Nuclear rDNA and internal transcribed spacer sequences clarify Caulerpa racemosa vars. from other Caulerpa species
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770; e-ISSN 1879-1522, more
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| Keywords |
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| Author keywords |
Caulerpa; rDNA gene sequence; internal transcribed spacer (ITS);Molecular phylogeny; Taiwan |
| Abstract |
Caulerpa species exhibit a high degree of morphological variation making some species difficult to define. Taiwan has Caulerpa species indigenous to its northern and southern seashores. The aim of this study was to determine phylogenetic and systematic relationships among Caulerpa species and to establish baseline DNA signature sequences for Taiwanese Caulerpa species with nuclear rDNA and ITS sequences. Caulerpa serrulata, Caulerpa webbiana, Caulerpa cupressoides and Caulerpa racemosa vars. microphysa, macrophysa, peltata and laetevirens were investigated in the present study. rDNA sequences of 872-1124 bp were amplified from nuclear DNA of 11 individual plants from each of the seven Caulerpa taxa, using the polymerase chain reaction (PCR). The amplified sequences were aligned and compared with those of other Caulerpa taxa. The sequence similarity was highest among specimens of C. racemosa var. peltata and var. laetevirens with less similarity between C. racemosa var.microphysa and var. macrophysa as well as C. cupressoides, C. serrulata and C. webbiana. Phylogenetic trees, inferred from neighbor-joining (N-J) and maximum parsimony (MP) analyses of the entire aligned sequence data set, reveal that specimens of C. racemosa var. peltata and var. laetevirens are closely related. Based on the present analyses, C. racemosa var. laetevirens, var. peltata, and var. turbinata are morphological variants of a single species. Phylogenetic trees with 90 and 100% bootstrap values highly support the placement of C. racemosa var. microphysa as a distinct species within Caulerpa. We conclude that nuclear rDNA and ITS sequences are useful for the identification of Caulerpa algae at the species level and for distinguishing C. racemosa vars. from other Caulerpa species. |
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