| Analysis of the DNA sequences of the rRNA genes (rDNA) and the internal transcribed spacer (ITS) regions has been used to study the phylogenetic relationships and the evolution of many organisms. The sequences encoding the nuclear rRNA repeat units have evolved relatively slowly and are useful to compare distantly related organisms. The 18S and 28S rDNA sequences are considered powerful taxonomic indicators because they are universally found in living cells and are highly conserved. The presence of highly variable stretches in the 28S rDNA permits the evaluation of the divergence between closely related species and eventually among varieties within a species. The non-coding ITS sequences evolve faster than the coding sequences, and may vary among species and populations.Chinese white olive (canarium album) is a multi-purpose tree of high economic value. It is not only a fruit tree but also a famous Chinese traditional medicine. There are abundant germplasm resources of canarium album in fujian privince and its genetic diversity, however, has been poor understood up to date. To evaluate germplasm variability and to discriminate between accessions, different accessions from 3 agro-ecological area of fujian privince were collected and investigated using RAPD-PCRs and 18S-26SrDNA-PCR-ITS. 69 selected oligonucleotide primers in RAPD-PCRs, the result showed that only one can classified part of those samples, and this result is unauthentic. 18S-26SrDNA and its ITS were been cloned and sequence. Sequence analysis showed that ITS1 is 232, ITS2 237 and 5.8 165. there are 1-25 variable sites in pairwise comparison to sample 13. Phylogenetic tree based on ITS1, ITS2 and 5.8S coding data was reconstructed by using DNAMAN methods. Which shows the variation at the level of molecular biology. Among 15 samples can separate to four kinds. It provided the basis for identifying canarium album from different geographical regions according to the variation of the ITS sequences. |
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