In silico polymorphic novel SSR marker development and the first SSR-based genetic linkage map in pistachio

Simple sequence repeats (SSRs) are co-dominant markers, and are very useful in constructing consensus maps in heterozygous perennial plant species like pistachio. Pistacia vera L. is the only cultivated species in the genus Pistacia. It is dioecious with a haploid chromosome count of n = 15. Saturated genetic linkage maps can be a reference to identify markers linked to economically important phenotypic traits that could be useful for early breeding and selection programs. Therefore, this study aimed to develop polymorphic SSR markers in silico and to construct the first SSR-based genetic linkage map in pistachio. The DNA sequences of three cultivars (Siirt, Ohadi, and Bagyolu) of P. vera and one genotype belonging to P. atlantica (Pa-18) were obtained by next-generation sequencing, and 625 polymorphic SSR loci were identified from 750 screened in silico polymorphic SSR primer pairs. The novel SSRs were used to construct SSR-based genetic linkage maps in pistachio along with published SSRs in Siirt x Bagyolu F1 population. Most (71.4%) of the SSRs were common markers that were used to construct consensus and parental maps spanning 15 linkage groups (LGs). A total of 384, 317, and 341 markers were mapped in the consensus, female, and male genetic maps with total lengths of 1511.3, 1427.0, and 1453.4 cM, respectively. The large number of SSR markers discovered and the first SSR-based genetic linkage map constructed in this study will be useful for anchoring loci for map integration, and will facilitate marker-assisted selection efforts for important horticultural traits in the genus Pistacia.