SNP-Based Genetic Analysis of Dimensional Stability and Wood Density in Eucalyptus pellita F.Muell. and Hybrids

Dimensional stability is a key trait for structural wood applications such as flooring, yet its genetic basis in Eucalyptus pellita F.Muell. and its hybrids remain poorly understood. Addressing this gap is essential for improving processing efficiency and product quality through targeted breeding. This study assessed variation in shrinkage and density, their relationships with growth and chemical traits, and associated genetic markers. Wood samples from E. pellita, E. pellita × E. urophylla S.T.Blake, and E. pellita × E. brassiana S.T.Blake were collected from two plantation sites in northern Australia. Radial and tangential shrinkage and density were measured alongside growth and chemical traits. SNP genotyping was conducted to identify markers linked to these physical properties. Significant differences were observed among hybrid types. E. pellita × E. urophylla recorded the lowest tangential unit shrinkage (0.06%), while E. pellita × E. brassiana had the highest basic density (651 kg/m3). Shrinkage and density showed moderate to strong correlations with growth and chemical traits. Several SNPs were associated with these properties; all were located in the intergenic region near Eucgr.A00211. Among these, only one SNP exceeded the −log10(p) significance threshold. These results provide early genetic insights and potential candidate markers for improving wood quality in Eucalyptus breeding programs. This exploratory study, constrained by a small sample size (n = 58), identifies putative SNPs for future validation in broader, multi-environment trials.