Cross-species amplification of nuclear EST-microsatellites developed for other Pinus species in Pinus nigra

Abstract

Due to the current lack of nuclear microsatellites (simple sequence repeats - SSRs) specifically developed for Pinus nigra, an important European coniferous species, we cross-species amplified 12 EST-SSRs (expressed sequence tagged SSRs) developed for other Pinus species in P. nigra in order to delineate loci which can be used for assessing levels of genetic diversity and genetic structuring in this species. We amplified these loci in individuals from seven populations from the central Balkans representing four recognized infraspecific taxa of P. nigra (ssp. nigra, var. gocensis, ssp. pallasiana, and var. banatica). Contrary to expectations on high transferability of EST-SSRs into related species, only three out of 12 tested loci were successfully amplified in P. nigra, but they displayed lack/low levels of polymorphism or generated multilocus amplification products. Thus, our estimates on levels of genetic diversity (H<inf>E</inf> = 0.183) and genetic differentiation (F<inf>ST</inf> = 0.007) were based on variability of a single locus harboring four alleles only and they should be taken with cautions. Our study highlights the need for the development of high-resolution molecular markers, such as co-dominant genic or genomic SSRs or predominantly biallelic SNPs, or utilization of anonymous dominant markers, such as AFLPs, for genotyping in P. nigra.