Determination of Genetic Relationships among Eight Cymbidium Species on The Basis of Internal Transcribed Spacer Region of rRNA gene

Abstract

Nuclear ribosomal DNA (rDNA) was analyzed to identify inter-specific genetic relationships among 8 Cymbidium species (Cymbidium insigne, C. ensifolium, C. marginatum, C. faberi, C. gyokuchin, C. kanran, C. forrestii, and C. goeringii). Nuclear rDNA including 2 internal transcribed spacer (ITS) regions and 5.8S, was amplified using polymerase chain reaction and sequenced. The sequences were compared via pair-wise multiple alignment to determine the genetic relationships among the studied species. The lengths of the ITS1, ITS2, and 5.8S regions were 235 bp, from 255 bp to 257 bp, and from 153 bp to 165 bp, respectively. Sequence similarities in the ITS region ranged from 78.7% between C. gyokuchin and C. kanran to 96.8% between C. ensifolium and C. kanran. A phylogenetic tree was constructed from nuclear rDNA nucleotide sequence data of the 8 cymbidiums and 1 outgroup species to estimate genetic relationships. The tree revealed that cymbidiums could be classified by their ecological traits, such as their temperature preference or inflorescence pattern. The phylogenetic data is applicable for identification, classification, and breeding of cymbidiums.