Tree growth, wood properties and saccharification traits in SwAsp Populus tremula trees grown in Ekebo Sweden

Background Wood represents the majority of the biomass on land and
constitutes a renewable source of biofuels and other bioproducts. However,
wood is recalcitrant to bioconversion, raising a need for feedstock
improvement in production of, for instance, biofuels. We investigated the
properties of wood that affect bioconversion, as well as the underlying
genetics, to help identify superior tree feedstocks for biorefining.
Results We recorded 65 wood-related and growth traits in a population of
113 natural aspen genotypes from Sweden. These traits included three
growth and field performance traits, 20 traits for wood chemical
composition, 17 traits for wood anatomy and structure, and 25 wood
saccharification traits as indicators of bioconversion potential. Glucose
release after saccharification with acidic pretreatment correlated
positively with tree stem height and diameter and the carbohydrate content
of the wood, and negatively with the content of lignin and the
hemicellulose sugar units. Most of these traits displayed extensive
natural variation within the aspen population and high broad-sense
heritability, supporting their potential in genetic improvement of
feedstocks towards improved bioconversion. Finally, a genome wide
association study (GWAS) revealed 13 genetic loci for saccharification
yield (on a whole tree biomass basis), with six of them intersecting with
associations for either height or stem diameter of the trees. Conclusions
The simple growth traits of stem height and diameter were identified as
good predictors of wood saccharification yield in aspen trees. GWAS
elucidated the underlying genetics, revealing putative genetic markers for
bioconversion of bioenergy tree feedstocks.