The genus Dracaena is the main source of dragon’s blood, which is a plant resin and has been used as traditional medicine since ancient times in different civilizations. However, the chromosome numbers and karyotypes present in this genus remain poorly understood. In this study, fluorescence in situ hybridization (FISH) using oligonucleotide probes for ribosomal DNAs (5S and 45S rDNA) and telomeric repeats (TTTAGGG)₃ was applied to analyze 4 related species: Dracaena terniflora Roxb., Dracaena cambodiana Pierre ex Gagnep., Aizong (Dracaena sp.), and Dracaena cochinchinensis (Lour.) S.C. Chen. In all 4 species, both 5S and 45S rDNA showed hybridization signals in the paracentromeric region of a pair of chromosomes; the sizes of the 45S rDNA signals were larger than those of the 5S rDNA. Importantly, the telomeric repeat signals were located in the telomeric regions of almost all chromosomes. The results indicated that the chromosome number of all 4 Dracaena species is 2n = 40, and the lengths of the mitotic metaphase chromosomes range from 0.99 to 2.98 μm. Our results provide useful cytogenetic information, which will be beneficial to future studies in genome structure of the genus Dracaena.
Cytogenet Genome Res

中文翻译：

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四种龙血树种的基于 FISH 的核型分析

龙血树属是龙血的主要来源，龙血是一种植物树脂，自古以来在不同文明中都被用作传统药物。然而，该属中存在的染色体数目和核型仍然知之甚少。在本研究中，使用核糖体 DNA（5S 和 45S rDNA）和端粒重复序列 (TTTAGGG) _{3 的}寡核苷酸探针进行荧光原位杂交 (FISH)分析 4 个相关物种：Dracaena terniflora Roxb.、Dracaena cabodiana Pierre ex Gagnep。矮宗 ( Dracaena sp.) 和Dracaena cochinchinensis(Lour.) SC 陈。在所有4个物种中，5S和45S rDNA在一对染色体的旁着丝粒区域均显示出杂交信号；45S rDNA 信号的大小大于 5S rDNA 的信号大小。重要的是，端粒重复信号位于几乎所有染色体的端粒区域。结果表明，所有4种龙血树属的染色体数目为2n = 40，有丝分裂中期染色体长度为0.99～2.98 μm。我们的研究结果提供了有用的细胞遗传学信息，这将有利于未来龙血树属基因组结构的研究。
细胞遗传基因组研究