An integrated genetic linkage map for almond based on RAPD, ISSR, SSR and morphological markers

Abstract

An integrated genetic linkage map of almond (Prunus dulcis) based on RAPD, ISSR, SSR and morphological markers was constructed using a pseudo-testcross mapping format and Joinmap 3.0. A total of 93 individuals from a F₁ full-sib family produced from a cross between ‘Nonpareil’ and ‘Lauranne’ was genotyped with 120 molecular markers (60 RAPD, 23 ISSR, 1 SCAR, and 36 SSR) to produce two parental maps. Hybridity of the mapping population was confirmed by DNA fingerprinting and cluster analysis using RAPD and ISSR markers, and SSR inheritance. The two parental maps were aligned using 12 molecular markers (2 RAPD, 4 ISSR, and 5 SSR) that were segregating in both parents (intercross markers). Two distorted markers were observed at the distal region of two linkage groups. A map position was provided for the kernel taste loci, on linkage group B, 49.1 cM from the ISSR marker (AG)₈YC-1786. Six linkage groups were obtained for the integrated map with a marker density of 11.5 cM/marker, covering 161.9 cM (Kosambi), representing a 31% coverage of the T x E Prunus reference map. This map provides an initial step for producing a SSR saturated integrated genetic linkage map of the almond genome, including morphological markers. The use of both peach and cherry SSRs illustrates the use of interspecific derived primers as a source of polymorphism generation in the Prunus genus, further enhancing the collaborative effort to produce a genus wide reference map for application in breeding programs and marker assisted selection.