Three maqui genotypes exhibited significantly higher anthocyanin content than the others, as measured by pH differential method and high-performance liquid chromatography-mass spectrometry. Significant genetic diversity was noted within each ecological population. ISSR-PCR analysis provided a fingerprinting approach applicable for differentiation of maqui genotypes.

This review is an overview of traditional and modern breeding methodologies being used to develop new Prunus cultivars (stone fruits) with major emphasis on peach, sweet cherry and Japanese plum. To this end, common breeding tools used to produce seedlings, including in vitro culture tools, are discussed. Additionally, the mechanisms of inheritance of many important agronomical traits are described. Recent advances in stone fruit transcriptomics and genomic resources are providing an understanding of the molecular basis of phenotypic variability as well as the identifi cation of allelic variants and molecular markers. These have potential applications for understanding the genetic diversity of the Prunus species, molecular marker-assisted selection and transgenesis. Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNPs) molecular markers are described as useful tools to describe genetic diversity in peach, sweet cherry and Japanese plum. Additionally, the recently sequenced peach genome and the public release of the sweet cherry genome are discussed in terms of their applicability to breeding programs.

This study reports the construction of high density linkage maps of Japanese plum (Prunus salicina Lindl.) using single nucleotide polymorphism markers (SNPs), obtained with a GBS strategy. The mapping population (An x Au) was obtained by crossing cv. “Angeleno” (An) as maternal line and cv. “Aurora” (Au) as the pollen donor. A total of 49,826 SNPs were identified using the peach genome V2.1 as a reference. Then a stringent filtering was carried out, which revealed 1,441 high quality SNPs in 137 An x Au offspring, which were mapped in eight linkage groups. Finally, the consensus map was built using 732 SNPs which spanned 617 cM with an average of 0.96 cM between adjacent markers. The majority of the SNPs were distributed in the intragenic region in all the linkage groups. Considering all linkage groups together, 85.6% of the SNPs were located in intragenic regions and only 14.4% were located in intergenic regions. The genetic linkage analysis was able to co-localize two to three SNPs over 37 putative orthologous genes in eight linkage groups in the Japanese plum map. These results indicate a high level of synteny and collinearity between Japanese plum and peach genomes.

No abstract

B. Carrasco, C. Díaz, M. Moya, M. Gebauer and R. García-González. 2012. Genetic characterization of Japanese plum cultivars (Prunus salicina) using SSR and ISSR molecular markers. Cien. Inv. Agr. 39(3): 533-543. The genetic characterization of 29 elite Japanese plum cultivars (Prunus salicina) and 4 Prunus cultivars was carried out by analyzing 97 Simple Sequence Repeat (SSR) alleles and 232 binary Inter Simple Sequence Repeat (ISSR) loci. A high level of genetic variability was found for these two molecular markers among the Japanese plum cultivars compared to other Prunus species. On average, the variability found by analyzing the SSR alleles were Na = 12.1, Ne = 5.2, Ho = 0.9, He = 0.8 and F= -0.127, whereas ISSR yielded values of h = 0.15 and I = 0.27. The genetic relationship among cultivars was estimated with Principal Coordinate Analysis (PCA) and a Bayesian clustering approach using the software program Structure. This program identified two subgroups (k=2). The first group included cultivars of four Prunus species: P. salicina, P. armeniaca, P. domestica and P. ceracifera, whose memberships ranged between 0.74 and 1.0. The second group included 19 Japanese plum cultivars and one plumcot cultivar, with memberships between 0.57 and 0.99. With some exceptions, similar relationships among cultivars were foundPCA. The level of genetic differentiation between two groups was low (G st =0.055 and  ST =0.04), and a low level of linkage disequilibrium (LD) was observed for all allele combinations. These results suggest that the high level of genetic variability, the low level of LD and the scarce degree of differentiation detected by Structure between the two genetic groups can be explained by the self-incompatibility mechanism that favors the exchange between genetically distant Prunus cultivars and by the intra-and interspecific hybridization strategies frequently used in plum breeding programs.