Flavonoid Supplementation: a New Method to Improve Eucalyptus Wood

The Eucalyptus genus plays an important role on the worldwide forest industry, with highly productive plantations supplying high-quality raw material for pulp and paper, wood and biomass that would otherwise come from native forests. The flavonoids, naringenin-chalcone and narigenin, are intermediates in phenylpropanoid metabolism in plants, occupying the central position as primary intermediates in flavonoid biosynthesis and are synthesized by chalcone synthase (CHS) and chalcone isomerase (CHI) respectively. It has been reported that supplementation of flavonoids can suppress growth and reduce lignin content in gramineous plants and our group has demonstrated by chemical analyses that flavonoid supplementation reduces extractives content and changes lignin monomeric composition on Eucalyptus grandis x Eucalyptus urophylla (E. urograndis) hybrid trees.

Here we present the complete transcriptome atlas of the previously chemically analyzed E. urograndis trees. RNA was extracted from xylem tissue and Illumina sequencing mRNA libraries prepared for narigenin-chalcone and narigenin supplemented trees on different time sets.

Results demonstrate significant changes on metabolic process, including cell growth, cell division and response to stress with differential gene expression on several important genes, heat shock proteins, dehydrins, sugar transporters and genes from the lignin pathway among them, providing an explanation to the chemical differences reported before and confirming flavonoid supplementation as a new, viable and interesting method for improving Eucalyptus wood quality for its utilization by paper and pulp industry and biomass exploitation.