The traceability of Eucalyptus clones using molecular markers

Abstract

The improvement of Eucalyptus clones plays a crucial role in modern silviculture. This study used a set of 17 microsatellite loci to analyze the genetic diversity and structure of 107 elite clones (80 E. grandis and 27 E. globulus). All clones were cultivated in Uruguay and were sourced from three different providers. Using the fingerprinting technique, an exclusive molecular profile was assigned for each clone, and the genotyping reaction showed differences between the two species. The cumulative probability of identifying two random individuals that share the same genotype (PI) with all 17 loci, was estimated as low for E. grandis (1.18×10-15) and E. globulus (4.03×10-14). The combined PIsibs was (1.05×10-5) and (2.17×10-5) for E. grandis and E. globulus, respectively. A total of 180 alleles were detected for E. grandis and 100 for E. globulus. We found a high mean number of alleles per locus (10 for E. grandis and 6 for E. globulus), and the results for mean polymorphic information content (PIC ) were (0.648) and (0.548), respectively. The observed heterozygosity (Ho ) ranged from 0.216 to 0.838 (mean = 0.509) for E. grandis and 0 to 1 (mean = 0.566) for E. globulus. Two core sets of seven EST-SSR loci were identified for each species. These markers revealed unambiguous fragment amplification, providing a minimum number of SSRs for effective clonal identification. The genetic structure analysis suggests that the germplasm of the E. grandis population is structured in four clusters, while the E. globulus population consists of two clusters.