We report a high-quality draft genome sequence of the domesticated apple (Malus × domestica). We show that a relatively recent (>50 million years ago) genome-wide duplication (GWD) has resulted in the transition from nine ancestral chromosomes to 17 chromosomes in the Pyreae. Traces of older GWDs partly support the monophyly of the ancestral paleohexaploidy of eudicots. Phylogenetic reconstruction of Pyreae and the genus Malus, relative to major Rosaceae taxa, identified the progenitor of the cultivated apple as M. sieversii. Expansion of gene families reported to be involved in fruit development may explain formation of the pome, a Pyreae-specific false fruit that develops by proliferation of the basal part of the sepals, the receptacle. In apple, a subclade of MADS-box genes, normally involved in flower and fruit development, is expanded to include 15 members, as are other gene families involved in Rosaceae-specific metabolism, such as transport and assimilation of sorbitol.

Background Most of the grapevine ( Vitis vinifera L.) cultivars grown today are those selected centuries ago, even though grapevine is one of the most important fruit crops in the world. Grapevine has therefore not benefited from the advances in modern plant breeding nor more recently from those in molecular genetics and genomics: genes controlling important agronomic traits are practically unknown. A physical map is essential to positionally clone such genes and instrumental in a genome sequencing project. Results We report on the first whole genome physical map of grapevine built using high information content fingerprinting of 49,104 BAC clones from the cultivar Pinot Noir. Pinot Noir, as most grape varieties, is highly heterozygous at the sequence level. This resulted in the two allelic haplotypes sometimes assembling into separate contigs that had to be accommodated in the map framework or in local expansions of contig maps. We performed computer simulations to assess the effects of increasing levels of sequence heterozygosity on BAC fingerprint assembly and showed that the experimental assembly results are in full agreement with the theoretical expectations, given the heterozygosity levels reported for grape. The map is anchored to a dense linkage map consisting of 994 markers. 436 contigs are anchored to the genetic map, covering 342 of the 475 Mb that make up the grape haploid genome. Conclusions We have developed a resource that makes it possible to access the grapevine genome, opening the way to a new era both in grape genetics and breeding and in wine making. The effects of heterozygosity on the assembly have been analyzed and characterized by using several complementary approaches which could be easily transferred to the study of other genomes which present the same features.

Until recently, only a small number of low- and mid-throughput methods have been used for single nucleotide polymorphism (SNP) discovery and genotyping in grapevine (Vitis vinifera L.). However, following completion of the sequence of the highly heterozygous genome of Pinot Noir, it has been possible to identify millions of electronic SNPs (eSNPs) thus providing a valuable source for high-throughput genotyping methods.

We have developed an integrated map from five elite cultivars of Vitis vinifera L.; Syrah, Pinot Noir, Grenache, Cabernet Sauvignon and Riesling which are parents of three segregating populations. A new source of markers, SNPs, identified in ESTs and unique BAC-end sequences was added to the available IGGP reference set of SSRs. The complete integrated map comprises 1,134 markers (350 AFLP®, 332 BESs, 169 ESTs, 283 SSRs) spanning 1,443 cM over 19 linkage groups and shows a mean distance between neighbouring loci of 1.27 cM. Marker order was mainly conserved between the integrated map and the highly dense Syrah × Pinot Noir consensus map except for few inversions. Moreover, the marker order has been validated through the assembled genome sequence of Pinot Noir. We have also assessed the transferability of SNP-based markers among five V. vinifera varieties, enabling marker validation across different genotypes. This integrated map can serve as a fundamental tool for molecular breeding in V. vinifera and related species and provide a basis for studies of genome organization and evolution in grapevines.

The construction of a dense genetic map for Vitis vinifera and its anchoring to a BAC-based physical map is described: it includes 994 loci mapped onto 19 linkage groups, corresponding to the basic chromosome number of Vitis. Spanning 1245 cM with an average distance of 1.3 cM between adjacent markers, the map was generated from the segregation of 483 single-nucleotide polymorphism (SNP)-based genetic markers, 132 simple sequence repeats (SSRs), and 379 AFLP markers in a mapping population of 94 F(1) individuals derived from a V. vinifera cross of the cultivars Syrah and Pinot Noir. Of these markers, 623 were anchored to 367 contigs that are included in a physical map produced from the same clone of Pinot Noir and covering 352 Mbp. On the basis of contigs containing two or more genetically mapped markers, region-dependent estimations of physical and recombinational distances are presented. The markers used in this study include 118 SSRs common to an integrated map derived from five segregating populations of V. vinifera. The positions of these SSR markers in the two maps are conserved across all Vitis linkage groups. The addition of SNP-based markers introduces polymorphisms that are easy to database, are useful for evolutionary studies, and significantly increase the density of the map. The map provides the most comprehensive view of the Vitis genome reported to date and will be relevant for future studies on structural and functional genomics and genetic improvement.

Background Worldwide, grapes and their derived products have a large market. The cultivated grape species Vitis vinifera has potential to become a model for fruit trees genetics. Like many plant species, it is highly heterozygous, which is an additional challenge to modern whole genome shotgun sequencing. In this paper a high quality draft genome sequence of a cultivated clone of V. vinifera Pinot Noir is presented. Principal Findings We estimate the genome size of V. vinifera to be 504.6 Mb. Genomic sequences corresponding to 477.1 Mb were assembled in 2,093 metacontigs and 435.1 Mb were anchored to the 19 linkage groups (LGs). The number of predicted genes is 29,585, of which 96.1% were assigned to LGs. This assembly of the grape genome provides candidate genes implicated in traits relevant to grapevine cultivation, such as those influencing wine quality, via secondary metabolites, and those connected with the extreme susceptibility of grape to pathogens. Single nucleotide polymorphism (SNP) distribution was consistent with a diffuse haplotype structure across the genome. Of around 2,000,000 SNPs, 1,751,176 were mapped to chromosomes and one or more of them were identified in 86.7% of anchored genes. The relative age of grape duplicated genes was estimated and this made possible to reveal a relatively recent Vitis-specific large scale duplication event concerning at least 10 chromosomes (duplication not reported before). Conclusions Sanger shotgun sequencing and highly efficient sequencing by synthesis (SBS), together with dedicated assembly programs, resolved a complex heterozygous genome. A consensus sequence of the genome and a set of mapped marker loci were generated. Homologous chromosomes of Pinot Noir differ by 11.2% of their DNA (hemizygous DNA plus chromosomal gaps). SNP markers are offered as a tool with the potential of introducing a new era in the molecular breeding of grape.