Breeding sweet cherries at INRA-Bordeaux: from conventional techniques to marker-assisted selection
Sweet cherry breeding at INRA-Bordeaux started in the 1960s. Due to poor knowledge of the cultivars and to a narrow genetic base used for crosses, the first breeding program did not manage to release any new cultivar. Subsequently, a new program was launched in the 1980s by incorporating a large collection of genetic resources to the pool of genitors used. Many INRA cultivars were then commercialized. 'Fercer' was the first INRA cultivar producing big and firm fruits, hence, it was heavily used as genitor. Among the last cultivars released by INRA, 'Folfer' met tremendous success among French growers, due to its precocity, yield regularity, size, firmness and taste. By the end of the 1990s new tools were integrated into the breeding program, either to decipher complex traits such as rain-induced fruit cracking or to optimize the selection process, by the implementation of marker-assisted selection strategies. In 2007 a new breeding program was launched, it was reinforced in 2011 by the signature of a contract with a private nurserymen consortium, CEP Innovation. In the last 15 years, genetic maps have been built by working with two progenies issued from the crosses of cultivars 'Regina' and 'Lapins', and 'Regina' and 'Garnet'. QTL detection studies have been carried out on phenology-related traits as well as fruit quality traits. Studies aimed at discovering and validating candidate genes underlying the most significant QTL have been initiated, both by association genetics and functional genomics approaches. Modeling will be integrated as well in the breeding schemes in order to anticipate the consequences of climate change and to adapt sweet cherry cultivars to the future climatic conditions. The main results and their impact on future breeding strategies are presented and discussed.