Nuclear microsatellite markers for population genetic studies in sugar maple (Acer saccharum Marsh.)

A set of seven new nuclear microsatellite markers (nSSRs) was developed for sugar maple (Acer saccharum Marsh.) using paired-end Illumina sequencing. Out of 96 primers screened in a panel of six unrelated individuals, seven markers amplified polymorphic products. The utility of these markers, in addition to six already published microsatellites, for genetic variation and gene flow studies was assessed. Out of the seven newly developed markers, three amplified multiple fragments and were interpreted as dominant (absence/presence) markers, while four markers amplified a maximum of two amplification products per sample. The six published microsatellites and three of the four newly developed markers showed regular segregation in an open-pollinated single tree progeny. Observed heterozygosity (H-o) and expected heterozygosity (H-e) in 48 individuals from one population ranged from 0.436 to 0.917 and from 0.726 to 0.894, respectively. Dominant markers revealed 64 variable positions and moderate genetic variation within the population (H-o = 0.102, Shannon's I = 0.193). Paternity analyses in the program CERVUS at co-dominant markers showed effective dispersal of pollen in the sugar maple population both at 95% and 80% confidence levels. Dependent on the confidence level, the mean pollen dispersal distance within the population ranged from 33.25 m to 38.75 m and gene flow from outside the stand from 78% to 82%. The absence of fine-scale Spatial Genetic Structure (SGS) suggested effective dispersal of both seeds and pollen.