Abstract: The chalcone synthase (CHS) gene was cloned from the fresh cotyledons of Cassia tora, using genomic DNA as a template and a pair of specific primers for PCR amplification. The sequencing results showed that the Cassia tora CHS gene is 1 766 bp, containing two exons and one intron. The CHS gene of Cassia tora was submitted to GenBank with an accession number of (JX676773). The intron is located between 188-765 bp, in line with the GU-AG rule, and contained multiple enzyme digestion sites and cis-regulatory elements which may be involved in expression regulation. The intron of CHS gene had polymorphism, which may be led by the diversity of life history and living environment of different plants. The exon 2 of Cassia tora CHS was more conservative, encoding almost all functional sites of CHS. The NJ phylogenetic evolutionary tree of the amino acid sequence encoded by exon 2, accurately reflect the genetic relationship of the different plants, which can be used in different plant genetic differentiation and molecular evolution research.

Key words: Cassia tora , Chalcone synthase Intron , Gene cloning , Sequence analysis