Genetic dissection of fruit quality components in melon (Cucumis melo L.) using a RIL population derived from exotic 3 elite US Western Shipping germplasm Miriam K. Paris Æ Juan E. Zalapa Æ James D. McCreight Æ Jack E. Staub Received: 27 August 2007 / Accepted: 14 April 2008 / Published online: 30 April 2008 Ó Springer Science+Business Media B.V. 2008 Abstract Growing environment dramatically influ- ences melon (Cucumis melo L.; 2n = 2x = 24) fruit development and quality. Consequently, the character- ization of quantitative trait loci (QTL) controlling melon fruit quality for application in marker-assisted selection (MAS) requires an assessment of genotype by environ- mental interactions, trait correlations, and QTL efficacy. Therefore, fruit quality traits [soluble solids content (SSC), mesocarp pressure (MP), fruit diameter (meso- carp + exocarp; FD), seed cavity diameter (endocarp; SCD), seed cavity to FD ratio (C:D), fruit shape (FS), and percentage of exocarp netting (PN) at time of harvest] were examined in 81 recombinant inbred lines (RIL) at two growing locations (California. and Wis- consin, USA) to identify the map position and consistency of QTL for MAS in a Group Cantalupensis U.S. Western Shipping market type background. RIL developed from a cross between U.S. Department of Agriculture line USDA-846-1 and ‘Top Mark’ were used to identify 57 QTL in both location tested (SSC = 10, MP = 8, FD = 6, SCD = 9, C:D = 8, PN = 6, and FS = 10). The QTL were distributed across 12 linkage groups and explained a significant portion of the associated phenotypic variation (R 2 = 4–29%). Twelve of such QTL were consistently iden- tified in the two locations tested [SSC (ssc7.4 and ssc10.8), MP (mp7.2, mp10.3, and mplg7.5), SCD (scd1.1, scd5.4, and scd8.5), C:D (cd2.1), and PN (pn2.1), FS (fs1.1 and fs2.3)]. The map positions of 18 QTL (FS = 7, SSC = 6, C:D = 3, SCD = 1, and PN = 1) were in equivalent (i.e., collinear) genomic regions with previous studies in Group Inodorus-based maps. Six of the collinear QTL were detected in both locations in our study (ssc7.4, ssc10.8, fs1.1, fs2.3, pn2.1, and scd5.4). The collinearity of these QTL with those identified in other maps, and their consistency across diverse growing environments portends their broad applicability in melon MAS. Keywords Composite interval mapping Á Cucumis melo Á Fruit shape Á Quantitative trait loci (QTL) Á Soluble solids Á Unadapted germplasm Abbreviations BLUPs Best linear unbiased predictions BLUEs Best linear unbiased estimations FD Fruit diameter Miriam K. Paris, Juan E. Zalapa contributed equally to the work described in this manuscript. M. K. Paris Á J. E. Zalapa (&) Á J. E. Staub USDA/ARS, Vegetable Crops Unit, Department of Horticulture, University of Wisconsin, 1575 Linden Dr., Madison, WI 53706, USA e-mail: jezalapa@wisc.edu J. D. McCreight U. S. Department of Agriculture, Agricultural Research Service, Agricultural Research Station, 1636 East Alisal, Salinas, CA 93905, USA 123 Mol Breeding (2008) 22:405–419 DOI 10.1007/s11032-008-9185-3