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Title: Map-based molecular diversity, linkage disequilibrium and association mapping of fruit traits in melon

item TOMASON, Y - West Virginia State University
item NIMMAKAYALA, P - West Virginia State University
item Levi, Amnon
item REDDY, U - West Virginia State University

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2013
Publication Date: 3/11/2014
Citation: Tomason, Y., Nimmakayala, P., Levi, A., Reddy, U.K. 2014. Map-based molecular diversity, linkage disequilibrium and association mapping of fruit traits in melon. Molecular Breeding. 31:829-841.

Interpretive Summary: Melon is an important vegetable crop in the United States and throughout the world, and there is a continuous demand by growers and consumers for quality melons with high vitamin and nutritional content. USDA, ARS maintains a large number of melon accessions collected in different parts of the world. These accessions have wide phenotypic diversity and are considered a useful source for enhancing disease resistance and fruit quality in existing melon varieties. In this study, ARS scientists collaborated with scientists at West Virginia State University, using new molecular (DNA) tools and advanced genetic analysis software to find genes that affect the melon fruit quality. The data in this study should be useful for seed company breeders and researchers that employ DNA markers in their breeding programs, aiming to improve melon fruit quality and resistance to diseases and pests.

Technical Abstract: The wide phenotypic diversity, in melon fruits, is the result of consumer preferences combined with genotype fitness to the different agro-climatic zones. There is no sufficient information with respect to the extent of genetic divergence, population structure and linkage disequilibrium (LD) in melon. In this study, 268 mapped single, locus microsatellite markers were used to resolve population structure and LD pattern among 87 East European, Euro-North American or Asian melon (Cucumis melo) accessions. Mixed linear model (MLM) was implemented to detect quantitative trait loci (QTL) for various fruit traits. Various QTL with moderate to high stringency were detected for fruit shape, fruit weight, soluble solids, and rind pressure. The positions of most of these QTLs are in agreement with others previously reported; indicating that genome wide association mapping analysis could be a useful tool in melon breeding programs. Still, several small differences in QTL positions and strength were generated in the genome wide association versus genetic mapping analyses. These differences might be bridged using larger sets of melon accessions, larger genetic populations, and high throughput marker panels.