Location: Forage and Range ResearchTitle: A consensus linkage map for molecular markers and quantitative trait loci associated with economically important traits in melon (Cucumis melo L.) Author
Submitted to: BMC Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2011
Publication Date: 7/28/2011
Citation: Diaz, A., Fergany, M., Formisano, G., Ziarsolo, P., Blanca, J., Staub, J.E., Cuevas, H.E., Zalapa, J.E. 2011. A consensus linkage map for molecular markers and quantitative trait loci associated with economically important traits in melon (Cucumis melo L.). BMC Microbiology. www.biomedcwntral.com/1471-2229/11/111. Interpretive Summary: Genetic maps describe the molecular structure of chromosomes (where genes are placed in a linear fashion). Genetic maps can be used to improve our knowledge of an organism and can, in the case of domesticated plants and animals, provide for tools to improve productivity. For plants, genetic maps can be used to define economically important traits related to productivity and quality. Points (marks) of chromosomes that are made up of DNA define the molecular structure of chromosomes. Often points on chromosomes are marks related to a function or process of a gene, which are called markers. In molecular biology, tools are available that can be used to define these marks or points on a chromosome. In the case of melon, molecular tools were used separately by several international organizations (government and universities) to define the genetic structure of melon chromosomes and to identify points on the chromosome where economically important yield and quality traits were located (genetic maps). A group of scientists used computer software to merge the findings of these several efforts to form a unified single genetic map that possessed all the information from the separate maps. The development of this integrated and unified map will allow geneticists and plant breeders to better understand and develop strategies for the improvement of yield and quality of melon. This increase in efficiency through improved genetic knowledge will allow for more rapid development of improved U.S. shipping and fresh market cultivars, thus making the US producer more globally competitive.
Technical Abstract: A number of molecular marker linkage maps have been developed for melon (Cucumis melo L.) over the last two decades. However, these maps were constructed using different marker sets, thus, making comparative analysis among maps difficult. In order to solve this problem, a consensus genetic map in melon was constructed using primarily highly transferable anchor markers that have broad potential use for mapping, synteny, and comparative quantitative trait loci(QTL) analysis, increasing breeding effectiveness and efficiency via markerassisted selection (MAS). Under the framework of the International Cucurbit Genomics Initiative (ICuGI, http://www.icugi.org), an integrated genetic map has been constructed by merging data from eight independent mapping experiments using a genetically diverse array of parental lines. The consensus map spans 1150 cM across the 12 melon linkage groups and is composed of 1592 markers (640 SSRs, 330 SNPs, 252 AFLPs, 239 RFLPs, 89 RAPDs, 15 IMAs, 16 indels and 11 morphological traits) with a mean marker density of 0.72 cM/marker. One hundred and ninety-six of these markers (157 SSRs, 32 SNPs, 6 indels and 1 RAPD) were newly developed, mapped or provided by industry representatives as released markers, including 27 SNPs and 5 indels from genes involved in the organic acid metabolism and transport, and 58 EST-SSRs. Additionally, 85 of 822 SSR markers contributed by Syngenta Seeds were included in the integrated map. In addition, 370 QTL controlling 62 traits from 18 previously reported mapping experiments using genetically diverse parental genotypes were also integrated into the consensus map. Some QTL associated with economically important traits detected in separate studies mapped to similar genomic positions. For example, independently identified QTL controlling fruit shape were mapped on similar genomic positions, suggesting that such QTL are possibly repoonsible for the phenotypic variability observed for this trait in a broad array of melon germplasm.