Genetic variation in the intergenic spacer of ribosomal DNA of Imperata cylindrica (L.) Beauv. var. major (Cogongrass) populations in Taiwan

Genetic variation in the intergenic spacer (IGS) of ribosomal DNA (rDNA) re petitive sequences in inter- and intra-specific populations of Cogongrass [ Imperata cylindrica (L.) Beauv. var. major (Nees) Hubb] in Taiwan, was stud ied by employing PCR-amplified RFLP analysis. Each IGS region of 45 individ uals from 15 populations was amplified using a pair of complementary primer s to conserved regions in the 5 'end of 17S and 3' end of 25S rRNA genes. F ive IGS length variants were found at 2,730 bp, 2,830 bp, 2,930 bp, 3,030 b p and 3,130 bp. Of them, 2930 bp was the main type of IGS length of Cogongr ass in Taiwan. Within an individual Cogongrass, one to two IGS length types were distinguished. Those samples amplified by PCR were digested with 13 r estriction enzymes, and 283 bands were revealed. Of them, 248 bands were po lymorphic. Clustering analysis was conducted based on data obtained from ba nds distributed in all samples mentioned, and two major clusters were found . The Chuwei population was distinctly different from the remaining populat ions. Moreover, the findings of the PCR-amplified RFLP analysis also indica ted that the IGS region of rDNA provides a good genetic marker and a potent ial tool for the study of microevolutionary process.