title: Comparison of the distribution of the repetitive DNA sequences in three variants of Cucumis sativus reveals their phylogenetic relationships.
abstract: 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.
authors.affiliation: 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.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhao
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Lu
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jiajin
authors.initials: J
authors.lastname: Hu
authors.forename: Sanwen
authors.initials: S
authors.lastname: Huang
authors.forename: Weiwei
authors.initials: W
authors.lastname: Jin
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D018553:Cucumis sativus / Q000145:classification* / Q000166:cytology / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008677:Metaphase / Q000235:genetics; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D013045:Species Specificity; D020080:Tandem Repeat Sequences / Q000235:genetics
chemical_list: D018744:DNA, Plant