Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2000
Publication Date: N/A
Citation: Interpretive Summary: Genes are composed of DNA which regulates and controls all plant and animal functions. Genes are located on chromosomes, which are tread-like structures that are components of every cell. New biotechnology has afforded geneticists the opportunity of locating genes on chromosomes using a tool called molecular markers. Molecular markers (small segments of DNA) have been used in cucumber to determine the order of genes along the chromosomes. The identification of the order of genes on chromosomes allows geneticists to map the position of genes wih respect to themselves. Several maps have been constructed in cucumber based on information from different kinds (types) of molecular markers. However, each map that has been constructed only provides a portion of the total picture of the composition of the chromosomes (14) in cucumber. Therefore, experiments were designed to merge all the information from the currently available maps so that one large map would result which had all the information from the smaller maps. Computer analysis of data from the small maps yielded a more precise map. With this information cucumber breeders can more efficiently breed new cultivars. This increase in efficiency will utimately reduce the time needed for creation of economically important cultivars, and thus reduce the costs of production by seed companies.
Technical Abstract: Linkage maps in cucumber (Cucumis sativus var. sativus L.; C. s.) have been constructed using morphological traits, isozymes, restriction fragment length polymorphisms (RFLPs), and random amplified polymorphic DNAs (RAPDs) The lack of polymorphism in cucumber has led to the construction of relatively unsaturated maps (13 to 80-points). We have added AFLP markers to existing narrow- based (within C. s.) and wide-based (C.s. x C.s. var. hardwickii) maps. JoinMap v. 2.0 was used to construct maps and to join these with historical maps from several previous studies. Our narrow and wide-based merged maps contain 255 and 197 markers, respectively, including morphological traits, disease resistance loci, isozymes, RFLPs, RAPDs, and AFLPs. Condensation of total map distance occurred in merged maps compared to historic maps using many of the same markers. This phenonmenon is most likely due to differences in map construction algorithms. The merged maps represent the "best fit" of the data used and are an important first step towards the construction of a comprehensive linkage map for cucumber. Identification of additional anchor markers between the narrow and wide-based maps presented here may allow their future integration into a unified model.