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...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.展开更多
基金This research was supported by the National Science Foundation of China(No.31025018)the Ministry of Science and Technology(No.2011CB944600) to W.Jinby the Ministry of Agriculture("948"program 2008-Z42) to S.Huang
文摘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.
