Building high-density peach linkage maps based on the ISPC 9K SNP chip for mapping mendelian traits and QTLS: benefits and drawbacks

"FruitBreedomics" European project has been designed by an international consortium including scientists, stakeholders and breeding companies. One of its aims is to increase the efficiency of breeding programs in apple Malus xdomestica) and peach Prunus persica) by enabling Marker Assisted Breeding MAB) using novel genomic tools. In the frame of this project, five peach mapping populations from the UGAFL (Unite de Genetique et Amelioration des Fruits et Legumes) peach breeding program two intraspecific F-2, two interspecific F-1 derived from P. davidiana and one self-pollinated derived from 'Bolinha') segregating for mendelian traits and/or Quantitative Trait Loci QTLs) for pest resistance and fruit quality were genotyped using the 9K SNP Illumina Infinium II Bead-chip delivered by the International Peach SNP Consortium IPSC). Based on these data, genetic maps were then constructed; however mapping results were contrasted depending on the population considered. All maps aligned with the 8 pseudo-molecules of the Prunus persica Whole Genome sequence v1.0 IPGI), but the best polymorphisms and coverage were obtained with the F-2 populations, for which twenty to twenty-nine percent of the SNPs were polymorphic covering 500 loci on average. However, these loci were unevenly distributed, although covering most of the peach genome. In contrast, for the F-1 populations, only 5% of the SNPs were polymorphic in P. davidiana and the selfing of 'Bolinha' resulting in low coverage and very heterogeneous distributions. As primary consequence, this demonstrates the poor transferability of such a tool between species, even tightly related, and additionally highlights the relatively low efficiency of SNPs in term of useful polymorphism when parents belong to close peach germplasms. Consequently, regions containing QTLs and major genes could be insufficiently covered and need additional SNP development for MAB. The relevancy of using general medium-range SNP bead-chips for breeding purposes is discussed in this study

Building high-density peach linkage maps based on the ISPC 9K SNP chip for mapping mendelian traits and QTLs: benefits and drawbacks

“FruitBreedomics” European project has been designed by an international consortium including scientists, stakeholders and breeding companies. One of its aims is to increase the efficiency of breeding programs in apple and peach by developing Marker Assisted Breeding (MAB) using novel genomic tools. In the frame of this project, six peach mapping populations (two intraspecific F2, two interspecific F1 derived from P. davidiana, one self pollinated derived from Bolinha and one advanced pseudo-backcross) segregating for mendelian traits and/or Quantitative Trait Loci (QTLs) for pest resistance and fruit quality were genotyped using an Infinium II Illumina bead-chip containing 8144 SNPs derived from the sequencing of the peach genome. Mapping results were contrasted depending on the population considered. Relevancy of using general medium-range SNP bead- chips for breeding purposes is discussed in this stud

An integrated approach for increasing breeding efficiency in apple and peach in Europe

Despite the availability of whole genome sequences of apple and peach, there has been a considerable gap between genomics and breeding. To bridge the gap, the European Union funded the FruitBreedomics project (March 2011 to August 2015) involving 28 research institutes and private companies. Three complementary approaches were pursued: (i) tool and software development, (ii) deciphering genetic control of main horticultural traits taking into account allelic diversity and (iii) developing plant materials, tools and methodologies for breeders. Decisive breakthroughs were made including the making available of ready-to-go DNA diagnostic tests for Marker Assisted Breeding, development of new, dense SNP arrays in apple and peach, new phenotypic methods for some complex traits, software for gene/QTL discovery on breeding germplasm via Pedigree Based Analysis (PBA). This resulted in the discovery of highly predictive molecular markers for traits of horticultural interest via PBA and via Genome Wide Association Studies (GWAS) on several European genebank collections. FruitBreedomics also developed pre-breeding plant materials in which multiple sources of resistance were pyramided and software that can support breeders in their selection activities. Through FruitBreedomics, significant progresses were made in the field of apple and peach breeding, genetics, genomics and bioinformatics of which advantage will be made by breeders, germplasm curators and scientists. A major part of the data collected during the project has been stored in the FruitBreedomics database and has been made available to the public. This review covers the scientific discoveries made in this major endeavour, and perspective in the apple and peach breeding and genomics in Europe and beyond. A Europe-led effort to bridge the gap between genomics and breeding offers a new resource to support apple and peach production. A team led by François Laurens from the Research Institute in Horticulture and Seeds (IRHS) in Angers, France, review the tools, methodologies and scientific discoveries made through FruitBreedomics, a project that ran between 2011 and 2015 and involved 28 different research and private companies from around the world. These new molecular and bioinformatics tools include DNA arrays for mapping genetic diversity, computer software for analyzing genetic information and novel methods for understanding commercially important traits such as fruit quality and resistance to stresses. The project's materials should help apple and peach producers better plan their breeding programs so as to meet grower and consumer demand for high-quality fruit with desired characteristics