing of PCR products, but the rDNA repeat units of A. laxifolia and A. cupressoides have not been homogenized, there are many polymorphic sites and insersion/deletions in the ITS1 regions, so their ITS1 sequences were determined by cloning PCR products and then sequencing. There are polymorphic sites but no insersion/deletions in ITS2 region of A. laxifolia and A. cupressoides, so the direct sequencing of PCR products can also be used to display variable nucletides at one site. The results in our studies show that the different ITS regions of Athrotaxis have been homogenized at different extent, so the methods of direct sequencing of PCR products or sequencing by cloning PCR products can be selected to determine their sequences.