RESYNTHESIS AND VORIs: Two New Marker-Based Approaches for Peach Breeding

A challenge in breeding clonally reproduced crops such as peach is to produce, by conventional hybridization, individuals reasonably close to a high performance, partly heterozygous, cultivar with a few key differences of agronomic interest. We propose two methods based on monitoring the whole genome with molecular markers in different progenies.

Resynthesis: The objective is to select with markers from the selfed progeny of a top cultivar: a) individuals with most of the genome in heterozygosis like the original cultivar and only a few fragments in homozygosis (15% or less of the genome), or b) two complementary nearly-homozygous lines that crossed would produce a cultivar genetically similar to the original one. The interest of b) is that new valuable genes can be introduced in one of the lines by marker-assisted introgression (MAI) and add new properties to an elite genotype in a predictable timeframe.     

VORIs (Varieties Obtained by Resynthesis and Introgression): This method combines MAI with resynthesis to obtain two parents that crossed generate a cultivar similar to an original one incorporating a new gene of interest from a wild or exotic parent. Two lines of breeding proceed in parallel: Line 1 involves three generations, F1 (selection for non-recombined chromosomes of the recurrent parent), BC1 (selection for individuals with a few introgressions) and BC1S1 (selection for homozygous individuals with a single introgression). Line 2 involves two consecutive selfing generations from the recurrent parent where marker selection is done for a nearly-homozygous set of chromosomes complementary to that obtained in Line 1.