Genetic Diversity and Structure through Three Cycles of a Eucalyptus urophylla S.T.Blake Breeding Program

• Main Authors: Wanhong Lu, Roger J. Arnold, Lei Zhang, Jianzhong Luo
• Format: Article
• Language: English
• Published: MDPI AG 2018-06-01
• Series: Forests
• Subjects: microsatellite locus; Hardy-Weinberg equilibrium; genetic differentiation; breeding population; artificial selection
• Online Access: http://www.mdpi.com/1999-4907/9/7/372

Eucalyptus urophylla S.T.Blake is an important commercial tropical plantation species worldwide. In China, a breeding program for this species has progressed through three cycles but genetic diversity and structure in the breeding populations are uncertain. A sampling of field trials from these populations was carried out to evaluate their genetic diversity and structure using 16 microsatellite loci. Significant deviations from Hardy-Weinberg equilibrium were recorded at all 16 loci in the populations. Overall expected and observed heterozygosity (He and Ho) estimates of 0.87 and 0.59 respectively for the first cycle population, and 0.88 and 0.60 respectively for the third cycle population, revealed reasonably high levels of genetic diversity. The genetic differentiation coefficient (Fst) revealed low differentiation among pairs of provenances (from the species’ native range) comprising the first cycle population (range: 0.012–0.108), and AMOVA results showed that the majority of molecular genetic variation existed among individuals rather than among provenances for the first cycle population and among individuals rather than among field trial sources in the third cycle population. Levels of genetic diversity appeared to remain unchanged from the first to third cycle populations, and the results indicate prospects for maintaining if not increasing diversity through recurrent breeding. Likely effects of artificial directional selection, prior to sampling, on both populations examined are discussed along with implications for future E. urophylla breeding.