QTL analysis of fruit quality traits in two peach intraspecific populations and importance of maturity date pleiotropic effect

Abstract

Two intraspecific peach breeding populations have been used to conduct a quantitative trait locus (QTL) analysis of fruit quality traits: an F 1 from the cross Bolero (B) x OroA (O) and an F 2 from the cross Contender (C) x Ambra (A). A total of 344 Prunus simple sequence repeats (SSRs) were analyzed in B, O, C, A parents and CxA F 1 hybrid. Eight SSR were mapped for the first time in peach. A multiplex-ready polymerase chain reaction (PCR) protocol has allowed considerable time and cost saving during genotyping steps. Two maps (B map and O map) were produced for BxO population following the pseudo-test cross strategy and one for CxA. No marker could be mapped on G6 for the B map, on G4 and G8 for the O map and on G5 for the CxA map. Both populations were phenotyped over 2 years for maturity date (MD), fruit weight, external fruit skin overcolor, juice total soluble solids (SSC, Brix degree), juice titrable acidity and juice pH. Data for blooming time and flower type were scored only for BxO in 2007. All traits had a normal distribution, except for MD which was bimodal in BxO and trimodal in CxA, where it was scored as a co-dominant trait. Up to two QTLs per trait were detected in each population, and most of them were located in the same region forming clusters of QTLs, especially on G4. This is likely due to a major pleiotropic effect of MD masking the identification of other QTLs for different traits.

Comparison of the genetic determinism of two key phenological traits, flowering and maturity dates, in three Prunus species: peach, apricot and sweet cherry

“…The authors indicated that maturity date is a possible Mendelian trait. In the C Â A progeny, the QTL explained 97.5% of the variation in 2007 and 97.7% in 2008 (Eduardo et al, 2011). QTLs controlling maturity date were also detected on LG4 in another peach progeny (Verde et al, 2002), and in almond (Sánchez-Pérez et al, 2007).…”

“…The highest effect was detected for the peach J Â F (EV ¼ 70.4%). A QTL with a major effect was also reported to be located on LG4 in two peach progenies: an F 1 from 'Bolero' and 'OroA' and an F 2 derived from the cross between 'Contender' and 'Ambra' (C Â A) (Eduardo et al, 2011) (Figure 2). The authors indicated that maturity date is a possible Mendelian trait.…”

“…The most significant QTLs were detected on LG4 and LG6. In one of the peach populations studied, a QTL detected on LG4 could be considered as a major gene, as the percentage of explained variance was close to 98% (Eduardo et al, 2011). In almond, QTLs with low effect were mapped to LG4 and LG5 (Sánchez-Pérez et al, 2007).…”

“…For peach, QTLs mapped to LG2 and LG6 (Verde et al, 2002), LG2, LG3 and LG4 (Quilot et al, 2004), and LG1, LG4 and LG6 (Eduardo et al, 2011). The most significant QTLs were detected on LG4 and LG6.…”

Breeding rootstocks for Prunus species: Advances in genetic and genomics of peach and cherry as a model

“…Another research group (Eduardo et al, 2010) used two progenies from peach crosses to search for QTLs related to fruit quality characteristics. One population was an F 1 population of 'Bolero' (B) × 'OroA' (O) with 129 individuals.…”