Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/12/2000
Publication Date: N/A
Citation: N/A Interpretive Summary: Genes, the action factors which regulate life in living organisms, are located on chromosomes which are present in every cell of organisms. Genes are positioned on chromosomes in linear arrays such that every gene has a specific location on chromosomes. Much emphasis recently has been placed on determining the location of genes on chromosomes by biotechnologies. As information on their location becomes available, genetic maps are made such that genes can be located on specific chromosomes. We have developed several such maps in cucumber using several different biotechnologies. These maps show the location of different genes but cannot be compared to one another unless they are brought together using maps that show all the relationships found in the separate maps. We designed experiments and used computer analysis to merge the several maps into a unified map. This gives plant geneticists and plant breeders a better understanding of the genetics of cucumber and allows them the potential to create cucumber cultivars with higher yield and better quality more rapidly.
Technical Abstract: Linkage maps in cucumber (Cucumis sativus var. sativus L.) 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 used the computer programs MapMaker v.1.0 and JoinMap v.1.0 to construct and join the map of Fanourakis and Simon (1987), Knerr and Staub (1992), Kennard et al. (1994), and Meglic and Staub (1996). These map-merging experiments produced a 134-point narrow-based map consisting of morphological traits, disease resistance loci, isozymes, RFLPs, and RAPDs spanning 431 cM having a mean interval distance of 3.2 cM. A second map was constructed using data from two relatively wide crosses in cucumber; GY-14 (C.s.) x PI 183967 (C. sativus var.hardwickii) (Kennard et al., 1994) and H-19 (C.s.) x G421 (C.s.) (Serquen et al. 1996) produced a 147-point wide based merged map spanning 458 cM where the mean marker interval was 3.1 cM. In some cases, single and flanking marker-trait relationships were relatively close (1 to 3 cM) in both consensus maps [e.g., downy mildew resistance (dm) and scab resistance (Ccu)]. These maps represent the "best fit" of the data used, but difficulties were encountered when manipulating large data sets having missing values. Moreover, the two maps could not be merged because of a paucity of common anchor points.