QTL ANALYSIS OF AGRONOMIC TRAITS IN A BC₁ PEACH POPULATION

The purpose of the present study was to identify tight linkage between important agronomic traits and molecular markers with the aim of using them in Marker Assisted Selection (MAS) in the peach breeding programs at ISF. Quantitative trait loci (QTLs) influencing several agronomic traits were identified in a BC1 population issued from a cross between a selection of Prunus persica (IF 7310828) used as female recurrent parent and an accession of the related wild species P. ferganensis carrying a source of resistance to powdery mildew. One hundred and nine molecular markers (RFLPs, SSRs and RAPDs), spaced through the genome, were used to analyze 70 random progeny of this population. Fourteen characters, including blooming time, ripening time, disease resistance and traits related to tree architecture and fruit quality, were analyzed for 3-5 years on each tree of the BC1 progeny. QTLs were identified for internode length, blooming time, ripening time, skin color, soluble solids content and Sphaerotheca pannosa resistance. Most of the QTLs were consistent through the years showing that the expression of the genes is largely independent of the environmental conditions. All of them displayed the same effect as the parental phenotype. For each trait the detected QTLs explained up to 42% of the total variance.