The internal transcribed spacer of ribosomal DNA as a marker for identifying species and hybrids of the Oncidiinae

The internal transcribed spacer (ITS) of ribosomal DNA (rDNA) was used as a marker to identify genetic differences among 24 accessions of species and hybrids of the Oncidiinae based on PCR-amplified RFLP analysis. The ITS reg ion of rDNA in 24 respective accessions of the Oncidiinae was amplified by a pair of complementary primers to conserved regions at the 3' end of 17S a nd 5' end of 25S of rRNA genes. The ITS was found to be about 730 by in len gth, and there was no obvious variation in length among the 24 accessions s tudied. The PCR-amplified samples were digested with ten restriction enzyme s and subjected to electrophoresis. Among the 166 bands that appeared, 159 were polymorphic. Cluster analysis was then done based on the pattern of ba nd distribution in all samples studied. Four major groups and two individua l clusters not belonging to any of the four groups were identified based on molecular data. The results of the study provide a DNA marker that can ser ve as a good tool to identify new hybrids of Oncidiinae flowers at the mole cular level. This technique could be applied to protect the rights of plant breeders in the future.