Mapping quantitative trait loci associated with chilling requirement, heat requirement and bloom date in peach (Prunus persica)

Abstract

Summary• Chilling requirement, together with heat requirement, determines the bloom date, which has an impact on the climatic distribution of the genotypes of tree species. The molecular basis of floral bud chilling requirement is poorly understood, despite its importance to the adaptation and production of fruit trees. In addition, the genetic nature of heat requirement and the genetic interrelationships among chilling requirement, heat requirement and bloom date remain unclear.• A peach (Prunus persica) F 2 population of 378 genotypes developed from two genotypes with contrasting chilling requirements was used for linkage map construction and quantitative trait loci (QTL) mapping. The floral bud chilling and heat requirements of each genotype were evaluated over 2 yr and the bloom date was scored over 4 yr.• Twenty QTLs with additive effects were identified for three traits, including one major QTL for chilling requirement and two major QTLs for bloom date. The majority of QTLs colocalized with QTLs for other trait(s). In particular, one genomic region of 2 cM, pleiotropic for the three traits, overlapped with the sequenced peach EVG region.• This first report on the QTL mapping of floral bud chilling requirement will facilitate marker-assisted breeding for low chilling requirement cultivars and the map-based cloning of genes controlling chilling requirement. The extensive colocalization of QTLs suggests that there may be one unified temperature sensing and action system regulating chilling requirement, heat requirement and bloom date together

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

“…On LG1, QTLs for flowering date were detected in the two peach progenies and in the sweet cherry 'Lapins' , in the same region as both QTLs for flowering date and chilling requirements detected in peach and the evergrowing locus (Fan et al, 2010). On LG5, two QTLs for flowering date were detected in the peach J Â F and in the sweet cherry 'Regina' .…”

“…The one on the upper part of the chromosome located in the same region as a QTL for flowering date with major effect detected in the apricot 'Z506-07 (Campoy et al, 2011). On LG7, QTLs for flowering date were detected for the four analyzed progenies, and were also detected on the same LG in the peach F 2 population issued from the cross 'Contender' Â 'Fla.92-2C' (Fan et al, 2010) and in the apricot F 1 population issued from 'Perfection' Â A1740 (Olukolu et al, 2009). For maturity date, less QTLs with higher EVs were detected compared with flowering date.…”

“…In peach one major QTL for chilling requirements was identified on LG1, co-localizing with a QTL for flowering date, and overlapping the evergrowing region (Fan et al, 2010). Another QTL mapped on LG7 and co-localized also with a QTL for flowering date.…”

“…Earlygold map), QTLs were detected in the T Â E F 2 population on four linkage groups (LG), LG1, LG4, LG6 and LG7 (Joobeur, 1998). In peach, QTLs have been detected over four different populations on all LGs except LG8 (Dirlewanger et al, 1999;Verde et al, 2002;Quilot et al, 2004;Fan et al, 2010). In almond, the major gene Lb was first mapped on LG4 using the progeny from a cross between 'D-3-5' , a Lb/lb heterozygous genotype, and 'Bertina' (Ballester et al, 2001).…”

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

“…Fan et al (2010) used an F 2 population of 378 peach trees from a cross between two genotypes with contrasting chilling requirements to construct a linkage map and chart QTLs. The map included 96 SSRs (36 shared with the T×E map), 30 AFLPs, and one morphological marker in eight linkage groups covering 535 cM, with a mean distance of 4.2 cM between markers.…”