Selection of SSR markers for population studies in Eucalyptus globulus seed orchards

Background Eucalyptus globulus is a widely planted species in temperate regions of the world for pulpwood production. Its good characteristics for kraft pulping in addition to a broad adaptability to different site conditions have led this species to be employed in commercial plantations and to be included in breeding programs [1]. Uruguay has approximately 300.000 hectares forested with E. globulus being the most cultivated species in the country and representing 45% of the total forested area. The main objectives of many Uruguayan breeding programs for E. globulus are the increase of volume per hectare, basic density and pulp yield. The strategies for genetic improvement used in many breeding programs in Uruguay require seed multiplication in seed orchards to obtain genetic gain [2]. In long-term breeding programs, the strict selection of reproductive populations restricts the number of genotypes involved in the final orchard, thus reducing genetic diversity and increasing the risk of depression through inbreeding in the following generations. The use of SSRs (simple sequence repeat) markers as selecting strategies of seed orchards in other species such as Eucalyptus dunni, has proved to be an excellent tool to reduce inbreeding [3,4]. The transferability of SSR markers across Eucalyptus species has been widely studied [5-8]. The aim of this work was to select highly polymorphic SSR markers of E. globulus to assist breeding programs.