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.

Zeballos, JL.; Adibi, W.; Giménez Millán, R.; Monforte Gilabert, AJ.; Moreno, MA.; Gogorcena, Y. (2016). Mapping QTLs associated with fruit quality traits in peach Prunus persica (L.) Batsch using SNP maps. Tree Genetics and Genomes. 12(3):1-17. doi:10.1007/s11295-016-0996-9. AbstractFruit 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 F 1 nectarine population derived from 'Venus' and 'Big Top' cultivars. The progeny were evaluated over 4 years for agronomical and biochemical characteristics, and genotyped using 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 ten 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 12LGs 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.LG4 in 'Venus' and LG5 in 'Big Top' showed the highest numbers of QTLs. This work represents the first study in an F 1 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.

were selected. The progeny also showed variability for all the evaluated CI symptoms and 16 27 genotypes showed considerable lower susceptibility to CI. After 2 weeks of cold storage, 28 leatheriness and bleeding were the main CI symptoms observed, whereas flesh browning was 29 predominant after 4 weeks. 30 CONCLUSIONS: It was possible to find varieties with high phenolics concentration and 31 relatively low or intermediate CI susceptibility (22, 33, 68, 80, 81, 96 and 120). However, the 32 correlations observed between CI and phenol contents highlight their potential influence on 33 susceptibility to internal browning. This relationship should be considered in the current 34 breeding programs to select cultivars with high bioactive compound contents, health-35 enhancing properties and good post-harvest performance. 36 37

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 LG 6 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.

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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 wellbeing. This study was conducted in a F1 population derived from the cross 'Venus' x '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 Lascorbic acid (vitamin C), total phenolics, flavonoids, anthocyanins contents and antioxidant capacity.

Peach fruit quality is dependent on preharvest treatments and orchard practices. The aim of this study is to evaluate the effects of preharvest potassium silicon fertilization on fruit postharvest quality. Two peach cultivars (“Early Bomba” and “Plagold 17”) were sprayed with three concentrations of potassium silicon (K-Si) at fruit set, stone hardening, and physiological maturity stages. The applied treatments corresponded to control (T0 = 0% K-Si) pulverized with distilled water and two K-Si treatments (T1 = 3% K-Si and T2 = 4.5% K-Si). The blooming and harvesting dates, vegetative growth and agronomical parameters were analyzed over two growing seasons (2021–2022). Peach fruits were stored at 5 °C and 95% RH during two cold storage periods (2 and 4 weeks) followed by 2 days at room temperatures. The fruit weights (FW), color, firmness, soluble solids content (SSC), titratable acidity (TA), pulp stone ratio (P/S) and fruit weight loss (FWL) were evaluated. The anthocyanins, flavonoids, total phenolics, carotenoids and antioxidant capacity (DPPH) were determined. Vitamin B5 and vitamin C were analyzed by HPLC. The ethylene rate and the chilling injury symptoms (CI) were analyzed after two cold storage periods (2 and 4 weeks). Results showed that the applied potassium silicon treatments (3% K-Si and 4.5% K-Si) enhanced the FW, SSC, TA, FWL, fruit composition and CI. Anthocyanins and total phenolics increased after cold storage period under K-Si treatments. The nectarine cultivar (cv) Early Bomba showed low sensibility to chilling injury symptoms as compared to the cv Plagold 17.

Changes in antioxidant status, biochemical and hormonal responses, were investigated in three olive cultivars (Arbequina, Arbosana and Chetoui) grown in a super-high-density orchard under partial root-zone drying (PRD) irrigation. Four irrigation treatments were applied during two growing seasons (2015 and 2016); control treatment (100% ETC) irrigated at 100% of crop evapotranspiration on both parts of the root-zone and three PRD irrigation treatments (100% PRD, 75% PRD and 50% PRD) irrigated at 100%, 75%, and 50% of crop evapotranspiration only on one alternated part of the root-zone. The results indicated that the three studied olive cultivars showed a clear difference in their response to PRD irrigation.In fact, PRD irrigation has led to a strong activation of secondary metabolites with antioxidant properties such as pigments, phenols and flavonoids. Other metabolic changes, including the accumulation of soluble sugars and proline have been also triggered by PRD irrigation. Among the studied cultivars, Arbequina displayed the highest levels for proline, total soluble sugars, phenols and flavonoids, and the lowest ones for MDA and H2O2.The increase in SOD, CAT and POD activity and the reduction and PPO activity under PRD irrigation were more pronounced in 2016 season with highest activities obtained from cultivar Arbequina.For all the three cultivars, PRD irrigation increased phytohormones concentration in both, roots and leaves and the highest levels were recorded in 2016. In leaves, Arbequina showed the lowest levels of ABA and the highest levels of JA, SA and IAA. PRD irrigation also induces a higher accumulation of ABA, JA and IAA in dried roots than in wetted ones.Taken together, biochemical mechanisms induced by PRD irrigation were more effective in Arbequina suggesting better protection of their foliar functions compared to other cultivars and its higher adaptability to PRD.