Genetic Control and Location of QTLs Involved in Antioxidant Capacity and Fruit Quality Traits in Peach [Prunus persica (L.) Batsch]

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. INTRODUCTION Peach and nectarine fruit [Prunus persica (L.) Batch] are the second most important fruit crop in the European Union (EU) after apples (Iglesias and Echeverría, 2008). Peach, a member of the Prunoideae subfamily, is one of the most widely grown and the best genetically characterized species in the Rosaceae family, it is a self-fertile and naturally self-pollinating fruit species with very low genetic variability (Scorza et al., 1985). As a result of its small genome size, the developing genomic resources, and the colinearity of the peach genome within Prunus, diploid peach has become a model genome for these fruit crops, providing a platform for comparative studies within the entire Rosaceae (Abbott et al., 2002). Peach fruit contain ascorbic acid (vitamin C), carotenoids (provitamin A), and phenolic compounds that are good sources of antioxidants (Byrne, 2002). Phenolic compounds represent the major sources of antioxidant capacity in peaches (Cantin et al., 2009; Chang et al., 2000); although vitamin C also contributes to antioxidant capacity (Gil et al., 2002). These naturally occurring substances not only have a role in the visual appearance (pigmentation and browning) and taste (astringency) of fruit, but also have health-promoting properties, acting as antioxidants by scavenging harmful free radicals which are implicated in most degenerative diseases (Rice-Evans et al., 1996; Cantín et al., 2009). These benefits make phenolic compounds an interesting target for breeding programmes. The development of molecular markers and linkage maps provides efficient tools to locate genes or quantitative trait loci (QTLs) involved in agronomical characters and could be helpful for monitoring of breeding programs (Young, 1996). QTLs for traits, which determine fruit quality in peach, have been localized on maps (Dirlewanger et al., 1998). Most of the QTLs affecting fruit quality characters have been localized in few linkage groups. In linkage group 6, QTLs associated with sucrose, sorbitol, soluble solid content, malic acid and citric acid have been identified (Dirlewanger et al., 1999; Etienne et al., 2002).