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17 Pag., 5 Tabl., 3 Fig. ; Epidemiological studies suggest that consumption of fruit rich in phenolic compounds is associated with health-protective effects due to their antioxidant properties. For these reasons quality evaluation has become an important issue in fruit industry and in breeding programs. Phytochemical traits such as total phenolics, flavonoids, anthocyanins, L-ascorbic acid, sugar content and relative antioxidant capacity (RAC) were analyzed over four years in flesh fruit of an F1 population "Venus" × "Big Top" nectarines. Other traits such as harvesting date, yield, fruit weight, firmness, soluble solids concentration (SSC), pH, titratable acidity (TA) and ripening index (RI) were also determined in the progeny. Results showed high variability among genotypes for all analyzed traits. Total phenolics and flavonoids showed significant positive correlations with RAC implying that both are important antioxidant bioactive compounds in peaches. We found genotypes with enhanced antioxidant capacity and a better performance than progenitors, and in consequence the best marketability. ; This study was supported by the Spanish MICINN (Ministry of Science and Innovation) grants AGL-2008-00283 and the Regional Government of Aragón (A44). W. Abidi and S. Jiménez were supported by a JAE-Pre and JAE-Doc fellowships from CSIC, respectively. ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed

43 Pags.- 2 Tabls.- 4 Figs.- 4 Suppl. Tabls.- 1 Suppl. Fig. The definitive version is available at: http://link.springer.com/journal/11295 ; Fruit quality is an essential criterion used to select new cultivars in peach breeding programs and is determined based on a combination of organoleptic and nutritional traits. The aim of this study was to identify quantitative trait loci (QTLs) for fruit quality traits in an F1 nectarine population derived from 'Venus' and 'Big Top' cultivars. The progeny were evaluated over 4 years for agronomical and biochemical characteristics and genotyped using simple sequence repeat (SSR) markers and 'IPSC 9K peach SNP array v1'. Two genetic maps were constructed using 411 markers. The 'Venus' map spanned 259 cM on nine linkage groups (LGs) with 104 markers. The 'Big Top' map spanned 464 cM on 10 LGs with 122 markers. Single or Multiple QTL models mapping was applied separately for each year and all years combined. A total of 54 QTLs mapped over 12 LGs belonged to seven peach chromosomes. Most of the QTLs were consistent over the 4 years of study and were validated with the multi-year analysis. QTLs for total phenolic, flavonoid, and anthocyanin contents were reported for the first time in peach. LG 4 in 'Venus' and LG 5 in 'Big Top' showed the highest numbers of QTLs. This work represents the first study in an F1 nectarine family to identify peach genomic regions that control fruit quality traits using 'IPSC 9K SNP array v1' and provides useful information for marker-assisted breeding to produce peaches with better antioxidant content and healthy attributes. ; This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) grants AGL-2008-00283, AGL2011- 24576, and AGL2014-52063-R and was co-funded by the FEDER and the Regional Government of Aragón (A44) with European Social Fund. W. Abidi was supported by a JAE-Pre fellowship from the Consejo Superior de Investigaciones Científicas (CSIC), which enabled him to visit the University of California, Davis, and the IBMCP, Valencia, Spain. J.L. Zeballos received a master fellow funded by the Spanish Agency for International Cooperation and Development (AECID). ; Peer reviewed

8 Pags.- 1 Tabl. 2 Figs. From author's contribution at VIII International Peach Symposium (Matera, Italy. June 17-20, 2013). The definitive version is available at: http://www.actahort.org/index.htm ; Fruit quality is the main criterion used for selection of new varieties in peach, and it is usually defined by the conjunction of organoleptic and nutritional traits and postharvest behavior. The aim of this study was the identification of quantitative trait loci (QTL) for several fruit quality traits using an F1 segregating population of 75 seedlings derived from the cross between 'Venus' and 'Big Top' nectarine cultivars. The progeny was evaluated over several years for agronomic and pomological characteristics (including basic quality traits and antioxidant compounds content) and also genotyped using SNPs included in the 'IPSC 9K peach SNP array v1' developed by the International Peach SNP Consortium, which carries 8,144 SNPs. Two preliminary dense genetic linkage maps were constructed for 'Venus' and 'Big Top', with 160 and 208 markers placed onto 11 linkage groups, respectively. A second round was used to identify QTLs that were mapped over twelve LG representing seven peach chromosomes. Some of the QTLs mapped in the same position of previously reported QTLs, interestingly QTLs for fructose in LG6 and phenolic compounds in LG2 were detected for the first time. LG4 in 'Venus' and LG5 in 'Big Top' maps presented the highest density of QTLs controlling several traits. This work represents the first study identifying QTLs for fruit quality traits using the high-density SNP array 'IPSC 9K peach SNP array v1' in an F1 nectarine family. ; This work was supported by the Spanish MICINN (Ministry of Science and Innovation) grants AGL-2008-00283 and AGL2011-24576 and co-funded by FEDER and the Regional Government of Aragón (A44). W. Abidi and J.L. Zeballos were supported by a JAE-Pre fellowship from CSIC and a Master fellow funded for the AECID (Spanish Agency for International Cooperation and Development). ; Peer reviewed

7 Pags., 1 Tabl., 2 Figs. The definitive version is available at: http://www.actahort.org/index.htm ; In peach fruits, phenolic compounds serve as a major source of potential antioxidants which are known to play a significant role in fruit quality and in human well being. This study was conducted in a F1 population derived from the cross 'Venus' × 'Big Top' nectarines in order to investigate the variability in the fruit antioxidant content and to study the genetic control and location of QTLs involved in fruit quality traits. Biochemical analyses have been performed to measure L-ascorbic acid (vitamin C), total phenolics, flavonoids, anthocyanins contents and antioxidant capacity. ; This study was funded by the Spanish MIC1NN (Ministry of Science and Innovation) grant AGL-2008-00283, cofunded by FEDER, and the Regional Government of Aragon (A44). W. Abidi was supported by a JAE fellowship from CSIC (Consejo Superior de Investigaciones Científicas). ; Peer reviewed