National Maize Improvement Center of China, Key Laboratory of Crop Genetic Improvement and Genome of Ministry of Agriculture, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Beijing 100193, China.
J Genet Genomics. 2011 Jan;38(1):39-45. doi: 10.1016/j.jcg.2010.12.005.
Repetitive DNA sequences with variability in copy number or/and sequence polymorphism can be employed as useful molecular markers to study phylogenetics and identify species/chromosomes when combined with fluorescence in situ hybridization (FISH). Cucumis sativus has three variants, Cucumis sativus L. var. sativus, Cucumis sativus L. var. hardwickii and Cucumis sativus L. var. xishuangbannesis. The phylogenetics among these three variants has not been well explored using cytological landmarks. Here, we concentrate on the organization and distribution of highly repetitive DNA sequences in cucumbers, with emphasis on the differences between cultivar and wild cucumber. The diversity of chromosomal karyotypes in cucumber and its relatives was detected in our study. Thereby, sequential FISH with three sets of multi-probe cocktails (combined repetitive DNA with chromosome-specific fosmid clones as probes) were conducted on the same metaphase cell, which helped us to simultaneously identify each of the 7 metaphase chromosomes of wild cucumber C. sativus var. hardwickii. A standardized karyotype of somatic metaphase chromosomes was constructed. Our data also indicated that the relationship between cultivar cucumber and C. s. var. xishuangbannesis was closer than that of C. s. var. xishuangbannesis and C. s. var. hardwickii.
具有可变性的重复 DNA 序列，无论是在拷贝数上还是在序列多态性上，都可以与荧光原位杂交（FISH）相结合，作为研究系统发生和识别物种/染色体的有用分子标记。黄瓜有三个变种，分别是普通黄瓜（Cucumis sativus L. var. sativus）、硬皮黄瓜（Cucumis sativus L. var. hardwickii）和西双版纳黄瓜（Cucumis sativus L. var. xishuangbannesis）。利用细胞学标记物，尚未很好地探索这三个变种之间的系统发生关系。在这里，我们专注于黄瓜中高度重复 DNA 序列的组织和分布，重点关注栽培黄瓜和野生黄瓜之间的差异。本研究检测到了黄瓜及其亲缘植物的染色体核型多样性。因此，我们在同一中期细胞上进行了三组多探针混合物（组合重复 DNA 与染色体特异性 fosmid 克隆作为探针）的顺序 FISH，这有助于我们同时识别野生黄瓜 C. sativus var. hardwickii 的 7 条中期染色体中的每一条。构建了体细胞中期染色体的标准化核型。我们的数据还表明，栽培黄瓜与 C. s. var. xishuangbannesis 的关系比 C. s. var. xishuangbannesis 与 C. s. var. hardwickii 的关系更密切。
